Patent Publication Number: US-2002007168-A1

Title: Breathable disposable absorbent articles

Description:
FIELD OF THE INVENTION  
       [0001] This invention relates to disposable absorbent articles such as diapers, briefs, pants, incontinent garments and the like, and it is particularly related to such articles which exhibit breathability, and are therefore commonly referred to in the art as “breathable” absorbent articles.  
       BACKGROUND OF THE INVENTION  
       [0002] Disposable absorbent articles such as disposable baby diapers and adult incontinent briefs, underpants, guards and the like articles are widely used in the homes and in various health care facilities and institutions. Indeed the use of such articles has become a sanitary practice, and while initially such absorbent articles were used mostly for baby care, more recently their use has been expanded for adults as well. In both instances, the absorbent article must be designed to effectively prevent leakage of urine and other fecal materials, while insuring body fit and comfort.  
       [0003] Present commercially available absorbent articles are generally unitary in structure, pre-shaped and pre-folded and comprise an absorptive pad having a liquid permeable top sheet facing the wearer&#39;s body, a liquid impermeable backsheet on the opposite side, and an absorbent sheet or panel disposed between the top sheet and the backsheet. The absorbent article comprises a front side portion, a crotch portion and a backside portion, and further includes elastic members along the circumference of the waist and around the leg openings. The underlying objective in the design and construction of these absorbent articles has been to maximize prevention of leakage of body fluids and fecal materials through the legs&#39; openings. The prior art workers in this field have recognized that while the backsheet of the absorbent article must be liquid impermeable, they have also recognized that, in addition, the backsheet must be breathable in order to afford comfort to the wearer. Indeed there are numerous patents which disclose diapers and incontinent adult briefs having breathable backsheets. For example, U.S. Pat. No. 5,263,948 issued to Karami et al. on Nov. 23, 1993 describes breathable disposable diapers and contains a list of representative patents which illustrate the state of the art of breathable absorbent articles. The aforementioned Karami et al. patent describes a breathable absorbent article aimed at providing optimum breathability while preventing fluid and solid leakages through the side edges of the crotch area of the diaper.  
       [0004] A breathable disposable diaper is also described in U.S. Pat. No. 4,900,137, issued to Kenneth B. Buell on Feb. 13, 1990. In the Buell patent, the diaper is provided with breathable leg cuffs formed of a material which permits passage of the vapors while retarding fluid leakage.  
       [0005] An absorbent article with breathable side panels is described in U.S. Pat. No. 5,628,737 issued to Dobrin et al. on May 13, 1997.  
       [0006] Notwithstanding attempts by others in this industry to provide absorbent articles which prevent leakage of urine and other body exudates, and which also exhibit satisfactory breathability and comfort to the wearer, there is still need for providing such absorbent articles which exhibit optimum improvements in these characteristics.  
       [0007] Accordingly, it is a general object of the present invention to provide breathable absorbent articles such as baby diapers, adult incontinent underpants, briefs, guards and the like.  
       [0008] It is another object of the present invention to provide such absorbent articles which, due to their unique construction provides optimum breathability while affording excellent body fit and comfort to the wearer.  
       [0009] It is a further object of this invention to provide absorbent articles of the type herein described which are relatively simple to manufacture at affordable commercial prices.  
       [0010] The foregoing and other objects and features of the present invention will be more fully comprehended and appreciated from the ensuing detailed description and the accompanying drawing which form parts of this application.  
       [0011] It must be understood throughout this application that the term “breathable” refers to articles and garments having a backsheet which is either totally, or partially breathable, both of which hereinafter will be referred to as “breathables.” 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0012] In the various figures which constitute the drawings illustrating the present invention, and wherein like reference numerals refer to like parts:  
     [0013]FIG. 1 is a plan stretched view of the back of a diaper made according to this invention;  
     [0014]FIG. 2 is of a sectional view taken along the line  2 - 2  of FIG. 1;  
     [0015]FIG. 3 is a sectional view similar to FIG. 2 but taken along the line  3 - 3  of FIG. 1; and  
     [0016]FIG. 4 is an elevational sectional view taken along the line  4 - 4  of FIG. 1.  
    
