Odor-removing cover for absorbent pads and method of making same

An absorbent pad has a cover formed of non-woven fibrous material, which is coated with a fluorocarbon polymer and odor absorber(s). The cover sheet is apertured around a critical zone to overcome undesired surface tension effects. The method of producing the cover includes providing a water-based mixture that includes 1% by weight of a fluorocarbon composition. An odor absorbing reagent is added to the mixture which then is applied to a nonwoven web of fibrous material. The treated web is dried to remove the excess water from the mixture, and the fluorocarbon composition component is cured to form a hydrophobic coating around the reagent and to bind the reagent to the web. The drying and curing steps can be accomplished by applying a flow of air heated to a temperature in a range from about 100.degree. C. to about 120.degree. C. to the web until the water has been removed.

BACKGROUND OF THE INVENTION 
The present invention relates to an improved cover for an absorbent 
personal care product and to the products using such cover. More 
particularly, the invention relates to the cover for a feminine pad and to 
pads using such cover. Absorbent pads designed to be worn by humans to 
absorb bodily fluids, such as urine, menstrual fluid, perspiration, etc., 
include such articles as disposable diapers, sanitary napkins, panty 
shields, underarm shields, and incontinence pads. In use, these articles 
release malodorous vapors. Various compounds, chemicals, mixtures, and 
like materials (i.e., absorbents such as activated carbon, clay, and 
zeolites) are known to combat some of these malodorous compounds. Odor 
absorbents such as activated carbon have been incorporated into sheet 
materials or fabrics for use in protective articles and clothing. 
Additionally, because some odor absorbent agents are less effective once 
they have become wetted, various methods have been employed to minimize 
the exposure of the odor absorbents to moisture. These methods include: 
locating the odor absorbents outside of the liquid absorbent layer(s) of 
the products, protecting the absorbents with liquid impermeable/vapor 
permeable sheet materials, sandwiching the odor absorbents between two 
protective layers, hydrophobically coating the absorbents with various 
compounds to render them liquid impermeable, etc. Particular examples are 
discussed below. 
U.S. Pat. No. 4,732,805 to Maoos discloses an active carbon material that 
is coated with a gas permeable surface of particulate hydrophobic material 
which preferably is a fluorocarbon resin such as polytetrafluoroethylene 
(PTFE). The active carbon can be in the form of a fabric known as charcoal 
cloth or a felted material, and in such cases the hydrophobic material is 
present in a range from about 5 to 10% by weight of the active carbon. The 
coating of fluorocarbon resin protects the activated carbon from absorbing 
water while allowing the undesirable vapors to permeate through the resin 
and be adsorbed by the activated carbon. To apply the coating, the 
activated carbon material is preferably immersed in an aqueous suspension 
of the hydrophobic material and then dried by applying a flow of air 
heated to a temperature around 100.degree. C. The hydrophobic material may 
be present in the suspension in a preferred that the hydrophobic material 
be present at a concentration of at least 1.5% by weight. When the 
hydrophobic material is polytetrafluoroethylene, the suspension preferably 
is stabilized by an anionic wetting agent, but Maoos prefers that no 
binder or other component is included. The particle size of the 
hydrophobic material in suspension preferably is between micron and 0.01 
micron, with a mean particle size preferably of one tenth of a micron. 
U.S. Pat. No. 3,939,838 to Fujinami, et al discloses an article for 
treating menstrual fluid which employs a cover member forming an 
enclosure, an absorbent layer positioned within the enclosure for 
absorbing the menstrual fluid, a water-proofing layer also positioned 
within the enclosure for preventing the fluid from permeating to the 
outside of the cover member, and a deodorizer composition such as active 
carbon and the like located within the enclosure and having the function 
of absorbing and holding the menstrual fluid and simultaneously removing 
the odor released from the menstrual fluid. Active carbon, active silica, 
active alumina, ion exchange resin, chlorophyll, and the like are used as 
the deodorizers. The deodorizer is contained in sheets that are made of 
cellulose fiber. The deodorizer sheets can be interposed between the 
respective absorbent layers and the respective water-proofing layers, or 
in the absorbent layer and/or in the water-proofing. 
U.S. Pat. No. 3,693,622 to Jones discloses waste fluid absorption devices, 
including sanitary napkins and tampons, comprising a coplanar multiple ply 
of thin absorbent tissue paper impregnated in selected exterior border 
areas with non-toxic, waste fluid repellent compositions. Typically, the 
repellent impregnant can be non-volatile polyfluorocarbon fluids; 
non-volatile dimethyl polysiloxane fluids; non-volatile hydrocarbon oil 
fluids; non-volatile fluid long chain fatty acid alkyl esters, and 
non-volatile mono-, di-, and tri-glyceride esters of long chain fatty 
acids. 
U.S. Pat. No. 4,467,013 to Baldwin discloses non-woven bioactive, water and 
alcohol-repellent medical fabrics provided with a bioactive finish which 
is substantive on the fabric and is able to destroy migrating and 
cross-contaminating bacteria, algae and fungi. Specifically, a process for 
preparing a water and alcohol repellent, bacteriostatic non-woven medical 
substrate includes applying a solution of a specific silicone quaternary 
amine together with a water-repelling fluorocarbon and a wax/resin 
fluorocarbon extender, to produce the desired repellent surface. The 
fluorocarbon repellent component is typically a dispersion of 
fluoropolymer in water. 
