Patent Abstract:
A disposable absorbent article comprising a liquid permeable topsheet, a liquid impermeable backsheet, and an absorbent core interposed between the topsheet and the backsheet. The absorbent member is defined by a pulp-less absorbent core having a superabsorbent material providing efficient fluid handling characteristics. The absorbent core may be defined by its fluid handling properties including, but not limited to, greater absorbency rate index (ARI) and greater percentage absorbency rate index (PARI) as compared to absorbent articles of conventional pulp-containing technology.

Full Description:
RELATED APPLICATION  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/640,918, filed Dec. 31, 2004, the entire contents being incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention relates to disposable pulpless absorbent articles including superabsorbent materials which absorb water and aqueous liquids and provide improved properties, in particular faster absorption time, while maintaining acceptable fluid capture and retention properties.  
       BACKGROUND OF THE INVENTION  
       [0003]     For fit, comfort and aesthetic reasons and from environmental aspects, there is an increasing trend to make disposable absorbent articles smaller and thinner. Disposable absorbent articles often contain superabsorbent materials and fiber or fluff to improve liquid handling characteristics of the articles. One may propose that the physical size of such articles could simply be reduced by decreasing the content of the high volume fluff fiber within the articles. However, since fiber acts to quickly, but temporarily, absorb liquid insults prior to capture by the superabsorbent material, a reduction of fiber content may lead to unacceptable fluid handling characteristics, such as liquid leakage, slow liquid capture and gel blocking.  
         [0004]     Superabsorbent refers to a water-swellable, water-insoluble, organic or inorganic material capable of absorbing at least about 10 times its weight and up to about 30 times its weight in an aqueous solution containing 0.9 weight percent sodium chloride solution in water. A superabsorbent polymer is a crosslinked neutralized polymer which is capable of absorbing large amounts of aqueous liquids and body fluids, such as urine or blood, with swelling and the formation of hydrogels, and of retaining them under a certain pressure in accordance with the general definition of superabsorbent. The superabsorbent polymers that are currently commercially available are crosslinked polyacrylic acids or crosslinked starch-acrylic acid graft polymers, in which some of the carboxyl groups are neutralized with sodium hydroxide solution or potassium hydroxide solution. As a result of these characteristic properties, these polymers are chiefly used for incorporation into sanitary articles, such as babies&#39; diapers, incontinence products and sanitary towels.  
         [0005]     In future absorbent article constructions, it is expected that there will be less fiber material, or potentially none at all. The superabsorbent polymer of future diaper constructions must have a sufficiently high absorption rate to maximize the use of available capillary spaces and to compensate for the reduction or substantial elimination of typically fast absorbing fibers.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention is directed to disposable pulpless absorbent articles including superabsorbent materials which absorb water and aqueous liquids and provide improved properties, in particular faster absorption time while maintaining acceptable fluid retention properties. To offset a reduction in fiber levels an improved superabsorbent material may be necessary in order to provide acceptable fluid handling characteristics, such as equivalent total retention capacity of body fluids, etc.  
         [0007]     Disposable absorbent articles according to the present invention have higher centrifugal retention capacity (CRC) values, higher absorbency rate index (ARI) values and/or higher percentage absorbency rate index (PARI) as compared to products manufactured with existing pulp-containing technologies.  
         [0008]     It is therefore an object of the present invention to provide a disposable absorbent article having a superabsorbent composition with an increased rate of liquid absorption, particularly within the targeted insult region. It is another object is to maintain acceptable liquid handling properties and liquid retention characteristics even when the fiber content is reduced or eliminated and the amount of superabsorbent material is increased in percent by weight based on the absorbent structure. This may be achieved by increasing the absorption rate of the superabsorbent polymer. Additionally, the selective placement of superabsorbent material within the absorbent core may yield benefits.  
         [0009]     Absorbent articles according to the present invention contain minimal or no fluff material in order to address the increasing trend to make sanitary articles smaller and thinner. To offset a reduction in fiber levels an improved superabsorbent material may be used to provide acceptable fluid handling characteristics, such as equivalent total retention capacity of body fluids.  
         [0010]     The present invention is also directed to a method of manufacturing a pulpless disposable absorbent article having acceptable or better fluid handling capabilities as compared disposable absorbent articles containing fiber or fluff. These and other objects of the invention will be more readily apparent when considered in reference to the following description and when taken in conjunction with the accompanying drawings.  
         [0011]     Still other embodiments of the inventive disposable article and their manufacturing methods will become readily apparent to those skilled in the relevant art from the following detailed description of the drawings, wherein the various embodiments of the invention are described by way of illustrating the best mode contemplated for carrying out the invention. The invention is capable of other and different embodiments, its several details are capable of modification and its several structural or processed details are capable of modification in various and obvious respects, all without departing from the spirit and the scope of the present invention. Accordingly, the following drawings and detailed description of the drawings are to be regarded as illustrative in nature and not restrictive. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The present invention will be more fully understood and further advantages will become apparent when reference is made to the following detailed description of the invention and the accompanying drawings wherein like numerals represent like elements, and in which:  
         [0013]      FIG. 1  representatively shows a perspective view of an a disposable absorbent article of the present invention.  
         [0014]      FIG. 2  depicts a top plan view of disposable absorbent article.  
         [0015]      FIG. 3  depicts a top plan view of the disposable absorbent article of  FIG. 2 .  
         [0016]      FIG. 4  depicts top plan views of forms of disposable absorbent articles suitable for application of the present invention.  
         [0017]      FIG. 5  is a graphical representation of the CRC values over time for the various samples of Table 1.  
         [0018]      FIG. 6  is a graphical representation of the CRC values in percentage form for the various samples of Table 1. 
     
