WO1996012459A2 - Absorbent structure with fluid-impermeable patch - Google Patents

Absorbent structure with fluid-impermeable patch Download PDF

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Publication number
WO1996012459A2
WO1996012459A2 PCT/US1995/013565 US9513565W WO9612459A2 WO 1996012459 A2 WO1996012459 A2 WO 1996012459A2 US 9513565 W US9513565 W US 9513565W WO 9612459 A2 WO9612459 A2 WO 9612459A2
Authority
WO
WIPO (PCT)
Prior art keywords
fluid
absorbent
absorbent structure
patch
thickness
Prior art date
Application number
PCT/US1995/013565
Other languages
French (fr)
Other versions
WO1996012459A3 (en
WO1996012459B1 (en
Inventor
Kishore K. Kar
Robert J. Thomas
Thomas L. Staples
Original Assignee
The Dow Chemical Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by The Dow Chemical Company filed Critical The Dow Chemical Company
Publication of WO1996012459A2 publication Critical patent/WO1996012459A2/en
Publication of WO1996012459A3 publication Critical patent/WO1996012459A3/en
Publication of WO1996012459B1 publication Critical patent/WO1996012459B1/en

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Classifications

    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00Bandages or dressings; Absorbent pads
    • A61F13/15Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/51Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the outer layers
    • A61F13/511Topsheet, i.e. the permeable cover or layer facing the skin
    • A61F13/513Topsheet, i.e. the permeable cover or layer facing the skin characterised by its function or properties, e.g. stretchability, breathability, rewet, visual effect; having areas of different permeability
    • A61F13/51305Topsheet, i.e. the permeable cover or layer facing the skin characterised by its function or properties, e.g. stretchability, breathability, rewet, visual effect; having areas of different permeability having areas of different permeability
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00Bandages or dressings; Absorbent pads
    • A61F13/15Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/53Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium
    • A61F13/534Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad
    • A61F13/537Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad characterised by a layer facilitating or inhibiting flow in one direction or plane, e.g. a wicking layer
    • A61F13/53704Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad characterised by a layer facilitating or inhibiting flow in one direction or plane, e.g. a wicking layer the layer having an inhibiting function on liquid propagation
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00Bandages or dressings; Absorbent pads
    • A61F13/15Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/53Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium
    • A61F13/534Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad
    • A61F13/537Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad characterised by a layer facilitating or inhibiting flow in one direction or plane, e.g. a wicking layer
    • A61F13/53708Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad characterised by a layer facilitating or inhibiting flow in one direction or plane, e.g. a wicking layer the layer having a promotional function on liquid propagation in at least one direction
    • A61F13/53717Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad characterised by a layer facilitating or inhibiting flow in one direction or plane, e.g. a wicking layer the layer having a promotional function on liquid propagation in at least one direction the layer having a promotional function on liquid propagation in the horizontal direction
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00Bandages or dressings; Absorbent pads
    • A61F13/15Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/53Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium
    • A61F13/534Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad
    • A61F13/537Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad characterised by a layer facilitating or inhibiting flow in one direction or plane, e.g. a wicking layer
    • A61F13/5376Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad characterised by a layer facilitating or inhibiting flow in one direction or plane, e.g. a wicking layer characterised by the performance of the layer, e.g. acquisition rate, distribution time, transfer time
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00Bandages or dressings; Absorbent pads
    • A61F13/15Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/15203Properties of the article, e.g. stiffness or absorbency
    • A61F2013/15284Properties of the article, e.g. stiffness or absorbency characterized by quantifiable properties
    • A61F2013/15365Dimensions

