US 3029817 A
Description (OCR text may contain errors)
April 1962 K. J. HARWOOD ETAL 3,029,817
CELLULOSIC PRODUCT 5 Sheets-Sheet 1 Filed May 9, 1960 April 17, 1962 Filed May 9, 1960 K- J- HARWQOD ET AL CELLULOSIC PRODUCT 3 Sheets-Sheet 2 April 17, 1962 K. J. HARWOOD ETAL 3,02 ,817
CELLULOSIC PRODUCT Filed May 9, 1960 3 Sheets-Sheet 3 United States Patent G 3,629,817 CELLULUSKC PRUDUCT Kenneth J. Harv-road, John C. Bietzinger, and Winterton U. Day, Neenah, Win, assignors to Kimberly-Clark Gorporation, Neenah, Wis., a corporation of Delaware Filed May 1969, Ser. No. 27,922 8 Glaims. (El. 128-299) This invention relates broadly to improvements in absorbent bandages, and more particularly to bandages of the sanitary napkin type.
The present application is a continuation-in-part of and merges two U.S. applications, Serial Nos. 664,538 and 665,369 which were concurrently filed on June 10, 1957, and now abandoned. Those applications disclosed what applicants believed at the time of filing to comprise two distinct though closely related inventions. Since filing the above applications, the incorporation of the invention in all Kotex brand sanitary napkins manufactured and sold in the U.S. by applicants assignee has resulted in a more complete understanding of the theory of operation. As a result thereof, applicants now believe that employment of a fluid control element comprising hydrophllic fibers as taught in application 664,538 involves the same inventive concept as does employment of a control element consisting of hydrophobic fibers as taught in application 665,369. Stated differently, the concept is now seen as a unitary one which may clearly be explained with out the necessity of distinguishing between positive and negative capillarity. The theory of operation of the fluid control elements is modified and expanded herein and he drawings have been reduced in number. The retained structure illustrative of various embodiments of the invention is identical to that in. the originally filed applications.
A major object of the present invention is to provide an improved fluid control element particularly adapted for incorporation in sanitary napkins and the like designed for optimum efficiency when properly used but which must remain capable of serving their intended purpose even though with somewhat less eiiiciency when improperly used.
Another object is to provide a fluid absorbent bandage with a substantially non-absorbent control element in association with elements of high fluid absorbency to serve, with the aid of gravity, in a manner allowing fluid passage through the control element in one direction while substantially preventing fluid passage therethrough in an opposite direction.
A further object is to provide an improved reversible sanitary napkin having high fluid retentivity and good form retention characteristics without sacrifice of softness and resulting user comfort.
Other objects and advantages will become apparent from the drawings and the description, as will various modifications and adaptations of the described structure without departure from the inventive concept as defined in the appended claims.
In the drawings,
FIGURE 1 is a perspective view of a bandage such as a surgical dressing and shown partially open to illustrateincorporation therein of the inventive principles,
FIGURE 2 is a perspective view of a sanitary napkin incorporating the invention, the constructional details being shown fragmentarily enlarged.
FEGURE 3 is a cross sectional view of a sanitary napkin of the general type shown in FIGURE 2, with a single control element incorporated therein,
FIGURE 4 is a view similar to FlGURE 3 and illustrating a napkin construction incorporating dual control elements,
FIGURE 5 is a view similar to FIGURE 4 out show- 3,029,817 Patented Apr. 17, 1962 "ice ing a modified construction which includes a centrally disposed baflle,
FIGURE 6 is a perspective view of a sanitary napkin incorporating a still further modification of the invention,
FIGURE 7 is a view similar to FIGURE 6 illustrating another embodiment of the invention,
FEGURE 8 illustartes cross sectionally the configuration of the mid-section of the sanitary napkin of FIG- URE 6 as properly worn, and
FIGURE 9 is a view similar to FIGURE 8, but showing the napkin of FIGURE 6 as improperly worn.
