Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3741212 A
Publication typeGrant
Publication dateJun 26, 1973
Filing dateAug 2, 1971
Priority dateAug 2, 1971
Also published asCA960004A1
Publication numberUS 3741212 A, US 3741212A, US-A-3741212, US3741212 A, US3741212A
InventorsR Schutte
Original AssigneeScott Paper Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Diaper system and absorbent pad therefor
US 3741212 A
Abstract  available in
Images(1)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

United States Patent [191 Schutte A DIAPER SYSTEM AND ABSORBENT PAD THEREFOR [75] Inventor: Richard W. Schutte, Newton Square,

[73] Assignee: Scott Paper Company, Delaware County, Pa.

[22] Filed: Aug. 2, 1971 [21] Appl. No.: 168,133

[52] US. Cl. 128/287 [51] Int. Cl. A61f 13/16 [58] Field of Search 128/284, 286, 287, 128/290 [56] References Cited UNITED STATES PATENTS 2,833,283 5/1958 Spahr et al 128/290 W 2,890,700 6/1959 Lonberg-Holm 128/284 3,065,751 11/1962 Gobbo, Sr. et a1. 128/287 3,171,773 3/1965 Estes et al 128/287 3,430,629 3/1969 Murphy 128/284 3,543,756 12/1970 Murphy et a1. 128/284 3,603,314 9/1971 Aberg 128/284 3,653,382 4/1972 Easley et a1 128/284 Primary Examiner-Charles F Rosenbaum Att0rneyMartin L. Faigus et al.

[57] ABSTRACT A diaper system having an elongate, fluid impervious June 26, 1973 pad-retaining garment and an elongate, disposable absorbent pad removably retained in the garment. The elongate, disposable absorbent pad includes an absorbent layer disposed within a covering envelope having a porous, elongate, adhesively bonded, fibrous facing cover web, and a backing cover web of a wet-strength paper stock. The absorbent layer includes a fluff batt of cellulosic fibers, and a lower layer of creped paper wadding disposed adjacent the bottom face of the fluff batt and having a transverse dimension at least substantially equal to the transverse dimension of the fluff batt. The facing cover web overlies a facing surface of the absorbent layer and has elongate side margins extending around elongate sides of the absorbent layer and overturned upon, and secured to the backing cover .web. The backing cover web has a lower wet-crossdirection energy absorption level than the facing cover web, a higher wet-cross-direction energy absorption level than the lower layer of creped paper wadding, and is less permeable to the passage of urine than the facing cover web and the lower layer of creped paper wadding. Side regions of the absorbent pad include the absorbent layer and are infolded to define side panels having upper exposed surfaces defined by portions of the facing cover web. The backing cover web has elongate side margins terminating short of the infolded side regions so that the backing cover web is not disposed to underlie the portions of the facing cover web defining the upper exposed surfaces of the side panels.

15 Claims, 3'Drawing Figures m mmmzs ma 3.741.212

INVENTOR. Richard W. Schufie ATTORNEY- DIAPER SYSTEM AND ABSORBENT PAD THEREFOR BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a diaper system, and to an absorbent pad for use in said diaper system. More specifically, this invention relates to a diaper system having an elongate, disposable absorbent pad for use with a fluid impervious pad-retaining garment; and to the elongate, disposable absorbent pad per se.

2. Description of the Prior Art Absorbent pads for use with fluid impervious padretaining garments in a diaper system are known in the prior art. One such absorbent pad is disclosed in U.S. Pat. application Ser. No. 108,560, filed Jan. 21, 1971, and assigned to Scott Paper Company. This prior art absorbent pad is from about 4 to 5 inches wide and is disposed in its flat condition within a water-proof pouch or channel of a fluid impervious pad-retaining garment. This absorbent pad includes a composite absorbent member comprising a fluff batt of short, wood pulp fibers disposed between upper and lower layers of creped paper wadding which are free of wet-strength resins. A porous, nonwoven facing cover web is disposed over the upper layer of creped paper wadding and has elongate side margins extending around elongate sides of the composite absorbent member and overturned upon and bonded to the lower layer of creped paper wadding so as to leave exposed the central portion of the lower layer of creped paper wadding. This construction of an absorbent pad permits the lower layer of creped paper wadding to contact moisture instantly and to immediately physically disintegrate when the absorbent pad is held within the vortex of a flushed toilet or other stream of water. This physical disintegration of the creped paper wadding exposes the inner fluff batt to water, which causes said inner fluff batt to disintegrate. The facingcover web of nonwoven material is non-bulky, flexible, and also is disposable in an ordinary toilet bowl. Therefore, the entire absorbent pad is disposable in an ordinary toilet.