    
     DETAILED DESCRIPTION  
       [0019]     The present invention concerns a disposable absorbent article having an absorbent core structure used to absorb and retain liquids, such as urine or blood. The absorbent core structure is typically, or forms typically part of, a disposable absorbent article, such as preferably diaper and training pants, sanitary napkins, panty liners, and adult incontinence products.  
         [0020]     The absorbent core structure forms part of a disposable absorbent article which is adapted to be worn adjacent to the body of a wearer to absorb and contain various exudates discharged from the body. The absorbent article may be configured to closely conform to the body of the wearer to assist in effective containment of body exudates.  
         [0021]     In one embodiment, an absorbent article of the present invention will be described in terms of a disposable diaper which is adapted to be worn about the lower torso of a child. It is understood that the articles and methods of the present invention are equally adaptable for other types of absorbent articles, such as adult incontinent products, training pants, feminine hygiene products, other personal care or health care garments, and the like.  
         [0022]      FIG. 1  representatively shows one example of a disposable absorbent article generally indicated at  10  and incorporating aspects of the present invention.  FIG. 1  illustrates a diaper in a perspective view as worn by a user.  
         [0023]     The illustrated diaper  10  includes a body  12  which generally defines a front waist region  14 , a rear waist region  16 , and a crotch region  18  which extends between and connects the front and rear waist regions  14  and  16 . The body  12  further defines a pair of laterally opposed side edges  20 , a pair of longitudinally opposed waist edges  22 , an interior body facing surface  24  which is configured to contact the wearer, an outer garment facing surface  26  opposite the interior surface  24  which is configured to contact the wearer&#39;s clothing in use. The outer surface  26  may be defined by an outer cover layer  34  and the interior surface  24  may be defined by a body side liner  36 . Diaper  10  includes an absorbent core  38  which may be located between the outer cover  34  and the body side liner  36 .  
         [0024]     The front waist region  14  comprises the portion of the diaper  10  which, when worn, is positioned on the front of the wearer while the rear waist region  16  comprises the portion of the diaper  10  which, when worn, is positioned on the back of the wearer. The crotch region  18  comprises the portion of the diaper  10  which, when worn, is positioned between the legs of the wearer and covers the lower torso of the wearer. The laterally opposed side edges  20  of the diaper  10  generally define portions of the leg openings. The waist edges  22  of the absorbent body  12  of the diaper  10  are configured to encircle the waist of the wearer when worn and provide a waist opening when fastened that defines a waist perimeter dimension.  
         [0025]     The disposable absorbent article according to the present invention provides a close fitting seal around the thighs of the user, thereby significantly improving its leakage prevention capability. The close fitting seal of the inventive garment is at least partially provided through addition of fastening element  40 . The fastening element  40  may include known adhesive elements or hook fastening devices. A hook fastening element may be selected so as to be engageable with the loops formed on the surface of a nonwoven fabric. Thus, the nonwoven material of the stretchband panel provides the loop element of a hook and loop fastening system similar to those generally known in the art. In further embodiments, a loop landing tape may be located near the front waist region of the outside face of the inventive article, and a pair of hook fastening elements may be located near the rear waist region. The loop landing tape may be constructed from a knitted, extruded, or non-woven material, as is generally known in the art. A variety of fastener systems and devices are known to those of ordinary skill in the art. A particular fastener choice would not otherwise alter the scope of the appended claims.  
         [0026]     The diaper  10  may further include leg elastics, containment flaps, and waist elastics as are known to those skilled in the art. For example, the absorbent body  12  of the disposable diaper  10  may include a pair of containment flaps which are configured to provide a barrier to the lateral flow of exudates. The containment flaps may be located along the laterally opposed side edges  20  of the absorbent body  12 .  
         [0027]     The disposable diaper  10  may further optionally include elastics at the waist edge  22  of the diaper  10  to further prevent leakage of body exudates. For example, the disposable diaper may further comprise elastic waist features that help provide improved fit and containment of body exudates.  
         [0028]     A diaper  10  according to the present invention may also include a pair of leg elastic members which are connected to the laterally opposed side edges  20  in the crotch region  18  of the diaper  10 . The leg elastics are generally adapted to fit about the legs of a wearer in use to maintain a positive, contacting relationship with the wearer to effectively reduce or eliminate the leakage of body exudates from the diaper  10 . Materials suitable for use as the leg elastics and waist elastic are well known to those skilled in the art. Exemplary of such materials are sheets or strands or ribbons of a polymeric, elastomeric material which are adhered to the outer cover  34  in a stretched position, or which are attached to the outer cover  34  while the outer cover is pleated, such that elastic constrictive forces are imparted to the outer cover  34 . The leg elastics may also include such materials as polyurethane, synthetic and natural rubber. Leg elastics, containment flaps and waist elastics may include elastic foam materials, elastic films (apertured, woven and non-woven, for example), elastic scrim material, elastic non-woven materials, elastic composites, and selectively activated elastic materials.  