Since the introduction of sanitary napkins about forty years ago and their subsequent wide acceptance in many countries of the world, a large amount of research and development effort has been directed to their improve ment. While manufacturers of these highly competitiveproducts have progressively improved their construction, it is generally recognized by persons skilled in the art that improvements to date, While substantial, still fall short of long sought optimum objectives. More specifically, manufacturers heretofore have been able substantially to increase the absorbent capacity of napkins only by accepting certain undesirable characteristics such as undue bulk, reduction in softness, or at the expense of reversibility. While non-reversible napkins with satisfactory absorbent characteristics are known, it is recognized in the industry that they do not provide a complete answer since it has proved impractical, if not impossible, to educate all users as to the proper application thereof. If worn reversed such a napkin fails to performits intended function. The industry has long conceded that a napkin of optimum design must incorporate all of the desirable characteristics of softness, retention of form during use, good liquid absorption even when improperly worn, and the ability to I resist strike-through and attendant bottom and side stains, even when the napkin is subjected to excessive quantities of fluid. In addition, such a napkin should be highly effective in dispersing absorbed fluid throughoutsubstantial portions of the napkin to permit most effective utilization of absorbing elements and resulting minimization of bulk and density.
/ In addition to the absorbency characteristics, the napi not only becomes uncomfortable to wear but also tends to lose its ability to maintain itself in a desired position.
While a napkin should have a soft and comfortable feel. under both dry and damp conditions, softness must beaccompanied by good form retention characteristics.
An additional desirable characteristic of a napkin is that it be reversible, that is, that it may worn with either side next to the body with adequate comfort and without loss of fluid acceptance, or absorbent capacity. Since napkins are often applied hurriedly and often without reference to manufacturers directions, the above optimum characteristics are of very considerable importance. Napkins which include a fluid impermeable member between the bottom surface and the absorbent core of the napkin, and those which have devices on the bottom side of the napkin for fastening the napkin to an over-all sup porting member do not serve their intended function as fluid absorbers when reversed, hence are irreversible nap-' kins. Napkins may be considered to be completely reversible if either side may be worn next to the body without any substantial loss of the napkins intended ab If the Many attempts have been made to produce napkins which combine these foregoing attributes. Usually, however, a change which enhances one attribute results in a corresponding loss in another. For example, compressed paper laminations have been introduced into the absorbent centers of napkins to improve their form retention. Such improvement in form retention may, however, result in a loss of softness of the napkin. Conversely, attempts to gain softness by increased use of fluff near the surface of the napkin may result in a loss of form retention.
One of the most important efforts to improve napkins has been in the direction of prevention of strike-through. Pads have been constructed with impermeable plastic films, or waxed impervious paper sheets at or near the bottom of the pad. Some of these devices may improve the fluid retention characteristics of a pad at the expense of reversibility. Sanitary napkins and bandages of the types which are used for wound dressings, burn dressings, hospital pads, etc. are all similar in that they are required to absorb body fluids while being maintained in contact with the surface of the human body. The fundamental concept of the present invention is applicable not only to sanitary napkins but also to such other types of bandages.
Incorporation of the invention in a bandage 18 of the surgical wound dressing type is shown in FIGURE 1. The bandage comprises a conventional gauze outer wrapper 20 which may be of suitable woven or non-woven fluid pcrvious material, an absorbent core or batt 22, and a control element 24- adjacent thereto.
Since the invention resides in the construction of and the cooperative relation between one or more non-absorbent control elements and other elements of high fluid absorbency, the basic principles will be first discussed with reference to both the absorbent bandage 18 of FIG. 1 and a simply constructed sanitary napkin which is shown cross sectionally in FIG. 3. Each pad includes a highly absorbent core or batt 22 and a control element 24, both of which are enclosed in wrapper 20. The batt 22 is of a conventional highly absorbent material of the type used for absorbent bandages, and may be absorbent cotton, absorbent creped wadding, loosely felted fibrated wood pulp fluff or other types of fluff materials. Such a core provides the major amount of absorptive capacity, hence bulk of the pad. Although the core is sometimes illusstrated herein as a single element it may consist of laminations of a single absorbent material or of combinations of wadding and fluff or other absorbent materials, and preferably includes one or more fluid spreading elements.