The lower layer of creped paper wadding in the prior art absorbent pad had insufficient wet-cross-direction wet toughness to maintain its structural integrity when saturated with urine, and therefore, failed to function satisfactorily as part of the covering envelope to maintain the structural integrity of the inner components of the absorbent pad during use of the diaper system. Supporting the lower layer of creped paper wadding on a surface of a pad-retaining garment of the diaper system did not overcome this strength deficiency. Furthermore, the lower layer of creped paper wadding was so highly permeable to the passage of urine that urine penetrating through the thickness of the absorbent pad during use of the diaper system was easily transmitted through the lower layer of creped paper wadding to flow along the pad-retaining garment and leak from marginal regions thereof. Stating this another way, the lower layer of creped paper wadding did not provide a sufficient barrier to urine transmission to prevent leakage from the diaper system. Another disadvantage encountered in the above-described absorbent pad was the inefficient distribution of absorbent material for adequately retaining urine to prevent leakage from the diaper system.

The problem of inefficient distribution of absorptive material in the abovedescribed absorbent pad was overcome by widening the absorbent pad, and infolding side regions of the pad to define elongate side panels having upper exposed surfaces positioned adjacent a child during use of the diaper system. In use, the rear portions of the side panels were flared open to define a wide confining region for fecal matter, and the forward portions of the side panels were maintained in their infolded position to provide double thick portions having a sufficient quantity of absorbent material for retaining a sufficient quantity of urine to prevent an undesirable level of leakage from the diaper system. To enhance the strength of. the covering envelope, and to alleviate the problem of high fluid transmission through the bottom of the covering envelope, the lower layer of creped paper wadding was replaced with a backing cover web of a wet-strength paper stock having a greater wet-cross-direction energy absorption level than the creped paper wadding, and being less permeable to the passage of urine than said lower layer of creped paper wadding. This backing cover web extended the full width of the absorbent pad to thereby be included in the side panels to aid in maintaining the structural integrity of the fluff batt in the regions of said side panels. The backing cover web, in the region of the side panels, was therefore disposed between the porous, nonwoven facing cover web and the fluff batt. Since, as stated above, the backing cover web was purposefully designed tobe less permeable to the passage of urine than the previously utilized lower layer of creped paper wadding, it provided a physical impedi- SUMMARY OF THE INVENTION The elongate, disposable absorbent pad of this invention includes an elongate absorbent layer and a covering envelope. The absorbent layer comprises a fibrous fluff batt and a layer of creped paper wadding disposed in intimate contact with at least a lower face of said fluff batt and having a transverse dimension at least substantially equal to the transverse dimension of said fluff batt. This absorbent layer is disposed within the covering envelope which comprises a fluid pervious, adhesively bonded fibrous facing cover web and a backing cover web of wet-strength paper stock. The backing cover web is disposed contiguous to and in overlying relationship with the lower layer of creped paper wadding. The facing cover web has elongate side margins extending around elongate sides of the absorbent layer, and overturned upon and secured to the backing cover web. Side regions of the absorbent pad structural integrity of the absorbent pad during its use in the diaper system. In addition, the backing cover web has a lower wet-cross-direction energy absorption level than the facing cover web to act as a shock absorber to loads encountered by the absorbent pad during use of the diaper system of this invention. To further explain, the loads which are initially applied to the facing cover web during use of the diaper system are transmitted around marginal edges of the absorbent pad to the backing cover web. Since the backing cover web has a lower wet-cross-direction energy absorption level than the facing cover web, it will tend to tear and relieve stresses prior'to the applied load reaching, or exceeding the energy absorption level of the facing cover web to thereby prevent the facing cover web from tearing and exposing inner components of the absorbent pad to the skin of a child during use of the diaper system.

The backing cover web is sufficiently less permeable to the passage of urine than the lower layer of creped paper wadding to constitute a partial moisture barrier for inhibiting the passage of urine through the back surface of the absorbent pad. By reducing the permeability of the backing cover web to the passage of urine, excessive leakage through the absorbent pad, onto the fluid pervious pad-retaining garment, and past marginal edges of said pad-retaining garment is reduced. The backing cover web is excluded from the side panels of the absorbent pad so that it will not provide an impediment to urine transmission from. the upper exposed surfaces of the side panels into the highly absorbent fluff batt.

The lower layer of creped paper wadding is included in the side panels between the facing cover web and the absorbent fluff batt. This lower layer of creped paper wadding has been found to have sufficient strength in conjunction with the overlying facing cover web to provide support for said fluff batt in the regions of said side panels when said lower layer is positioned in the perineal region of the child to initially receive the impingement of urine thereon. By maintaining the side panels infolded in this forward region, a large absorptive capacity for urine is provided. Since the backing cover .web is disposed on a surface of the pad-retaining garment, it will not engage the skin of a child, and therefore any tearing of this backing cover web resulting from excessive laods encountered by theabsorbent pad during use of the diaper system will not expose inner components of the absorbent pad to the skin of a child.