U.S. Pat. No. 3,068,187 to Bolstad discloses segmented fluorine-containing 
copolymers useful for imparting repellency to oil and water and resistance 
to soiling to a variety of substrates. Fibrous, porous and continuous 
surfaces may be treated with these segmented polymers. The segmented 
copolymers may be applied as a surface treatment by known methods of 
coating such as spraying, brushing or impregnation from an aqueous or 
organic solvent dispersion or an organic solvent solution of the segmented 
copolymer. 
U.S. Pat. No. 3,683,917 to Comerford discloses a product for absorbing and 
retaining body fluids comprising a cellulosic absorbent body or core, a 
cellulosic covering, and a biodegradable, water impervious barrier sheet 
or layer which comprises a water repellent material deposited on a 
cellulosic tissue. Among such water repellent materials are: various 
fluorocarbons such as PTFE, CTFE, FEP, etc.; "Scotchguard" Repellents 
FC-208, FC-210, FC-212, FC-214, etc.; silicones such as Dri-Film 1040, a 
methyl hydrogen polysiloxane and Dri-Film 1042 and 1043, modified methyl 
hydrogen polysiloxanes; cationic starch type water repellents such as 
"Cyansize" (American Cyanamid) and "Aquapel", a ketone dimer emulsified 
with a cationic starch, sold by Fancourr Co.; etc. 
U.S. Pat. No. 4,565,727 to Giolia, et al discloses an air and water vapor 
permeable, toxic vapor absorptive non-woven fabric material comprising a 
wet-laid sheet containing fibrillated acrylic fiber, and an activated 
carbon constituent selected from the group consisting of activated carbon 
fiber, activated carbon particles, and mixtures of activated carbon fiber 
and activated carbon particles. The material is produced via the 
wet-laying process, utilizing fibrillated acrylic fibers as the binder 
material, whereby the material is prepared by wet-laying the activated 
carbon constituent and fibrillated acrylic fibers from a water suspension 
thereof. 
U.S. Pat. No. 4,217,386 to Arons, et al discloses a laminated, highly 
sorbent, active carbon fabric which is permeable to water vapor while 
sorbing substantial quantities of toxic chemical vapors, and process of 
making such a laminated fabric. Arons, et al is concerned with the 
formation of a multilayered, usually five-layered, laminated structure 
comprising: an inner woven fabric made of yarns of active carbon, produced 
by carbonizing high polymer yarns forming the fabric and thereafter 
activating the carbon; two outer layers (webs) of spunbonded non-woven 
fabric, prepared from continuous filaments of a high polymer; and two 
intermediate layers (mats), one on each side of the active carbon fabric. 
The final five layered, laminated fabric structure is produced by 
superimposing the layers as described above and fusion welding the five 
layers together over spaced apart areas. The woven active carbon fabric of 
the invention may be prepared by spinning high polymer yarns of various 
types, such as regenerated cellulose yarns of various conventionally 
produced types, polyacrylonitrile yarns, phenol-formaldehyde yarns, pitch 
yarns, or other suitable high polymer yarns, weaving such yarns into 
fabrics, carbonizing the fabrics, and activating the carbonized fabrics, 
all accomplished conventionally. 
U.S. Pat. No. 4,459,332 to Giolia discloses an air and water vapor 
permeable, toxic vapor absorptive fabric material. The toxic vapor 
absorptive ingredient is activated carbon fiber flocking having deposited 
in the voids formed therebetween, activated carbon powder. The invention 
comprises, in superimposed relationship: (a) a first inactive, woven or 
non-woven fabric; (b) a first air and water vapor permeable adhesive layer 
having activated carbon fiber flocking positioned on the surface thereof 
away from the first inactive fabric and activated carbon powder deposited 
in the voids formed between the flocking; (c) a second air and water vapor 
permeable adhesive layer and; (d) a second inactive layer of woven or 
non-woven fabric. The materials which form components (b) and (c) are 
produced from water vapor and air permeable adhesives preferably in the 
form of a foam. Component (b) is prepared by first coating the fabric 
material (a) with the adhesive foam. The side coated with the adhesive is 
then flocked with the activated carbon fibers. The activated carbon fibers 
are deposited upon the foam adhesive side of the coated fabric (a) by any 
known mechanical flocking method, preferably before the adhesive is heat 
cured. The fiber flocking is usually sprinkled on top of the foam adhesive 
coating. To the flocked side of the fabric is then added activated carbon 
powder while a vacuum is applied from the fabric side to draw the powder 
into the voids between the flocked carbon fibers. 
U.S. Pat. No. 3,439,678 to Thomas discloses a plied fabric having high 
water resistance and comprising at least two layers, each formed from a 
woven fabric which is resistant to standing water and is air and water 
vapor permeable. The fabrics are composed of fibers which are hydrophobic 
in themselves or are composed of fibers which subsequently are rendered 
hydrophobic by suitable coating means. One type of coating composition 
deemed especially suitable by Thomas is the fluoro chemical type textile 
finish which is marketed by Minnesota Mining & Manufacturing Co. (a.k.a. 