         [0029]     The diaper  10  may be of various suitable shapes. For example, in the unfastened configuration, the diaper may have an overall rectangular shape, T-shape or an approximately hourglass shape. The various aspects and configurations of the invention can provide distinctive combinations of softness, body conformity, reduced red-marking of the wearer&#39;s skin, reduced skin hydration, improved containment of body exudates and improved aesthetics.  
         [0030]     The various components of the diaper  10  may be integrally assembled together employing various types of suitable attachment means, such as adhesive, sonic and thermal bonds or combinations thereof. In the illustrated shown embodiments, for example, the outer cover  34  and body side liner  36  are joined to each other. Similarly, other diaper components, such as the leg elastics and primary fasteners, may be assembled into the diaper  10  by employing the above-identified attachment mechanisms. Desirably, the majority of the diaper components are assembled together using ultrasonic bonding techniques for reduced manufacturing cost and improved performance.  
         [0031]     The outer cover  34  of the diaper  10  may suitably be composed of a material which is either liquid permeable or liquid impermeable. It is generally preferred that the outer cover  34  be formed from a material that is substantially impermeable to liquids. A typical outer cover can be manufactured from a thin plastic film or other flexible liquid-impermeable material. For example, the outer cover  34  may be formed from a polyethylene film. If it is desired to present the outer cover  34  with a more cloth-like feeling, the outer cover  34  may comprise a polyolefin film having a nonwoven web laminated to the outer surface thereof, such as a spunbond web of polyolefin fibers. For example, a stretch-thinned polypropylene film may have thermally laminated thereto a spunbond web of polypropylene fibers. Methods of forming such cloth-like outer covers are known to those skilled in the art.  
         [0032]     Further, the outer cover  34  may be formed of a woven or nonwoven fibrous web layer which has been totally or partially constructed or treated to impart a desired level of liquid impermeability to selected regions that are adjacent or proximate the absorbent core  38 . Still further, the outer cover  34  may optionally be composed of a micro-porous “breathable” material which permits vapors to escape from the absorbent core  38  while still preventing liquid exudates from passing through the outer cover  34 . For example, the outer cover  34  may comprise a stretched microporous polyolefin film having a nonwoven web laminated to the outer surface thereof, such as a spunbond web of polyolefin fibers. The outer cover  34  can also be embossed or otherwise provided with a matte finish to provide a more aesthetically pleasing appearance.  
         [0033]     The bodyside liner  36  suitably presents a bodyfacing surface which is compliant, soft feeling, and nonirritating to the wearer&#39;s skin. Further, the bodyside liner  36  may be less hydrophilic than the absorbent core  38 , to present a relatively dry surface to the wearer, and may be sufficiently porous to be liquid permeable, permitting liquid to readily penetrate through its thickness. A suitable bodyside liner  36  may be manufactured from a wide selection of web materials, such as porous foams, reticulated foams, apertured plastic films, natural fibers (for example, wood or cotton fibers), synthetic fibers (for example, polyester or polypropylene fibers), or a combination of natural and synthetic fibers. The bodyside liner  36  is suitably employed to help isolate the wearer&#39;s skin from liquids held in the absorbent core  38 .  
         [0034]     Various woven and nonwoven fabrics can be used for the bodyside liner  36 . For example, the bodyside liner maybe composed of a meltblown or spunbonded web of polyolefin fibers. The bodyside liner may also be a bonded-carded web composed of natural and/or synthetic fibers. The bodyside liner may be composed of a substantially hydrophobic material, and the hydrophobic material may, optionally, be treated with a surfactant or otherwise processed to impart a desired level of wettability and hydrophilicity. The bodyside liner  36  may further include a lotion or treatment applied thereto to which is configured to treat or be transferred to the wearer&#39;s skin.  
         [0035]     The absorbent core  38  of the diaper  10  contains particles of a high-absorbency material commonly known as superabsorbent material. In a particular embodiment, the absorbent core  38  comprises superabsorbent hydrogel-forming particles. The superabsorbent particles may be selectively placed into desired zones of the absorbent core  38  to better contain and absorb body exudates. The concentration of the superabsorbent particles may also vary through the thickness of the absorbent core  38 . Alternatively, the absorbent core  38  may comprise a laminate of fibrous webs and superabsorbent material or other suitable means of maintaining a superabsorbent material in a localized area.  
         [0036]     The high-absorbency material can be selected from natural, synthetic, and modified natural polymers and materials. The high-absorbency materials can be inorganic materials, such as silica gels, or organic compounds, such as crosslinked polymers. The term “crosslinked” refers to any means for effectively rendering normally water-soluble materials substantially water insoluble but swellable. Such means can include, for example, physical entanglement, crystalline domains, covalent bonds, ionic complexes and associations, hydrophilic associations such as hydrogen bonding, and hydrophobic associations or Van der Waals forces.  
         [0037]     Examples of synthetic, polymeric, high-absorbency materials include the alkali metal and ammonium salts of poly(acrylic acid) and poly(methacrylic acid), poly(acrylamides), poly(vinyl ethers), maleic anhydride copolymers with vinyl ethers and alpha-olefins, poly(vinyl pyrolidone), poly(vinyl morpholinone), poly(vinyl alcohol), and mixtures and copolymers thereof. Further polymers suitable for use in the absorbent core include natural and modified natural polymers, such as hydrolyzed acrylonitrile-grafted starch, acrylic acid grafted starch, methyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, and the natural gums, such as alginates, xanthum gum, locust bean gum, and the like. Mixtures of natural and wholly or partially synthetic absorbent polymers can also be useful in the present invention. Such high-absorbency materials are well known to those skilled in the art and are widely commercially available.  
