Unitized sanitary napkin

This invention relates to a novel absorbent structure and absorbent products containing this absorbent structure. More particularly, the absorbent structure of this invention contains a high-loft, bulky, low-density cover layer, a higher density transfer layer, a very high density, retentive reservoir layer and an impermeable barrier layer. The cover and barrier layers are sealed around their periphery and, preferably, all the layers are bonded to each other to form a unitized structure.

This application is related to commonly assigned, copending patent 
applications Ser. No. 242-271 filed Sep. 12, 1988, now U.S. Pat. No. 
4,992,324 (attorney Docket No. J&J 1238) entitled "Flexible Absorbent 
Board" and Ser. No. 242-274 filed Sep. 12, 1988, now U.S. Pat. No. 
5,038,989 (attorney Docket No. J&J 1267), entitled "Apparatus for 
Partially Slitting Absorbent Boards". 
FIELD OF THE INVENTION 
This invention relates to structures for absorbing body exudate. More 
particularly, the invention relates to absorbent structures which can be 
used in sanitary napkins, incontinence and wound dressing products and the 
like, which are unusually absorbent and retentive. 
BACKGROUND OF THE INVENTION 
Historically, women's sanitary protection products have been relatively 
unreliable in preventing staining of women's undergarments and outer 
garments during their menstrual periods. For example, large, bulky pads, 
which have high absorbency rates due to the use of hydrophilic materials 
such as wood pulp and rayon in their construction, nevertheless are often 
unable to retain absorbed mentrual fluid. They also tend to deform in use, 
leading to discomfort and the staining of undergarments and outer 
clothing. Even more recently developed, thinner pads, which contain 
polymer superabsorbent materials designed to aid in retaining fluid, have 
high failure rates. Furthermore, both types of pads tend to buckle and 
deform in an undesirable manner under pressure such that they cannot 
maintain contact with the perineal area. This distortion can create canals 
or paths along which menstrual fluid can flow without being absorbed, 
thereby causing staining as the fluid is channelled away from the 
absorbent. Although multiple longitudinal channels may be desired, most 
prior art pads merely buckle to create a few large voids, which is 
undesirable. 
When resilient material is added to pads in order to prevent deformation, 
the pads become uncomfortable and extremely expensive to make. Further, 
bulky pads are not significantly more failure-proof than thinner pads. 
It is, therefore, an object of this invention to provide an absorbent 
structure capable of quickly absorbing and retaining large quantities of 
body fluid. 
It is another object of that invention to provide a sanitary napkin capable 
of absorbing menstrual fluid quickly and efficiently and retaining that 
fluid in the absorbent structure of the napkin so as to limit failure. 
Yet another object of this invention is to provide a sanitary napkin which 
is flexible and conformable, yet resilient to bunching and twisting. 
Additional objects of this invention will become evident in the ensuing 
description. 
SUMMARY OF THE INVENTION 
The product of this invention relates to an absorbent structure which is 
not only extremely thin and flexible, but suprisingly resilient and 
absorbent. More particularly, the absorbent product of this invention 
relates to a laminated structure composed of several layers which are 
bonded to each other, including the following: 
a) a fluid permeable cover layer having an inner surface and an outer 
surface; 
b) a fluid transfer layer composed of a web of substantially hydrophilic 
fibers, having a first surface and a second surface. The second surface of 
the fluid transfer layer is bonded to the inner surface of the cover 
layer; 
c) a highly absorptive reservoir layer composed of a substantially 
hydrophilic material, having a first surface and a second surface. The 
second surface is bonded to the first surface of the fluid transfer layer; 
and 
d) a fluid imperious barrier layer which is optionally bonded to the first 
surface of the reservoir layer. 
The cover and barrier layers extend beyond the edges of the fluid transfer 
layer and the reservoir layers and are sealed to each other around the 
periphery of the absorbent structure. Preferably, the cover and barrier 
layers are fused so as to create a fluid barrier seal around the periphery 
of the structure. This seal may be a thin line of fused areas or a thicker 
line. If a thin line, the remainder of the peripheral area may be 
adhesively sealed. 
This invention also relates to sanitary napkins which can be constructed 
using the absorbent structure of this invention. Preferably, a sanitary 
napkin of this invention is composed of an absorbent system and a liquid 
impermeable barrier layer. The absorbent system preferably includes a 
bulky high-loft cover containing hydrophilic fibers, a fluid transfer 
layer adjacent the cover and an absorbent reservoir layer adjacent the 
liquid transfer layer and the barrier layer. The absorbent system is 
laminated with all the layers bonded together such that they form a 
unitized structure. 
A plan view of a sanitary napkin of this invention, shown in FIG. 1, 
illustrates that the napkin is preferably generally hourglass-shaped, with 
a major and minor axis. The longitudinal sides of the napkin are generally 
and symmetrically concave relative to the major axis. The minor axis is 
disposed perpendicular to the major axis, or the narrowest point of 
bioconcavity between the longitudinal sides. The cover is preferably 
sealed to the barrier layer around the perimeter of the napkin as 
described, supra. 
The absorbent structure of this invention is also useful in infant and 
adult diapers, wound dressings and other products used to absorb body 
fluid.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Preferably, the absorbent structure of this invention has four elements: a 
cover layer, a fluid transfer layer, a reservoir layer and a barrier 
layer. 
The cover layer is intended to substantially contact the body at the 
location at which fluid is being produced. In the case of a sanitary 
napkin, this would be the perineal area. The cover layer is preferably a 
relatively bulky, high-loft nonwoven web material having a basis weight of 
between about 0.1 and 1.0 oz/yd.sup.2. More preferably, the basis weight 
should be between about 0.25 and 0.75 oz/yd.sup.2. Most preferably, it 
should be about 0.5 oz/yd.sup.2. Fiber staple length is preferably between 
about 0.5 and 2 inches. More preferably, staple length should be between 
about 1.25 and 1.75 inches. Most preferably, it should be about 1.5 
inches. However, so long as the cover retains the appropriate bulk and 
porosity, staple length is not critical. The fiber denier is preferably 
between about 1 and 2.5. More preferably, the denier is between about 2.5 
and 3.25. Most preferably, it should be about 3. The cover layer may be 
composed of only one type of fiber, such as polyester, or it may be 
composed of bicomponent or conjugate fibers having a low melting point 
component and a high melting point component. The fibers may be selected 
from a variety of natural and synthetic materials such as nylon, 
polyester, rayon, (in combination with other fibers), cotton, acrylic 
fiber and the like and combinations thereof. 
Bicomponent fibers may be made up of a polyester core and a polyethylene 
sheath. The use of appropriate bicomponent materials results in a fusible 
nonwoven fabric. Examples of such fusible fabrics are described in U.S. 
Pat. No. 4,555,430, issued Nov. 26, 1985 to Mays. Using a fusible fabric 
increases the ease with which the cover layer may be bonded to the 
adjacent transfer layer and/or to the barrier layer. 