3M Company) under the SCOTCHGARD.RTM. trademark. The coating composition 
may be applied by any well known method such as padding, spraying, 
immersion, or the like. 
U.S. Pat. No. 3,995,636 to Murray, et al discloses a catamenial device such 
as a tampon which comprises a segment of a rapidly re-expandable 
hydrophilic polymeric foam held in compression by a constraining means. 
The constraining means comprises a coating material that includes a 
mixture of sodium bicarbonate and citric acid. The coating material may be 
provided by the application of a solution to the surface of the foam 
segment, or by full impregnation. Murray, et al discloses that the 
restoration of a slightly acidic environment in the vaginal area prevents 
the undue accumulation of noxious odor and irritation which results from 
the enzymatic reduction of the uric acid, urea, amino acids and the like 
to ammonia and volatile amines. 
U.S. Pat. No. 4,508,775 to Adiletta discloses a flexible, microporous, 
hydrophobic and oleophobic film-like composite structure comprising from 
about 25 to about 75 parts by weight of inorganic reinforcing microfibers, 
particularly glass, and from about 75 to about 25 parts by weight of a 
polymeric binding agent, preferably a copolymer of ethylene and vinyl 
acetate. A treating agent, preferably a fluorinated hydrocarbon, is 
present in an amount sufficient to render the composite structure 
hydrophobic and oleophobic. Alternatively, the treating agent may be 
combined with the microfibers and binding agent in the slurry prior to 
laydown and formation of the sheet material. The composite structure may 
be used in combination with a carbon or chemical liner in protective 
clothing, in which case it may be desirable to protect the carbon liner 
layer from body perspiration by laminating an abrasion resistant layer of 
material, such as a non-woven, spun bonded monofilament polyester, to the 
charcoal liner on the side opposite the composite structure. 
U.S. Pat. No. 4,194,041 to Gore. et al discloses a water-proof article that 
prevents liquid water from penetrating through to undergarments while at 
the same time permitting moisture vapor to pass out through the article. 
The article is layered: a microporous hydrophobic outer layer which 
permits the passage of moisture vapor but resists penetration by liquid 
water at pressures up to about 345 kiloNewtons per meter squared 
(kN/M.sup.2); a hydrophilic inner layer permitting the transfer of 
moisture vapor but preventing surface tension lowering agents such as 
those contained in perspiration and/or body oils from reaching the 
hydrophobic layer. Gore, et al discloses that a film of porous, expanded 
polytetrafluoroethylene, which has been heated above its crystalline melt 
point after expansion, has been found to be an ideal hydrophobic layer for 
rainwear applications. These films are highly porous yet the pores are 
very small in size. The latter fact results in high water entry pressure. 
Other hydrophobic materials for use in the outer layer include highly 
crystalline films of expanded PTFE, which have been heated above their 
crystalline melt point, and films of other microporous hydrophobic 
polymers such as polypropylene. 
U.S. Pat. No. 4,169,187 to Glazar discloses a powder coating composition of 
epoxy resins obtained by blending two types of epoxy resins with a curing 
agent. One resin is of the epichlorohydrin-bisphenol-A-type. The other 
resin is an epichlorohydrin-bisphenol-A modified with an epoxy-novolac. 
The Glazer patent discloses using the mixture for coating the interior of 
food and beverage containers and for a lining in hot-water services when 
finely divided polyvinylidine fluoride powder is added for hydrophobicity. 
OBJECTS AND SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an improved feminine 
pad. 
A further object of the present invention is to provide an absorbent pad 
cover having a lasting deodorant effect. 
It is another object of the invention to provide an absorbent pad having a 
cover which is stain-free, clean, and dry when in use. 
Still another object of the invention is to provide an improved nonwoven 
pad cover having deodorants which adhere strongly to the nonwoven base 
substrate. A related object is to provide an improved pad having deodorant 
particles which do not come loose during handling and usage. 
Yet another object of the invention is to provide an absorbent pad which 
improves the utilization of odor absorber(s) by providing same in a pad 
cover, yet protects the odor absorber(s) against the contamination by 
bodily fluids such as menses during usage. 
A further object of the invention is to provide an improved absorbent pad 
in which the deodorant is disposed so that the deodorant properties are 
durable over the life of the product and exhausted only in the process of 
removing and/or neutralizing odor causing vapors. 
Additional objects and advantages of the invention will be set forth in 
part in the description which follows, and in part will be obvious from 
the description, or may be learned by practice of the invention. The 
objects and advantages of the invention may be realized and attained by 
the methods and combinations particularly pointed out in the appended 
claims. 
To achieve the objects and in accordance with the purpose of the invention, 
as embodied and broadly described herein, the odor absorbing cover for an 
absorbent pad comprises a nonwoven web of fibrous material, a fluorocarbon 
polymer composition adhered to the fibers throughout the web, an odor 
absorbing reagent bound to the web by the fluorocarbon composition and 
rendered hydrophobic thereby, and a plurality of apertures defined through 
the web. One portion of the surface of the web defines a critical zone in 
which the number of apertures per square inch ranges from about 6 
apertures to about 1100 apertures. 