Control element 24 preferably consists of fluid repellent fibers such as synthetic fibers, but certain other fibers which to some extent are wettable may be employed. Regardless of the particular fibers used, they must, however, retain inherent resiliency, both when dry and when wet, and be of sutficient length to impart to said element 24 the characteristics of a relatively open springy mat. While it is preferred that such fibers range in length from about 1 inch upwardly (especially when synthetic fibers are used, hence the length thereof is a matter of selection), it is also possible to fabricate element 24 of certain natural fibers which are somewhat shorter in length, as for example, about /1 inch. It is important, however, that regardless of the fibers employed, element 24 presents in effect a three-dimensional structure of very low density rather than assuming the characteristics of a relatively flat fibrous web wherein the fibers are haphazardly disposed but resting upon other fibers to extend substantially in a common plane. The relatively long intertwined resilient fibers of control element 24 do not lie flat, one upon the other, but instead extend in all directions with individual fibers widely separated to provide a three dimensional highly open springy structure, as distinguished from the non-springy flat and relatively closed web resulting from the mere deposit of shorter fibers to produce a relatively closed paper-like web. The function of control element 2:; is that of a fluid insulator with a very low degree of capillary attraction to fluids migrating through adjacently positioned highly absorbent elements. However, due to the open springy mat-like characteristics of the control element, it otters no substantial resistance to drops of liquid or to larger liquid accumulations which under certain conditions of use are drawn down through the element by the force of gravity.
The non-reversible bandage 18, FIG. 1, illustrates the inventive principles applied in their simplest form with control element 24 contiguously engaging a fibrous batt 22 or the like and having high fluid absorbency characteristics. Elements 24 and 22 are maintained in unitary assembly by a gauze-like or other highly fluid permeable wrapper 20. Bandage 13 is shown in the reverse or improper position of use with the wrapper fold and control element 2d positioned upwardly of absorbent element 22, whereas when properly used element 22 is positioned to contact the fluid source. With the fluid source adjacent the upper surface of the napkin as shown, very little fluid is absorbed by wrapper 20, and due to the non-absorbent nature of element 24, very little fluid can migrate there through by a wicking action. Since there is therefore little tendency toward fluid dispersion laterally of either wrapper 2d or control element 24, fluid arriving at the bandage either in drops or in larger quantities merely drops downwardly under the aid of gravity and through the relatively open springy mat-like insulator 24, the widely separated fibers of which offer no substantial re sistance to such passage, nor do they promote lateral dispersion of the fluid. Upon completion of direct passage downwardly through element 24 the fluid enters highly absorbent batt 22 to be dispersed therein in all directions by migration through that highly absorbent clement. Control element 24 thus serves as an open valve to allow free passage of fluid therethrough, and since it does not absorb liquid or lose its springiness upon exposure to liquid, it performs the important function of insuring that the napkin retains good form-sustaining characteristics during use, even when wet.
FIGURE 3 illustrates the napkin in its proper position for use with the top surface of the napkin to be placed adjacent the Users body, it being understood that the napkin is then held transversely arced downwardly as shown in FIGURES 8 and 9. As the fluid passes through the highly permeable wrapper 2t) and into batt 22 the high fluid absorbency characteristics of batt 22 insure fluid migration by wicking in all directions. Batt 22 is intended to absorb an amount of fluid to which the napkin is normally subjected and to disperse that fluid substantially throughout batt 22 before it reaches the bottom surface of the batt. However, when the pad is subjected to excessive amounts of fluid, such migration may continue downwardly through batt 23 with the result that the bottom surface thereof becomes wet. However, even under most conditions of exposure to excessive amounts of fluid, control element 24 continues effectively to insulate the bottom portions of wrapper 26 from the fluid absorbed by batt 22.
