U.S. patent number 3,683,917 [Application Number 05/022,312] was granted by the patent office on 1972-08-15 for absorbent product comprising a fluid impervious barrier of a repellent tissue and a hydrocolloid.
Invention is credited to John M. Comerford.
United States Patent |
3,683,917 |
Comerford |
August 15, 1972 |
ABSORBENT PRODUCT COMPRISING A FLUID IMPERVIOUS BARRIER OF A
REPELLENT TISSUE AND A HYDROCOLLOID
Abstract
An absorbent product for absorbing and retaining body fluids and
exudates comprising a cellulosic absorbent body or core, a
cellulosic covering or facing material, and a biodegradable, water
imprevious barrier sheet or layer comprising a cellulosic tissue
having a basis weight of from about 6 pounds to about 30 pounds, a
water repellent material deposited on the cellulosic tissue in an
amount equal to from about 0.1 percent by weight to about 0.5
percent by weight, based on the weight of the treated tissue,
whereby the cellulosic tissue is classified as a repellent tissue,
and from about 0.002 to about 0.03 gram per square inch of a
hydrocolloidal material on the repellent tissue, said
hydrocolloidal material being capable of swelling in body fluids
and exudates and cooperating with the repellent tissue to form an
impervious barrier to body fluids and exudates.
Inventors: |
Comerford; John M. (Belle Mead,
NJ) |
Family
ID: |
21808939 |
Appl.
No.: |
05/022,312 |
Filed: |
March 24, 1970 |
Current U.S.
Class: |
604/368; 604/373;
604/376; 604/378; 604/381 |
Current CPC
Class: |
A61F
13/15252 (20130101); A61L 15/28 (20130101); A61L
15/28 (20130101); A61L 15/52 (20130101); A61L
15/62 (20130101); C08L 1/26 (20130101); A61F
13/534 (20130101); A61F 2013/53445 (20130101); A61F
2013/51441 (20130101); A61F 2013/530131 (20130101); A61F
2013/530481 (20130101); A61F 2013/51443 (20130101) |
Current International
Class: |
A61F
13/15 (20060101); A61L 15/52 (20060101); A61L
15/62 (20060101); A61L 15/28 (20060101); A61L
15/16 (20060101); A61f 013/16 () |
Field of
Search: |
;128/284,287,240,296 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Rosenbaum; Charles F.
Claims
What is claimed is:
1. In an absorbent product for absorbing and retaining body fluids
and exudates comprising a cellulosic absorbent body, a cellulosic
covering material, and a fluid impervious barrier sheet when in use
therebetween, the improvement wherein the fluid impervious barrier
sheet is biodegradable and comprises:
a. a cellulosic tissue having a basis weight of from about 6 to
about 30 pounds and a repellency time of less than 4 seconds;
b. said tissue carrying water repellent material present in an
amount equal to from about 0.1 to about 0.5 percent by weight based
on the weight of the tissue, thereby imparting to the water
repellent carrying tissue a repellency time of about 15 to about
150 seconds; and
c. said water repellent material carrying tissue having deposited,
on the surface facing said absorbent body, a hydrocolloidal
material; whereby said hydrocolloidal material cooperates with said
treated tissue to form a barrier, impervious to body fluids and
exudates, when said barrier is in contact with said fluids and
exudates.
2. An absorbent product as defined in claim 1 wherein the water
repellent material is a cationic starch.
3. An absorbent product as defined in claim 1 wherein the water
repellent material is a fluorocarbon.
4. An absorbent product as defined in claim 1 wherein the water
repellent material is a silicone.
5. An absorbant product as defined in claim 1 wherein the
hydrocolloid is present in an amount equal to from about 0.002 to
about 0.03 grams per square inch.
6. An absorbent product as defined in claim 1 wherein the
hydrocolloidal is a guar gum.
7. An absorbent product as defined in claim 1 wherein the
hydrocolloidal is sodium carboxymethyl cellulose.
8. In a sanitary napkin for absorbing and retaining body fluids and
exudates comprising a cellulosic absorbent body, a cellulosic
covering material, and a fluid impervious barrier sheet when in use
therebetween, the improvement wherein the fluid impervious barrier
sheet is biodegradable and comprises:
a. a cellulosic tissue having a basis weight of from about 6 to
about 30 pounds and a repellency time of less than 4 seconds;
b. said tissue carrying water repellent material present in an
amount equal to from about 0.1 to about 0.5 percent by weight based
on the weight of the tissue, thereby imparting to the water
repellent carrying tissue a repellency time of about 15 to about
150 seconds; and
c. said water repellent material carrying tissue having deposited,
on the surface facing said absorbent body, a hydrocolloidal
material; whereby said hydrocolloidal material cooperates with said
treated tissue to form a barrier, impervious to body fluids and
exudates, when said barrier is in contact with said fluids and
exudates.