The diametric size of the apertures preferably is in the range of from 
about 1 millimeter to about 2 millimeters, but can be in the range of from 
about 0.8 millimeters to about 10 millimeters. Moreover, the aperture 
density in the critical zone preferably ranges from about 50 apertures per 
square inch to about 300 apertures per square inch. In addition, the 
percent of the critical zone that constitutes open area preferably ranges 
from about 10% to about 40%, but can range from about 2% to about 90%. 
The material used to form the nonwoven web preferably is chosen from the 
group of fibers that includes polyester fibers, polyamide fibers, 
cellulosic fibers, and polyolefin fibers. Suitable polyolefin fibers 
include polypropylene fibers, polyethylene fibers, polybutylene fibers, 
etc. The nonwoven web preferably is formed as a spunbond web, or a 
thermally bonded carded web, or a web composed of fibers with diameters 
ranging from about 10 microns (.mu.m) to about 100 .mu.m. The fluorocarbon 
composition preferably includes a perfluoroalkyl acrylic copolymer, such 
as Zepel 6700.RTM., available from DuPont. The fluorocarbon composition 
preferably is placed in a water-based mixture in which the fluorocarbon 
composition constitutes about 1% by weight of the mixture. 
Two common odor absorbing reagents are activated carbon and ABSCENTS.TM. (a 
white, crystalline synthetic molecular sieve product, sometimes referred 
to by the label "synthetic zeolite", available from UOP, which is a joint 
venture formed by Allied-Signal, Inc. and Union Carbide Corporation). 
Carbon has negative attributes such as dusting and difficult 
processability. As to the latter attribute, carbon is not soluble in 
fluorocarbons and thus tends to flake when its fluorocarbon mixture dries. 
This flaking is not desirable in a consumer product. ABSCENTS.TM.is a 
synthetic zeolite that appears white to the naked eye, but has a high cost 
and is not soluble in water or other mild solvents. 
Preferably, the odor absorbing reagent appears white to the naked eye. The 
preferred reagent is sodium bicarbonate because of its white appearance, 
odor absorbing effectiveness, nontoxicity and does not come loose during 
handling and usage. In addition, sodium bicarbonate is inexpensive. Other 
suitable odor absorbing reagents include: carbonates, bicarbonates, 
phosphates, biphosphates, sulfates, and bisulfates of alkali and alkaline 
earth metals; ascorbic acid, boric acid, citric acid, and maleic acid. 
The cover of the present invention can be used as the cover of a sanitary 
pad intended to combat odors in use. Such pad preferably further includes 
a baffle, which is formed as a sheet that is liquid impermeable. The 
baffle should prevent the flow of liquids and vapors therethrough, so that 
vapors must pass through the odor absorbing cover in order to escape from 
the pad. Preferably, the materials used to form the baffle are 
polypropylene and/or polyethylene films. Such pad also preferably includes 
a mass of liquid absorbing material disposed between the cover and the 
baffle. The liquid absorbent material can include such materials as 
cellulose, wood fluff, coform materials, meltblown materials, carded 
materials, sphagnum moss, etc. Furthermore, structures and materials other 
than liquid absorbing material can be disposed between the cover and the 
baffle, as desired. For example, deodorant materials can be disposed in 
and around the liquid absorbing material or beneath liquid impermeable 
baffles disposed inside the sanitary pad. Moreover, these deodorant 
materials can be provided in sheet form or particle form. 
In further accordance with the present invention, a method is provided for 
producing a cover for a sanitary pad. As embodied herein, a nonwoven web 
of material as described above is treated with a water-based liquid 
mixture that includes a fluorocarbon composition and at least one odor 
absorbing reagent. The fluorocarbon composition and odor absorbing 
reagents suitable for this treatment are described above and hereafter. 
The treated web is dried to remove the water from the mixture. The 
fluorocarbon composition is cured to form a hydrophobic coating around the 
reagent and to bind the reagent to the web. The drying and curing steps 
preferably are accomplished by applying a flow of heated air to the web 
until the water has been removed. Preferably, the air is heated in a 
temperature range of from about 100.degree. C. to about 120.degree. C., 
with a temperature of about 110.degree. C. being most preferred. 
The method further includes defining a plurality of apertures through the 
web. The apertures can be formed preferably by puncturing the web with hot 
pins, by treating the web with laser perforation, or by hydraulic 
rearrangement of the fibers. In an example of the latter alternative 
method of mechanically forming the apertures, the nonwoven web can be 
hydroentangled or hydraulically apertured using the aforementioned 
water/odor absorbent/fluorocarbon mixture as the fluid which mechanically 
forces apertures in the nonwoven web and simultaneously saturates the web 
with the mixture. 