Definitions

  • Absorbent structures are used in absorbent devices for personal use, such as diapers, sanitary napkins, incontinent devices and garments, training pants, and m other applications, such as surgical or medicinal absorbent pads or drapes, bed pads and cable shielding
  • the incorporation of superabsorbent polymers in an absorbent structure greatly increases the absorbing power of the structure
  • U S Patent No 4,880,419 discusses the problems of distribution and containment of the superabsorbent polymer within the absorbent structure, and the problems of gel blocking and lack of wicking of the polymer itself
  • the patent discloses an absorbent article which has discrete superabsorbent containing layers and wicking means which is wound about and between the superabsorbent containing layers
  • U S Patent No 4,973,325 discusses fluid handling problems encountered in the use of several absorbent structure containing devices and discloses an absorbent article containing a pair of absorbents positioned adjacent to each other The article has a coaxially aligned transfer member for facilitating movement of body fluid from the cover downward and outward to distant areas of absorbent
  • U S Patent No 5, 151 ,091 discusses fluid handling problems that may result from the greater longitudinal dimension of various personal absorbent products
  • the patent discloses an absorbent product having means to direct the fluid flow substantially along the longitudinal direction of the product and substantially limit transverse flow which can result in side failures U.
  • S Patent No 4,778,459 discloses a disposable diaper which contains an expanse of impermeable material including a channel for guiding urine to an island of absorbent material.
  • U S. Patent No. 3,927,673 discloses an absorbent article for diapers which has a water impervious i nterlayer sheet with a plurality of small holes therethrough disposed between the top sheet and the absorbent pad
  • U S Patent No. 's 4, 699, 619 and 5, 176,668 disclose methods by which it was attempted to verify that the structural elements of the device actually work i n the way they were designed to work by measuring the distribution of fluid in the structure after insult This was done by cutting, weighing, drying and weighing again various sections of the structure to determine fluid distribution.
  • the invention in another embodiment relates to an absorbent structure comprising: (A) an absorbent layer having dimensions of length, width and thickness, the absorbent layer having at least an upper surface with dimensions of length and width, wherein the ratio of length to thickness is from 1 to 1000 and the ratio of width to thickness is from 1 to 500, (B) a fluid-permeable layer adjacent to the upper surface of the absorbent layer; and (C) a fluid-impermeable patch centrally located on a part of at least one surface of the fluid-permeable layer, the area of the patch being from 2 to 90 percent of the area of the upper surface of the absorbent layer
  • the absorbent structure of this invention is suitable for use in various absorbent articles and absorbent devices, such as, for example, disposable diapers, sanitary napkins, incontinent devices and garments, and training garments Depending upon the requirements of the device or garment in which the absorbent structure is used, the absorbent structure may be produced in a wide variety of sizes and shapes For the most effective use of the absorbent structure of this invention, the absorbent
  • Magnetic resonance imaging is used in the analytical method of this invention to study the location of aqueous fluids absorbed in absorbent structures in three dimensional space without mechanically impacting the structures. Because of the rapidity of the method, fluid flow can be observed in real time, and the effects of multiple fluid insults upon an absorbent structure can be observed sequentially
  • FIG 1 is a schematic of the experimental layout
  • FIG. 2 is a view showing the scanning protocols used for MRI scanning of absorbent structures
  • FIG 3A is a contour plot of a coronal scan
  • FIG 3B is a surface plot B of a coronal scan.
  • FIG 4 is a graphic illustration of data for total signal versus volume of insulting fluid.
  • FIG 5A is a screen image from an MRI scan of a transverse slice of an absorbent structure
  • FIG. 5B is a surface plot corresponding to FIG 5A
  • FIG 5C ⁇ s a profile of the maxima of moisture content corresponding to FIG 5A and FIG 5B
  • FIG 6A is a series of profile plots showing fluid movement over time for a first fluid insult
  • FIG 6B is a series of profile plots showing fluid movement over time for a second fluid insult
  • FIG 6C is a series of profile plots showing fluid movement over time for a third fluid insult
  • FIG 7A is a surface plot for the first fluid insults to an absorbent structure
  • FIG 7B is a surface plot for the second successive fluid insult to an absorbent structure
  • FIG 7C is a surface plot for the third successive fluid insult to an absorbent structure
  • FIG 8A is a side view of contour lines of various relative moisture contents in an absorbent structure without a fluid-impermeable patch after a first fluid insult as measured by MRI
  • FIG 8B is a side view of contour lines of various relative moisture contents in an absorbent structure without a fluid-impermeable patch after a second fluid insult as measured by MRI
  • FIG 8C is a side view of contour lines of various relative moisture contents in an absorbent structure without a fluid-impermeable patch after a third fluid insult as measured by MRI
  • FIG 8D is a side view of contour lines of various relative moisture contents in an absorbent structure with a fluid-impermeable patch after a first fluid insult as measured by MRI
  • FIG 8E is a side view of contour lines of various relative moisture contents in an absorbent structure with a fluid-impermeable patch after a second fluid insult as measured by MRI
  • FIG 8F is a side view of contour lines of various relative moisture contents in an absorbent structure with a fluid-impermeable patch after a third fluid insult as measured by MRI
  • the absorbent structure comprises an absorbent layer whose primary function is to absorb fluid insults to the structure
  • the absorbent layer desirably is composed of fluff or a blend of fluff and superabsorbent polymer
  • the fluff may generally be one or more of a number of fibrous, fiber-containing or non-fibrous materials which are themselves high in fluid absorption capacity
  • Desirable materials for fluff include, for example, cotton lintels and comminuted wood pulp
  • a preferred type of fluff is comminuted wood pulp
  • the absorbent layer may be composed primarily of or consist essentially of superabsorbent polymer.
  • superabsorbent polymer is present in one or more alternative forms including woven or nonwoven fibers, fabric, particles, powder or a sheet.
  • the fluff functions to provide containment means for the superabsorbent polymer particles.
  • the fluff also functions to provide rapid initial absorption of fluid insults with subsequent transport of the fluid to the superabsorbent polymer.
  • the superabsorbent polymer may be in the form of a powder or small particles, fibers, film or a combination thereof. Where the absorbent layer is composed primarily of superabsorbent polymer in various forms, the functions discussed above for fluff can be performed by one or more of the various superabsorbent polymer forms.
  • the absorbent layer of an absorbent structure contains at least 0.1 gram of superabsorbent polymer, preferably at least 1 gram and more preferably 3 grams or more of superabsorbent polymer. While a high superabsorbent polymer content is primarily a matter of cost, desirably the absorbent layer of an absorbent structure contains less than 1 kg, preferably less than 100 grams and more preferably 15 grams or less of superabsorbent polymer.
  • the fluff used may be a blend of fluff with modified cellulose, other cellulosic materials, or other synthetic materials.
  • Desirable materials include meltblown synthetic fibers and meltblown synthetic fibers containing fluff. Particularly desirable are combinations with superabsorbent polymer.
  • Desirable synthetic materials include, for example, polyethylene, polypropylene, polyesters, polyamides, copolymers of polyesters and polyamides and bicomponent fibers.
  • Modified cellulose fibers include those produced to have high wet stiffness.
  • Alternative forms for the absorbent layer include a laminate consisting of an absorbent film with cellulose tissue on one or both sides.
  • Other desirable forms include an open cell foam, an open cell foam in combination with fluff and/or superabsorbent polymer. Cellulose of synthetic fiber tissue may be wrapped or woven around or within the absorbent layer. The layer may be of varying density, thickness and composition to control liquid holding capacity and liquid distribution.
  • a wide variety of superabsorbent polymers may be used in the absorbent layer, such as, for example, those disclosed and described in U.S. Patent No.'s 5,075,344; 5,064,582; 5,045,614; 4,861,849; 4,833,222; 4,833,198; 4,708,997; 4,666,983; 4,734,478; 4,857,610; 4,605,401 ; 5,145,906; 5,322,896; 4,541 ,871 ; 4,808,637; 4,812,486; RE 32,649; 4,286,082; 5,280,079; 5,280,078; 5,281 ,673; 5,281 ,683; 5,241,009; 5,284,936; 5,286,827; 5,281 ,683; 5, 124,188; 5,002,986; 5,102,597 and 4,043,952.
  • the overall dimensions of the absorbent structure of this invention can vary greatly, depending upon the materials of construction and the particular use for which the structure is intended.
  • the absorbent layer has basically the same length and width as the overall absorbent structure.
  • the absorbent layer may have an upper surface area which is from 35 to 99 percent of the area of the absorbent structure.
  • the length of the absorbent layer desirably is from 5 cm to 100 cm, preferably from 10 cm to 75 cm, and more preferably from 20 cm to 50 cm.
  • the width desirably is from 2 cm to 30 cm, preferably from 4 cm to 20, and more preferably from 7 cm to 15 cm.
  • the thickness of the absorbent layer desirably is from 0.1 cm to 5 cm, preferably from .15 cm to 2.5 cm, and more preferably from 0.2 cm to 1.2 cm.
  • the fluid-permeable layer is permeable to insulting fluid liquids, primarily aqueous liquids, having dissolved or suspended therein a wide variety of inorganic and organic materials.
  • Preferred materials for the fluid-permeable layer include, for example, airlaid or meltblown synthetic fibers, which may be bonded or partially bonded thermally or, for example, with latex adhesive.
  • Synthetic polymeric materials for use in the fluid-permeable layer include, for example, rayon, polyester, polyethylene and polypropylene
  • the fluid-permeable layer has basically the same length and width as the overall absorbent structure, or at least the same length and width as the overall absorbent layer.
  • the fluid-permeable layer may have a surface area which is from 35 percent to 350 percent of the area of the absorbent structure, or the absorbent layer
  • the fluid-impermeable patch desirably is in the form of a film, and may be produced from any of the aforementioned synthetic and natural materials.
  • the patch is a thermoplastic film produced from a thermoplastic resin
  • the patch may be in the form of a tightly woven cloth produced from natural or synthetic fibers including synthetic polymer fibers.
  • the film or cloth should be fluid- impermeable, that is, it should not absorb or pass a significant amount of fluid liquid insults and should substantially block the passage of fluid liquid insults
  • the area of the fluid-impermeable patch is less than the surface area of the fluid- permeable layer, if present, and the underlying upper surface of the absorbent layer
  • the area of the fluid-impermeable patch is from 2 to 90 percent of the area of the fluid-permeable layer or the absorbent layer, preferably from 5 to 70 percent, more preferably form 10 to 50 percent and still more preferably from 20 to 40 percent
  • the length of the fluid- impermeaDle patch desirably is from 3 cm to 90 cm, preferably from 5 cm to 60 cm, and more preferably from 10 cm to 40 cm.
  • the width desirably is from 1 cm to 25 cm, preferably from 2 cm to 18, and more preferably from 4 cm to 12 cm.
  • the thickness of the fluid-impermeable patch desirably is from 1 ⁇ m to 300 ⁇ m, preferably from 5 ⁇ m to 200 ⁇ m, and more preferably from 10 ⁇ m to 75 ⁇ m
  • the fluid-impermeable patch is present on at least one of the two surfaces of the fluid-permeable layer It may be positioned on the surface next to the upper surface of the absorbent layer so that the patch is between the fluid-permeable layer and the upper surface of the absorbent layer Or it may be positioned on the outer surface of the fluid-permeable layer, in which case the fluid-permeable layer is between the patch and the absorbent layer
  • the patch may be produced on the target area of an absorbent structure by imprinting or embossing the target area of the existing structure with a plastic or resinous material to render it fluid-impermeable
  • the fluid-impermeable aspect of the patch may be present on both surfaces of the fluid-permeable layer, as well as throughout it Alternatively, if the structure contains no separately definable fluid-permeable
  • the dimensions of the fluid-permeable layer are the same as the overall absorbent structure Often this is the layer which is in contact with the wearer of a personal care device or garment within which the absorbent structure is incorporated