BRIEF DESCRIPTION OF THE-DRAWINGS FIG. 1 is an isometric view of the absorbent pad of this invention with parts broken away to show details of construction;

FIG. 2 is a plan view of the diaper system of this invention'; and FIG. 3 is a sectional view along line 3-3 of FIG. 1. DESCRIPTION OF THE PREFERRED EMBODI- MENT OF THE INVENTION Referring to FIGS. 1 and 2, the diaper system of this invention includes a pad-retaining garment l2 and a unique, elongate disposable absorbent pad 14. The disposable absorbent pad 14 is comprised of an elongate, absorbent layer 16 disposed within a covering envelope 18. The elongate, absorbent layer 16 of the dis-. posable absorbent pad 14 includes an elongate fluff batt 20 having a lower layer of creped paper wadding 22 disposed adjacent the bottom face of the fluff batt to define a backing surface 23 of the absorbent layer nate the upper layer of creped paper wadding 24, al-

though in the preferred embodiment of this invention the upper layer of creped paper wadding performs the desirable function of cooperating with the lower layer of creped paper wadding to support the fluff batt 20. The number of plies of creped paper wadding which is utilized in each of the upper and lower layers can be varied within wide limits. In practice, two plies of creped paper wadding in each of the upper and lower layers have proven satisfactory to aid in supporting the fluff batt 20.

The fluff batt 20 preferably is comprised of short cellulosic fibers of a paper-making length less than onefourth inch, and preferably is an air-laid batt manufactured on a .Ioa Fiberizer, I-Iammermill, or the like. This fluff batt 20 preferably is profiled to define a forward one-half section 26 having a greater weight of fibers therein than a rearward one-half section 28 whereby the forward section 26 is thicker and/or more dense than the rearward section 28. An embossed pattern is impressed into the fluff batt 20 through the upper and lower layers of creped paper wadding 22 and 24 to define compressed regions in the form of transversely spaced, elongate channels 30 separated by elongate high loft regions 32 to aid in directing fluid along the elongate direction of the fluff batt. In addition, the formation of an embossed pattern in the fluff batt 20 through the upper and lower layers of creped paper wadding functions to stabilize the fluff batt to prevent splitting of the fluff batt into separated clumps which impairs the fluid absorbing capability of said fluff batt. It is within the purview of this invention to utilize fluff batts other than the above-described profiled, embossed fluff batt 20 in the absorbent layer 16. The above-described structure of the absorbent layer, including a profiled, embossed fluff batt therein, forms the subject matter of a separate patent application titled DIAPER SYSTEM AND ABSORBENT PAD THEREFOR, filed on even date, and is the invention of George G. DeNight et al.

The covering envelope 18 has forward and rearward end margins 40 and 42 which extend beyond end margins of the fluff batt 20, and which are closed by transverse end seal bands 41 and 43. The upper and lower layers of creped paper wadding 22 and 24 also extend beyond the end margins of the fluff batt 20 and are inciuded in the seal bands 41 and 43. The specific structure of the transverse end seal bands does not form a part of the present invention but is preferably of the structure indicated in copending application Ser. No. 137,839, filed Apr. 27, l97l, and assigned to Scott Paper Company, the subject matter of which is hereby incorporated by reference.

The covering envelope 18 includes a porous, elongate, adhesively bonded fibrous facing cover web 44, and a backing cover web 46 of a wet-strength paper stock. The elongate backing cover web 46 is disposed adjacent the backing surface 23 of the absorbent layer 16, and the porous, elongate, facing cover web 44 is disposed adjacent the facing surface 25 of said absorbent layer. The facing cover web 44 has side margins 48 and 50 which extend around side margins of the absorbent layer 16, and which are overturned upon and secured to the backing cover web 46 adjacent side margins 52 and 54 of said backing cover web. The facing cover web 44 is secured to the backing cover web 46 by elongate, securing stripes 57 of any suitable adhesive material, but preferably, a hot melt adhesive is utilized (FIG. 3).