9. In a diaper for absorbing and retaining body fluids and exudates
comprising a cellulosic absorbent body, a cellulosic covering
material, and a fluid impervious barrier sheet when in use
therebetween, the improvement wherein the fluid impervious barrier
sheet is biodegradable and comprises:
a. a cellulosic tissue having a basis weight of from about 6 to
about 30 pounds and a repellency time of less than 4 seconds;
b. said tissue carrying water repellent material present in an
amount equal to from about 0.1 to about 0.5 percent by weight based
on the weight of the tissue, thereby imparting to the water
repellent carrying tissue a repellency time of about 15 to about
150 seconds; and
c. said water repellent material carrying tissue having deposited,
on the surface facing said absorbent body, a hydrocolloidal
material; whereby said hydrocolloidal material cooperates with said
treated tissue to form a barrier, impervious to body fluids and
exudates, when said barrier is in contact with said fluids and
exudates.
Description
This invention relates to absorbent products for absorbing and
retaining body fluids and exudates and more particularly is
concerned with sanitary napkins for the absorption and retention of
menstrual fluids.
Although the present invention will be described with particular
reference to a sanitary napkin as the preferred embodiment of the
present invention, it is to be appreciated that the principles of
the inventive concept are equally applicable to other absorbent
products or to any product in which a water impervious barrier
layer or sheet is of use. Such other products include, for example,
diapers, surgical dressings, underpads, compresses, and the
like.
Absorbent products such as sanitary napkins usually comprise a
relatively dense, fibrous body or core of one or more layers of
highly absorbent fibers conventionally in the form of carded cotton
or rayon cellulosic webs, air layered cotton or rayon cellulosic
webs, comminuted wood pulp bats, tissue pulp, crepe or cellulose
wadding, absorbent paper, or like materials.
Such a fibrous body or core is usually wrapped within a soft, fluid
permeable cover which may be a woven, nonwoven, knitted, lace, or
like fabric normally made from cellulosic fibers.
Additionally, a waterproof or fluid impervious baffle or barrier
sheet is often used within the wrapper whereby any fluids deposited
on the top surface of the sanitary napkin and which are not
completely absorbed and retained by the fibrous body or core are
prevented from passing through the sanitary napkin to the bottom
surface thereof. Such a waterproof or fluid impervious barrier
sheet presents so-called "strike-through" of fluid and such a
feature has been incorporated in the vast majority of sanitary
napkins presently sold on the market today.
Unfortunately, such a waterproof or fluid impervious barrier sheet,
as currently used, possesses many disadvantages. For example,
practically all of these fluid impervious barrier sheets are water
insoluble and not dispersible in water and are not biodegradable
whereby disposal of the used sanitary napkin presents a problem.
Also, many of these fluid impervious barrier sheets are crisp and
noisy and undesirably call attention to the fact that a sanitary
napkin is being used. Additionally, many of these fluid impervious
barrier sheets are not sufficiently soft or flexible and do not
satisfactorily conform to the anatomical contours of the
wearer.
It is therefore a principal purpose of the present invention to
provide a barrier sheet for absorbent products such as sanitary
napkins, which barrier sheet will be fluid impervious in use, but
which will be biodegradable, soft, flexible and conformable and not
crisp or noisy.
This is accomplished by using as the barrier sheet a cellulosic
tissue having a specified weight range, treating the tissue with
specified amounts of water repellent materials whereby a certain
degree of water repellency but not complete waterproofing is
created therein, and depositing on the treated tissue a specified
amount of a hydrocolloidal material which is capable of swelling in
body fluids or exudates whereby it cooperates with the water
repellent tissue to form an impervious barrier to body fluids and
exudates.
As used herein, "tissue" is a general term indicating a class of
light weight cellulosic papers of characteristic gauzy texture and
in some cases translucent, made in basis weights lighter than about
30 pounds (basis 500 sheets -- 24 .times. 36 inches). Tissues used
herein range in basis weights of from about 6 pounds to about 30
pounds, and preferably from about 12 pounds to about 20 pounds.
Also, as used herein, the terms "waterproof" or "water impervious"
are used to describe materials which are completely impermeable to
the passage of water or moisture and which will retain this
property throughout their expected service life under normal use.