  • the thickness of the fluid-permeable layer will range from 0 2 mm to 10 mm
  • fluid-impermeable is defined as absorbing or passing less than 5 percent of a fluid insult within 5 minutes of the onset of the insult Assuming some motivating force, such as, for example, gravity, hydraulic pressure or hydrostatic pressure, greater than 95 percent of the fluid insult is diverted from the insult point on the fluid-impermeable patch and along the surface of the patch to its edge, where it is directed to the fluid-permeable layer for transmission to the absorbent layer
  • the effect of the patch is to spread the flow of the insulting stream over a larger area of the absorbent structure by diverting it to the edges of the patch
  • a relatively large total area of the fluid-permeable layer and the absorbent layer are contacted with the insulting stream
  • Any given local area of the absorbent layer of the structure is contacted by only part of the impinging stream, and, thus, is less likely to be overwhelmed and saturated than if assaulted directly by the total insult
  • the insult only partially impinges upon the fluid-impermeable patch at least some of the insulting fluid is directed to an area of the fluid-permeable layer and the absorbent layer which otherwise would not be an initial point of contact
  • the diversionary action of the fluid-impermeable patch has o the effect of increasing the total area of the f I uid-permeable layer and the absorbent layer subject to initial contact with the insulting fluid in comparison to a structure with no patch Depending upon the motivational force behind the insult this can be very rapid, as would be observed, for example, when saline solution is poured onto a solid surface of some solid material, such as the top of a table With a larger percentage of the absorbent layer subject to 5 initial insult, and a smaller percentage of the total insulting fluid impinging upon any given area of the absorbent layer, secondary problems in absorbent structures, such as gel blocking and the necessity of transport away from the insult site through, for example, wicking, are considerably reduced The result is a more efficient use of the absorbent materials in the absorbent layer 0 In view of the above described aspects of the absorbent structure of this invention, for use in various absorbent devices and garments, the absorbent structure should be positioned therein so that the fluid-imperme
  • the device or garment may include various other layers or other structural elements in combination with the absorbent structure, such as, for example, those disclosed in U S Patents Nos 5,261 ,899, 5,258,221 , 5, 171 ,236, 5,234,422, 5,098,422, 5, 135,522, 4,904,249, 4,834,739, 5 4,944,735, 5, 180,622, 5,264,082, 5, 149,335, 5, 149,334, 5, 124,188 and 5,260,345, 5,268,224, 5,200,248, 5, 190,563 and 5,061 ,259 MRI of Absorbent Structures
  • Nuclear magnetic resonance (NMR) spectroscopy is an analytical technique that allows one to obtain a characteristic spectrum of com pi ex components in mixtures.
  • the signal one sees in NMR is proportional to the number of particular atoms in the sample
  • the most common atom to observe in NMR is hydrogen
  • MRI magnetic resonance imaging
  • CAT computer aided tomography
  • the resolution of the signal can be modulated by the settings of the instrument.
  • the time required to collect a signal from a particular location is one of these settings, and therefore one must compromise among the speed of data collection, the precision of the map of moisture content, which is related to pixel size, and the size of the region of interest
  • These signal intensities can be related to the concentrations of water at these various locations by comparison with the signal from liquid water and the baseline signal from air
  • any possible signal contribution from the stru ⁇ ural elements of the absorbent structure itself can be corrected for or subtracted from the signal after insult.
  • FIG 1 is a schematic of the experimental layout
  • the holding device is shown with the plastic block 12 over the absorbent structure 11 , also referred to herein as a pad
  • the insult to the absorbent structure is introduced through a flexible plastic tube 13
  • an absorbent structure was fitted into this holding device and the entire assembly was set into the head coil 14 of the MRI instrument
  • the head coil 14 is surrounded by the magnet 15
  • the specimen was aligned with two laser beams indicating the center of the magnetic field
  • the fluid insult was introduced into the sample by a hand-operated syringe connected by a flexible plastic tube to the vertical delivery tube machined from the plastic block
  • 25 mL of fluid was delivered in 1-2 seconds
  • the fluid supply and syringe operator were positioned approximately 5 meters (15 ft) from the sample to avoid the strong magnetic field around the detector
  • the long flexible plastic delivery tube which connected the syringe to the sample was filled with fluid before the experiments were begun
  • the fluid used was 0 9 weight percent aqueous NaCI
  • FIG 2 shows the first plane scanned, which is termed the "transverse" plane 22
  • a transverse scan is a scan in the transverse plane
  • FIG 2 shows the plastic block 12, the absorbent structure 1 1 and the wetted region 21 of the absorbent structure 1 1, the wetting due to the insult
  • a scan in the "coronal" plane 23, known as a coronal scan was then done.
  • FIG. 2 shows a view of a coronal plane 23 below the plane of the absorbent structure 1 1 for clarity of illustration. Of course, the actual coronal scan was performed in the coronal plane which contains the absorbent structure 1 1.
  • the thickness of the scanned planar region was intentionally set to include the entire pad This integrated signal intensity reflects the total relative moisture content through the thickness of the pad.
  • the coronal scan was followed with 32 high resolution transverse scans "stepping" through the sample from back to front with si ices of less than a centimeter in thickness These are similar to the initial high speed transverse scans of the center slice, but the resolution in the two scanned dimensions is much better because the scan time is longer.
  • FIG. 3A is a typical contour plot of the coronal image.
  • the contours represent various relative moisture contents accumulated through the whole thickness at each position across the span after 24 mL of 0.9 weight percent saline solution has been introduced into the center
  • FIG. 3B The data for FIG. 3A and FIG. 3B are the same, that is, the signal strength is summed over the whole thickness as a function of the two "flat" dimensions of the sample.
  • FIG 4 shows a plot of the total signal from these coronal images after each insult for a particular series of experiments, one of which is shown with circles, the other with boxes. Deviations from zero intercept are due to inconsistent filling and draining of portions of the fluid delivery line. An improvement of the apparatus would include positive shutoff of flow after the insult to prevent this problem
  • FIG. 5A shows a view of a typical monochrome image as it would be viewed on the screen of a high speed scan of a transverse slice showing fluid coming into the absorbent structure 11 , here represented by the dashed outline, from the top
  • the top of FIG 5A corresponds to the upper part of the plastic block
  • FIG 5B is a surface plot of the relative signal intensity inside the solid outline of FIG 5A
  • the arrow 51 in FIG 5B indicates a viewing angle of this surface
  • FIG 5C is the profile of maxima of moisture content as viewed from arrow 51 and oriented as in reality with the top of the image corresponding to the upper part of the plastic block
  • the large spike near the bottom of the profile corresponds to the wetness of the upper surface of the absorbent structure at the instant an image is taken In this particular image taken at the initial moment of insult, the fluid is moving down the delivery tube and wetting the top surface of the pad before penetrating it The peaks above the large spike are the result of this fluid in the delivery tube
  • the profile view of the baseline scan at 0 seconds shows a large broad peak near the bottom which corresponds to the absorbed fluid from the first insult
  • the large broad peak near the bottom of the baseline scan at 0 seconds of FIG 6C corresponds to the absorbed fluid from the first and second insults
  • FIG s 7A, FIG 7B and FIG 7C are presented three surface plots from three successive insults on the same scale Note the flat tops all coming to the same height This represents saturation, and subsequent insults simply make the saturated region bigger In general, we have either saturated plateau or unsaturated plains regions, there is not much intermediate "damp" area
  • FIG s 8A-8F illustrate the distribution of three 25 mL insults of saline solution in pads with and without a fluid-impermeable patch
  • FIG 8A Without a patch, FIG 8A, the fluid was distributed over a radially symmetrical area approximately 5 cm (2 inches) in diameter, the average fluid concentration in this region is approximately 450 units, corresponding essentially to saturation
  • FIG 8D With a 5 cm (2 x 2 inch) patch, FIG 8D, the same amount of fluid is distributed over a toroidally-shaped region approximately 7 5 cm (3 inches) in diameter with a 2 5 cm (one inch) diameter drier region in the middle
  • the average fluid concentration in the ring of wetness was only about 150 units with peaks around 300 units
  • FIG 8B and FIG 8C without the patch
  • FIG 8E and FIG 8F with the patch
  • the deflector patch led to more efficient distribution of the fluid over a larger portion of the pad Modification of this configuration with respect to shape, relative size, o placement, and permeability can be envisioned
  • Absorbent structures consisting of composite pads prepared by standard 5 techniques were used to simulate the central portion of a larger absorbent structure, such as that typically found in a diaper
  • Cellulose fluff was disintegrated with compressed air and layered onto tissue forming 35 6 x 35 6 cm (14 x 14 inch) pads, which were then covered with tissue and then pressed to 1 25 cm (1/2 inch) thickness
  • Four 15 x 15 cm (6 x 6 inch) samples weighing 28 to 31 grams were cut from the larger pads and stored at 1 25 cm (1/2 inch) thickness in a constant temperature and humidity room at 21°C (70°F), 50 percent relative humidity, until used
  • a fluid-impermeable patch was placed in the middle of the top surface immediately under the tissue layer right after the compression step In other pads the patch was omitted
  • a pad was fitted into a holding device and the entire assembly was set into the head coil of a Siemens MAGNETOM SP/4000 magnetic resonance imager (operating at 1 tesla, 42 MHz proton), commonly used for medical diagnosis, so that magnetic resonance imaging (MRI) could be performed on the absorbent structure
  • This instrument allows the determination of the signal strength at any location within the sample
  • This signal can be used to determine the concentration of water at these various locations by comparison with the signal from liquid water and the baseline signal from air
  • the output from the instrument is a map of the signal intensities from a set of volume elements distributed throughout the selected sets of the three dimensions of the sample pad
  • the resolution of the signal that is, the dimensions of the volume element can be modulated by the settings of the instrument
  • the time required to collect a signal from a particular location is one of these settings, and therefore one must compromise among the speed of data collection, the size of the sample, and the precision of the map of moisture content fluid was introduced into the sample by a hand-operated syringe connected by a flexible plastic tube
  • FIG 3A is a contour plot of an absorbent structure 15 x 15 cm x 1 25cm (6 x 6 x 1/2 inch) obtained by magnetic resonance imaging
  • the contours represent various relative moisture contents accumulated through the whole thickness at each position across the span after 25 mL of 0 9 weight percent saline solution has been introduced into the center
  • the view of FIG 3A is down the delivery axis upon which the fluid insult has been delivered to the target area of the surface of the absorbent structure
  • FIG 3A shows that the maximum relative moisture content is located at the center of the ⁇ nsult poi nt, which appears to be saturated Moving across the structure outward from the center of the insult point, we then find successive contours representing progressively less relative moisture content as the distance from the insult point is increased. This is precisely what would be expected from a rapid insult of fluid.
  • FIG. 8A shows profiles of relative moisture content at various positions along one side of a 15 x 15 cm x 1.25cm (6 x 6 x 1/2 inch) absorbent structure which has no patch.
  • FIG. 8A shows a relatively high moisture content in the immediate area surrounding the insult site which then falls off with increasing distance from the insult site.
  • FIG. 8D shows the same view as FIG. 8A, but for an absorbent structure of this invention, which has a centrally located fluid-impermeable patch.
  • FIG.s illustrate the distribution of 25 mL of 0.9 weight percent saline solution, with and without a fluid-impermeable patch. Without a patch, the fluid was distributed over a radially symmetrical area approximately 5 cm in diameter; the average fluid