Referring to FIGS. 2 and 3, side regions of the absorbent pad 14 are infolded along elongate fold lines 58 and 60 to form side panels 62 and 64 in overlying relationship with the elongate, facing cover web 44 in a center region 66 of said absorbent pad 14. Side panels 62 and 64 have upper exposed surfaces 68 and 70, respectively, and inner end margins 69 and 71 which terminate short of each other to leave exposed a portion of the facing cover web 44 in the center region 66. This exposed portion of center region 66, in conjunction with upper exposed surfaces 68 and 70 of the side panels 62 and 64 defines the upper exposed surfaces of the absorbent pad 14 when said absorbent pad is positioned on a fluid-impervious retaining garment 12 to form the diaper system of this invention. The side panels 62 and 64 are retained in their infolded positions by a suitable securing means, such as securing dots or tacks 72, 74, of adhesive, or the like, disposed adjacent the forward end margin 40 of the covering envelope 18 between the side panels 62 and 64 and the facing cover web 44. The upper exposed surfaces 68 and 70 of the side panels are defined by portions of the facing cover web 44 initially disposed on the back side of the absorbent pad 14 prior to folding, and therefore, the lower layer of creped paper wadding 22 is disposed between the facing cover web 44 and the fluff batt in said side panels. The lower layer of creped paper wadding, in conjunction with the overlying facing cover web provides support for the fluff batt in the side panels to maintain the structural integrity of the fluff batt in this region. The elongate, side margins 52 and 54 of the backing cover web 46 are disposed adjacent the fold lines 58 and 60, respectively, so that the backing cover web 46 is not disposed in underlying relationship with the portions of the facing cover web defining the upper exposed surfaces 68 and 70 of the side panels 62 and 64. The unique structural relationship among the facing cover web 44, the backing cover web 46 and the lower layer of creped paper wadding 22, which structural relationship is the essence of this invention, is dictated by the required physical properties in the absorbent pad 14 of this invention as will be explained hereinafter.

The facing cover web 44 must have sufficient strength to assure that the structural integrity of the disposable absorbent pad 14 is maintained during its use in the diaper system 10. Since the facing cover web 44 is in contact with a child during use of the diaper system 10, the integrity of said facing cover web must be maintained to prevent inner components of the absorbent pad 14, such as the fluff batt 20, from coming into contact with, and sticking to a childs skin. In addition to the abovedescribed strength requirement, the facing cover web 44 must be highly permeable to urine to permit the urine to pass substantially instantaneously into the absorbent layer 16 which has a high absorptive capacity, i.e., ability to store large quantities of urine without leaking.

The strength of the facing cover web 44 is determined by its energy absorption level, i.e., the ability to absorb energy without tearing or losing its structural integrity. The energy absorption level is a function of both tensile strength and extensibility of said web, and is measured in units of work, i.e., inch-pounds. The critical strength property of the facing cover web 44 is its wet-cross-direction energy absorption level, since the greatest amount of work is absorbed in the crossdirection of the facing cover web during use of the diaper system 10, and the criticality of the strength requirement in the facing cover web exists when the disposable absorbent pad 14 is wet. The method of determining wet-cross-direction energy absorption levels will be described later in this application. The wetcross-direction energy absorption level in acceptable facing cover webs of this invention is in the range of from about 0.11 to about 0.19 inch-pounds, and preferably in the range of from about 0.16 to about 0.19 inch-pounds.

An acceptable facing cover web 44 according to this invention has a fluid permeability of greater than 15 darcies, and preferably in the range of from about 16.2 to about 18.2 darcies as calculated in a manner which is described later in this application. One facing cover web 44 which has both the requisite wet-crossdirection energy absorption level and fluid permeability is a pattern bonded, carded web of percent rayon staple fibers 1% denier, 2-inch length. The adhesive utilized to pattern bond such a web is preferably an acrylic latex, such as E-32, manufactured by Rohm and Haas, and this latex accounts for approximately 18-2O percent by weight of the web. It is contemplated that any adhesively bonded, fibrous web having the requisite wet-cross-direction energy absorption level and fluid permeability, as set forth above, will be acceptable as a facing cover web in the disposable absorbent pad 14 of this invention. Such webs may be nonwoven, apertured webs comprising 100 percent wood pulp fibers of a short papermaking length less than one-fourth inch; 100 percent longer staple synthetic fibers; or blends of short paper-making fibers and longer synthetic fibers.