The cover layer preferably has a relatively high degree of wettability, 
although the individual fibers comprising the cover may not be 
particularly hydrophobic. The cover material should also contain a great 
number of relatively large pores. This is because the cover layer is 
intended to absorb body fluid rapidly and transport it away from the body 
and the point of deposition. Preferably, the fibers which make up the 
cover layer should not lose their physical properties when they are 
wetted, i.e. they should not collapse or lose their resiliency when 
subjected to water or body fluid. The cover may be treated to allow fluid 
to pass through it readily. The cover layer also functions to transfer the 
fluid quickly to the other layers of the absorbent structure. The cover 
should be able to transport fluid both vertically, to subjacent layers and 
horizontally, away from the point of deposition. Thus, the cover is 
preferably wettable, hydrophilic and porous. When composed of synthetic 
hydrophobic fibers such as polyester or bicomponent fibers, the cover may 
be treated with a surfactant to impart the desired degree of wattability. 
Apertured polymer films having large pores may be used as cover materials, 
although they are not wettable. Because of their high porosity, such films 
accomplish the function of quickly transferring body fluid to the inner 
layers of the absorbent structure. Apertured coextruded films such as 
RETICULON.TM. brand apertured film, for example, described in U.S. Pat. 
No. 4,690,679, are useful as cover layers in the absorbent structures of 
this invention. Another apertured film useful in the cover layer of the 
products of this invention is described in U.S. Pat. No. 4,342,314, issued 
Aug. 3, 1982 to Rodel et al. 
An important aspect of the cover layer and the other layers of the 
absorbent structure of this invention is their pore size distribution. 
There should be many large pores in the cover layer, in order to ease the 
passage of fluid into the interior of the absorbent structure. Preferably, 
at least 15% of the pores should be greater than 300 .mu.m in radius. More 
preferably, at least 30% of the pores should be greater than 300 .mu.m in 
radius. 
Another important attribute of the cover layer is water permeability. The 
cover layer should be highly fluid permeable, such that fluid passes 
through it quickly. Preferably, the cover layer has a water permeability 
of at least about 50 ft.sup.3 /ft.sup.2 /min. at a pressure differential 
of 0.17 psi. More preferably, the water permeability should be greater 
than about 60 ft.sup.3 /ft.sup.2 /min. Most preferably, the water 
permeability should be greater than about 75 ft.sup.3 /ft.sup.2 /min. 
Yet another important aspect of the cover layer is its ability to be 
wetted. In a basket wattability test, in which 5 grams (g) of material is 
placed in a basket in a reservoir and the time for the basket to sink is 
measured, the cover layer should be wettable enough such that it causes 
the basket to sink in less than 2 seconds. The Basket Sink Test is 
described in ASTM standard publication and assigned ASTM No. D-1117. 
The cover layer, if it is composed of a fabric, should have a very low 
density, preferably less than about 0.10 g/cm.sup.3, and more preferably, 
less than about 0.05 and even 0.02 g/cm.sup.3 at 0.03 psi pressure 
differential. The cover layer should be the least dense of the layers 
which compose the absorbent structure of this invention. The other layers 
are progressively denser, thus establishing a density gradient, which 
functions to wick fluid away from the body. The cover layer may be 
relatively thick in comparison to conventional absorbent structure covers, 
but preferably should be less than about 0.10 to about 0.15 inch at 0.03 
psi. More preferably, the cover should have a thickness of from about 0.01 
to about 0.05 inch at 0.03 psi since a relatively thick cover contributes 
to the comfort of the absorbent structure when worn against the skin. 
Adjacent to the cover layer on its inner side and bonded to the cover layer 
is the fluid transfer layer. The transfer layer provides a means of 
receiving body fluid from the cover layer and holding it until the 
highly-dense reservoir layer has an opportunity to absorb the fluid. The 
transfer layer is, preferably, more dense than and has a larger proportion 
of smaller pores than the cover layer. These attributes allow the transfer 
layer to contain body fluid and hold it away from the outer side of the 
cover layer, thereby preventing the fluid from rewetting the cover layer 
and its surface. However, the transfer layer is, preferably, not so dense 
as to prevent the passage of the fluid through the layer into the 
reservoir layer. 
The transfer layer may be composed of fibrous materials, such as wood pulp, 
polyester, rayon, flexible foam (i.e. aminoether or low retention foam), 
or the like, or combinations thereof. For example, the transfer layer may 
be 100% pulp or contain pulp and rayon in a ratio of between about 97:3 
and about 80:20. The transfer layer should have a relatively high degree 
of water permeability, have a pore size distribution which renders it 
capable of acting as a "holding tank" for the reservoir layer and it 
should retain its structural integrity in use, such that it is free of 
cracking, splitting or tearing and resists deformation when worn. 
The transfer layer may also be composed of a blend of wood pulp with 
thermoplastic fibers for the purpose of stabilizing the layer and 
maintaining its structure integrity. For example, polyolefin fibers with 
the appropriate length and strength, such as low density polyethylene 
(such as PULPEX.RTM., available from Hercules Corp.), or bicomponent 
fibers having polyethylene or polyester cores and a lower melting 
polyolefin sheath may be used, or polypropylene, polyvinylacetate, or 
other polyolefin fibers or thermoplastic pulp equivalents and the like. 
Blending such fibers with wood pulp or the like adds stability and 
integrity to the transfer layer material. The ratio of thermoplastic fiber 
to pulp is preferably about 1:99 to about 50:50. More preferably, the 
ratio should be between about 3:97 and about 20:80. The fibers of the 
transfer layer may range in length from about 0.0117 in for ground wood 
pump to about 3 inches for the stabilizing thermoplastic fibers. 
Preferably, the fibers are between about 0.25 inches to about 1 inch in 
length if the nonwoven web of the transfer lay is intended to be 
stabilized by thermal bonding at the fibers' point of contact, fiber 
length is not critical so long as the strength and integrity of the web is 
preserved. 
Preferably, the basis weight of the web which comprises the transfer layer 
is from about 2.75 oz/yd.sup.2 to about 3.50 oz/yd.sup.2. More preferably, 
the basis weight of the transfer layer should be from about 3.00 
oz/yd.sup.2 to about 3.25 Oz/yd.sup.2 This basis weight is relatively 
higher than that of the cover layer. 
The density of the transfer layer should also be higher than that of the 
cover layer. This increase in density aids in wicking the fluid away from 
the cover layer and retaining it in the transfer layer so as to prevent 
rewetting the surface of the cover layer. The cover layer is, therefore, 
drier and more comfortable against the skin than if it were subject to 
being rewetted by fluid. Preferably, the density should range from about 
0.02 to about 0.10 g/cm.sup.3 at 0.03 psi. More preferably, the density 
should be from about 0.04 g/cm.sup.3 to about 0.08 g/cm.sup.3 Most 
preferably, the density should range from about 0.06 g/cm.sup.3 to about 
0.08 g/cm.sup.3. 
The transfer layer should have a thickness of less than about 0.20 inches 
at 0.03 psi. More preferably, it should be between about 0.05 inches and 
0.15 inches in thickness. Most preferably, it should be between about 0.06 
and about 0.12 inches thick. 
The water permeability of the transfer layer should be at least about 12 
ft.sup.3 /ft.sup.2 /min. at 0.17 psi. This rate is relatively lower than 
that of the cover layer. Theoretically, the transfer layer should act as a 
"holding tank" for the body fluid as it flows through the cover layer and 
awaits discharge into the reservoir layer. The reservoir layer, while 
having a large fluid holding capacity, may be relatively slow in absorbing 
fluid, but holds it tenaciously. Thus, the transfer layer allows the 
reservoir layer to absorb fluid slowly while preventing the fluid from 
rewetting the cover layer. This aids in preventing failure of the 
absorbent structure. Bonded together, the cover and transfer layers should 
have a water permeability of at least about 10 ft.sup.3 /ft.sup.2 /min. 