Abstract

This invention relates to an absorbent structure, preferably containing superabsorbent polymer in an absorbent layer, and in particular, to a structure with a centrally located fluid-impermeable patch which redirects an insulting fluid around it in a manner to increase the overall containment efficiency of the structure. The absorbent structure of this invention is suitable for use in various absorbent articles and absorbent devices, such as, for example, disposable diapers, sanitary napkins, incontinent devices and garments, and training garments. The invention also relates to methods to determine the location of moisture within an absorbent structure and to study fluid flow and absorption of aqueous fluid by absorbent structures in real time.

Description

ABSORBENT STRUCTURE WITH FLUID-IMPERMEABLE PATCH
This invention relates to an absorbent structure, preferably containing superabsorbent polymer, and in particular, to a structure with diversionary means at the central insult site which redirects the insulting fluid in a manner to increase the overall containment efficiency of the structure The invention also relates to methods to determine the location of moisture within an absorbent structure and to study fluid flow and absorption of aqueous fluid by an absorbent structure in real time
Absorbent structures are used in absorbent devices for personal use, such as diapers, sanitary napkins, incontinent devices and garments, training pants, and m other applications, such as surgical or medicinal absorbent pads or drapes, bed pads and cable shielding The incorporation of superabsorbent polymers in an absorbent structure greatly increases the absorbing power of the structure
However, depending upon the device or garment in which the structure is used and the nature of the insult to which the structure is subjected, little of the absorbing power of the superabsorbent polymers in the structure may be effectively utilized When there is a localized insult wherein the insulting fluid impinges upon a relatively small area of the absorbent structure at a rapid rate, such as, for example, when a baby urinates in a diaper, the insulted area of the structure may be initially overwhelmed Thus, a basic problem requiring a solution in the field of absorbent structure design is the rapid absorption of a localized insult and distribution of the insulting fluid through the structure so that it can be effectively absorbed by the superabsorbent polymer
U S Patent No 4,880,419 discusses the problems of distribution and containment of the superabsorbent polymer within the absorbent structure, and the problems of gel blocking and lack of wicking of the polymer itself The patent discloses an absorbent article which has discrete superabsorbent containing layers and wicking means which is wound about and between the superabsorbent containing layers
U S Patent No 4,973,325 discusses fluid handling problems encountered in the use of several absorbent structure containing devices and discloses an absorbent article containing a pair of absorbents positioned adjacent to each other The article has a coaxially aligned transfer member for facilitating movement of body fluid from the cover downward and outward to distant areas of absorbent
U S Patent No 5, 151 ,091 discusses fluid handling problems that may result from the greater longitudinal dimension of various personal absorbent products The patent discloses an absorbent product having means to direct the fluid flow substantially along the longitudinal direction of the product and substantially limit transverse flow which can result in side failures U. S Patent No 4,778,459 discloses a disposable diaper which contains an expanse of impermeable material including a channel for guiding urine to an island of absorbent material.
U S. Patent No. 3,927,673 discloses an absorbent article for diapers which has a water impervious i nterlayer sheet with a plurality of small holes therethrough disposed between the top sheet and the absorbent pad
U. S Patent No. 3,934,588 discloses a disposable diaper structure with facing layers having areas of preferential flow made by variations in the thickness of the material U S Patent No. 4,699,619 discloses an absorbent structure which employs cellulosic layers of differing density and pore size to control fluid flow by wicking
The prior art has recognized the problems of directing the flow of the insulting fluid away from the immediate insult site to structural areas of high absorbency, and various designs have been proposed with structural elements to accomplish this end However, most of the actual measurements made on absorbent devices report only the overall characteristics of the device. Few attempts have been made to correlate actual functional workings of a device with the theoretical design of the absorbent structure
U S Patent No. 's 4, 699, 619 and 5, 176,668 disclose methods by which it was attempted to verify that the structural elements of the device actually work i n the way they were designed to work by measuring the distribution of fluid in the structure after insult This was done by cutting, weighing, drying and weighing again various sections of the structure to determine fluid distribution.
It would be advantageous to have available a more effective absorbent structure for use in absorbent articles which has means for distribution of fluid insults and more efficient absorption thereof. Further, it would be useful to have an analytical method for observing fluid distribution within the structure, especially a rapid method allowing real time observation of fluid flow
In one embodiment the invention relates to an absorbent structure comprising:
(A) an absorbent layer having dimensions of length, width and thickness, the absorbent layer having at least an upper surface with dimensions of length and width, wherein the ratio of length to thickness is from 1 to 1000 and the ratio of width to thιcκness is from 1 to 500; and
(B) a fluid-impermeable patch centrally located adjacent to or covering a part of the upper surface of the absorbent layer, the area of the patch being from 2 to 90 percent of the area of the upper surface of the absorbent layer
In another embodiment the invention relates to an absorbent structure comprising: (A) an absorbent layer having dimensions of length, width and thickness, the absorbent layer having at least an upper surface with dimensions of length and width, wherein the ratio of length to thickness is from 1 to 1000 and the ratio of width to thickness is from 1 to 500, (B) a fluid-permeable layer adjacent to the upper surface of the absorbent layer; and (C) a fluid-impermeable patch centrally located on a part of at least one surface of the fluid-permeable layer, the area of the patch being from 2 to 90 percent of the area of the upper surface of the absorbent layer The absorbent structure of this invention is suitable for use in various absorbent articles and absorbent devices, such as, for example, disposable diapers, sanitary napkins, incontinent devices and garments, and training garments Depending upon the requirements of the device or garment in which the absorbent structure is used, the absorbent structure may be produced in a wide variety of sizes and shapes For the most effective use of the absorbent structure of this invention, the absorbent structure should be positioned in the device or garment in which it is used with the fluid-impermeabie patch between the absorbent layer and the anticipated source of the fluid insult for which the device or garment is designed
In another embodiment this invention relates to a method for determining the location of aqueous fluid within an absorbent structure with the use of magnetic resonance imaging comprising the steps of:
(A) performing a magnetic resonance imaging scan on the absorbent structure,
(B) collecting and storing data from the magnetic resonance imaging scan;
(C) visually displaying the data
Magnetic resonance imaging (MRI) is used in the analytical method of this invention to study the location of aqueous fluids absorbed in absorbent structures in three dimensional space without mechanically impacting the structures. Because of the rapidity of the method, fluid flow can be observed in real time, and the effects of multiple fluid insults upon an absorbent structure can be observed sequentially
FIG 1 is a schematic of the experimental layout FIG. 2 is a view showing the scanning protocols used for MRI scanning of absorbent structures
FIG 3A is a contour plot of a coronal scan
FIG 3B is a surface plot B of a coronal scan.
FIG 4 is a graphic illustration of data for total signal versus volume of insulting fluid.
FIG 5A is a screen image from an MRI scan of a transverse slice of an absorbent structure
FIG. 5B is a surface plot corresponding to FIG 5A FIG 5C ιs a profile of the maxima of moisture content corresponding to FIG 5A and FIG 5B
FIG 6A is a series of profile plots showing fluid movement over time for a first fluid insult FIG 6B is a series of profile plots showing fluid movement over time for a second fluid insult
FIG 6C is a series of profile plots showing fluid movement over time for a third fluid insult
FIG 7A is a surface plot for the first fluid insults to an absorbent structure FIG 7B is a surface plot for the second successive fluid insult to an absorbent structure
FIG 7C is a surface plot for the third successive fluid insult to an absorbent structure
FIG 8A is a side view of contour lines of various relative moisture contents in an absorbent structure without a fluid-impermeable patch after a first fluid insult as measured by MRI
FIG 8B is a side view of contour lines of various relative moisture contents in an absorbent structure without a fluid-impermeable patch after a second fluid insult as measured by MRI FIG 8C is a side view of contour lines of various relative moisture contents in an absorbent structure without a fluid-impermeable patch after a third fluid insult as measured by MRI
FIG 8D is a side view of contour lines of various relative moisture contents in an absorbent structure with a fluid-impermeable patch after a first fluid insult as measured by MRI
FIG 8E is a side view of contour lines of various relative moisture contents in an absorbent structure with a fluid-impermeable patch after a second fluid insult as measured by MRI
FIG 8F is a side view of contour lines of various relative moisture contents in an absorbent structure with a fluid-impermeable patch after a third fluid insult as measured by MRI
The absorbent structure comprises an absorbent layer whose primary function is to absorb fluid insults to the structure The absorbent layer desirably is composed of fluff or a blend of fluff and superabsorbent polymer The fluff may generally be one or more of a number of fibrous, fiber-containing or non-fibrous materials which are themselves high in fluid absorption capacity Desirable materials for fluff include, for example, cotton lintels and comminuted wood pulp A preferred type of fluff is comminuted wood pulp Alternatively, the absorbent layer may be composed primarily of or consist essentially of superabsorbent polymer. In this embodiment, superabsorbent polymer is present in one or more alternative forms including woven or nonwoven fibers, fabric, particles, powder or a sheet. In a combination of fluff with superabsorbent polymer, the fluff functions to provide containment means for the superabsorbent polymer particles. The fluff also functions to provide rapid initial absorption of fluid insults with subsequent transport of the fluid to the superabsorbent polymer. The superabsorbent polymer may be in the form of a powder or small particles, fibers, film or a combination thereof. Where the absorbent layer is composed primarily of superabsorbent polymer in various forms, the functions discussed above for fluff can be performed by one or more of the various superabsorbent polymer forms.