The backing cover web 46 must have sufficient structural integrity when wet, i.e., a sufficiently high wetcross-direction energy absorption level, to function as part of the covering envelope 18 in maintaining the structural integrity of the disposable absorbent pad during its use in the diaper system 10. The backing cover web 46 has a lower wet-cross-direction energy absorption level than the facing cover web 44 to act as a shock, or load-absorbing member for forces applied directly to the facing cover web 44 during use of the diaper system 10. Since the backing cover web 46 has a lower wet-cross-direction energy absorption level than the facing cover web 44, the backing cover web will tend to tear, and leave the facing cover web 44 intact, when the energy applied to the cover envelope l8 during use of the absorbent pad 14 exceeds the wet-crossdirection energy absorption level of said backing cover web. Since this lattermentioned energy absorption level will be exceeded before the wet-cross-direction energy absorption level of the facing cover web 44 is reached, the backing cover web will tear first to thereby reduce the stress level in the cross-direction of the wet facing cover web and prevent the energy applied to the facing cover web from exceeding its wet-cross-direction energy absorption level. The backing cover web 46 has a greater wet-cross-direction energy absorption level than the lower layer of creped paper wadding 22 to function properly as part of the covering envelope 18 to aid in maintaining the structural integrity of the absorbent pad 14. In the preferred embodiment of this in vention, the backing cover web .46 has a wet-crossdirection energy absorption level in the range of from about 0.01 to about 0.06 inch-pounds, and preferably, the wet-cross-direction energy absorption level is in the range of from about 0.01 to about 0.03 inch-pounds. The backing cover web 46 has a permeability to urine which is less than the permeability of the porous facing cover web 44 and the lower layer of creped paper wadding 22. This lower fluid permeability is required so.

that the backing cover web 46 can suitably act as a barrier to prevent urine from easily passing therethrough to thereby prevent excessive urine leakage from the diaper system 10. In the preferred embodiment of this invention, the backing cover web 46 has a fluid permeability of under darcies, and preferably in the range of from about 2.7 to about 4.0 darcies, as calculated in a manner to be described later. In addition, the backing cover web has absorbent qualities to aid in storing urine which strikes completely through the thickness of the fluff battand lower layer of creped paper wadding to thereby function as an absorbent component of the absorbent pad 14.

Any fibrous web having the requisite wet-crossdirection energy absorption level and fluid permeability, as set forth above, is acceptable as a backing cover web. Preferably, the backing cover web is .a wet-laid web-having a fiber content of 100 percent short, wood pulp, paper-making fibers of less than one-fourth inch, said web containing a polymeric, water soluble, thermosetting resin in the range of from about 2 percent to about 4 percent by weight of the backing cover web to provide wet strength in said web. The wet-strength res- .ins' utilized in the backing cover web 46 of this invention are preferably cationic, such as melamine and urea formaldehyde composites; however, it is contemplated that other polymeric, water soluble, thermosetting resins can be-utilized, such as those which are anionic or nonionic. I

- In the-preferred embodiment of this invention the creped paper wadding has a wet-cross-direction energy absorption level in the range of from about 0.001 to about 0.003 inch-pounds; and a fluid permeability exceeding S darcies, and preferably exceeding 5.6 darcies. Creped paper wadding, as utilized throughout the specification and claims, refers to a wet-formed web of 100 percent short, wood pulp fibers of a papermaking length of less than one-fourth inch, said web being free of wet-strength resins and having a crepe ratio of from about 50 percent to about 225 percent, wherein said crepe ratio is defined as 100 times the difference between the dryer and reel speed divided by the reel speed.

Referring to FIG. 2, the pad-retaining garment 12 of diaper system preferably is made from a fluid impervious, flexible sheet material, such as polyethylene, polypropylene, or polyvinyl chloride. The garment 12 has a forward marginal edge 80 adapted to be positioned around the front area ofa child and a rearward marginal edge 82 adapted to be positioned around the rear area of a child (FIG. 2). A forward region 84 of the regaining garment 12 is interconnected to a rearward region 86 through an intermediate region 88. The intermediate region 88 has a reduced transverse dimension defining the crotch and thigh encircling region of the retaining garment 12. Opposite transverse edges of the forward region 84 are provided with male snap elements 90, 92 which are adapted to cooperate with opposed female snaps 94, 96, respectively, which are disposed adjacent opposite transverse edges of the rearward region 86 to permit the retaining garment to be fastened about a child. The diaper system 10 is worn by a child in a bikini fashion with the forward marginal edge 80 of the pad-retaining garment 12 disposed below the abdomen ofa child about 2 or 3 inches above the crotch area. Any suitable fastening means can be utilized in place of the male and female snap fasteners; the particular fastening means not forming a part of this invention. Elastic material is fastened adjacent the forward marginal edge 80, the rearward marginal edge 82 and opposed longitudinal edges 97, 99 defining the intermediate region 88 of the retaining garment 12 to insure that the impervious retaining garment 12 closely conforms to the legs and waist region of a child. A holding device 98 is secured to the forward marginal edge 80 of the pad-retaining garment and has a stem portion 100 extending rearwardly from said forward marginal edge and terminating in a cross member 102. The cross member 102 has pad-retaining members 104, 106, respectively disposed rearwardly of the securing tacks 72, 74 to retain the absorbent pad 14 within the padretaining garment 12. This holding device 98 is the invention of Paul J. Jarusik et al., and is covered in copending application Ser. No. 101,292 assigned to Scott Paper Company.