In a predetermined portion of the web, the number of apertures per square 
inch ranges from about 6 apertures to about 1100 apertures and preferably 
ranges from about 50 apertures per square inch to about 300 apertures per 
square inch. This predetermined portion of the web (a.k.a. the critical 
zone) preferably defines a rectangular or oblong area measuring about four 
inches in the lengthwise direction of the web and about 11/2 inches in the 
widthwise direction of the web and centrally located on the surface of the 
web. The apertures ensure that the menstrual fluid impinging upon the 
outer surface of the web is quickly transferred through the web to the 
underlying liquid absorbent material in a sanitary pad in which the web is 
used as a cover. This ensures that the cover is kept as clean and dry as 
possible. The apertures are sized and provided in sufficient numbers per 
unit of web surface area in order to overcome the liquid repellent surface 
tension effects that are imposed by the nature of the materials preferred 
for forming the nonwoven web and by the presence of the hydrophobic 
fluorocarbon composition adhered throughout the fibers of the web. 
Since the baffle of a pad is vapor impermeable, odor causing vapors cannot 
escape from the pad except through the cover, which is permeable to both 
liquid and vapor. However, in the cover of the present invention, odor 
absorbing reagents are disposed throughout the cover to interact with, and 
thereby either neutralize or remove, the odor causing vaporous molecules 
attempting to escape from the pad. The effectiveness of the odor absorbing 
reagents is assured, notwithstanding their potential exposure to the 
menstrual liquid passing initially through the cover. The hydrophobic 
coating provided by the particles of the fluorocarbon composition serves 
to protect the odor absorbing reagents when liquids are passing through 
the cover. Moreover, the same hydrophobic particles of the fluorocarbon 
composition do not prevent the vapor molecules from accessing the odor 
absorbing reagents and being removed or neutralized thereby. Accordingly, 
in a manner of speaking, the cover of the present invention permits the 
odor absorbing reagents to selectively interact with and thereby remove 
the odor causing vapors attempting to escape from the pad. 
The accompanying drawings, which are incorporated in and constitute a part 
of this specification, illustrate one embodiment of the invention and, 
together with the description, serve to explain the principles of the 
invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Reference now will be made in detail to the preferred embodiments of the 
present invention, one or more examples of which are illustrated in the 
accompanying drawings. Each example is provided by way of explanation of 
the invention, not limitation of the invention. In fact, it will be 
apparent to those skilled in the art that various modifications and 
variations can be made in the present invention without departing from the 
scope or spirit of the invention. For instance, features illustrated or 
described as part of one embodiment, can be used on another embodiment to 
yield a still further embodiment. Thus, it is intended that the present 
invention cover the modifications and variations of this invention 
provided they come within the scope of the appended claims and their 
equivalents. 
In accordance with the present invention, a liquid permeable cover is 
provided. The cover can be used as a topsheet for a pad used to absorb 
bodily fluids. The cover of the present invention is particularly suited 
for controlling odor created by the presence of the bodily fluids which 
have been discharged from the body of the user and carried into the 
absorbent pad. A preferred embodiment of the cover of the present 
invention is shown in FIG. 1 in a sanitary pad which is represented 
generally by the numeral 10. The ends of pad 10 have been cut away to 
facilitate the description herein. As embodied herein and shown in FIG. 1 
for example, a liquid permeable cover 12 forms a cover that would be 
positioned in contact with the body of the user of pad 10. Cover 12 can be 
combined with a liquid impermeable baffle 14 to surround a mass of liquid 
absorbent material 16 disposed between cover 12 and baffle 14. Cover 12 
can be joined to baffle 14 in any of the conventional means such as heat 
sealing, adhesive applications, crimping, spot bonding, etc. Absorbent 16 
can be constructed of any of the conventional materials used to form the 
liquid absorbing material of a sanitary pad. Examples of materials 
suitable for absorbent 16 include cellulose, wood fluff, coform materials, 
meltblown materials, carded materials, sphagnum moss, superabsorbent 
synthetic polymers, etc. 
Baffle 14 preferably is formed as a film that is impermeable to the passage 
of both liquids and vapors therethrough. Preferably, the materials used to 
form baffle 14 are polypropylene and/or polyethylene. Baffle 14 can be 
formed by a laminate that functions to prevent the flow of liquids and 
vapors therethrough. 
In accordance with the present invention, the cover preferably includes a 
nonwoven web of fibrous material. As embodied herein and shown in Figs. 1 
and 2 for example, a section 18 has been removed from cover 12 of FIG. 1 
and shown schematically in greater detail in FIG. 2. In order to avoid 
unduly complicating FIG. 2, only a small portion of a single fiber 20 is 
illustrated. But for this selective illustration, numerous other fibers 
would be visible in the schematic view shown in FIG. 2. Fiber 20 is 
represented in cross-section in FIG. 2 and may be any of a number of 
fibers or filaments which can be used to produce nonwoven webs. For 
example, fiber 20 can be formed preferably as a polyolefin fiber, such as 
a polypropylene fiber, a polyethylene fiber or a polybutylene fiber; a 
polyester fiber; a polyamide fiber; or a cellulosic fiber. Preferably, 
fibers 20 are polyolefin fibers having diameters which range from about 10 
microns (.mu.m) to about 100 .mu.m. Fibers 20 are combined to form a 
nonwoven web 22 which forms cover 12. Nonwoven web 22 can be formed in a 
number of conventional ways, such as a spunbond web, a thermally bonded 
carded web, etc. 