         [0038]     The high absorbency material may be in any of a wide variety of geometric forms. As a general rule, it is preferred that the high absorbency material be in the form of discrete particles. However, the high absorbency material may also be in the form of fibers, flakes, rods, spheres, needles, or the like. As a general rule, the high absorbency material is present in the absorbent body in an amount of from about 85 to about 100 weight percent based on total weight of the absorbent core  38 .  
         [0039]     One superabsorbent material suitable for use in an embodiment of the present invention has a vortex time of approximately 30 seconds. Alternative superabsorbent materials having similar or higher vortex times may also be practicable. A range of vortex times for superabsorbent materials which may used to practice the present invention is between 10 and 120 seconds.  
         [0040]     The superabsorbent material may be selectively placed within the absorbent core  38  so that more material is within the target zone or portions thereof as compared to portions of the core  38  outside of the target zone. Additionally, the amount of superabsorbent material or even the composition of a superabsorbent material may vary depending on the particular zone or portion of the core  38 .  
         [0041]     The absorbent core  38  may have any of a number of shapes. For example, the absorbent core may be rectangular, I-shaped, or T-shaped. In the embodiment of  FIG. 1 , the absorbent core is generally rectangular in shape. The size and the absorbent capacity of the absorbent core  38  should be compatible with the size of the intended wearer and the liquid loading imparted by the intended use of the absorbent article.  
         [0042]      FIG. 2  illustrates a disposable absorbent article  10  including an absorbent core  38  divided into ten generally equally spaced sections or zones numbered one through ten.  FIG. 3  discloses the target region of the article  10  defined between approximately Zone 2 through Zone 7. In this example, the target region of the absorbent article is generally defined as the portion between the 10% to 80% dimensions as measured from the front edge  44  of the absorbent core  38 . The absorbent article  10  of  FIG. 3  is a general representation of an absorbent article and alternative sizes, shapes and features would be appreciated by those of ordinary skill in the art. For example, the side edges of an alternative embodiment of an absorbent article according to the present invention may be concave or otherwise non-linearly configured.  
         [0043]      FIG. 4  illustrates various alternative embodiments of absorbent articles  10  and depicts target zones for these embodiments. As illustrated, the target regions of the products may be defined as a portion of the overall absorbent core  38  or even as the entire absorbent core  38  (as shown in adult incontinence pad  46 ). The insult target region is the primary region receiving liquid or fecal insults during product use. The target insult region may be defined, as shown in  FIGS. 2 and 3 , to include multiple zones of the absorbent core  38 .  
         [0044]     Table 1 includes Centrifugal Retention Capacity (CRC) data of various current absorbent products and a preferred embodiment of the present invention, referred to as “Working Product T3CM”. Less preferred embodiments utilizing aspects of the present invention are referred to as Experimental Products A and B. Referring again to  FIG. 2 , the CRC data was compiled for various size  4  (10 kg-17 kg) diapers divided into ten equal length zones. The CRC was measured at 0.5, 1, 2, 4 and 30 minutes.  
         [0045]     The CRC data of Table 1 was collected by experimentation according to the following test protocol.  
         [0046]     Zoned Centrifuge Retention Capacity Test  
         [0047]     Equipment and materials:  
         [0048]     1. Large plastic tray  
         [0049]     2. Hanging apparatus with clips  
         [0050]     3. Plastic weighing pans  
         [0051]     4. Measuring rule  
         [0052]     5. Fine tip, permanent marker pen  
         [0053]     6. Scissors  
         [0054]     7. Timer  
         [0055]     8. 0.9% saline solution  
         [0056]     9. Electronic top loading scale accurate to 0.01 gm.  
         [0057]     10. Centrifuge (1400 rpm) with drain  
         [0058]     Procedure 
        1. Position the plastic tray under the hanging apparatus. Fill with an excess amount of 0.9% saline solution.     2. Weigh 14 diapers and record the weight of each diaper as WI.     3. Measure the length of the core of each diaper and divide into 10 sections of equal length. Using a permanent, fine tip marker pen, draw a line marking the longitudinal edge of each of the 10 sections.     4. Starting from the front of the diaper number the sections 1 through to 10, with 10 being the rearmost section.     5. Take two of the weighed and marked diapers and immerse in the saline solution for 30 seconds. Ensure that during this time the diapers are fully immersed.     6. After the allotted time, remove the diapers from the saline solution and immediately transfer to the centrifuge, placing the diapers in the centrifuge with the nonwoven against the centrifuge wall. Start the centrifuge and spin for 3 minutes.     7. Remove the diapers from the centrifuge, place the diapers in the tared weighing pans and record each weight as WF.     8. With the scissors carefully cut along the lines separating each of the ten sections of the diaper. Weigh each divided section of the diaper, gathering up any pieces of core material that may have dropped out of each section during cutting and including in these in the weight measurement. Record the weight of each section as Sn, where n is the section number.     9. Repeat steps 5 to 8 but successively increase the immersion time to 1 minute, 2 minutes, 4 minutes, 10 minutes and 30 minutes.     10. Finally, take two weighed, diapers and divide into the marked sections. Weigh each section to record the dry, unswollen weight of each section as Dn.     11. Perform calculations: 
 