The transfer layer should be quite wettable, with a basket sink time of 
less than about 2 seconds. When constructed of stabilized wood pulp as 
hereinafter described, the typical pore size distribution of the transfer 
layer is such that about of the pores are larger than 300 .mu.m in radius 
and at least about 50% are smaller than 300 .mu.m. 
The transfer layer may be treated with surfactant on one or both sides in 
order to increase its wettability, although generally the transfer layer 
is relatively hydrophilic and may not require treatment. The transfer 
layer is preferably bonded on both sides to the adjacent layers, i.e. the 
cover layer and the reservoir layer. 
Immediately adjacent to and bonded to the transfer layer is the fluid 
reservoir layer. The reservoir layer is preferably a highly dense 
absorbent layer having a fine porosity. It has a large fluid holding 
capacity and is extremely retentive. In essence, it acts as a capillary 
"pump" to absorb body fluid away from the transfer layer. 
However, the reservoir layer need not be as rapidly wicking as the cover 
layer and the transfer layer. The basket sink time of the material of the 
reservoir layer may be as high as 3.0 seconds. Preferably, the reservoir 
layer is less than approximately 0.10 inch in thickness, and more 
preferably between about 0.045 and 0.070 inch at 0.03 psi. When 
constructed of compressed peat moss board as hereinafter described, the 
reservoir layer typically has a density of between about 0.20 g/cm.sup.3 
and 1.0 g/cm.sup.3. The average pore size of the dry compressed reservoir 
at 0.03 psi layer prior to wetting should be about 0.5-30 cm, preferable 
0.5 to about 10 cm. The surface area of the pores should be greater them 
about 2 m.sup.2 /g. Preferably, it should be greater than about 5 m.sup.2 
/g. In the wet state, the reservoir layer preferably has a pore size 
distribution such that less than about 10% of the pores are larger than 
300 .mu.m in radius and at least about 90% of the pores are smaller than 
300 .mu.m. If the reservoir layer is made of swellable, initially 
compressed material, the pore sizes change upon exposure to water, thus 
pore size distribution and/or porosity information is given in wet and dry 
states. 
The reservoir layer should be capable of absorbing and retaining fluid 
without permitting it to sluts through the layer, and so that the fluid 
does not flow back into the transfer and cover layers under normal use. It 
should also be extremely thin, but have a large capacity for holding 
fluids. 
Most preferably, the reservoir layer is composed of compressed peat moss 
board. This board is made from sphagnum peat moss in accordance with 
processes delineated in U.S. Pat. No. 4,473,440 and patents referred to 
therein. The board may be formed by any of the methods set forth in U.S. 
Pat. Nos. 4,170,515 (issued to J-M LaLancette et al. on Oct. 9, 1979); 
4,226,232 (issued to Y. Levesque on Oct. 7, 1980), 4,215,692 (issued to Y. 
Levesque on Aug. 5, 1980) and 4,507,122 (issued to Y. Levesque on May 26, 
1985) and then subjected to the methods set forth in U.S. Pat. No. 
4,473,440 (issued to K-J. Ovans on Sep. 25, 1984). 
The peat moss board useful in the reservoir layer of the products of this 
invention may be made from a plurality of narrow, longitudinally extending 
strips disposed adjacent to one another and interconnected by an integral 
fibrous component extending between adjacent strips as described in 
copending patent application Ser. No. 242,271 filed Sep. 12, 1988 now U.S. 
Pat. No. 4,992,324 (attorney docket No. J&J 1238). The absorbent structure 
is preferably fabricated from a calandared peat moss board having a 
fibrous component admixed therewith, as set forth in U.S. Pat. No. 
4,473,440. The fibrous component is suitably a natural or synthetic 
textile fiber such as rayon, polyester, nylon, acrylic or the like, having 
a length of from about 0.25 to 1.5 inches and a denier of from about 1.0 
to 5. The fibrous component may be present in an amount from about 2 to 
20% by weight, most preferably from 4 to 8%. The absorbent board may also 
comprise other components such as wood pulp, synthetic wood pulp, 
thermomechanical pulp, mechanically ground pulp, polymers, surfactants, 
superabsorbents and the like. 
The absorbent structure comprising of peat moss as the primary absorbent 
component is formed as a board by air or wet laying and calendering to 
obtain a relatively thin, i.e. from about 0.01 to 0.10 inch thick 
relatively dense, i.e. from about 0.2 to 1.0 g/cm.sup.3 sheet like 
structure. The structure may include a layer of Kraft tissue laminated on 
one or both surfaces of the peat moss layer. The absorbent board thus 
formed is a relatively thin structure similar to those described in the 
aforementioned U.S. patent references. 
The absorbent peat moss board or other suitable compacted absorbent 
structure is processed to increase the flexibility thereof by partially 
severing the structure into a plurality of narrow strips which remain 
interconnected by an integral fibrous component of the structure. The 
board may be suitably severed by passing between a pair of rolls having a 
plurality of parallel spaced apart ridges or teeth extending 
circumferentially around the outer surface of the rolls. The two rolls are 
adjusted so that the opposing teeth are offset from each other without 
contact so that when the absorbent board is passed between the rolls, 
alternate strips of the friable board material are displaced relative to 
one another in the plane of the board. The displacement is sufficient to 
disrupt the friable absorbent material of the board such as the peat moss 
or wood pulp and delineate the individual strips without cutting or 
otherwise substantially disrupting the fibrous component of the board. 
The partially severed product consists of a plurality of individual strips 
of the absorbent board having a width corresponding to the spacing of the 
teeth on the shearing rolls, and interconnected by the fibrous component 
extending between adjacent strips. The fibrous component provides a 
hinge-like action, and the resulting product has extreme transverse 
flexibility while maintaining transverse structural integrity. The partial 
shearing does not substantially affect flexibility in the longitudinal 
direction of the strips however, and if such flexibility is desired, the 
absorbent board may be embossed or micro corrugated in a generally 
transverse direction before or after the partial shearing operation. 
In addition to increasing flexibility, the partial shearing of the 
absorbent board enhances the rate of liquid absorption by increasing the 
effective surface area of the board as a result of the edges of the slit 
material being available to the fluid. The partial shearing also imparts 
directional absorbent capacity to the absorbent boards since fluid wicks 
preferentially along the slits in the longitudinal direction of the 
material. By orienting the slit material in the longitudinal direction of 
a sanitary napkin or diaper, the incidence of edge failure in such 
products is consequently reduced. 
The fibrous component extending between an interconnecting adjacent strips 
of absorbent material permits the absorbent element to be transported, 
rolled and handled during processing and assembly of absorbent products. 
The enhanced rate of fluid absorption and the directional absorption 
characteristics of the absorbent element permit it to be used directly as 
the primary absorbent in absorbent products with the resulting products 
being exceptionally thin, flexible and effective. 