In use, the rear portion of the absorbent pad 14 is manually flared open as is shown in FIG. 2 to provide a wide confining region for fecal matter. This wide region is desirable to prevent the fecal matter from escaping from the diaper system 10 to'soil the retaining garment 12. A wide confining structure is not required in the forward section of the diaper into which urine is initially directed, and this portion remains folded during use to provide a high absorptive capacity for urine. Since the backing cover web is in contact with the retaining garment l2, tears in the backing cover web will not expose wet inner components, such as fluff batt 20, to a child to permit such inner components to stick to the child. I

Since the backing cover web is excluded from the side panels 62 and 64, its lower permeability will not affect the transmission of fluid from the upper exposed surfaces of the side panels into the fluff batt 20. It has been found that while the lower layer of creped paper wadding does not function suitably as a part of the covering envelope 18 by itself, it. does have sufficient strength to maintain the integrity of the fluff pad in the side panels of the absorbent pad14 when it is disposed between the facing cover web and the fluff batt in said side panels. Furthermore, the lower layer of creped paper wadding is highly permeable to the passage of urine, and thereforepermits rapid transmission of urine side panels, which causes excessive leakage from the diaper system 10.

CALCULATION OF WET-CROSS-DIRECTION ENERGY ABSORPTION LEVEL The wet-cross-direction energy absorption level, E, in inch-pounds, is obtained by clamping a strip of a water saturated specimen which is l-inch wide in the jaws of an Instron tensile tester. The jaws are initially separated 2 inches apart, with any noticeable slack being pulled out of the strip before clamping. The cross machine direction of formation of the strip is aligned with the direction of jaw separation, and strain is applied to the specimen by moving the jaws apart at a constant rate of 2 inches/minute. The area under the load-elongation curve is measured by an Instron integrator which is described in Instron Manual No. l-- l-l (C). The reading from the integrator is converted directly into work, or energy by the following formula:

E X/5,000 (l) (s) (units in inch-pounds) whereinz E wet-cross-direction energy absorption level in inch-pounds,

l full-scale load in pounds (this value is set on the Instron tensile tester),

s rate of sample extension in inches/minutes, and

X the integrator reading.

The integrator reading is divided by 5,000 because the full-scale integration carried out for 1 minute results in a count of 5,000, and we are concerned with the fraction of this full-scale integration which results from testing the specific specimen. Therefore, the energy absorption level is the amount of work which can be absorbed by a l-inch specimen under the abovedescribed test conditions prior to breaking of the specimen, and all values of energy absorption level set forth in this application are calculated values resulting from the data obtained in the above-described test.

CALCULATION OF FLUID PERMEABILITY The permeability, K, indarcies, is determined by placing a 2% inch diameter sample consisting of five plies of the material to be tested between a pair of 2% inch diameter porous screens. The porous screens utilized in this test are manufactured by Perforated Products, Inc., 68 Harvard St., Brookline, Mass, andare identified as 30 G. Each perforated screen has the following specifications:

Number of openings 30/lineal inch Whole diameter 0.024 inch Plate thickness 0.0028 inch Percent Open area 50 percent.

The dry basis weight of the five-ply sample, and the dry thickness is determined prior to disposing the sample between the screens. Five plies of material are utilized to insure a greater accuracy in the testing procedure, than if only one ply is utilized. The sample-screen assembly is inserted into a 2% inch diameter tubular vessel, and disposed on a bottom supporting surface thereof. The region of the bottom surface of the vessel underlying the sample-screen assembly is porous, and a water inlet is disposed adjacent the bottom surface of the tubular vessel to pass water through the samplescreen assembly. After the sample is saturated with water, the thickness of the specimen is adjusted to the previously determined original dry thickness of the sample by compressing the specimen-screen assembly with a foot extending from a caliper from which the thickness can be directly read. The caliper is adjusted for screen thickness to permit an accurate setting of the sample thickness by itself. A pressure head of 3 inches of water is created through the sample-screen assembly, and water is passed through said assembly and exits through an outlet nozzle where it is collected in a graduated container over a known increment of time to determine the flow rate of the water through the sample-screen assembly. The pressure drop across the screens as a function of flow rate is determined prior to disposing the specimen between the screens, and the appropriate pressure drop across the screens is subtracted from the preset pressure head of 3 inches to thereby calculate the pressure drop across the sample itself. The permeability, K, in darcies, is calculated from the following formula:

=qn P where:

q flow rate (centimeters lsecond) 1; viscosity of water (poise) L sample thickness (centimeters) A area of sample (centimeters AP pressure drop across the sample (dynes/centimeters p density of the sample (grams/cubic centimeter) g acceleration due to gravity (centimeters/- seconds All tests were run with water since water is more readily available than urine, and because water has a viscosity which is extremely close to that of urine, and therefore, behaves very similar to urine. The viscosity of water is approximately 0.01 poise, whereas the viscosity of urine is approximately 0.008 poise. All values of fluid permeability, K, which are set forth in this application relate to the calculated fluid permeabilities predicated on the use of water, rather than urine.