In still further accordance with the present invention, the cover includes 
a fluorocarbon polymer composition adhered to the fibers throughout the 
web. As embodied herein and shown schematically in FIG. 2 for example, 
three discrete masses of fluorocarbon polymer composition 24 are shown. 
Two are shown adhering to fiber 20 of web 22. One mass 24 is shown in 
cross-section in the boundary of an aperture 28 defined through web 22. 
For purposes of schematic illustration in FIG. 2, cross-hatching of 
composition 24 is intended to represent a cross-sectional view of a bead 
of composition 24, while the absence of cross-hatching is intended to 
illustrate a plan view of a bead of composition 24. A suitable 
fluorocarbon composition includes a perfluoroalkyl acrylic copolymer 
available from DuPont under the trade name Zepel 6700 and consisting of 
about 15% to about 20% perfluoroalkyl acrylic copolymer, about 1% to about 
2% alkoxylated carboxylic acid and about 3% to about 5% ethylene glycol. 
Other suitable fluorocarbon compositions are polytetrafluoroethylene and 
SCOTCHBAND.TM. brand fluorocarbon composition available from 3M Company. 
The Zepel 6700.TM. fluorocarbon composition is preferred. Preferably, a 
water-based mixture is prepared with about 1% by weight Zepel 6700.TM. 
fluorocarbon composition, and the nonwoven web is dipped into this mixture 
and excess of the mixture can be removed by squeezing, for example. The 
fluorocarbon composition adheres to the fibers of the web when the web is 
removed from the mixture. The mixture also can be applied by spraying or 
other conventional coating methods. 
In still further accordance with the present invention, odor absorbing 
reagents are bound to the web by the fluorocarbon composition and rendered 
hydrophobic by the composition. This fluorocarbon composition forms a 
coating that is liquid impermeable while remaining vapor permeable. To 
promote this necessary condition, the amount of fluorocarbon composition 
used in the mixture preferably is limited to about 1% by weight. 
Examples of suitable odor absorbing reagents for practicing the present 
invention include one or more of the following materials: carbonates, 
bicarbonates, phosphates, biphosphates, sulfates, and bisulfates of alkali 
and alkaline earth metals; ascorbic acid, boric acid, citric acid and 
maleic acid. Sodium bicarbonate is the preferred odor absorbing reagent 
because of its non-toxic history, its white color, and its low cost. 
Preferably, the odor absorbing reagent appears white under natural light to 
the naked eye of an observer. This is a desirable cosmetic feature of a 
product that is to be used in a consumer environment such as a sanitary 
pad. Accordingly, while activated carbon has desirable odor absorbing 
properties, its black color renders it less suitable for the use in 
applications such as the present invention. 
As embodied herein and shown in FIG. 2 for example, an odor absorbing 
reagent 26 is schematically illustrated as a diamond shape being 
surrounded by and embedded within fluorocarbon composition particles 24, 
which are themselves schematically represented in cross-section so as to 
permit viewing of reagent 26. Preferably, reagents 26 are provided in the 
mixture including fluorocarbon composition 24 and are present there when 
the mixture is applied to web 22. 
In still further accordance with the present invention, the fluorocarbon 
composition is cured to form a hydrophobic coating around the odor 
absorbing reagents and to bind the reagents to the web. As embodied 
herein, after the web has been treated with fluorocarbon/water/odor 
absorbent mixture by dipping, spraying or other conventional coating 
methods, for example, the web treated with the fluorocarbon composition is 
cured to form a hydrophobic coating around the reagent and to bind the 
reagent to the web. Preferably, the curing is accomplished by the step of 
heating the treated web. For example, such heating preferably is 
accomplished by blowing heated air onto the web. The air preferably is 
preheated to a temperature of from about 100.degree. C. to about 120 
.degree. C. The heated preferably is accomplished by blowing heated air 
onto the web. The air preferably is preheated to a temperature of from 
about 100.degree. C. to about 120.degree. C. The heated air evaporates the 
water and activates the fluorocarbon composition o cure same. The 
fluorocarbon composition adheres to the fibers of the web and surrounds 
and encapsulates the odor absorbing particles. Accordingly, the odor 
absorbing particles are bound to the web and thereafter shielded from 
contact with water and other liquids. 
as noted above, a water-based mixture including about 1% by weight 
fluorocarbon composition can be applied to web 22 and can contain 
particles of odor absorbing reagents. Many of these odor removal 
capabilities of such odor absorbing reagents like activated carbon and 
zeolites. However, during the curing of the fluorocarbon composition by 
the application of heat, the web is also dried to removed the water from 
the mixture. Odor causing vapors are capable of penetrating through the 
hydrophobic coating formed by the fluorocarbon composition so that the can 
be absorbed by the odor absorbing reagent particles. 