Peat moss board has s large proportion of extremely tiny pores and 
capillaries which give it the ability to absorb an enormous capacity of 
fluid and retain it. The peat moss board swells as it absorbs fluid, 
however, this swelling does not cause it to lose its capacity for 
absorbing fluid. Rather, the swelling contributes to the ability of the 
reservoir layer to generally maintain the structural integrity of the 
absorbent structure in use. Peat moss board has the unique capability of 
"drying" adjacent materials by continuing to pull moisture away from them, 
over a long time period such that little or no moisture remains in the 
adjacent materials. Peat moss board also has the capability of being 
deodorant by controlling odors and is easily made antimicrobial. It can be 
made to be thin and flexible, if treated appropriately such as by partial 
slitting as described above, or by tenderizing in accordance with the 
process set forth in U.S. Pat. No. 4,605,402, without substantial loss of 
fluid holding capacity. The tenderizing process includes the steps of 
microcorrugating compressed board by passing the web through fluted 
intermeshing rolls and then perf embossing the board by using techniques 
such as those set forth in U.S. Pat. No. 3,817,827. Thee processes for 
softening or making the board more flexible known to those of skill in the 
art may be used to render the board flexible of the reservoir layer, there 
are many other highly absorbent and retentive material systems which can 
be used in the reservoir layer. For example, pulp-superabsorbent systems 
such as those described in U.S. Pat. No. 4,610,678 (Weisman, et al., Sep. 
9, 1986) or U.S. Pat. No. 4,103,062 (Aberson et al., Jul. 25, 1978) may 
function as a reservoir layer of the product of this invention. Such 
absorbent structures contain a mixture of hydrophilic fibers such as wood 
pulp fluff and discrete particles of a water insoluble hydrogel such as 
silica gels or crosslinked polymers. The resulting absorbent structure may 
also be cut or tenderized to render it flexible and suitable for use in 
the products of this invention. 
Melt blown fiber systems such as those described in U.S. Pat. No. 4,100,324 
(Anderson et al., Jul. 11, 1978) may also be useful in making the 
reservoir layer of the absorbent structure of this invention. In short, 
any highly-dense, highly-absorbent and highly-retentive absorbent material 
which can be made thin and flexible may function as material out of which 
acceptable reservoir layer may be made. Such absorbent structures may 
differ in density, pore size and other physical characteristics from the 
above-described peat moss board, while nevertheless possessing the liquid 
absorption and retention properties required for the reservoir layer. 
The absorbent structures of this invention are necessarily bonded between 
all layers. Bonding not only preserves the physical integrity of the 
structure, it also improves the fluid transfer between layers. The 
absorbent structures of this invention may be laminated and/or embossed in 
order to improve the contact between layers. 
FIG. 3 illustrate s one embodiment or the absorbent structure of this 
invention. Overlying the absorbent structure is the high-loft, high-bulk 
cover layer 300. Cover layer 300 is adhesively-bonded to transfer layer 
350 with adhesive bonding 340, which has been randomly sprayed onto the 
inner surfaces of cover layer 300, transfer layer 350 and reservoir layer 
360. Transfer layer 350 is, in turn, adhesively bonded to reservoir layer 
360. Reservoir layer 360 is also bonded to impermeable barrier 370. Fluid 
enters the absorbent structure through highly porous cover layer 300. 
Cover layer 300 quickly transfers the fluid to transfer layer 350. 
Transfer layer 350 holds the fluid until reservoir layer 360 has an 
opportunity to absorb the fluid. The adhesive bonding 340 maintains 
intimate contact between the layers and enables them to effect a better 
transfer of fluid than if the layers were not bonded. 
The absorbent structures of this invention are useful in sanitary napkin 
and other body fluid-absorbing products. The sanitary napkin products made 
in accordance with this invention are uniquely thin, flexible, absorbent 
and conformable yet resilient to stress exerted in the transverse, or 
x-direction when wet. Such sanitary napkins can be made to conform in 
shape to the crotch-portion of an undergarment. Preferably, they are 
hourglass-shaped and cover a large proportion of the undergarment's 
surface. However, they may be made in any configuration known to those 
skilled in the art. 
Due to their flexibility, the sanitary napkins of this invention conform to 
the changes in the three-dimensional shape of undergarments as they are 
worn. In use, they form many fine longitudinal channels, or "fluting", 
which aid in fluid transport. Yet, the sanitary napkins of this invention 
are surprisingly resilient to stresses exerted in the transverse, or 
x-direction, when exposed to fluid. This provides a large surface area 
available for fluid uptake so as to substantially prevent failure. 
In contrast, the sanitary napkins of the prior art tend to bunch or rope 
when worn, causing transverse creases and large longitudinal creases, 
causing large, undesirable voids in the absorbent sections. This decreases 
available surface area. This bunching is caused by the movement of the 
thighs, exerting forces across the x-direction of the absorbent. Bunching 
creates pockets or canals which divert fluid from the central absorbent 
system and from which fluid leaks from the pad onto the 
A preferred embodiment of the sanitary napkin of this invention is depicted 
in FIGS. 1 and 2. The sanitary napkin of this invention contains a 
high-bulk, high-loft cover layer 10. Immediately adjacent and bonded to 
cover 10 is fluid transfer layer 20. Transfer layer 20 is composed of 
non-woven fabric of higher density than that of cover 10, as described 
above. Transfer layer 20 may be bonded to cover 10 with pressure-sensitive 
adhesive, thermosetting adhesive, hot melt adhesive or the like, which can 
be sprayed onto the surface of the layers or applied by printing. In the 
alternative, cover 10 and transfer layer 20 may contain thermoplastic 
fibers which can be exposed to heat and melted such that they form bonds 
Immediately adjacent to and bonded to transfer layer 20 is fluid reservoir 
layer 30. Reservoir layer 30 is preferably shaped rectangularly and 
extends substantially along the longitudinal axis of the napkin. However, 
reservoir layer 30 preferably does not abut the longitudinal end 40 of 
cover 10 nor does it abut the longitudinal ends 45 of transfer layer 20. 
This construction is intended to substantially prevent end failure by 
obviating contact between the fluid-containing portion of the napkin and 
the end of the napkin, thus allowing fluid to flow to and remain in the 
reservoir layer, although this aspect is not critical. This construction 
is also preferred at the lateral sides 50 of the napkin. 
Optionally,reservoir layer 30 is adhesively bonded to impermeable barrier 
layer 70. Barrier layer 70 is bonded to cover layer 10 around the 
periphery of the napkin. Preferably, a thin peripheral seal is created 
between the edge of transfer layer 20 and the extreme periphery of the 
barrier and cover layers to provide a fluid barrier. The area outside the 
peripheral seal, which may be made by heat, ultrasonic or mechanical 
means, may be adhered using pressure sensitive adhesive or the like. 
Optionally, the sanitary napkins of this invention have relatively small 
tabs 60 extending from their longitudinal sides. Such tabs 60 should 
extend no more than about one-third the length of the lateral side 50 of 
the napkin, i.e. length a--a should be less than one-third of length b--b. 
These tabs should not have absorbent material from the reservoir or 
transfer layers extending across their surface, although the cover may 
optionally be coextensive with tabs 60. The function of the tabs is merely 
to secure the napkin to the undergarment at its lateral sides 50. Tabs 60 
also aid in maintaining the napkin's structural integrity in the 
x-direction when subjected to stress from thigh motion and fluid 
absorption. If cover material is coextensive with the tabs in order, it 
may assist in wicking fluid away from the side area and afford ease in 
processing. 