Overall centrifuge retention capacity  CRC=WF−WI  
 
Retention capacity per section at time  t=Sn−Dn  
       
 
         [0070]    
       
         
               
             
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                   
               
               
                 Core profile and CRF absorbency rate per zone 
               
             
          
           
               
                   
                 Immersion 
                 CRC 
                 FRONT           Centrifuge Retention Capacity per section (g) → REAR 
               
             
          
           
               
                 Product 
                 Time (min) 
                 (g) 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
                 9 
                 10 
               
               
                   
               
             
          
           
               
                 Experimental 
                 0.5 
                 67 
                 4.7 
                 7.8 
                 7.6 
                 8.2 
                 7.8 
                 7.6 
                 7.6 
                 4.5 
                 4.5 
                 3.6 
               
               
                 product A 
                 1 
                 82 
                 6.5 
                 9.7 
                 9.4 
                 9.3 
                 9.7 
                 9.8 
                 8.6 
                 5.6 
                 5.4 
                 4.1 
               
               
                   
                 2 
                 109 
                 8.2 
                 11.4 
                 12.8 
                 14.0 
                 12.7 
                 13.2 
                 11.8 
                 8.5 
                 7.2 
                 5.5 
               
               
                   
                 4 
                 216 
                 18.1 
                 22.6 
                 23.3 
                 24.4 
                 26.0 
                 24.0 
                 22.6 
                 19.8 
                 18.7 
                 13.0 
               
               
                   
                 30 
                 538 
                 55.6 
                 70.2 
                 72.7 
                 70.0 
                 62.3 
                 56.6 
                 50.8 
                 32.1 
                 42.3 
                 23.0 
               
               
                 Pampers 
                 0.5 
                 83 
                 9.6 
                 9.1 
                 9.5 
                 10.8 
                 11.3 
                 7.7 
                 5.7 
                 5.8 
                 5.7 
                 6 
               
               
                 Baby Dry 
                 1 
                 116 
                 12.9 
                 15.7 
                 14.4 
                 16.2 
                 12.6 
                 12.7 
                 7.7 
                 7.4 
                 8.5 
                 8 
               
               
                 (10-17 kg) 
                 2 
                 111 
                 12.3 
                 12.9 
                 12.9 
                 14.3 
                 14.3 
                 12.4 
                 6.7 
                 7.1 
                 8.2 
                 8.1 
               
               
                   
                 4 
                 152 
                 15.5 
                 20.8 
                 20.6 
                 15.8 
                 21.9 
                 18 
                 11.3 
                 9.5 
                 8.9 
                 8.7 
               
               
                   
                 30 
                 281 
                 33.2 
                 36.6 
                 37.9 
                 36 
                 33.7 
                 29.5 
                 22.5 
                 12.4 
                 16.2 
                 21.2 
               
               
                 Luvs - Ultra 
                 0.5 
                 91 
                 7.8 
                 10.7 
                 8.2 
                 10.7 
                 11.2 
                 11.4 
                 9.3 
                 7.2 
                 7.3 
                 6 
               
               
                 Leakguard 
                 1 
                 103 
                 9.2 
                 10.5 
                 12.8 
                 12.9 
                 10.6 
                 11 
                 9.5 
                 8.8 
                 7.7 
                 7.8 
               
               
                 (10-17 kg) 
                 2 
                 125 
                 8.5 
                 13.6 
                 14.3 
                 15.4 
                 13.2 
                 15.4 
                 14 
                 10.3 
                 9.1 
                 9.8 
               
               
                   
                 4 
                 158 
                 15.3 
                 16.4 
                 17.7 
                 24.5 
                 16.4 
                 21.3 
                 15 
                 9.4 
                 11.3 
                 8.6 
               
               
                   