Desirably, the absorbent layer of an absorbent structure contains at least 0.1 gram of superabsorbent polymer, preferably at least 1 gram and more preferably 3 grams or more of superabsorbent polymer. While a high superabsorbent polymer content is primarily a matter of cost, desirably the absorbent layer of an absorbent structure contains less than 1 kg, preferably less than 100 grams and more preferably 15 grams or less of superabsorbent polymer.
The fluff used may be a blend of fluff with modified cellulose, other cellulosic materials, or other synthetic materials. Desirable materials include meltblown synthetic fibers and meltblown synthetic fibers containing fluff. Particularly desirable are combinations with superabsorbent polymer. Desirable synthetic materials include, for example, polyethylene, polypropylene, polyesters, polyamides, copolymers of polyesters and polyamides and bicomponent fibers. Modified cellulose fibers include those produced to have high wet stiffness. Alternative forms for the absorbent layer include a laminate consisting of an absorbent film with cellulose tissue on one or both sides. Other desirable forms include an open cell foam, an open cell foam in combination with fluff and/or superabsorbent polymer. Cellulose of synthetic fiber tissue may be wrapped or woven around or within the absorbent layer. The layer may be of varying density, thickness and composition to control liquid holding capacity and liquid distribution.
A wide variety of superabsorbent polymers may be used in the absorbent layer, such as, for example, those disclosed and described in U.S. Patent No.'s 5,075,344; 5,064,582; 5,045,614; 4,861,849; 4,833,222; 4,833,198; 4,708,997; 4,666,983; 4,734,478; 4,857,610; 4,605,401 ; 5,145,906; 5,322,896; 4,541 ,871 ; 4,808,637; 4,812,486; RE 32,649; 4,286,082; 5,280,079; 5,280,078; 5,281 ,673; 5,281 ,683; 5,241,009; 5,284,936; 5,286,827; 5,281 ,683; 5, 124,188; 5,002,986; 5,102,597 and 4,043,952.
The overall dimensions of the absorbent structure of this invention can vary greatly, depending upon the materials of construction and the particular use for which the structure is intended. Usually, the absorbent layer has basically the same length and width as the overall absorbent structure. In alternative embodiments, the absorbent layer may have an upper surface area which is from 35 to 99 percent of the area of the absorbent structure.
When incorporated into some common absorbent devices, such as, for example, disposable diapers, incontinent devices or garments and training pants, the length of the absorbent layer desirably is from 5 cm to 100 cm, preferably from 10 cm to 75 cm, and more preferably from 20 cm to 50 cm. The width desirably is from 2 cm to 30 cm, preferably from 4 cm to 20, and more preferably from 7 cm to 15 cm The thickness of the absorbent layer desirably is from 0.1 cm to 5 cm, preferably from .15 cm to 2.5 cm, and more preferably from 0.2 cm to 1.2 cm.
The fluid-permeable layer is permeable to insulting fluid liquids, primarily aqueous liquids, having dissolved or suspended therein a wide variety of inorganic and organic materials. Among the more challenging fluid insults are those of biological origin, such as, for example, urine and blood Preferred materials for the fluid-permeable layer include, for example, airlaid or meltblown synthetic fibers, which may be bonded or partially bonded thermally or, for example, with latex adhesive. Synthetic polymeric materials for use in the fluid-permeable layer include, for example, rayon, polyester, polyethylene and polypropylene Usually, the fluid-permeable layer has basically the same length and width as the overall absorbent structure, or at least the same length and width as the overall absorbent layer. In alternative embodiments, the fluid-permeable layer may have a surface area which is from 35 percent to 350 percent of the area of the absorbent structure, or the absorbent layer
The fluid-impermeable patch desirably is in the form of a film, and may be produced from any of the aforementioned synthetic and natural materials. In a preferred embodiment the patch is a thermoplastic film produced from a thermoplastic resin Alternatively, the patch may be in the form of a tightly woven cloth produced from natural or synthetic fibers including synthetic polymer fibers. The film or cloth should be fluid- impermeable, that is, it should not absorb or pass a significant amount of fluid liquid insults and should substantially block the passage of fluid liquid insults
The area of the fluid-impermeable patch is less than the surface area of the fluid- permeable layer, if present, and the underlying upper surface of the absorbent layer
Desirably, the area of the fluid-impermeable patch is from 2 to 90 percent of the area of the fluid-permeable layer or the absorbent layer, preferably from 5 to 70 percent, more preferably form 10 to 50 percent and still more preferably from 20 to 40 percent
When incorporated into some common absorbent devices, such as, for example, disposable diapers, incontinent devices or garments and training pants, the length of the fluid- impermeaDle patch desirably is from 3 cm to 90 cm, preferably from 5 cm to 60 cm, and more preferably from 10 cm to 40 cm. The width desirably is from 1 cm to 25 cm, preferably from 2 cm to 18, and more preferably from 4 cm to 12 cm The thickness of the fluid-impermeable patch desirably is from 1 μm to 300 μm, preferably from 5 μm to 200 μm, and more preferably from 10 μm to 75 μm
In an embodiment wherein the upper surface of the absorbent layer is adjacent to, covered with or in contact with a fluid-permeable layer, the fluid-impermeable patch is present on at least one of the two surfaces of the fluid-permeable layer It may be positioned on the surface next to the upper surface of the absorbent layer so that the patch is between the fluid-permeable layer and the upper surface of the absorbent layer Or it may be positioned on the outer surface of the fluid-permeable layer, in which case the fluid-permeable layer is between the patch and the absorbent layer In an alternative embodiment the patch may be produced on the target area of an absorbent structure by imprinting or embossing the target area of the existing structure with a plastic or resinous material to render it fluid-impermeable When produced in this way and used with a fluid-permeable layer, the fluid-impermeable aspect of the patch may be present on both surfaces of the fluid-permeable layer, as well as throughout it Alternatively, if the structure contains no separately definable fluid-permeable layer, the imprinting or embossing may be done directly upon the absorbent layer
Generally, the dimensions of the fluid-permeable layer are the same as the overall absorbent structure Often this is the layer which is in contact with the wearer of a personal care device or garment within which the absorbent structure is incorporated There is a wide range of suitable thicknesses for the fluid-permeable layer, depending upon the materials of construction and amount of compression within the device or garment Generally, the thickness of the fluid-permeable layer will range from 0 2 mm to 10 mm
While some insults may be of a gradual or semi-continuous nature, others which are particularly problematical are those resulting from a rapid physiological discharge of a fluid of biological origin, such as, for example, urination or the hemorrhaging of blood In this context, fluid-impermeable is defined as absorbing or passing less than 5 percent of a fluid insult within 5 minutes of the onset of the insult Assuming some motivating force, such as, for example, gravity, hydraulic pressure or hydrostatic pressure, greater than 95 percent of the fluid insult is diverted from the insult point on the fluid-impermeable patch and along the surface of the patch to its edge, where it is directed to the fluid-permeable layer for transmission to the absorbent layer
With a rapid insult of fluid on the fluid-impermeable patch, the effect of the patch is to spread the flow of the insulting stream over a larger area of the absorbent structure by diverting it to the edges of the patch Thus, soon after initial contact with the absorbent structure, a relatively large total area of the fluid-permeable layer and the absorbent layer are contacted with the insulting stream Any given local area of the absorbent layer of the structure is contacted by only part of the impinging stream, and, thus, is less likely to be overwhelmed and saturated than if assaulted directly by the total insult Even if the insult only partially impinges upon the fluid-impermeable patch, at least some of the insulting fluid is directed to an area of the fluid-permeable layer and the absorbent layer which otherwise would not be an initial point of contact
That part of the absorbent layer which is under the patch is not wasted Fluid which has been diverted by the patch to the edges thereof before coming in contact with the absorbent layer can spread outward toward the extremities of the absorbent structure, and it can also spread inward, under the patch The overall efficiency of utilization of the absorbent layer and the materials therein is, thus, increased
The diversionary action of the fluid-impermeable patch, as described above, has o the effect of increasing the total area of the f I uid-permeable layer and the absorbent layer subject to initial contact with the insulting fluid in comparison to a structure with no patch Depending upon the motivational force behind the insult this can be very rapid, as would be observed, for example, when saline solution is poured onto a solid surface of some solid material, such as the top of a table With a larger percentage of the absorbent layer subject to 5 initial insult, and a smaller percentage of the total insulting fluid impinging upon any given area of the absorbent layer, secondary problems in absorbent structures, such as gel blocking and the necessity of transport away from the insult site through, for example, wicking, are considerably reduced The result is a more efficient use of the absorbent materials in the absorbent layer 0 In view of the above described aspects of the absorbent structure of this invention, for use in various absorbent devices and garments, the absorbent structure should be positioned therein so that the fluid-impermeable patch is between the anticipated source of the insult and the absorbent layer of the structure In addition to varying the general location of the absorbent structure within the device or garment as needed, the size and shape of the 5 f luid-impermeable patch can be varied, as well as the percentage of the area of the upper surface of the absorbent layer which is shielded by the patch Any suitable shape for the patch may be used, such as, for example, square, rectangular, triangular, round or oval, or a more complex shape comprised of various parts of, or combinations of, the basic shapes This aspect of the absorbent structure may be varied as needed and as appropriate for the device or 0 garment in which the absorbent structure is used