FIGS. 4 and 5 illustrate additional embodiments of the sanitary napkins of 
this invention. FIG. 4 illustrates a napkin having slightly rounded 
lateral ends. FIG. 5 illustrates a napkin which does not have tabs at its 
longitudinal sides. 
The sanitary napkins made in accordance with this invention should have 
little or no fluid strikeback, i.e. menstrual fluid, once absorbed, should 
not reappear on the surface of the napkin. 
The thickness of the sanitary napkins of this invention measured in the 
z-direction should be no greater than about 0.250 inch when dry at 0.03 
psi. Preferably, it should be less than 0.200 inch thick. When peat moss 
board is used as a reservoir layer, the thickness should be no greater 
than about 0.400 inch when wet, as peat moss board expands upon wetting. 
If another type of reservoir layer is used the thickness should also be no 
greater than about 0.400 inch when wet. 
After the sanitary napkin of this invention is constructed and bonded 
together, the cover may be embossed using a pattern which extends along 
the longitudinal axis of the napkin. Of course, the embossing pattern can 
be of any shape or 
The theoretical water holding capacity (as measured by a Gravimetric 
Absorbency Testing System as set forth in U.S. Pat. No. 4,357,827) of the 
sanitary napkins of this inventions should be at least about 65 cc and, 
preferably, at least about 75 cc of 1% saline solution. The amount of 
force required to create the initial lateral deformation of a napkin of 
this invention should be no more than about 200 g when the napkin is dry 
and no more than about 250 g when the napkin is wet, although the force 
can exceed 400 g when dry if the reservoir layer has not been treated to 
render it more flexible. Reservoir layers can be made much more flexible 
when treated. 
The degree of force needed to bend the napkin of this invention a distance 
of 1.5 cm in the z-direction should be no more than about 50 g when dry 
and no more than about 55 g when wet. Preferably the force should be no 
more than about 35 g when dry and less than about, 30 g when wet. 
The degree of torque needed to bend the sanitary napkin of this invention 
90.degree. around its longitudinal, or y-axis should be no greater than 
about 200 g-cm when dry and no more than about 315 g-cm when wet, although 
it may be greater if the reservoir layer is not treated to render it more 
flexible. Preferably, if is less than about 120 g-cm when dry and less 
than about 200 g-cm when wet. 
The following examples are illustrative of certain preferred embodiments of 
this invention. However, in no way do these examples serve to limit this 
invention. 
Example 1 
A sanitary napkin in accordance with this invention was made by bonding 
together the following elements: (1) 100% Enka brand polyester fibrous 
nonwoven carded web, the fibers having a denier of 3, a staple length of 
1.5 inches; the nonwoven web having a basis weight of 0.5 oz/yd.sup.2, 
made by through-air bonding with no restraint; (2) a fluid transfer layer 
made of aerobonded stabilized pulp [10% bicomponent Enka.RTM., 60% rayon, 
80% pulp, 4% Nacan anionic vinyl acrylic copolymer binder]; (3) a creped, 
partially slit peat moss board reservoir layer and (4) an impermeable 
barrier made of polyethylene. The layers were bonded using fine lines of 
hot melt, pressure sensitive adhesive, which was printed onto the layers. 
This adhesive may be sprayed, so long as the adhesive lines are fine 
enough not to interfere with permeability. The cover and the polyethylene 
barrier were bonded around the periphery of the napkin using the adhesive 
and exposure to heat and pressure. The entire structure was laminated and 
embossed at a temperature of about 220.degree. F. and a pressure of about 
100 psi. The structure was then embossed along the longitudinal axis using 
a pattern of multiple sinusoidal lines. 
The pore size distribution of each layer was measured by desorption on a 
porous plate. Pore size distribution is determined by measuring the amount 
of fluid desorbed at particular hydrostatic pressure. This can be done 
using the apparatus described in U.S. Pat. No. 4,357,827. The amount of 
fluid desorbed at various pressures can be correlated to the pore size in 
accordance with the Laplace equation, p=2.gamma.cos.theta./R.sub.c where p 
is capillary pressure, .gamma. is the surface tension of the liquid, 
.theta. is the contact angle at the liquid-solid-air interface and R.sub.c 
is the capillary radious. The height of the capillary flow can be obtained 
by dividing the pressure, p, by the density of the fluid and g, 
gravitational force. This process is explained in more detail in 
Chatterjee, Absorbency, Elsevier Science Publishers, B.V., 1985, pp. 
36-40. The resulting distribution is set forth in Table IA, 
The components of the napkins of this Example were measured for wickability 
by placing them in a position 90.degree. relative to the horizontal plane 
with their ends submerged in water. The perpendicular distance along which 
the water was absorbed was measured after 5 minutes, 30 minutes, 1 hour 
and 2 hours. The results are set forth in Table IB. Table IB demonstrates 
that the cover layer is not very wickable, the transfer layer is somewhat 
wickable, while the reservoir layer is extremely wickable. 
Example 2 
The components of the napkin of Example 1 were measured in the x-direction 
and their densities calculated under four levels of pressure, 0.03 psi, 
0.10 psi, 0.20 psi and 0.50 psi. The thicknesses and densities of each 
layer are set forth in Table II. The total thickness of the sanitary 
napkin product of Example 1 at 0.03 psi is about 0.158 inches. 
Example 3 
The thickness of a sanitary napkin made in accordance with Example 1 was 
measured when dry under four pressures, 0.03 psi, 0.10 psi, 0.20 psi and 
0.50 psi. Three other sanitary protection products were also measured at 
each of these pressures, as follows: STAYFREE.TM. brand Maxipads available 
from Personal Products Co., ALWAYS.TM. brand Maxipads available from The 
Procter & Gamble Co., and STAYFREE.TM. brand Minipads available from 
Personal Products Co. These pads were then totally saturated with water, 
and their thicknesses again measured at various pressures. The dry and wet 
thicknesses measured are set forth in Table III. This test measured dry 
z-direction deformability and wet collapse due to pressure. Full-period 
protection pads are considerably thicker than those of Example 1, both 
when wet and dry. The STAYFREE.TM. brand Minipads, Maxipads and ALWAYS 
brand Maxipads tend to collapse when wet, as can be seen from Table III. 
However, the pads of Example 1 swell and retain their structure when wet. 
Example 4 
A Gravimetric Absorbency Test was performed on various sanitary protection 
products in order to indicate the theoretical water holding capacity of 
the products. The test procedure is outlined in Absorbency (P. K. 
Chatterjee, Elsevier Science Publishers, B. V., 1985, p. 67), and in U.S. 
Pat. No. 4,357,827. The results of this test are set forth in Table IV. A 
product made in accordance with Example 1 had a theoretical water holding 
capacity of about 83 cc, or about 10 times its weight in water, on or 
about the same order of magnitude as a STAYFREE.TM. brand Maxipad and an 
ALWAYS.TM. brand Maxipad, which had a capacity of about 12 times their 
respective weights. Yet, the product of Example 1 is considerably thinner 
than the commercially available maxipads. The theoretical water holding 
capacity of other sanitary protection products, including LIGHT DAYS.TM. 
brand panty liner, commercially available from Kimberly-Clark Co., a 
CAREFREE.TM. brand panty shield, commercially available from Personal 
Products Co. and a SURE & NATURAL.TM. brand Maxishield, commercially 
available from Personal Products Co. was also tested. 