Examples of waterproof or water impermeable materials are:
polyethylene and polypropylene sheets and films; materials having
knife-coated finishes comprising such ingredients as paraffins,
pigments, and resin binders with add-on weights of 10 to 90
percent; rubber or vinyl coated materials; films and sheets of
fluoroplastic materials and particularly chlorotrifluoroethylene
resins (CTFE), polytetrafluoroethylene resins (PTFE), fluorinated
ethylene-propylene resins (FEP), etc.
Water repellency, however, is a relative term, as contrasted to the
term "waterproof", and is applied to materials which are not
completely impermeable or impervious to the passage of water or
moisture. Water repellency is usually measured in terms of the time
in seconds which is required for water or a test fluid to pass from
one side of a sheet material to the other side. There are various
Standard Methods for determining the water resistance of fabrics
(ASTM D583-63 and AATCC 22-1967) and for paper and paper board
(ASTM D779-58 and TAPPI T433 m-44) but there are no industry-wide
officially accepted standards for specialty paper products such as
tissue.
The standard and accepted test used herein for determining the
repellency or water-resistance of tissue is as follows: Two plies
of highly absorbent tissue having substantially instantaneous
repellency times are placed on a flat glass plate and the tissue to
be tested is placed on the two highly absorbent tissues. A mirror
and light source are so arranged that an observer can readily see
the top and bottom surfaces of the plied tissues. A few drops of a
test fluid at room temperature are placed on the top surface of the
test tissue and a determination is made of the time in seconds
which is required for a wet spot to appear on the bottom surface of
the lowest highly absorbent tissue.
Due to the highly absorbent nature of the two lowermost tissues
which have substantially instantaneous repellency times, it may be
stated that the repellency time obtained for the three layers of
tissue is substantially equal to the repellency time for the test
tissue alone. The two lowermost tissues, however, do help the
observer in noting the appearance of a wet spot.
The plies of tissue are flat and lie in a horizontal plane on the
flat glass plate. No external pressure is applied and consequently
the only pressure urging the drops of water to pass through the
tissue material is the weight of the drops of water themselves. In
order to simulate in vivo conditions to a greater degree, a small
amount of a surfactant is added to the test fluid so that its
surface tension approximates the surface tension of blood or of the
body fluids with which the absorbent product will be used.
The test is performed on a minimum of three locations of the tissue
and the results are averaged to yield the repellency time in
seconds. This is necessary because of the wide variation in results
obtained in different locations of a test tissue.
If it were not for the water repellent treatment, the tissue used
in the application of the principles of the present invention would
have an extremely short water repellency time which would range
from substantially instantaneous up to as long as about 1/2 second
to about 4 seconds.
Subsequent to the water repellent treatment, the treated tissue has
a water repellency time which ranges from an average of about 15
seconds to an average of about 150 seconds. Such treated tissues
are classified as "water repellent" within the application of the
principles of the present invention. It must be kept in mind,
however, that such a term is a relative term and that it is
frequently loosely used in industry. Such accounts for the care
taken in defining the term as used herein.
Such values are, of course, to be contrasted to the values obtained
for waterproof or water impervious materials. Such materials, of
which polyethylene sheets and films are outstanding examples, have
water repellency times measured in weeks or longer.
The invention will be more fully understood from the description
which follows, taken in conjunction with the accompanying drawing
in which there are illustrated preferred designs and modes of
operation embodying the invention. It is to be understood, however,
that the invention is not to be considered limited to the
constructions disclosed except as determined by the scope of the
appended claims. In the drawings:
FIG. 1 is a perspective showing of an absorbent sanitary napkin
which is shown partially cutaway to illustrate the improved fluid
impervious barrier sheet of the present invention;
FIG. 2 is a cross-sectional view of the absorbent sanitary napkin
of FIG. 1, taken on the line 2--2 thereof;
FIG. 3 is a partially cutaway, perspective view of the improved
fluid impervious barrier sheet of the present invention, as it
would appear, if removed from the absorbent sanitary napkin of FIG.
1; and
FIG. 4 is a cross-sectional view of a diaper construction utilizing
the principles of the improved fluid impervious barrier sheet of
the present invention.
With reference to the drawings, and particularly FIGS. 1 and 2
thereof, there is shown an absorbent sanitary napkin 10 comprising
a relatively thick, elongated fibrous body or core 12,
predominantly comprising cellulosic fibrous materials such as
comminuted wood pulp, cotton, rayon, tissue pulp, crepe or
cellulosic wadding, absorbent paper, etc.
The fibrous absorbent core 12 is enclosed within a conventional
soft, fluid permeable, wrapper or cover 14 whose ends extend beyond
the ends of the fibrous absorbent core 12 to provide the usual
attachment tabs 16, 16. As noted in FIGS. 1 and 2, the upper facing
surface and lower backing surface of the sanitary napkin 10 are
soft and fluid permeable.