When the absorbent structure of this invention is used in an absorbent device or garment, the device or garment may include various other layers or other structural elements in combination with the absorbent structure, such as, for example, those disclosed in U S Patents Nos 5,261 ,899, 5,258,221 , 5, 171 ,236, 5,234,422, 5,098,422, 5, 135,522, 4,904,249, 4,834,739, 5 4,944,735, 5, 180,622, 5,264,082, 5, 149,335, 5, 149,334, 5, 124,188 and 5,260,345, 5,268,224, 5,200,248, 5, 190,563 and 5,061 ,259 MRI of Absorbent Structures
Nuclear magnetic resonance (NMR) spectroscopy is an analytical technique that allows one to obtain a characteristic spectrum of com pi ex components in mixtures. The signal one sees in NMR is proportional to the number of particular atoms in the sample The most common atom to observe in NMR is hydrogen
The extension of NM to medicine is the technique of magnetic resonance imaging (MRI) A typical MRI instrument uses nuclear magnetic resonance to see the hydrogens on water, the most prevalent chemical in the body. With MRI one can obtain a three dimensional map of water in the body Instruments in use today use "computer aided tomography" (CAT) to view a slice of the body in any of the three orthogonal planes This concept, based on constructing a real time image of a planar slice focused in the third dimension, remains the same when adapted to the study of absorbent structures We have used this technique to look at a flowing saline solution in a fiber matrix of an absorbent structure This work was done using a Siemens MAGNETOM™ SP/4000 magnetic resonance imager operating at 1 tesla of magnetic flux density and a frequency of 42 MHz to detect protons The instrument was operated by Regional Imaging Center located in Auburn, Michigan Various slices of the sample were scanned; the output was a map of signal intensities from the volume elements in the plane of the scan A monochrome image of the scanned section was visible on a screen to guide experimental efforts
The resolution of the signal, that is, the dimensions of the volume element, can be modulated by the settings of the instrument. The time required to collect a signal from a particular location is one of these settings, and therefore one must compromise among the speed of data collection, the precision of the map of moisture content, which is related to pixel size, and the size of the region of interest These signal intensities can be related to the concentrations of water at these various locations by comparison with the signal from liquid water and the baseline signal from air
For studies of single or multiple insults by aqueous fluids to absorbent structures containing various structural elements, including superabsorbent polymers, any possible signal contribution from the struαural elements of the absorbent structure itself can be corrected for or subtracted from the signal after insult. Usually these baseline contributions are very small or negligible This versatility in handling the collected data can be used to study the effect of multiple insults on an absorbent structure For example, after an absorbent structure has become relatively stable following one or more initial insults, a subsequent insult to the structure may be observed The distribution of the additional moisture content from the subsequent insult along with any redistribution of the moisture content due to the initial insult can be determined by subtracting the signal observed prior to the subsequent insult from the signal observed after the subsequent insult For each run in these experiments 1 1 files of 128 x 128 pixels and 32 files of 256 x 256 pixels were stored, as well as numerous values specifying the conditions of the scans Each pad configuration generated over 6 megabytes of data Following the generation and storage of this data, the method involves using means for data transfer, means for decoding, and means for visualization and display
In order to fix the specimens in the MRI unit a holding device was machined from cast polymethyl-methacrylate, a transparent plastic Plastic was necessary because most other materials would either absorb radiation or be affected by the intense magnetic field By relying on gravity the maximum load that could be applied to the sample was the 1 8 kPa (0 25 psι) due to the weight of the solid plastic block The dimensions of the coil limited the size of the holding assembly, and denser solid materials, such as metals, could not be used Higher loads can be applied to the absorbent structure by mechanical means, such as hydraulic pressure
FIG 1 is a schematic of the experimental layout The holding device is shown with the plastic block 12 over the absorbent structure 11 , also referred to herein as a pad The insult to the absorbent structure is introduced through a flexible plastic tube 13 For the experiment, an absorbent structure was fitted into this holding device and the entire assembly was set into the head coil 14 of the MRI instrument The head coil 14 is surrounded by the magnet 15 The specimen was aligned with two laser beams indicating the center of the magnetic field The fluid insult was introduced into the sample by a hand-operated syringe connected by a flexible plastic tube to the vertical delivery tube machined from the plastic block In these runs, 25 mL of fluid was delivered in 1-2 seconds The fluid supply and syringe operator were positioned approximately 5 meters (15 ft) from the sample to avoid the strong magnetic field around the detector The long flexible plastic delivery tube which connected the syringe to the sample was filled with fluid before the experiments were begun The fluid used was 0 9 weight percent aqueous NaCI solution
In some pads (absorbent structures) a fluid-impermeable patch was placed in the middle of the top surface immediately under the tissue layer In other pads the patch was omitted The pad was covered with liner material just before testing The method of this invention, as used in this study, is useful in determining the effect of structural elements, such as, for example, the fluid-impermeable patch on the flow pattern and ultimate distribution of the fluid insult upon the absorbent structure
The insult was monitored with one-second scans of the center section of the sample made at one-second intervals The scanned section was approximately 1 cm thick FIG 2 shows the first plane scanned, which is termed the "transverse" plane 22 Thus, a transverse scan is a scan in the transverse plane FIG 2 shows the plastic block 12, the absorbent structure 1 1 and the wetted region 21 of the absorbent structure 1 1, the wetting due to the insult After ten scans at a total elapsed time from the time of the insult of 20 seconds, no further rapid change in the images was observable. A scan in the "coronal" plane 23, known as a coronal scan, was then done. FIG. 2 shows a view of a coronal plane 23 below the plane of the absorbent structure 1 1 for clarity of illustration. Of course, the actual coronal scan was performed in the coronal plane which contains the absorbent structure 1 1.
For the coronal scan the thickness of the scanned planar region was intentionally set to include the entire pad This integrated signal intensity reflects the total relative moisture content through the thickness of the pad.
The coronal scan was followed with 32 high resolution transverse scans "stepping" through the sample from back to front with si ices of less than a centimeter in thickness These are similar to the initial high speed transverse scans of the center slice, but the resolution in the two scanned dimensions is much better because the scan time is longer.
The images observed on the screen during the experiments, which are maps of the intensity obtained from each of the three scanning protocols, provide only gross information Nevertheless, individual layers of fluff can be observed in high resolution scans with scan times of 16 seconds. The rapid scans of 1 second yield an image that is lower in contrast and more diffuse.
While gross information can be gained from the screen images, precise quantification requires numerical values for the signal strengths at each location. The collected data for the signal strength at each location were transferred to a data file of a VAX'" computer (Trademark of Digital Equipment Corporation, DEC) with the cooperation of both the Siemens Company and Digital Equipment Corporation. It was then possible to manipulate the signal values for each pixel for each scan of each run with computer programs for analysis and visualization of the data that allowed precise comparisons of moisture contents FIG. 3A is a typical contour plot of the coronal image. The contours represent various relative moisture contents accumulated through the whole thickness at each position across the span after 24 mL of 0.9 weight percent saline solution has been introduced into the center A different representation of the same data can be seen in a surface plot as shown in FIG. 3B The data for FIG. 3A and FIG. 3B are the same, that is, the signal strength is summed over the whole thickness as a function of the two "flat" dimensions of the sample.
Integration of the relative moisture values over the whole extent of the pad should be the equivalent of the 25 mL of the insult. FIG 4 shows a plot of the total signal from these coronal images after each insult for a particular series of experiments, one of which is shown with circles, the other with boxes. Deviations from zero intercept are due to inconsistent filling and draining of portions of the fluid delivery line. An improvement of the apparatus would include positive shutoff of flow after the insult to prevent this problem
FIG. 5A shows a view of a typical monochrome image as it would be viewed on the screen of a high speed scan of a transverse slice showing fluid coming into the absorbent structure 11 , here represented by the dashed outline, from the top The top of FIG 5A corresponds to the upper part of the plastic block FIG 5B is a surface plot of the relative signal intensity inside the solid outline of FIG 5A The arrow 51 in FIG 5B indicates a viewing angle of this surface FIG 5C is the profile of maxima of moisture content as viewed from arrow 51 and oriented as in reality with the top of the image corresponding to the upper part of the plastic block The large spike near the bottom of the profile corresponds to the wetness of the upper surface of the absorbent structure at the instant an image is taken In this particular image taken at the initial moment of insult, the fluid is moving down the delivery tube and wetting the top surface of the pad before penetrating it The peaks above the large spike are the result of this fluid in the delivery tube