Example 5 
A side compression initial deformation test, which measures the amount of 
force needed in the x-direction to begin to deform a pad, was performed in 
order to determine the x-direction resistance to deformation of various 
sanitary protection products. In this test, the sanitary napkin was held 
in a vise-like structure as illustrated in FIG. 6. The vise-jaws 50, 55 
were then brought toward one another at the rate of 50 mm/min. and the 
force required to first produce a bend in the sanitary napkin was measured 
using an Instron tester(Tensile and Compression Tester). The measurements 
were first made using various dry sanitary protection products. Fifteen cc 
of ersatz menstrual fluid was then deposited in the center of the napkins 
and they were tested again. The results of this test are set forth in 
Table V. Table V shows that, in dry side compression tests, the sanitary 
napkin of Example 1 is relatively easy to deform initially and would tend, 
therefore, to be conformable to the wearer's motion and undergarments. 
However, when wet, the force required to create an initial deformation 
increases, thus indicating that the product of Example 1 tends to resist 
collapse when wet, thus preserving its resiliency and structural 
integrity. 
Example 6 
A dry bending test, in which the degree of force needed for certain degrees 
of z-direction deformation, was performed to determine the degree of 
flexibility of the products of Example 1 compared to other full-menstrual 
period protection products. The apparatus used to perform this test is 
depicted in FIG. 8. A sanitary protectin product rests on arms 60 which 
are 6.4 cm apart. Each arm is 0.6 cm thick. Head 65 is brought downward 
against the napkin to deform it at a rate of 50 mm/min. Various napkins 
were tested both in a wet end a dry state. The deformation distance is 
measured as well as the load required to achieve that degree of 
deformation. The load required was measured using an Instron Tester. The 
results of this Example are set forth in Tables VIA and VIB. In fact, the 
flexibility is on the order of magnitude of that of small, thin, 
pantyliner-type products. This z-direction flexibility is retained when 
wet. 
Example 7 
A resilience-compression test was performed in order to determine the 
conformability of the napkins of Example 1. Results of this test indicate 
that the products of this invention are considerably more conformable and 
flexible both wet and dry than any other commercial pad tested. Convex, 
thigh-shaped forms 70 were positioned at the longitudinal sides of each 
napkin 75 without exerting force on the napkin as depicted in FIG. 9. The 
initial force needed to compress the dry napkin at a head speed of 14 
cycles/min. from 2.5" to a 1" gap was measured using an Instron Tester, 
Then, 15 cc of ersatz menstrual fluid was deposited on the middle of the 
pad and the compression motion continued. The results of this test are set 
forth in Table VII. In all pads except those made in accordance with 
Example 1, there was a drop in the amount of force required to compress 
the napkin without crushing it. In the case of the pads of Example 1, the 
product exhibits an increase in compressive resistance when wet. All other 
Example 8 
A torsion test was performed to determine the torque required to twist a 
napkin around its longitudinal axis 90.degree. both in a wet and a dry 
state. The napkin of Example 1 demonstrated the ability of retaining its 
resiliency and, in fact, increasing it, when wet. The napkins were clasped 
into a wire wise at each longitudinal end as depicted in FIG. 7. Each Vise 
had an extension, one of which rested upon a scale. The other extension 
could be used to twist the napkin in a clockwise direction 90.degree. 
around its longitudinal axis. The scale indicates the force required to 
twist the napkin. As shown in Table VIII, the napkin of Example 1 required 
considerably more force to twist it when wet than when dry. This indicates 
that the napkin actually becomes considerably more resilient when wet and 
will tend to resist bunching and roping in use. 
Example 9 
In order to determine the wetback properties of various sanitary protection 
products, a wetback test was performed. Fifteen cc of ersatz menstrual 
fluid was deposited on a napkin in its center. After 15 minutes, a 
circular piece of NU-GAUZE.TM. nonwoven rayon fabric commercially 
available from Johnson & Johnson Ltd. 4.5 cm in diameter was placed over 
the location at which the fluid was deposited. A plastic sheet was placed 
over the napkin and a 500 g weight also 4.5 cm in diameter was placed over 
the gauze for 5 minutes. After 5 minutes, the weight, plastic and gauze 
was removed, the gauze weighed and the volume of fluid absorbed by the 
gauze determined. The napkin made in accordance with Example 1 allowed the 
least amount of fluid to rewet the gauze. The results of this test are set 
forth in Table IX. 
Example 10 
An impact capacity test was performed on several sanitary napkins; 
including a napkin made in accordance with Example 1. The napkins were 
held in a 45 degree angle to the horizontal plane. Twenty-five cc of 
ersatz menstrual fluid was deposited onto the angled napkins. The napkins 
were each weighed to determine the amount of of fluid retained. A 
STAYFREE.TM. brand regular maxipad having a modified entangled fiber 
polyester cover retained 4 cc; a STAYFREE.TM. brand regular maxipad having 
an apertured fibrous cover (165 apertures per square inch) retained 13 cc; 
a napkin made according to Example 1 retained 22 cc; an ALWAYS.TM. brand 
maxipad retained 25 cc; and a SURE & NATURAL.TM. brand Maxishield retained 
17 cc. Example 11 
A sanitary napkin was prepared in accordance with Example 1, except that 
the reservoir layer was a four (4)-gram tenderized peat moss board insert 
rather than a partially slit, creped board. Upon testing for 
absorbent-related properties, the sanitary napkin of this example 
exhibited only trace amounts of wetback after wetting with 15 ml of ersatz 
menstrual fluid. The 45.degree. impact capacity was 22 cc. The 
theroretical water holding capacity for an 8.00 g. sample was 81 cc. The 
dry sample was 0.124 in. thick and, when wet, 0.307 in. thick. Testing for 
physical properties revealed that the dry sample was 0.124" thick at 0.03 
psi, 0.114" at 0.10 psi, 0.104" at 0.20 psi and 0.091" at 0.50 psi. The 
initial deformation peak upon side compression was 194 g. dry and 207 g. 
wet. The dry bending test showed that the load required to deform the pad 
0.5 cm was 15 g; to deform the pad 1.0 was 24 g; and to deform the pad 1.5 
cm was 26 g. When wet, the load required to deform the pad 0.5 cm was 37 
g; to deform the pad 1.0 cm was 47 g; and to deform the pad 1.5 cm was 51 
g. The resilience-compression test indicated that 0.59 kg of force was 
required to compress the dry pad and 0.55 g. of force was required to 
compress the wet pad. 282 g. cm of torque were required to twist the pad 
90.degree. when wetted. 