    
     SUMMARY OF THE INVENTION  
     [0017] The objects of this invention are achieved by providing a breathable disposable absorbent article which comprises:  
     [0018] (a) a backsheet having opposed side edges and opposed front waist and back edges connecting said side edges, and having a medial cutout portion on each of said side edges.  
     [0019] (b) a top sheet having corresponding opposed side edges and corresponding opposed front waist and back edges connecting said side edges, and a medial cutout portion on each of said side edges, said backsheet and said topsheet having the same general configuration, and being sealed together at their respective edges so as to form a unitary structure having leg openings defined by said medial cutout portions,  
     [0020] (c) an absorbent layer disposed between said topsheet and said backsheet for receiving body fluids and exudates,  
     [0021] (d) one or more releasable fastening tabs at each of said side edges disposed at one end of said absorbent article, and  
     [0022] (e) one or more landing zones, having an inner adherent surface adherent to said backsheet, and an opposed outer surface adapted to be releasably engaged to the fastening tabs.  
     [0023] These landing zones may be perforated and their outer surfaces may be treated with silicone, wax or some other suitable material for releasably adhering to the fastening tabs. A liquid and vapor impervious layer such as, e.g., a polyethylene, is interposed between the absorbent layer and the backsheet, and is preferably adhered or laminated to the backsheet to prevent leakage of the body fluid and exudates.  
     DETAILED DESCRIPTION OF THE INVENTION  
     [0024] Referring to FIG. 1, there is shown a diaper generally designated as  10  which is defined by the opposed side edges  12  and  14  and the end edge (back waist)  16  and end edge (front waist)  18  which connect the side edges. Each of the side edges  12  and  14  has a medial cutout portion which defines the leg openings  20  and  22  for insertion of the legs of the wearer there through when the end edge  18  (front waist end) is folded onto the end edge  16  (back waist end) to form the diaper structure as it is worn by the user. As is further shown in FIG. 1, each of the side edges  12  and  14  has laterally extending side ears or panels  24 . The diaper  10  also comprises a breathable backsheet  26 , a fluid pervious front or top sheet  28  facing the body of the wearer and an absorbent pad or layer  30  disposed between the top sheet and the back sheet as shown in FIGS.  2 - 4 . The top sheet is generally coextensive with the backsheet although this is not strictly necessary. Also shown in FIGS.  2 - 4 , is an acquisition layer  32  interposed between the top sheet  28  and the absorbent pad  30 . The acquisition layer serves to temporarily retain the body exudates and slowly distribute them through the absorbent pad  30  in order keep the skin dry. Referring again to FIGS.  2 - 4 , the composite layers also include the layer  34 , generally made of liquid and vapor impermeable polyethylene, spanning the length of the absorbent article and extending laterally toward the sides of the diaper, ending at the cutout portions  20 ,  22 . The polyethylene film  34  may be laminated to the backsheet  26  as seen from FIGS.  2 - 4  and thus provides an area which is liquid and vapor impervious.  
     [0025] As seen from FIG. 1, the backsheet  26  is provided with a pair of opposed, perforated (or non-perforated) films or landing zones  36 , 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 polyethylene or polypropylene. A pair of releasable tabs, e.g., adhesive tabs  38  are provided at the side panels or ears  24  on the front waist side edge  16  of the absorbent article such that when the back waist end  18  of the diaper  10  is folded onto the front waist end  16  of the diaper, the tabs  38  are securely adhered onto the corresponding surfaces of the landing zones  36 . Thus, the landing zone  36  has an inside surface which is adherent to the backsheet  26 , and an exterior surface which is adapted to be releasably fastened to the tabs  38 . To this end, the exterior surface of the landing zone  36  may be treated with silicone or other suitable material so as to render this surface releasably adherent to the tabs  38 . Instead of using a release agent or in cooperation 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  18  is folded onto the front waist  16  the releasable tabs  34  can be fastened at any point on the surfaces of the landing zones  36  thus affording adjustment and improved fit of the diaper around the waist of the wearer. Although two perforated landing zones are shown in FIG. 1, one or more such zones may be provided which may or may not be perforated, as desired.  
     [0026] The diaper  10  also comprises at least one or more elastic members or bands  40  disposed on the opposite sides  12  and  14 . Preferably, 2 to 4 such elastic bands are used and act as “gatherers” in the crotch region  42 . These elastic members are sometimes referred to in this art as crotch elastics and serve to prevent fluid leakage from the crotch area or leg openings of the diaper. The elastic bands  40  are usually under tension and are adhesively secured at the sides of the article between the top or cover sheet  28  and the polyethylene backing film  34 .  
     [0027] In making the absorbent article of the present invention, the top or cover sheet  28  is made of spunbond nonwoven polypropylene which is available from First Quality Fibers, Inc., McElhattan, Pa. The acquisition layer  30  is usually made of chemically bonded nonwoven polypropylene available from American Nonwovens, Columbus, Mo. Preferably the width of the acquisition layer  30  is substantially the same as the width of the absorbent pad  30 . This pad may be made of wood pulp fibers and superabsorbent polymers such as IM 7000 series available from Clariant Products, Inc., Portsmouth, Va., and Chemdal 200 Series, available from Chemdal, Inc., Palantin, Ill. Alternatively, the absorbent pad  30  may be of dual construction, in which case the absorbent polymer may be securely positioned between each layer of the absorbent material. As seen in FIG. 1, the absorbent pad  30  does not extend to the side panels or ears  24  and, therefore, in the construction contemplated by the present invention, the absorbent pad is on the target area where it can afford maximum protection against fluid leakage.  
     [0028] The layer  34  is a polyethylene backing film and is generally non-porous and is liquid, air and preferably vapor impermeable. This layer is placed under this absorbent layer  30  in order to prevent the body exudates from leaking and thus soiling the user&#39;s bed and clothing. This film usually covers the full area under the absorbent pad  30 . In a preferred construction, the backing film  34  is adhesively or thermally laminated to the backsheet  26 , which itself is made of spunbond-melt bond spunbond (SMS) 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 hydrophobic tissue may be used instead of, or in conjunction with the polyethylene layer. The hydrophobic tissue may be made of cellubasic fibers bonded together thermally, chemically or by the use of suitable sizing agents. The hydrophobic tissue layer is microporous, i.e., comprises extremely small pores which permit passage of air and moisture vapor, but prevents, or is resistant to, passage of liquid. For improved effectiveness, the hydrophobic tissue may be laminated (cold or hot) to the nonwoven backsheet.  
     [0029] One special feature of the absorbent article of this invention is that it affords optimum breathability to the wearer. In one embodiment, the side panels or ears  24  may be porous in order to permit passage of air therethrough. The landing zone  36  may be perforated and thus not only serve to impart breathability to the absorbent article but also provide for zones of engagement with the fastening tabs  34  when the back of the diaper is folded onto the front of the diaper for use by the wearer.  
     [0030] While the present invention has heretofore been described with certain degrees of particularities and with reference to absorbent diapers and the like garments, it must be understood that several modifications may be made in the structure of the article which are apparent from the forgoing disclosure. Such modifications include the selection of specific materials used to fabricate the different layers, the degree of porosity, size, configuration and distribution of the pores when using porous landing zones. Such modifications are nevertheless within the scope and contemplation of this invention.