The effectiveness of control element 24 as a fluid insulator when below batt 22 during proper use of the napkin is due to the inability of the element to wick or migrate fluid therethrough. As explained in connection with the FIG. 1 structure, unless fluid is introduced to the upper surface of element 24 either in the form of drops or in larger accumulations, fluid is not drawn through element 24 by gravity.
Drops or larger fluid accumulations do not form at the bottom surface of a highly fluid absorbent member such as batt 22 so long as fluid migration continues therein. This is true even when batt 22 is exposed to substantially more fluid than it is intended normally to absorb. If, for example, fluid migration continues downwardly through a central portion of batt 22 sufliciently to reach the bottom surface thereof, lateral fluid migration still continues and is effective to prevent the accumulation of liquid in the form of drops or larger accumulations along the lower surface of the batt. This remains true at least until all portions of batt 22 are completely saturated and further migration ceases. Control element 24 therefore remains highly effective as a fluid insulator to retain the bottom of the napkin dry even under conditions of exposure of batt 22 to substantially larger amounts of fluid than the napkin is designed normally to handle. Failure of control element 24 to serve its intended purpose may occur only after all portions of batt 22 become so fully saturated with fluid that migration ceases and fluid accumulations form at the bottom of batt 22. However, that is a condition which would rarely occur since the total absorptive capacity of batt 22 is suflicient to prevent such saturation except under the most extreme conditions.
While it is diflicult to determine the average amount of pressure to which a sanitary napkin may be subjected during use, it is believed that an arbitrary figure of approximately 1.1 pounds per square inch comes fairly close to representing a degree of pressure which may commonly be involved. The weight of control element 24 is not particularly critical. Where only a single element is employed, good results are obtained with an element varying in weight in respect to the weight of the pad filler throughout a range of l /2% to 25% of the filler weight. Where dual control elements are employed as described below in connection with the construction shown in FIGURES 4 and 5, the element weight may vary between 3 and 50% of the pad filler weight. The control element must, however, be constructed of loosely intertwined fibers which are of suflicient length and which retain sufficient inherent resiliency, even when wet, to impart to the element sufficient elasticity to resist close packing of the fibers thereof and retention, of the characteristics of a springy three dimensional structure when subjected to the normal range of pressures during usev It is very important that the control element resists pressures of use to the extent that the element fibers are not flattened down into a thin sheet-like configuration since fluids would then be readily wicked therethrough and the element would fail to function as a fluid insulator. As is well known in the art, those elements of a sanitary napkin or the like whose primary function is to absorb fluids, whether constructed of creped wedding or of cellulosic fibers in the form of a find, have certain characteristics of inherent resiliency when dry which largely disappear when subjected to fluid, and such elements become relatively shapeless and non-form-sustaining after absorbing fluids.
Since control element 24- readily passes fluids without absorbing them when the napkin is improperly worn and isolates but does not absorb fluids when the napkin is properly worn, element 24- remains inherently formsustaining during the enti e period of use. Element 24 thus serves a very important function in addition to its function as a unidirectional fluid isolator, since as above mentioned, both optimum efliciency and comfort are obtained only when a napkin retains its shape even after absorbing fluids.
The structure shown cross sectionally in FIGURE 3 differs from the FlGURE 1 structure by the addition of a control element cover sheet 25 disposed intermediate control element 24- and the wrapper 24; which is shown overlapped along the bottom of the pad. Cover sheet 25, which may be a thin layer of absorbent opaque material such as creped wadding, is provided to mask from view the bottom wall of absorbent material 22 which in the absence of the cover sheet may be seen through both the light weight fluid pervious wrapper 2t) and through the relatively open control element 24. As exudate migrates downwardly through batt 22 to the extent that the bottom thereof is stained, such stains in the absence of sheet 25 show through the transparent wrapper and control element. .Even though control elemeat 24 prevents the exudate from further downward migration, the stains present an objectionable appearance which is hidden by cover sheet 25. The absorbent capacity of the thin cover sheet 25 is, however, so small that it has no substantial effect on the fluid acceptance of accumulations adjacent the control element when the bandage is improperly worn.