Example 12 
A sanitary napkin was prepared in accordance with Example 1, except that 
the reservoir layer was a pair of compressed pulp board inserts from SURE 
& NATURAL.TM. Maxishields containing superabsorbent instead of a creped, 
partially-slit board. Upon testing for absorbent-related properties, the 
sanitary napkin of this example exhibited 0.06 g. of wetback fluid after 
wetting with 15 ml of ersatz menstrual fluid. The 45.degree. impact 
capacity was 20 cc. The theoretical water holding capacity for an 9.21 g. 
sample was 81 cc. The dry sample was 0.138 in. thick and, when wet, 0.313 
in. thick. Testing for physical properties revealed that the dry sample 
was 0.138" thick at 0.03 psi, 0.124" at 0.10 psi, 0.113" at 0.20 psi and 
0.100" at 0.50 psi. The initial deformation peak upon side compression was 
429 g. dry and 165 g. wet. The dry bending test showed that the load 
required to deform the pad 0.5 cm was 33 g; to deform the pad 1.0 cm was 
57 g; and to deform the pad 1.5 cm was 68 g. When wet, the load required 
to deform the pad 0.5 cm was 23 g; to deform the pad 1.0 cm was 28 g; and 
to deform the pad 1.5 cm was 30 g. The resilience compression test 
indicated that 2.86 kg of force was required to compress the dry pad and 
0.94 g of force was required to compress the wet pad. 164 g. cm of torque 
were required to twist the dry pad 90.degree.. 316 g. cm of torque were 
required to twist the pad 90.degree. when wetted. If this board were 
tenderized or partially slit or otherwise treated for flexibility, it 
would exhibit more flexibility. 
Example 13 
Various cover materials which may be useful in the products of this 
invention were tested for water permeability by constructing a "plug" made 
of the cover material approximately the same size at a porous plate. The 
plug was applied to porous plate and subjected to a pressure difference of 
about 0.17 psi in order to induce a steady flow through the plate and 
plug. The water permeability was then calculated using Darcy's Law, on: 
q=-K.DELTA.P/Lo, where q is the volume flex in the flow direction, 
.DELTA.P is the net pressure head that causes the flow and L.sub.o is the 
length of the sample in the direction of flow. K is a proportionality 
constant representing the flow conductivity of the porous medium with 
respect to the fluid. 
An Enka.RTM. polyester fiber cover having a basis weight of about 0.6 
oz/yd.sup.2, a density of 0.035 g/cc and a thickness of 0.25" was Sample 
1. A bicomponent fiber Enka.RTM., cover having a basis weight of about 
0.63 oz/yd.sup.2, was tested as Sample 2. A 100% thermally bonded 
polypropylene fiber cover having a basis weight of about 0.53 oz/yd.sup.2, 
a density of about 0.191 g/cc and a thickness of about 0.009" was Sample 
3. Sample 4 was an apertured fibrous cover having 165 apertures per square 
inch. Sample 5 was the cover of a CAREFREE.TM. brand panty shield; Sample 
6 was a fibrous polyethylene cover of a STAYFREE.TM. brand maxipad; and 
Sample 7 was the cover an ALWAYS.TM. brand maxipad; Sample 8 was the cover 
of LIGHTDAYS.TM. brand panty liner; Sample 9 was the cover of a 
STAYFREE.TM. brand minipad; and Sample 10 was the cover of a SURE & 
NATURAL.TM. brand maxishield. An increasing number of ;ies was measured to 
determine multiple-ply permeability. The results of this test are set 
forth in Table X. Table X demonstrates that Samples 1-3, the covers of 
this invention, have extremely high fluid permeability, i.e. 60 ft.sup.3 
/ft.sup.2 /min. 
Pore size determinations were made using Samples 1 and 3, The results of 
these determinations are set forth in Table XA. 
Example 14 
Various fibrous webs suitable for use as transfer layers in the absorbent 
structure of this invention were tested for water permeability as in 
Example 14. A 94% stabilized pulp, 6% rayon web having a basis weight of 
about 3.3 oz/yd.sup.2, (or 110 g/m.sup.2) a density of 0.035 g/cc and a 
thickness of 0.12" was tested as Sample X. The water permeability of 
Sample X was 34.0 ft.sup.3 /ft.sup.2 /min. 
Sample Y was 100% Kraft ground pulp web having a bias weight of about 3.3 
oz/yd.sup.2, (or 110 g/m.sup.2) a density of about 0.035 g/co and a 
thickness of about 0.124". Sample Y had a water permeability of about 25.4 
ft.sup.3 /ft.sup.2 /min. 
Sample Z was a stabilized pulp web containing 80% pulp and 20% Pulpex.TM. 
(thermally bonding fibers available commercially from Hercules Corp. 
Sample Z had a basis weight of about 3.3 oz/yd.sup.2 (or 110 g/m.sup.2), a 
density 0.092 g/cc and a thickness of 0.119". Sample Z had a water 
permeability of about 17.7 ft.sup.3 /ft.sup.2 /min. 
Samples x, y and z were also tested for wettability using a sink basket. 
Sample X had a basket sink time of 1.5 sec. Sample Y had a basket sink 
time of 1.2 sec. Sample Z had a basket sink time of 2.0 sec. 
The 90.degree. wicking test was also conducted on Samples X, Y and Z. 
Sample X wicked 4.5 cm. along its length; Sample Y, 5.5 cm; and Sample Z, 
3.5 cm. 
Pore size determinations using the porous plate method were performed upon 
Samples X, Y and Z, as well. The results of this test are set forth in 
Table XI. 
Of course, the absorbent system of this invention may be useful in many 
absorbent products known to those of skill in the art. For example, the 
absorbent system of this invention may be used in infant and adult 
diapers, adult incontinence devices, wound dressings and the like. 