What is claimed is:

1. An elongate, disposable, absorbent pad for use as an insert in a pad-retaining garment, comprising:

A. an elongate, absorbent layer having a facing and backing surface, comprising;

1. an elongate, fluff batt of cellulosic fibers having top and bottom faces and a transverse dimension defined by spaced, elongate side margins, and

2. a lower layer of creped paper wadding disposed adjacent the bottom face of said fluff batt for defining the backing surface of said absorbent layer, said lower layer of creped paper wadding having a transverse dimension at least substantially equal to the transverse dimension of said fluff batt;

B. a covering envelope comprising;

1. a fluid pervious, adhesively bonded fibrous facing cover web, and

2. a backing cover web of wet-strength paper stock,

said backing cover web having a lower wet-crossdirection energy absorption level than said facing cover web, a higher wet-cross-direction energy absorption level than said lower layer of creped paper wadding, and a lower permeability to the passage of urine than said facing cover web and said lower layer of creped paper wadding;

c. said absorbent layer disposed within said covering envelope with said facing cover web overlying the facing surface of said absorbent layer, and said backing cover web overlying and disposed adjacent the backing surface of said absorbent layer, said facing cover web having elongate side margins extending around the elongate side margins of said absorbent layer and in overlapping relationship with said backing cover web for substantially the entire elongate extent of the absorbent pad, securing means adhering overlapping sections of the facing cover web and the backing cover web together along substantially the entire elongate extent of overlap;

D. said absorbent pad having elongate side regions defined between a center region and opposed side edges, the side regions of said absorbent pad ineluding said absorbent layer being infolded to form side panels in overlying relationship with said center region, said side panels having upper exposed surfaces defined by portions of said facing cover web, said backing cover web having elongate side margins terminating short of the side regions of said absorbent pad which are infolded to form the side panels so that the backing cover web is excluded from underlying said portions of said facing cover web defining the upper exposed surfaces of said side panels, said backing cover web being adapted to be disposed on a surface of a padretaining garment.

2. T he elongate, disposable, absorbent pad according to claim 1, wherein said absorbent layer includes an upper layer of creped paper wadding disposed adjacent the top face of said fluff batt for defining the facing surface of said absorbent layer.

3. The elongate, disposable, absorbent pad according to claim 2, wherein said backing cover web has a wetcrss-direction energy absorption level in the range of approximately 0.01 to. 0.06 inch-pounds, and a fluid permeability of less than darcies.

4. The elongate, disposable, absorbent pad according to claim 3, wherein said backing cover web has a wetcross-direction energy absorption level in the range of approximately 0.01 to 0.03 inch-pounds, and a fluid permeability in the range of approximately 2.7 to 4.0 darcies.

5. The elongate, disposable, absorbent pad according to claim 3, wherein said facing cover web has a wetcross-direction energy absorption level in the range of approximately 0.11 to 0.19 inch-pounds, and a fluid permeability of greater than darcies.

6.- The elongate, disposable, absorbent pad according to claim 4, wherein said facing cover web has a wetcross-direction energy absorption level in the range of approximately 0.16 to 0.19 inch-pounds, and a fluid permeability in the range of approximately 16.2 to 18.2 darcies.

7. The elongate, disposable, absorbent pad according to claim 5, wherein said facing cover web is a nonwoven fabric comprising synthetic fibers.

8. The elongate, disposable, absorbent pad according I to claim 7, wherein said nonwoven fabric is a carded rayon web.

9. The elongate, disposable, absorbent pad according to 'claim 6, wherein said facing cover web is a nonwoven fabric comprising synthetic fibers.

10. The elongate, disposable, absorbent pad according to claim 9, wherein said nonwoven fabric is a carded rayon web.

11. In a diaper system:

A. an elongate, fluid impervious pad-retaining gar- B. an elongate, disposable absorbent pad positioned on a surface of said pad-retaining garment;

C. holding means secured to said pad-retaining garment for removably retaining said absorbent pad within said pad-retaining garment, said absorbent padcomprising:

1. an elongate, absorbent layer having a facing and backing surface, comprising;

a. an elongate, fluff batt of cellulosic fibers having a top and bottom face, and a transverse dimension defined by spaced, elongate side margins, and i b. a lower layer of creped paper wadding disposed adjacent the bottom face of said fluff batt for defining the backing surface of said absorbent layer, said lower layer of creped paper waddinghaving a transverse dimension at least substantially equal to the transverse dimension of said fluff batt;