In yet further accordance with the present invention, a plurality of 
apertures are defined thought nonwoven web forming the cover. One portion 
of the surface of the web defines a critical zone 30 in which the number 
of apertures per square inch ranges from about 6 apertures to about 1100 
apertures. As embodied herein and shown in FIG. 2 for example, a portion 
of an aperture 28 is shown defined through web 22 from one planar surface 
to the other. Such apertures can be formed by any of a number of methods. 
For example, hot pins can be thrust through web 22. In an alternative 
method, web 22 can e subjected to laser perforation. In yet another 
alternative method, the apertures are defined by subjection the web to 
hydraulic rearrangement. In one embodiment of the latter alternative 
method, the web is subjected to jets of fluid of sufficient energy to 
entangle or cut fibers. For example, the nonwoven web can be 
hydroentangled or hydraulically apertured using the aforementioned 
water/odor absorbent/fluorocarbon mixture as the fluid which mechanically 
forces apertures in the nonwoven web and simultaneously saturates the 
substrate with the mixture. Moreover, the provision of the apertures 
through cover 12 can be effected either before, during or after the 
application of the mixture containing the fluorocarbon composition and the 
odor absorbing reagents. This possibility provides some flexibility in 
engineering manufacturing methods for the cover and pad of the present 
invention. 
The apertures provided in the critical zone are necessary to render the 
cover o the present invention, including as it does the hydrophobic 
particles of fluorocarbon composition, sufficiently liquid permeable so 
that the bodily fluids are quickly passed through cover 12 and into the 
underlying liquid absorbent 16. Thus, the size of the apertures, the 
density of the apertures, the percent of the open area in the critical 
zone, and the amount of fluorocarbon composition present in the nonwoven 
web, have been chosen so that the surface tension effects of such 
combination des not impede the free flow of bodily fluids through cover 12 
and into liquid absorbent 16. This ensures that the cover remains clean 
and dry in use. 
Preferably, the diameter of the apertures ranges from about 0.8 millimeters 
to about 10 millimeters, and more preferably in the rang of about 1 
millimeter and to about 2 millimeters. Moreover, the aperture density in 
the critical zone preferably ranges from about 50 apertures per square 
inch to about 300 apertures per square inch. Furthermore, as shown in FIG. 
1 for example, this aperture density pertains only to a critical zone 30 
(indicated by a dashed line border), which preferably constitutes that 
portion of cover 12 measuring about 4 inches in the lengthwise direction 
of pad 10 and about 11/2inches in the widthwise direction of pad 10. 
Preferably, critical zone 30 defines a rectangular or oblong shape that is 
generally located centrally and symmetrically on the cover of the pad. 
Additionally, the apertures in the critical zone preferably define an open 
area that ranges between about 2% and about 90% of the critical zone area, 
and more preferably the open area formed by the apertures ranges from 
about 10% to about 40% of the open area of the critical zone. 
By providing odor absorbing reagents in the cover of a sanitary pad, the 
present invention places an odor absorbing barrier at the very site where 
the vapors will attempt to escape from the underlying pad. Vapors from the 
bodily fluids flow through the cover of the present invention with the 
liquid into the pads liquid absorbent layers. Some of these vapors are 
available to be absorbed or neutralized by the odor absorbing materials 
residing in the cover. Before these vapors can escape from the pad by 
exiting through the cover, the odor absorbing materials residing in the 
cover "remove" the vapors by absorbing or neutralizing them. In order to 
place the odor absorbers at this site (i.e., the cover), they must be 
protected from contact with the liquid which must be allowed to pass 
through the cover into the underlying liquid absorbent material. The 
fluorocarbon composition assists in this regard by protecting the reagent 
from contact with liquid. The fluorocarbon composition also adheres the 
reagent to the web which forms the cover. In addition, the fluorocarbon 
composition permits the penetration of odor causing vapors past the 
hydrophobic fluorocarbon particles so that the vapors can interact with 
the odor absorbing reagents. Structures and materials other than or in 
addition to absorbent 16 can be disposed between cover 12 and baffle 14, 
as desired. For example, deodorant materials, such as those mentioned 
above in the Background section, can be disposed in sheet form, particle 
form, etc. in and around liquid absorbent 16. For example, odor absorbing 
reagents can be treated with a fluorocarbon composition as described above 
to render them repellent of the menses. The treated reagents can be evenly 
distributed in the liquid absorbent material to the pad. Alternatively, 
the treated odor absorbing reagents can form a thin layer located between 
cover 12 and absorbent material 16. In yet another embodiment, the treated 
odor absorbing reagents may form a layer located between absorbent 
material 16 and baffle 14. The following examples are provided as 
illustrations of the invention and not limitations thereof. In these 
examples, the odor absorbing ability of a treated web material was 
determined using gas chromatography head space analysis, described as 
follows: 
A volatile mixture of 100 .mu.l di-n-propyl sulfide, 100 .mu.1 furaldehyde, 
100 .mu.l triethylamine, and 200 .mu.l isovaleric acid was prepared for 
the testing performed for Examples 1 and 2. In addition to the above 
ingredients included in the volatile mixture used to test Examples 1 and 
2, the volatile mixture prepared for the testing conducted for Example 3 
included an additional 100 .mu.l of pyridine. A 10 .mu.l volume of the 
respective volatile mixture was added by a pipetman, to a 40 milliliter 
Environmental Protection Agency (EPA) standard sample vial and sealed with 
a mininert screw cap. This serves as a blank to ensure the presence of all 
components of the mixture. 