TABLE IA 
______________________________________ 
PORE SIZE DETERMINATION 
Height Pore Radius 
(cm) (.mu.m) Cover Transfer 
Reservoir 
______________________________________ 
-1 &gt;1470 26.6% 5% 1.5% 
-5 1470-295 55.3% 17.8% 6.2% 
-10 295-147 18.1% 37.6% 11.7% 
-20 147-74 27.8% 29.3% 
-25 74-59 3.0% 5.2% 
-40 59-37 5.0% 9.2% 
&lt;-40 &lt;37 3.8% 36.9% 
______________________________________ 
TABLE IB 
______________________________________ 
90.degree. WICKING TEST 
Rise vs. Cover Transfer Reservoir 
Time (cm) Layer (cm) Layer (cm) 
Layer (cm) 
______________________________________ 
5 Min. &lt;0.5 3 (pulp) 9.0 
5 (rayon) 
30 Min &lt;0.5 3 (pulp) 15.5 
5 (rayon) 
1 Hour &lt;0.5 3 (pulp) 20.0 
5 (rayon) 
2 Hours &lt;0.5 3 (pulp) 23.5 
5 (rayon) 
______________________________________ 
TABLE II 
__________________________________________________________________________ 
THICKNESS AND DENSITY OF PRODUCT COMPONENTS 
AT VARYING PRESSURES 
COVER LAYER TRANSFER LAYER RESERVOIR LAYER 
(Basis Wt) 
(20 g/sq m) (105 g/sq m) (400 g/sq m) 
PRESSURE 
THICKNESS 
(DENSITY g/cc) 
THICKNESS 
(DENSITY g/cc) 
THICKNESS 
(DENSITY 
__________________________________________________________________________ 
g/cc) 
0.03 psi 
0.025" (0.035) 0.067" (0.068) 0.066" (0.240) 
0.10 psi 
0.021" (0.041) 0.058" (0.079) 0.061" (0.260) 
0.20 psi 
0.018" (0.048) 0.054" (0.085) 0.058" (0.280) 
0.50 psi 
0.013" (0.067) 0.045" (0.102) 0.051" (0.310) 
__________________________________________________________________________ 
TABLE III 
______________________________________ 
DRY AND WET THICKNESS (INCHES) 
OF SANITARY PROTECTION PRODUCTS 
STAY- STAY- 
FREE* ALWAYS* FREE* 
Example 1 
Maxipad Maxipad Minipad 
Pressure (psi) 
Dry Wet Dry Wet Dry Wet Dry Wet 
______________________________________ 
0.03 0.139 0.308 0.763 
0.636 
0.701 
0.709 
0.321 
0.274 
0.10 0.128 0.277 0.691 
0.611 
0.633 
0.652 
0.280 
0.227 
0.20 0.118 0.252 0.638 
0.550 
0.587 
0.590 
0.253 
0.192 
0.50 0.105 0.206 0.538 
0.430 
0.518 
0.468 
0.196 
0.145 
______________________________________ 
TABLE IV 
______________________________________ 
THEORETICAL WATER HOLDING CAITY 
Total Thickness 
Wt. (0.03 psi) 
Capacity % 
(g) (Dry/Wet) (cc) Collapse 
______________________________________ 
STAYFREE* 11.0 0.723/0.479 
133 33.7% 
Maxipad 
ALWAYS* 10.0 0.760/0.590 
123 22.4% 
Maxipad 
STAYFREE* 3.85 0.342/0.218 
16 36.3% 
Minipad 
LIGHT DAYS* 2.03 0.100/0.095 
13 5% 
Pantyliner 
CAREFREE* 1.92 0.178/0.282 
16 -58.4% 
Panty Shield 
Example 1 8.60 0.143/0.309 
83 -116% 
SURE & NATURAL* 
7.93 0.281/0.362 
142 -28.8% 
Maxishield 
______________________________________ 
TABLE V 
______________________________________ 
INITIAL DEFORMATION PEAK (SIDE COMPRESSION) 
DRY WET 
COMPRESSION 
COMPRESSION 
(g) (15 cc) (g) 
______________________________________ 
ALWAYS* Maxipad 
709 603 
STAYFREE* Maxipad 
565 426 
Example 1 152 200 
STAYFREE* Minipad 
113 88 
LIGHTDAYS* Pantyliner 
88 148 
CAREFREE* Panty 
54 65 
Shield 
SURE & NATURAL* 
290 224 
Maxishield 
______________________________________ 
TABLE VI 
______________________________________ 
DRY BENDING TEST 
(Deformation vs. Load) 
Deformation (cm) 
0 0.5 1.0 1.5 
______________________________________ 
CAREFREE* Panty Shield 
0 9 14 16 
LIGHTDAYS* Panty Liner 
0 14 22 23 
Example 1 0 21 30 31 
STAYFREE* Minipad 0 21 29 34 
STAYFREE* Maxipad 0 55 90 150 
ALWAYS* Maxipad 0 64 114 187 
SURE & NATURAL* Maxishield 
0 24 55 70 
______________________________________ 
TABLE VIB 
______________________________________ 
WET BENDING TEST 
(Deformation vs. Load) 
Deformation (cm) 
0 0.5 1.0 1.5 
______________________________________ 
CAREFREE* Panty Shields 
0 9 12 13 
LIGHTDAYS* Pantyliner 
0 53 64 71 
Example 1 0 16 20 21 
STAYFREE* Minipad 0 23 29 34 
STAYFREE* Maxipad 0 58 89 135 
ALWAYS* Maxipad 0 91 142 214 
SURE & NATURAL* Maxishield 
0 36 51 61 
______________________________________ 
TABLE VII 
______________________________________ 
RESILIENCE - COMPRESSION TEST 
DRY WET 
(kg) (kg) 
______________________________________ 
ALWAYS* Maxipad 4.00 1.98 
STAYFREE* Maxipad 2.91 1.54 
STAYFREE* Minipad 2.09 1.41 
LIGHTDAYS* Pantyliner 1.99 1.80 
CAREFREE* Panty Shield 
1.50 1.09 
Example 1 0.50 0.53 
SURE & NATURAL* Maxishield 
1.83 0.89 
______________________________________ 
TABLE VIII 
______________________________________ 
TORSION TEST 
(90.degree. Twist) 
Torque (g cm) 
DRY WET 
______________________________________ 
STAYFREE* Maxipad 479 508 
ALWAYS* Maxipad 338 367 
STAYFREE* Minipad 110 125 
Example 1 112 190 
LIGHTDAYS* Pantyliner 54 51 
CAREFREE* Panty Shield 
42 37 
SURE & NATURAL* Maxishield 
282 205 
______________________________________ 
TABLE IX 
______________________________________ 
WETBACK TEST 
Volume Picked up 
Product By Farbric (cc) 
______________________________________ 
STAYFREE* Maxipad 0.38 
(Polyester Cover) 
STAYFREE* Maxipad 0.40 
(Apertured Fibrous Cover) 
ALWAYS* Maxipad 0.01 
Example 1 Trace 
LIGHTDAYS PANTYLINER 0.20 
(3 cc Deposit) 
NEW FREEDOM* Thin Pad 
0.16 
SURE & NATURAL* Maxishield 
Trace 
______________________________________ 
TABLE X 
______________________________________ 
COVER PERMEABILITY 
(ft.sup.3 /ft.sup.2 /min. under 0.17 psi) 
No. of plies: 
Sample # 1 2 3 4 5 
______________________________________ 
1 83.6 74.2 62.9 54.9 -- 
2 66.8 56.1 45.5 40.9 34.3 
3 60.2 46.6 34.6 28.3 22.8 
4 54.0 30.1 15.6 12.3 -- 
5 51.5 44.7 37.0 34.8 24.2 
6 49.7 37.6 27.2 20.2 15.7 
7 49.7 26.1 19.5 10.7 9.35 
8 49.4 32.6 25.6 18.7 13.4 
9 44.6 27.6 20.2 14.0 10.2 
10 41.7 24.0 13.6 8.46 6.75 
______________________________________ 
TABLE XA 
______________________________________ 
PORE SIZE DETERMINATION OF COVER 
PORE 
RADIUS SAMPLE SAMPLE 
(.mu.m) 1 3 
______________________________________ 
&gt;1470 26.6% 0.0% 
1470 to 735 15.5% 0.0% 
735 to 490 15.5% 3.0% 
490 to 368 17.7% 4.0% 
368 to 294 6.6% 8.0% 
294 to 245 6.6% 3.0% 
245 to 210 4.4% 13.0% 
210 to 184 2.2% 16.0% 
&lt;184 4.9% 47.0% 
______________________________________ 
TABLE XI 
______________________________________ 
PORE SIZE DETERMINATION OF TRANSFER LAYER 
PORE 
RADIUS SAMPLE SAMPLE SAMPLE 
(.mu.m) X Y Z 
______________________________________ 
&gt;1470 15.5% 9.2% 13.4% 
1470 to 295 
17.0% 15.3% 19.5% 
295 to 147 12.5% 13.3% 12.1% 
147 to 98 10.0% 14.8% 12.1% 
98 to 74 10.0% 14.3% 20.3% 
74 to 59 10.9% 8.1% 10.2% 
59 to 37 16.2% 16.0% 7.4% 
&lt;37 7.9% 9.0% 4.5% 
______________________________________