                 30 
                 265 
                 20.4 
                 23.8 
                 28.1 
                 31.1 
                 26.9 
                 24.1 
                 29.4 
                 20.4 
                 27.7 
                 30.3 
               
               
                 Huggies 
                 0.5 
                 125 
                 11.1 
                 13.2 
                 14.9 
                 12.8 
                 12.3 
                 15.9 
                 12.8 
                 11.3 
                 10.3 
                 9.4 
               
               
                 Baby 
                 1 
                 146 
                 11.1 
                 16.8 
                 15.5 
                 14.3 
                 15.5 
                 16.5 
                 17.2 
                 13.4 
                 13.3 
                 10.7 
               
               
                 Shaped 
                 2 
                 187 
                 16 
                 21.4 
                 20.6 
                 18.8 
                 18.4 
                 20.6 
                 21.2 
                 16.4 
                 17.8 
                 14 
               
               
                 (10-17 kg) 
                 4 
                 234 
                 18.6 
                 28 
                 30.7 
                 29.2 
                 22.1 
                 28 
                 22.5 
                 18.3 
                 19.2 
                 16.8 
               
               
                   
                 30 
                 266 
                 20.5 
                 32.9 
                 33.5 
                 33.4 
                 25 
                 29.8 
                 28.4 
                 24 
                 19.9 
                 16.7 
               
               
                 White 
                 0.5 
                 127 
                 12.1 
                 16 
                 14.4 
                 14.1 
                 12.2 
                 14.8 
                 13.4 
                 10.2 
                 9.3 
                 9.5 
               
               
                 Cloud 
                 1 
                 160 
                 14.7 
                 17.2 
                 20.1 
                 20.5 
                 19.2 
                 17.3 
                 13.8 
                 11.1 
                 11.8 
                 12.8 
               
               
                 Diaper (10-17 kg) 
                 2 
                 188 
                 17.6 
                 16.9 
                 19.2 
                 20.6 
                 22.7 
                 19 
                 18.4 
                 15.1 
                 17.7 
                 18.9 
               
               
                   
                 4 
                 208 
                 22.3 
                 21.6 
                 24.8 
                 23.1 
                 20.3 
                 20.5 
                 20.9 
                 15.8 
                 16.7 
                 19.6 
               
               
                   
                 30 
                 330 
                 35.3 
                 35.8 
                 39.9 
                 35.7 
                 36.5 
                 36.5 
                 27.4 
                 26.4 
                 24.9 
                 27.2 
               
               
                 Experimental 
                 0.5 
                 191 
                 19.1 
                 19.1 
                 19.1 
                 19.1 
                 19.1 
                 19.1 
                 19.1 
                 19.1 
                 19.1 
                 19.1 
               
               
                 product B 
                 1 
                 251 
                 25.1 
                 25.1 
                 25.1 
                 25.1 
                 25.1 
                 25.1 
                 25.1 
                 25.1 
                 25.1 
                 25.1 
               
               
                   
                 2 
                 294 
                 29.4 
                 29.4 
                 29.4 
                 29.4 
                 29.4 
                 29.4 
                 29.4 
                 29.4 
                 29.4 
                 29.4 
               
               
                   
                 4 
                 350 
                 35.0 
                 35.0 
                 35.0 
                 35.0 
                 35.0 
                 35.0 
                 35.0 
                 35.0 
                 35.0 
                 35.0 
               
               
                   
                 30 
                 420 
                 42.0 
                 42.0 
                 42.0 
                 42.0 
                 42.0 
                 42.0 
                 42.0 
                 42.0 
                 42.0 
                 42.0 
               
               
                 Working 
                 0.5 
                 190 
                 11.7 
                 22.9 
                 24.2 
                 24.3 
                 24.3 
                 25.6 
                 22.6 
                 13.3 
                 12.4 
                 6.9 
               
               
                 product 
                 1 
                 232 
                 14.3 
                 28.4 
                 28.9 
                 30.7 
                 29.3 
                 30.6 
                 28.2 
                 15.4 
                 15.5 
                 9.0 
               
               
                 T3CM 
                 2 
                 308 
                 17.1 
                 35.7 
                 39.9 
                 39.1 
                 40.2 
                 40.1 
                 36.5 
                 22.4 
                 20.2 
                 18.1 
               
               
                   
                 4 
                 374 
                 23.9 
                 40.8 
                 48.8 
                 48.5 
                 48.2 
                 47.4 
                 43.1 
                 24.8 
                 32.4 
                 14.5 
               
               
                   
                 30 
                 483 
                 46.4 
                 52.7 
                 59.9 
                 62.7 
                 54.9 
                 57.3 
                 54.0 
                 39.4 
                 43.4 
                 14.4 
               
               
                   
               
             
          
         
       
     