2. a covering envelope comprising;

a. a fluid pervious, adhesively bonded fibrous facing cover web and I b. a backing cover web of wet-strength paper stock, said backing cover web having a lower wet-cross-direction energy absorption level than said facing cover web, a higher wet-crossdirection energy absorption level than said lower layer of creped paper wadding, and a lower permeability to the passage of urine than said facing cover web and said lower layer of creped paper wadding;

3. said absorbent layer disposed within said covering envelope with said facing cover web overlying the facing surface of said absorbent layer, and said backing cover web overlying and disposed adjacent the backing surface of said absorbent layer, said facing cover web having elongate side margins extending around the elongate side margins of said absorbent layer and in overlapping relationship with said backing cover web for substantially the entire elongate extent of the absorbent pad, securing means adhering overlapping sections of the facing cover web and the backing cover web together along substantially the entire elongate extent of overlap;

4. said absorbent pad having elongate side regions defined between a center region and opposed side edges, the side regions of said absorbent pad including said absorbent layer being unfolded to form side panels in overlying relationship with said center region, said side panels having upper exposed surfaces defined by portions of said facing cover web, said backing cover web having elongate side margins terminating short of the side regions of said absorbent pad which are infolded to form the side panels so that the backing cover web is excluded from underlying said portions of said facing cover web defining the upper exposed surfaces of said side panels, said backing cover web being disposed on a surface of said pad-retaining garment.

12. The diaper system according to claim 1 1, wherein said backing cover web has a wet-cross-direction energy absorption level in the range of approximately 0.01 to 0.06 inch-pounds, and a fluid permeability of less than 5 darcies; and wherein said facing cover web has a wet-cross-direction energy absorption level in the range of approximately 0.11 to 0.19 inch-pounds, and a fluid permeability of greater than darcies.

13. The diaper system according to claim 11 wherein said backing cover web has a wet-cross-direction energy absorption level in the range of approximately 0.01 to 0.03 inch-pounds, and a fluid permeability in synthetic fibers.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4501586 *Mar 11, 1983Feb 26, 1985Personal Products CompanyAbsorbent structure with reservoir
US4678464 *Feb 22, 1985Jul 7, 1987Personal Products CompanyAbsorbent structure with reservoirs and a channel
US4753644 *Jun 4, 1987Jun 28, 1988National Research Development CorporationIncontinence pads
US4781713 *Jun 10, 1987Nov 1, 1988Sherwood Medical CompanyIncontinence pad for females
US5019070 *Mar 1, 1988May 28, 1991Margaret RubenUndergarment shield
US5405342 *Jun 29, 1994Apr 11, 1995Kimberly-Clark CorporationDisposable absorbent article with flushable insert
US5458591 *Feb 14, 1995Oct 17, 1995Kimberly-Clark CorporationDisposable absorbent article with flushable insert
US5476457 *Feb 14, 1995Dec 19, 1995Kimberly-Clark CorporationDisposable absorbent article with flushable insert
US5613959 *Feb 14, 1995Mar 25, 1997Kimberly-Clark CorporationDisposable absorbent article with flushable insert
US6030373 *Apr 13, 1995Feb 29, 2000Kimberly-Clark Worldwide, Inc.Multi-attachment fastening system
US7629501Sep 8, 2006Dec 8, 2009Jennifer Lynn LabitReusable diapers
US8062276Mar 31, 2008Nov 22, 2011Jennifer Lynn LabitReusable diapers
US8110072May 4, 2009Feb 7, 2012The Procter & Gamble CompanyThrough air dried papermaking machine employing an impermeable transfer belt
US8262635Mar 31, 2008Sep 11, 2012Jennifer Lynn LabitReusable diapers
US8409163Jan 6, 2012Apr 2, 2013Jennifer Lynn LabitReusable diapers having first and second liquid-absorbent flaps
US8430857Jan 17, 2012Apr 30, 2013Jennifer Lynn LabitReusable diapers
US8518007Dec 7, 2009Aug 27, 2013Jennifer Lynn LabitReusable diapers
US8777915Sep 27, 2011Jul 15, 2014Jennifer Lynn LabitReusable diapers having seam allowances
WO2004082545A1 *Mar 18, 2004Sep 30, 2004Henri BriseboisLiquid-absorbing component for an absorbent article
Classifications
U.S. Classification604/375, 604/364, 604/373, 604/378, 604/365, 604/386
International ClassificationA61F13/15
Cooperative ClassificationA61F13/533, A61F13/505, A61F13/53418
European ClassificationA61F13/505, A61F13/533, A61F13/534B2