The preferred construction of FIG. 6 is designed for normal use shown in FIG. 8. In that position control element 2 is positioned below a major fluid absorbing assembly consisting of two layers 22 of wood pulp fibers in the form of had maintained spaced apart by one or more sheets of creped wadding 28 and a baflie of waxed paper or the like $9. The assembly of fluff, wadding and the baffle is enclosed in a light weight fluid absorbing wrapper 32 such as a sheet of creped wadding. Control element 24, disposed immediately below the major absorbent assembly may comprise a very loosely assembled fluid insulator consisting of resilient rayon fibers about 2 /2" in length and of a denier of about 15, the fibers having been assembled in springy mat formation by gar-netting or carding. The original non-compressed thickness of element 24 in this instance is between A5" and A.
Assemblies 34 and 36 each consisting of a few sheets of creped wedding are positioned respectively above the main absorbent element and below the fluid control element 24. A pair of fluid impermeable strips 49 and 42 extend along the sides of the assembled element to guard against staining, the entire assembly of elements being enclosed in the suitable wrapper 20, preferably of a light weight non-woven highly fluid permeable material.
While the cross sectional configuration of the central portion of a sanitary napkin when in the position of use varies somewhat due to the anatomical differences of users, F165. 8 and 9 accurately represent a rather commonly assumed configuration as determined by soliditying the napkin of FIG. 6 while in the position of use by starch or the like. A cut is then made transversely of the central portion thereof and by the use of dies the various elements are brought into clear contrast. While most of the various elements comprising the structure are maintained contiguously engaged by the exerted body pressures, it proves quite diflicult to distinguish one from the other when shown in that manner. Hence for purposes of better illustration, the various elements are shown somewhat spaced apart rather than in their true positions, although their cross sectional contours have been maintained.
As shown in FIG. 8, body exerted pressures place the uppermost elements of the napkin under more compression than the lowermost elements thereof, with the central portions of the uppermost elements compressed more than lateral portions thereof. The central portions of the uppermost elements assume the somewhat dished configuration as shown. As fluid passes through the pervious wrapper 20 to enter the elements! comprising a few creped wedding sheets, that element, being of limited fluid absorbency, is quickly saturated in the area of the fluid source, the fluid continuing to migrate through sheet 32 and into the uppermost fluff layer 22 of the major absorbing assembly. While substantial fluid migration occurs in layer 22, the central portion thereof soon becomes saturated with resultant fluid passage and satura-.
tion of the wadding sheet 28 which is in contacting engagement with baflle 36. Further downward fluid migration is resisted by the fluid repellent properties of bar'lle 34 with the result that the fluid substantially migrates into lateral portions of the lower fluff element or batt 22 as aided by the fluid repellent properties of the baffle.
While bailie 3% thus promotes fluid migration, there may be some fluid passage through the baflie as well as around the margins thereof and into the lower absorbent flufl element 22. Baffles are of two general types-those which merely resist fluid passage therethrough, and those which prevent any such passage. While either type may be employed, it will be assumed for purpose of this description that battle 3%) is of the former type. Under normal conditions of use the lower element 22 does not receive enough fluid to become even partially saturated, but such a condition may occur throughout an upper localized area of that element, thus ermitting fluid passage therethrough with resultant saturation of corresponding areas of wrapper element 3.2 which is in contiguous engagement with the upper surface of control element 24. Continued fluid migration through lateral portions of lower element 22 continues to prevent accumulations of fluid from forming at the upper surface of control element 24. Since element 24 will neither wick fluid not pass it until it accumulates, that element functions effectively as an insulator to confine further fluid migration within the main absorbent assembly, thus insuring a dry condition of lower creped wadding element 35 and the adjacent portion of wrapper It will be noted that the fluid repellent side strips it 42 assume a configuration preventing fluid from reaching those lower portions of wrapper lateraily of control element 24 and marginally of the element forming the main absorbent body through which fluid is free to migrate. Since fluid passage through upper light weight creped \vadding element 34 is confined largely to the centraily dished and compressed portion thereof, those portions of wrapper 20 engaging the outer downwardly arced portions of element 34 will remain dry, as will the other lower portions of the wrapper, since the converging portions thereof are completely protected by side strips 49 and 42 as above mentioned. Since the lower central area of the napkin is effectively protected by control element 24, fluid migration to the wrapper material is thus prevented in all areas which might come into contact with the underclothing of the user.