FIG s 6A, 6B and 6C show a series of similar profile plots showing the maximum moisture content viewed across the center line of the absorbent structure for every two seconds during three fluid insults Keeping in mind that the insult is administered by a hand operated syringe at a distance of 5 meters, the scans at 0 and 2 seconds in FIG 6A are basically the same flat baseline The scan at 4 seconds shows some fluid near the top, and the scan at 6 seconds corresponds to the major portion of the insult flowing through the flexible tube and arriving at the upper surface of the absorbent structure Little fluid movement occurs after the driving pressure of the hand operated syringe stops
In the FIG 6B series of scans, the profile view of the baseline scan at 0 seconds shows a large broad peak near the bottom which corresponds to the absorbed fluid from the first insult Similarly, the large broad peak near the bottom of the baseline scan at 0 seconds of FIG 6C corresponds to the absorbed fluid from the first and second insults
Another indication of the relatively small amount of capillary flow, that is, wicking, is the sharp gradient seen in the surface plots from the coronal views In FIG s 7A, FIG 7B and FIG 7C are presented three surface plots from three successive insults on the same scale Note the flat tops all coming to the same height This represents saturation, and subsequent insults simply make the saturated region bigger In general, we have either saturated plateau or unsaturated plains regions, there is not much intermediate "damp" area
To demonstrate the effect of a deflector region, that is, a fluid-impermeable patch placed near the target area of an absorbent structure, the profiles of relative moisture content at a series of positions for two different absorbent structures, one with a fluid- impermeable patch and one without a fluid-impermeable patch, were compared FIG s 8A-8F illustrate the distribution of three 25 mL insults of saline solution in pads with and without a fluid-impermeable patch These curves represent vertical sections through surface plots similar to those in FIG s 7A-C
Without a patch, FIG 8A, the fluid was distributed over a radially symmetrical area approximately 5 cm (2 inches) in diameter, the average fluid concentration in this region is approximately 450 units, corresponding essentially to saturation With a 5 cm (2 x 2 inch) patch, FIG 8D, the same amount of fluid is distributed over a toroidally-shaped region approximately 7 5 cm (3 inches) in diameter with a 2 5 cm (one inch) diameter drier region in the middle The average fluid concentration in the ring of wetness was only about 150 units with peaks around 300 units The effects of two additional insults on each pad, up to a total of 75 mL in each, are shown in subsequent plots, FIG 8B and FIG 8C without the patch, and FIG 8E and FIG 8F with the patch Even after three insults to the absorbent structures, which simulate diapers, the sample with the patch does not have such a well developed "plateau" of saturation as indicated for the control This quantifies what a user of a diaper containing such an absorbent o structure would experience as a drier, more comfortable feel Using a deflector region allows utilization of more of the core, and, hence, improves efficiency
Examination of the test samples showed the diaper pad without the patch to be wet on both its surfaces and the pad with the patch to have the fluid more uniformly distributed and much less wet on its surfaces Both of these absorbent structures were 5 constructed with a polypropylene nonwoven on the upper surface, which was insulted An additional example utilizing no nonwoven material but with the patch showed intermediate performance
The deflector patch led to more efficient distribution of the fluid over a larger portion of the pad Modification of this configuration with respect to shape, relative size, o placement, and permeability can be envisioned
This technique showed the surprising result of how little natural wicking occurred in these experiments By directly observing the fluid in real time the question of whether the analysis technique affects the result, as would be the case with cutting and weighing, can be eliminated Of course wicking occurs under some conditions, such as higher loads which 5 compress the pads to a greater extent creating smaller diameter capillaries with higher capillary pressures
Another major interest is what is the effect of superabsorbents and further, the effect of differences in superabsorbents Ascertaining the correlation of superabsorbent properties with fluid distribution has in the past been very difficult This technique simplifies 0 this correlation
This technique provides a map of water concentration in three dimensional space as a function of time Examples of the Absorbent structure
Absorbent structures consisting of composite pads prepared by standard 5 techniques were used to simulate the central portion of a larger absorbent structure, such as that typically found in a diaper Cellulose fluff was disintegrated with compressed air and layered onto tissue forming 35 6 x 35 6 cm (14 x 14 inch) pads, which were then covered with tissue and then pressed to 1 25 cm (1/2 inch) thickness Four 15 x 15 cm (6 x 6 inch) samples weighing 28 to 31 grams were cut from the larger pads and stored at 1 25 cm (1/2 inch) thickness in a constant temperature and humidity room at 21°C (70°F), 50 percent relative humidity, until used
In some pads a fluid-impermeable patch was placed in the middle of the top surface immediately under the tissue layer right after the compression step In other pads the patch was omitted
A pad was fitted into a holding device and the entire assembly was set into the head coil of a Siemens MAGNETOM SP/4000 magnetic resonance imager (operating at 1 tesla, 42 MHz proton), commonly used for medical diagnosis, so that magnetic resonance imaging (MRI) could be performed on the absorbent structure This instrument allows the determination of the signal strength at any location within the sample This signal can be used to determine the concentration of water at these various locations by comparison with the signal from liquid water and the baseline signal from air The output from the instrument is a map of the signal intensities from a set of volume elements distributed throughout the selected sets of the three dimensions of the sample pad The resolution of the signal, that is, the dimensions of the volume element can be modulated by the settings of the instrument The time required to collect a signal from a particular location is one of these settings, and therefore one must compromise among the speed of data collection, the size of the sample, and the precision of the map of moisture content fluid was introduced into the sample by a hand-operated syringe connected by a flexible plastic tube to the vertical delivery tube machined from the plastic block The desired amount of fluid was drawn into the syringe through a Y-shaped connection with one side open and the other closed; for delivery the other was opened and the first side closed Generally, 25 mL of fluid was delivered in 1-2 seconds The fluid supply and syringe operator were positioned approximately 5 meters (15 ft) from the sample to avoid the strong magnetic field around the detector The long flexible plastic delivery tube which connected the syringe to the sample was filled with fluid before the experiments were begun The fluid used was an aqueous solution which contained 0 9 percent weight percent NaCI
FIG 3A is a contour plot of an absorbent structure 15 x 15 cm x 1 25cm (6 x 6 x 1/2 inch) obtained by magnetic resonance imaging The contours represent various relative moisture contents accumulated through the whole thickness at each position across the span after 25 mL of 0 9 weight percent saline solution has been introduced into the center The view of FIG 3A is down the delivery axis upon which the fluid insult has been delivered to the target area of the surface of the absorbent structure FIG 3A shows that the maximum relative moisture content is located at the center of the ι nsult poi nt, which appears to be saturated Moving across the structure outward from the center of the insult point, we then find successive contours representing progressively less relative moisture content as the distance from the insult point is increased. This is precisely what would be expected from a rapid insult of fluid.
FIG. 8A shows profiles of relative moisture content at various positions along one side of a 15 x 15 cm x 1.25cm (6 x 6 x 1/2 inch) absorbent structure which has no patch. The
5 horizontal axis represents distance in cm from the point of insult at 0. The vertical axis is arbitrary numerical units directly proportional to moisture. FIG. 8A shows a relatively high moisture content in the immediate area surrounding the insult site which then falls off with increasing distance from the insult site.
These results show that MRI is an effective analytical tool for the measurement of
10 aqueous fluid distribution within an absorbent structure. When an absorbent structure in scanned repeatedly after a fluid insult at scan times which are short relati e to the flow and ultimate disposition of the fluid insult, the movement over time of the fluid insult can be followed. This information can be used as the basis for inferences related to the various distribution mechanisms at work within the absorbent structure after insult by a fluid.
15 FIG. 8D shows the same view as FIG. 8A, but for an absorbent structure of this invention, which has a centrally located fluid-impermeable patch.
These FIG.s illustrate the distribution of 25 mL of 0.9 weight percent saline solution, with and without a fluid-impermeable patch. Without a patch, the fluid was distributed over a radially symmetrical area approximately 5 cm in diameter; the average fluid
20 concentration in this region is approximately 450 units. With a 5 x 5 cm (2 x 2 inch) patch, the same amount of fluid is distributed over a toroidally-shaped region approximately 7 cm in diameter with a 2.5 cm diameter relatively dry region in the middle; the average fluid concentration in the ring of wetness was only about 150 units with peaks around 300 units.
The effect of two additional insults on each absorbent structure, up to a total of
25 75 mL in each, were also studied with this MRI method. Even after three insults to the absorbent structures, the sample with the patch does not have a "plateau" of saturation as extensive (around 450 units) as indicated for the control. This quantifies what a user of such a diaper would experience as a drier, more comfortable feel.
Examination of the final samples showed the absorbent structure without the
30 patch to be wet on both its surfaces and that with the patch to have the fluid more uniformly distributed and much less wet on its surfaces. Both of these simulated diapers were constructed with a polypropylene nonwoven on the top (insulted) surface. An additional example utilizing no nonwoven material but with the patch showed intermediate performance. It is known that the nonwoven material is useful when compared to simple fluff. Therefore, we can conclude
35 that the patch is of greater value than this liner, but the best performance was shown when both the liner and the patch were used.