         [0071]     Table 1 illustrates that Working Product T3CM had substantially greater CRC values for each zone as compared to currently available diapers. For example, the CRC value for zone 5 of the Working Product T3CM was 54.9 grams at 30 minutes while the CRC values of zone 5 of the Pampers Baby Dry, Luvs—Ultra Leakguard and Huggies Baby Shaped products were 33.7 grams, 26.9 grams and 25 grams, respectively.  
         [0072]     It was determined through consumer use testing that a pulpless product (Experimental Products A &amp; B) that has similar CRC values as current fluff/SAP products would have an insufficient lock up rate. The performance of the Working Product T3CM is achieved through selective zoning and use of a rapid vortex rate SAP.  
         [0073]     One skilled in the art would recognize that a superabsorbent material with a fast vortex rate (less than 40 sec.) used in a conventional fluff/SAP core will lead to gel blocking and premature product failure. Whereas in the Working Product T3CM a fast vortex rate SAP yields acceptable performance without gel blocking.  
         [0074]     Each of currently available products of Table 1 includes conventional pulp fibers acts (which act as temporary reservoirs to capture liquid prior to absorption by the superabsorbent material). In comparison, products according to the present invention are pulpless.  
         [0075]     In another aspect of the invention, the absorbent core by weight contains between 0% to 15% pulp, 55% to 100% superabsorbent, 0% to 45% adhesive or binder or other additive, 0% to 45% nonwoven. A more preferred range of pulp is between 0% and 10% and a yet more preferred range of pulp is between 0% and 5%. As used herein, the term “pulpless absorbent core” is defined to mean an absorbent core having less than approximately 15% pulp. Pulp can include hydrophilic fibers such as: cellulose fibers, for example, mechanical pulp, chemical pulp, semichemical pulp, digested pulp, as obtained from wood; and artificial cellulose fibers, for example, rayon, acetates. Among the above-exemplified fibers, cellulose fibers are widely preferred in existing products. In addition, the hydrophilic fibers may comprise synthetic fibers such as polyamides, polyesters, and polyolefins. Pulp is not limited to the above-exemplified hydrophilic fibers.  
         [0076]     Table 2 provides Absorbency Rate Index values for the tested product samples of Table 1. The Absorbency Rate Index (ARI) is defined as:  
         [0077]     ARI (zone 2 to 7)=Sum of CRC (zone 2 to 7 at 0.5, 1, 2 and 4 minutes)  
         [0078]     For example, the ARI of the Pampers Baby Dry product is the sum of: 54, 79, 74 and 108, or 315. In comparison the ARI of the Working Product T3CM is 828 (144+176+231+277). Table 2 provides minimum ARI values for a Target Desired Rate (720), a more preferred desired rate (756), and a yet more preferred desired rate (815).  
                                                                                                           TABLE 2                           Core absorbency rate in Zone 2 to 7 (Sum of Zone 2 to 7 CRC)                                                    Even               Pampers   Luvs - Ultra   Huggies                   More   more           Ex-   Baby Dry   Leakguard   Baby   White Cloud       Working   Target   desired   desired           perimental   (10-17 kg)   (10-17 kg)   Shaped    Diaper   Experimental   product   desired   rate or   rate or           product A   (US)   (US)   (10-17 kg)   (10-17 kg)   product B   T3CM   rate   higher   higher                        Immersion                                               time (min)        0.5   47   54   62   82   85   115   144   135   138.6   150        1   57   79   67   96   108   151   176   150   159.6   180        2   76   74   86   121   117   176   231   195   205.8   225        4   143   108   111   161   131   210   277   240   252.0   260       30   383   196   163   183   212   252   341   320   325.0   330       Absorbency       Rate Index       0 to 4 min   322   315   326   459   441   652   828   720   756   815                  
 
         [0079]     Table 3 provides comparison between a significantly larger diaper (15-18 kg) and the minimum ARI values for a Target Desired Rate (720), a more preferred desired rate (756), and a yet more preferred desired rate (815). Table 3 illustrates that a pulpless absorbent article according the present invention has an ARI value that is greater than the ARI of a substantially larger product, i.e., White Cloud Training Pant (15-18 kg).  
                                                           TABLE 3                           Core absorbency rate in Zone 2 to 7 (Sum of Zone 2 to 7 CRC)                White Cloud   Target       Even more           Training Pants   desired   More desired   desired           (15-18 kg)   rate   rate or higher   rate or higher                        Immersion                       time (min)       0.5   139   135   138.6   150       1   150   150   159.6   180       2   196   195   205.8   225       4   205   240   252.0   260       30   293   320   325.0   330       Absorbency       Rate Index       0 to 4 min   690   720   756   815                  
 