It is known that regardless of manufacturers instructions a certain small percentage of sanitary napkins capable of being worn reversed will be so used. As above mentioned, it is a major feature of napkins incorporating the invention that when worn reversed they still function at least as well as prior art napkins of the same general construction. As fluid enters what is normally the lower side of the napkin of FIG. 6, when worn in the reversed position of FIG. 9, it readily passes through wrapper 2i) and element 36. Due, however, to limited lateral fluid migration within element 36, the mid portion of that element becomes readily saturated. Such saturation is due to the negligible wicking action of control element 24 therebelow and in direct contact therewith plus the absence of any available major absorbent element through which the fluid might migrate. As the fluid thus accumulates along the lower surface of the mid portion of element 36 it falls by gravity downwardly through element 24 and rapidly passes through light Wrapper 32 to enter the uppermost batt 22 of the major absorbent assembly wherein the fluid migrates in all directions.
With continued fluid flow, the fluid may pass through the central portion of upper batt 22, but since bafile directly engages the lower surface thereof, substantial lateral migration through the downwardly directed portions of batt 22 occurs before a limited amount of the fluid seeps through balfle 30 or migrates around the margins thereof, through creped wadding 23, and into lowermost fluff batt 22. While continued fluid flow may ultimately result in the saturation of centrally disposed creped wadding element 34 which is protected by control element 24 when the napkin is properly worn, that occurs only under unusual conditions. Side strips it and 42 still function to confine fluid migration within the assembly forming the major absorbent member, hence under normal conditions the napkin will satisfactorily serve its intended purpose. It will be noted, however, that control element 24, since remaining substantially dry, continues to serve its desirable form sustaining function while providing an open valve through which fluids may readily pass although not serving the fluid insulator function as when in the FIG. 8 position. While the total absorbent capacity of the napkin of FIG. 6 may not substantially be increased when properly worn, control element 24 is effective in preventing side and bottom stains when the napkin is subjected to amounts of fluid sufficient to result in such stains in prior art napkins of the same type and size or when the present napkin is improperly worn. When properly worn the napkin thus eliminates the necessity of using supplementary absorbent devices during periods of very heavy flow.
The invention readily lends itself to the construction of the completely reversible napkins shown in FIGS. 4 and 5 wh rein a symmetrical construction includes a pair of control elements 24 maintained in spaced relation on alternate sides of a main fluid absorbent body 22. The FIG. 4 construction employs a single absorbent body such as a batt of fluff 22 whereas the construction of FIG. 5 employs a pair of absorbent baits 22 disposed on opposite sides of a bafiie 3%. Regardless of whether such napkins are worn in the FIG. 8 or MG. 9 position they function equally Well since the uppermost control element 24 functions as above described in connection with FIG. 9 while the lower control element functions as described in respect to FIG. 8. The provision of double control elements increases manufacturing costs as well as increasing somewhat the ratio of total bulk to absorbing capacity. it fills the need, however, for a premium product which will perform with equal efliciency regardless of how worn.
While the control element of FIG. 6 is preferably of an uncompressed thickness of /53 to A", the invention is not limited to either the thickness or weight of the element. It may be desirable in some instances to provide a substantially thicker control element 24 as shown in FIG. 7. It has been found that accumulated fluids pass readily th ough control elements of an uncompressed thickness of /2 or more. Elements of increased thickness substantially improve the form-sustaining properties of napkins and may also be desirable in some types of medical bandages.