Claims

WHAT IS CLAIMED IS
1 An absorbent structure comprising
(A) an absorbent layer having dimensions of length, width and thickness, the absorbent layer having at least an upper surface with dimensions of length and width, wherein the ratio of length to thickness is from 1 to 1000 and the ratio of width to thickness is from 1 to 500, and
(B) a fluid-impermeable patch centrally located adjacent to or covering a part of the upper surface of the absorbent layer, the patch having dimensions of length, width and thickness, the area of the patch being from 2 to 90 percent of the area of the upper surface of the absorbent layer
2 The absorbent structure of Claim 1 wherein the length of the absorbent layer is from 5 cm to 100 cm, the width of the absorbent layer is from 2 cm to 30 cm and the thickness of the absorbent layer is from 0 1 cm to 5 cm
3 The absorbent structure of Claim 1 wherein the length of the fluid- impermeable patch is from 3 cm to 90 cm, the width of the fluid-impermeable patch is from 1 cm to 25 cm and the thickness of the fluid-impermeable patch is from 1 μm to 300 μm
4 The absorbent structure of Claim 1 wherein the absorbent layer comprises one or more of fluff, superabsorbent polymer, cellulosic materials, modified cellulose, cellulose tissue, meltblown synthetic fibers, polyethylene, polypropylene, polyester, polyamide, copolymer of polyester or polyamide, open cell foam, and bicomponent fiber
5 The absorbent structure of Claim 1 wherein the fluid-impermeable patch comprises one or more of airlaid or meltblown synthetic fibers including rayon, polyester, polyethylene and polypropylene, natural fibers including cotton and cellulose, a thermoplastic film or resin, tightly woven cloth and latex adhesive 6 The absorbent structure of Claim 1 wherein the fluid-impermeable patch is produced by imprinting or embossing the absorbent structure with a plastic or resinous material
7 The absorbent structure of Claim 1 wherein the fluid-impermeable patch absorbs or passes less than 5 percent of a fluid insult within 5 minutes of the onset of the insult 8 An absorbent structure comprising
(A) an absorbent layer having dimensions of length, width and thickness, the absorbent layer having at least an upper surface with dimensions of length and width, wherein the ratio of length to thickness is from 1 to 1000 and the ratio of width to thickness is from 1 to 500, (B) a fluid-permeable layer adjacent to the upper surface of the absorbent layer; and
(C) a fluid-impermeable patch centrally located on a part of at least one surface of the fluid-permeable layer and having dimensions of length, width and thickness, the area of the patch being from 2 to 90 percent of the area of the upper surface of the absorbent layer
9. The absorbent structure of Claim 8 wherein the length of the absorbent layer is from 5 cm to 100 cm, the width of the absorbent layer is from 2 cm to 30 cm and the thickness of the absorbent layer is from 0.1 cm to 5 cm.
10. The absorbent structure of Claim 8 wherein the length of the fluid- impermeable patch is from 3 cm to 90 cm, the width of the fluid-impermeable patch is from 1 cm to 25 cm and the thickness of the fluid-impermeable patch is from 1 μm to 300 μm.
1 1. The absorbent structure of Claim 8 wherein the absorbent layer comprises one or more of fluff, superabsorbent polymer, cellulosic materials, modified cellulose, cellulose tissue, meltblown synthetic fibers, polyethylene, polypropylene, polyester, polyamide, copolymer of polyester or polyamide, open cell foam, and bicomponent fiber.
12 The absorbent structure of Claim 8 wherein the fluid-permeable layer comprises one or more of airlaid or meltblown synthetic fibers including rayon, polyester, polyethylene and polypropylene, and natural fibers including cotton and cellulose
13. The absorbent structure of Claim 8 wherein the fluid-impermeable patch comprises one or more of airlaid or meltblown synthetic fibers including rayon, polyester, polyethylene and polypropylene, natural fibers including cotton and cellulose, a thermoplastic film or resin, tightly woven cloth and latex adhesive 14. The absorbent structure of Claim 8 wherein the fluid-impermeable patch is produced by imprinting or embossing the absorbent structure with a plastic or resinous material.
15. The absorbent structure of Claim 8 wherein the fluid-impermeable patch absorbs or passes less than 5 percent of a fluid insult within 5 minutes of the onset of the insult 16. A method for determining the location of aqueous fluid within an absorbent structure with the use of magnetic resonance imaging comprising the steps of.
(A) performing a magnetic resonance imaging scan on the absorbent structure;
(B) collecting and storing data from the magnetic resonance imaging scan;
(C) visually displaying the data. 17. The method of Claim 16 wherein steps (A) and (B) are performed two or more times so that fluid flow with the absorbent structure may be observed
PCT/US1995/013565 1994-10-24 1995-10-11 Absorbent structure with fluid-impermeable patch WO1996012459A2 (en)

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Cited By (10)

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EP0861645A3 (en) * 1997-02-28 2000-02-09 Uni-Charm Corporation Disposable training pants for infants
US7264615B2 (en) 2001-04-03 2007-09-04 Kimberly-Clark Worldwide, Inc. Absorbent insert for use with an outer absorbent garment
WO2008021173A3 (en) * 2006-08-08 2008-05-08 Procter & Gamble Method of evaluating performance characteristics of articles
WO2008055991A2 (en) * 2006-11-10 2008-05-15 Evonik Stockhausen Gmbh Visualization of the liquid distribution in sanitary articles
US7615675B2 (en) 2001-05-14 2009-11-10 The Procter & Gamble Company Wearable article having a temperature change element
US7767876B2 (en) 2003-10-30 2010-08-03 The Procter & Gamble Company Disposable absorbent article having a visibly highlighted wetness sensation member
US7977528B2 (en) 2001-05-14 2011-07-12 The Procter & Gamble Company Disposable absorbent article having refastenable side seams and a wetness sensation member
US8445743B2 (en) 2001-11-26 2013-05-21 The Procter & Gamble Company Wearable article enhancing awareness of urination
US8737704B2 (en) 2006-08-08 2014-05-27 The Procter And Gamble Company Methods for analyzing absorbent articles
US9244022B2 (en) 2011-06-16 2016-01-26 The Procter & Gamble Company Mannequins for use in imaging and systems including the same

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DE2029766A1 (en) * 1969-05-16 1971-12-23 Georgia-Pacific Corp., Portland, Oreg. (V.StA.) Multi-layer absorbent pad
FR2515029A1 (en) * 1981-10-28 1983-04-29 Schickedanz Ver Papierwerk HYGIENIC COMPRESSED ADSORPTION SUCH AS A HYGIENIC TOWEL OR THE LIKE
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Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0861645A3 (en) * 1997-02-28 2000-02-09 Uni-Charm Corporation Disposable training pants for infants
US6320096B1 (en) 1997-02-28 2001-11-20 Uni-Charm Corporation Disposable training pants for infants with wetness indicator
US7264615B2 (en) 2001-04-03 2007-09-04 Kimberly-Clark Worldwide, Inc. Absorbent insert for use with an outer absorbent garment
US8273940B2 (en) 2001-05-14 2012-09-25 The Procter & Gamble Company Wearable article having a temperature change element
US7977528B2 (en) 2001-05-14 2011-07-12 The Procter & Gamble Company Disposable absorbent article having refastenable side seams and a wetness sensation member
US7615675B2 (en) 2001-05-14 2009-11-10 The Procter & Gamble Company Wearable article having a temperature change element
US8445743B2 (en) 2001-11-26 2013-05-21 The Procter & Gamble Company Wearable article enhancing awareness of urination
US7781640B2 (en) 2003-10-30 2010-08-24 The Procter & Gamble Company Disposable absorbent article having a visibly highlighted wetness sensation member
US7767876B2 (en) 2003-10-30 2010-08-03 The Procter & Gamble Company Disposable absorbent article having a visibly highlighted wetness sensation member
US7949163B2 (en) 2006-08-08 2011-05-24 The Procter & Gamble Company Method of evaluating performance characteristics of articles
WO2008021173A3 (en) * 2006-08-08 2008-05-08 Procter & Gamble Method of evaluating performance characteristics of articles
US8737704B2 (en) 2006-08-08 2014-05-27 The Procter And Gamble Company Methods for analyzing absorbent articles
US9224032B2 (en) 2006-08-08 2015-12-29 The Procter & Gamble Company Methods for analyzing absorbent articles
WO2008055991A3 (en) * 2006-11-10 2008-10-16 Evonik Stockhausen Gmbh Visualization of the liquid distribution in sanitary articles
WO2008055991A2 (en) * 2006-11-10 2008-05-15 Evonik Stockhausen Gmbh Visualization of the liquid distribution in sanitary articles
US9244022B2 (en) 2011-06-16 2016-01-26 The Procter & Gamble Company Mannequins for use in imaging and systems including the same

Also Published As

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WO1996012459B1 (en) 2001-04-12

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