         [0080]     One important aspect of the present invention is the realization that the ARI of a pulpless product must be significantly greater than ARI values of prior absorbent articles which incorporated pulp within an absorbent core. For the conventional fluff/SAP core, additional, though temporary, fluid capacity is provided by the fluff. Whereas in a pulpless core, fluid capacity is achieved solely through the SAP material and not through the fluid capacity of the fluff, i.e., there is little or no temporary fluid storage for a pulpless core. Since a pulpless absorbent core may not effectively wick liquid, the insult target region absorbency rate of an article according to the present invention must be sufficient high in order to prevent premature leakage.  
         [0081]     Zones 2 to 7 effectively define the target insult region of the typical absorbent article in diaper form. Since a pulpless absorbent does not effectively wick fluid, the absorbent product&#39;s target region absorbency rate must be sufficient high to prevent premature leakage. Table 2 shows that current conventional diapers all have substantially lower target zone CRC values than a product according to the present invention, e.g., Working Product T3CM. In a preferred embodiment, a pulpless absorbent article according to the present invention provides an ARI value of 700 grains or greater in order to prevent premature leakage.  
         [0082]     Table 4 provides core absorbency rate data expressed in percentage form. For each sample, a percentage of absorbency at time intervals of 0.5, 1, 2 and 4 minutes was obtained by dividing the amount absorbed at a given time interval by the total amount absorbed at 30 minutes. For example, the core absorbency rate data expressed in percentage form for the Working Product T3CM at 0.5 minutes was calculated by dividing 144 (from Table 2) by 483 (from Table 1), or 30%. Continuing with this example, the core absorbency rate data expressed in percentage form at 4 minutes was calculated by dividing 277 (Table 2) by 483 (Table 1), or 57%.  
         [0083]     Table 4 also contains the Percentage Absorbency Rate Index (PARI) from 0 to 4 minutes for the various samples where PARI is defined as the following;  
         [0084]     PARI (zone 2 to 7)=Sum of percentage CRC (zone 2 to 7) at 0.5, 1, 2 and 4 minutes. For example, the PARI value of the Working Product T3CM is calculated as follows: PARI=30+36+48+57=171%.  
         [0085]     Table 4 also discloses targeted preferred ARI and PARI values for embodiments of the present invention. As suggested by Table 4, a pulpless absorbent product according to the present invention would preferably have a PARI value of approximately 170% or greater in order to prevent premature leakage.  
                                                                                                           TABLE 4                           Core absorbency rate in Zone 2 to 7 (Sum of Zone 2 to 7 CRC) expressed as a percentage of total       absorbency                                                    Even                   Luvs -   Huggies   White               More   more           Ex-   Pampers   Ultra   Baby   Cloud       Working   Target   desired   desired           perimental   Baby Dry   Leakguard   Shaped   Diaper   Experimental   product   desired   rate or   rate or           product A   (10-17 kg)   (10-17 kg)   (10-17 kg)   (10-17 kg)   product B   T3CM   rate   higher   higher                        Immersion                                               time (min)        0.5    9%   19%   23%   31%   26%   27%   30%   32.1%   33.0%   35.7%        1   11%   28%   25%   36%   33%   36%   36%   35.7%   38.0%   42.9%        2   14%   26%   32%   45%   35%   42%   48%   46.4%   49.0%   53.6%        4   27%   38%   42%   61%   40%   50%   57%   57.1%   60.0%   61.9%       30   71%   70%   62%   69%   64%   60%   71%   76.2%   77.0%   78.6%       Absorbency       Rate Index       0 to 4 min   60%   112%    123%    173%    134%    155%    171%    171.4%   180.0%   194.0%                  
 
         [0086]    
       
         
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                   
               
               
                 Free Swell absorption rate of entire product (zones 1-10) 
               
               
                 Free Swell Capacity (g/diaper) 
               
             
          
           
               
                 Product: 
                   
                 Pampers 
                 Luvs - Ultra 
                   
                   
                   
                   
               
               
                 Immersion 
                 Experimental 
                 Baby Dry 
                 Leakguard 
                 Huggies Baby 
                 White Cloud 
                 Experimental 
                 Working 
               
               
                 time (min) 
                 product A 
                 (10-17 kg) 
                 (10-17 kg) 
                 Shaped (US) 
                 Diaper (10-17 kg) 
                 product B 
                 product T3CM 
               
               
                   
               
             
          
           
               
                 0.5 
                 118 
                 382 
                 451 
                 411 
                 343 
                 152 
                 295 
               
               
                 1 
                 142 
                 445 
                 523 
                 426 
                 409 
                 207 
                 401 
               
               
                 2 
                 194 
                 482 
                 615 
                 467 
                 495 
                 287 
                 532 
               
               
                 4 
                 372 
                 510 
                 659 
                 567 
                 553 
                 358 
                 631 
               
               
                 30 
                 681 
                 556 
                 845 
                 768 
                 734 
                 549 
                 773 
               
               
                   
               
             
          
         
       
     
         [0087]     Table 5 provides free swell absorption rate data for the investigated products of Table 1. Table 5 shows that the Working Product T3CM has an free swell which offers comparable performance to currently available products. Even though the Experimental Products A and B have similar free swell capacity as compared to conventional fluff/SAP products, Products A and B failed to provide acceptable performance as indicated in consumer use testing.  
         [0088]      FIG. 5  is a graphical representation of the CRC values over time for the various samples of Table 1.  FIG. 4  also illustrates targeted desired rates for embodiments of the present invention.  
         [0089]      FIG. 6  is a graphical representation of the CRC values in percentage form for the various samples of Table 1.  FIG. 5  also illustrates targeted desired rates for embodiments of the present invention.  
         [0090]     Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Technology Classification (CPC): 0