1. In a sanitary napkin, a core of highly fluid absorbent material, a control element in contiguous association therewith, and a fluid pervious outer wrapper maintaining said core and control element in unitary assembly, said control element comprising inherently resilient fibers of sufiicient length and intertwined in sufliciently spacedapart relation to define an open springy mat-like element of appreciable thickness and characterized by very large interstitial passages whereby said control element resists fluid migration therethrough by capillary attraction while offering substantially no resistance to the gravity aided passage of fluid droplets through said passages.
2. The device of claim 1 wherein the fibers of said control element are of synthetic plastic material.
3. An absorbent bandage comprising a core of wettable fibers of sufiicient density to insure high fluid absorbency, a fluid permeable wrapper, and a fibrous fluid insulating control element disposed between said core and wrapper,
said control element consisting of a suflicient number of inherently resilient fibers of at least about /1" in length and sufiicicntly intertwined to define an open springy matlike element of appreciable thickness, said element providing very large interstitial passages intermediate said core and wrapper through which fluid droplets readily pass under the pull of gravity while offering high resistance to fluid migration therethrough by capillary attraction.
4. A reversible absorbent bandage comprising a highly fluid absorbent fibrous core, a contiguously associated liquid control element consisting of loosely intertwined resilient fibers of suflicient length and in suflicient spacedapart relation to define a springy mat-like element of appreciable thickness and having very large interstitial passages therethrough, boththe fiber density of said control element and the wettability of the fibers thereof being sufliciently low to prevent wicking therethrough of liquid present in said core in less than saturating amounts while allowing gravity aided passage therethrough of liquid in droplet form.
5. A reversible absorbent bandage comprising a core of highly fluid absorbent fibrous material, a contiguously associated control element of very loosely associated inherently resilient fibers of at least about A" in length to impart to said control element the characteristics of a springy mat of appreciable thickness, the fiber density of said control element being sufficiently low and the fibers thereof being intertwined in a manner to define a 3-dirnensional skeleton-like structure providing very large interstitial passages allowing the rapid passage therethrough of fluid droplets in the direction of gravity pull during subjection of said element to body exerted pressures during use, the fluid absorbency characteristics of said control element due to capillary attraction being sufliciently negligible in respect to the fluid absorbency characteristics of said core whereby fluid entering said core and migrating therethrough to contact the surface fibers of said control element will not be wicked through said element.
6. A reversible sanitary napkin comprising an elongate absorbent pad of laminated construction including a pair of spaced, highly absorbent batts and an intermediate spreader element, a control element outwardly of each of said batts, and a fluid pervious wrapper enclosing and maintaining said batts and elements in unitary assembly, said control elements consisting of inherently resilient spaced-apart relation to define open springy mat-like structures of appreciable thickness and characterized by large interstitial passages, whereby said control elements resist fluid migration therethrough by capillary attraction While oflering substantially no resistance to the gravity aided passage of fluid droplets through said passages.
7. In a sanitary napkin, a pad-like member of high fluid absorbency comprising a pair of fibrous batts and a fluid repellent bafiie disposed therebetween, a plurality of sheets of wadding adjacent one side of said member, the fluid absorbing capacity of said wadding sheets being low in respect to the capacity of said batts, a fluid control element disposed adjacent one of said batts, said control element consisting of loosely intertwined fluid repellent fibers of suflicient thickness and length to define a very open springy mat-like structure of appreciable thickness and characterized by very large interstitial passages which impart to said element the characteristic of resisting fluid migration therethrough by capillary attraction while oflering substantially no resistance to gravity aided passage of fluid droplets through said passages, an element of low fluid absorbency disposed on the other side of said control element, and a fluid pervious Wrapper enclosing and maintaining said batts, wadding sheets, and control element in unitary assembly.
8. The device of claim 7 wherein the fibers of said control element are of synthetic plastic material and at least about A in length.
References Cited in the file of this patent UNITED STATES PATENTS 2,312,501 Stonehill Mar. 2, 1943 2,418,907 Schreiber Apr. 15, 1947 2,464,640 Fourness Mar. 15, 1949 2,905,176 Davidson Sept. 22, 1959