A known quantity of cover material to be tested (in out examples 250 
milligrams) is placed in a 40-ml EPA vial. After the addition of 10 .mu.l 
of the appropriate volatile mixture described above, the vial is sealed 
with a mininert screw cap and is incubated at 37.degree. C. for 2 hours 
for Examples 1 & 2 and 31/2hours for Example 3. (When testing a sheet 
form, an untreated sheet can be used as the control, and in such case is 
run under the same conditions). After the allotted incubation period, a 10 
microliter head space sample from each vial is injected into a Hewlett 
Packard 5890.TM. gas chromatograph using the following parameters: 
______________________________________ 
Initial Time = 1.00 minutes 
Initial Temp. = 
35.degree. C. 
Ramp Rate = 10.degree./minute 
Final Temp. = 75.degree. C. 
Final Time = 0.15 minutes 
Inj. B = 175.degree. C. 
Det. B = 300.degree. C. 
Oven Max. = 300.degree. C. 
Equib. Time = 0.15 minutes 
Flow B (He) = 15.0-16.0 milliliters per minute 
Range (Sig. 1) = 
4 
Zero (Sig. 1) = 
2 
Attn. (Sig. 1) = 
2 
______________________________________ 
A Hewlett Packard 3390 A.TM. integrator was used to record the area count 
at the retention time of each of the five volatile components, and the 
percent absorption was calculated according to the following formula in 
which: X =the total area under the peak recorded by the integrator for the 
blank; Y=the total area under the peak recorded by the integrator for the 
sample. 
##EQU1## 
In Examples 1, 2 and 3, area count numbers for the blank were used as the 
base numbers to calculate the percent absorption rather than using the 
area count numbers obtained in testing a control (untreated) web. 
A control (untreated) web was not run for Examples 1 and 2. However, a 
control web was tested for Example 3, and the results of this test are 
presented following Example 3. 
EXAMPLE 1 
One gram of a molecular sieve (synthetic zeolite) sold by UOP Corporation 
under the name SMELLRITE.TM. was added to 100 milliliters of 1% solution 
of Zepel 6700.TM.. This 1% solution is 99% by weight water and 1% by 
weight fluorocarbon composition suspended in the water. This solution was 
stirred thoroughly to disperse the zeolite. A polypropylene spunbonded web 
having a basis weight of 0.6 ounces per square yard was prepared by 
forming apertures in a central strip along the web. The aperture pattern 
consists of an aperture diameter of 1.37 millimeters, a hole density of 90 
holes per inch squared, and a percent open area of 20. This web then was 
dipped into the suspension, and excess solution was squeezed out of the 
web. A flow of air heated to a temperature of 110.degree. C. was applied 
to the web until the web had dried. The odor absorption performance of the 
treated web was evaluated by the above-described gas chromatography head 
space analysis method. About 0.25 grams of the treated web was exposed to 
0.01 milliliters of a solution containing known volatiles for two hours. 
These volatiles were selected as representative of the odor causing 
volatiles present in menstrual fluid. The percentages of the volatiles 
removed by the treated web (the percent absorption) are given as follows: 
triethylamine 88%; furaldehyde 59%; isovaleric acid 95%; di-n-propyl 
sulfide 78%. As noted above, pyridine was not among the volatiles included 
in the test solution for this example. 
EXAMPLE 2 
One gram of baking soda supplied by Church & Dwight Co., Inc., was 
dissolved in 100 milliliters of solution containing 1% by weight Zepel 
6700.TM.. The spunbonded web described in Example 1 was treated with the 
solution by the technique mentioned in Example 1. The treated web was 
evaluated by the method detailed above. The percentage of volatiles 
removed by the treated web (the percent absorption) are given as follows: 
triethylamine 48%; furaldehyde 32%; isovaleric acid 95%; di-n-propyl 
sulfide 76%. As noted above, pyridine was not among the volatiles included 
in the test solution for this example. 
EXAMPLE 3 
Six grams of SMELLRITE.TM. synthetic zeolite, sold by UOP, was added to 300 
milliliters of a mixture including water and 1% by weight of Zepel 
6700.TM.. The mixture was stirred to disperse the zeolite. The web was 
treated as described in Example 1. The percentages of volatiles removed by 
the treated web (the percent absorption) are given as follows: 
______________________________________ 
triethylamine 44% 
pyridine 43% 
furaldehyde 36% 
isovaleric acid -412% 
di-n-propyl sulfide 
68% 
______________________________________ 
A negative number indicates that the component was not removed. This can 
occur in a multichemical sample because the absorption of one component 
can result in a release of another component by shifting the chemical 
equilibrium. 
The control (untreated) web removed the following percentage of volatiles: 
______________________________________ 
triethylamine 14% 
pyridine 29% 
furaldehyde 0% 
isovaleric acid 
243% 
di-n-propyl sulfide 
63% 
______________________________________