A fluid impervious barrier sheet 18 is positioned under the fluid
absorbent core 12 and is in such a position that any body fluids or
exudates which are deposited on the upper facing surface of the
cover 14 and are of such volume that they pass through the
absorbent core 12 will be checked and will go no farther when they
contact the fluid impervious barrier sheet 18.
As shown more clearly in FIG. 3, the base or supporting layer of
the fluid impervious barrier sheet 18 comprises a cellulosic tissue
layer or layers 20 having properties as defined and described
previously. It is to be appreciated that such tissue material is
relatively thin, soft, fragile, conformable, and highly absorbent.
It is of very light weight, having a basis weight of from about 6
to about 30 pounds and preferably from about 12 to about 20 pounds,
is very porous, and contains very many minute openings and "pin
holes". The water-repellency or water-resistance of such a tissue
layer is practically negligible and the time required for a drop of
test fluid to pass through a test ply of such material is less than
about 4 seconds, or as little as almost substantially
instantaneous.
Although one ply of tissue is used in the previously described
repellency test and two plies of tissue are used in the preferred
embodiment of the inventive concept, it is to be appreciated that a
different number of tissues may be used in the absorbent product.
For example, merely a single layer of tissue may be used, or three,
four or more may be used, as desired or required. The total weight
of the tissue layer or layers, however, remains in the range of
from about 6 pounds to about 30 pounds, basis weight.
The tissue material 20 is treated with specified amounts of a water
repellent material 22 whereby a certain degree of water repellency
or water resistance but not complete waterproofing is created
therein. Such water repellent treatment may be accomplished in many
ways such as, for example, by inclusion of the water repellent
material 22 in the beater, head box, or other part of the
papermaking machine whereby it is incorporated in an "in-line"
operation directly onto the cellulosic fibrous materials during
their manufacture into tissue. Or, if desired, the water repellent
materials 22 may be applied after the formation of the tissue
sheet, in an "off-line" operation, such as by a spraying operation
or by a padding or dipping treatment.
In any event, the amount of water repellent material 22 which is
applied must be controlled to relatively narrow ranges of dry
add-ons of from about 0.1 percent by weight to about 0.5 percent by
weight, based on the dry weight of the treated tissue sheet. Within
the more commercial aspects of the present invention, a range of
dry add-ons of from about 0.2 percent by weight to about 0.3
percent by weight, based on the dry weight of the treated tissue
material, has been found more desirable.
Many water repellent materials have been found suitable for
application to the tissue material for the purpose of the present
invention. Among such water repellent materials are: various
fluorocarbons such as CTFE, PTFE, FEP, etc.; "Scotchgard"
Repellents FC-208, FC-210, FC-212, FC-214, etc.; silicones such as
Dri-Film 1040, a methyl hydrogen polysiloxane (General Electric)
and Dri-Film 1042 and 1043, modified methyl hydrogen polysiloxanes
(General Electric); cationic starch type water repellents such as
"Cyanasize" (American Cyanamid) and "Aquapel", a ketene dimer
emulsified with a cationic starch, sold by Fancourt Co.; etc.
As used herein, therefore, repellent tissue is defined as a tissue
which has been so treated that its water repellency or water
resistance falls in the above-defined range. The values of such
range, namely, from about 15 seconds to about 150 seconds, are to
be contrasted to the values obtained in testing waterproof or water
impervious materials which range from many hours to days, weeks, or
even longer.
The water repellent tissue is still relatively thin, soft, fragile,
flexible, and conformable but is not quite as porous as it was
prior to the water repellent treatment. There still remains,
however, a large number of minute openings and pin holes, however,
and the tissue is repellent and water resistant but not waterproof
or water impervious.
After the tissue material has been treated with the water repellent
material, it is then given a second treatment with a hydrocolloidal
material 24 which is capable of swelling sufficiently upon contact
with body fluids and exudates whereby substantially all of the
minute openings and pin holes are closed and the tissue becomes
substantially water-impervious or waterproof. Such a condition is
reached, however, only after the hydrocolloidal material 24 has
swollen sufficiently.
The amount of hydrocolloidal material 24 which is applied to the
treated tissue is kept within relatively narrow ranges and is in
the range of from about 0.002 to about 0.03 gram per square inch of
repellent tissue. Within the more commercial ranges of the present
invention, a range of from about 0.003 to about 0.02 gram per
square inch of repellent tissue is preferred.
The amount of hydrocolloidal material 24 which is applied to the
treated tissue may be expressed in terms of the amount which is
applied per sanitary napkin. Such an amount varies as desired or
required depending upon the particular hydrocolloidal material
used. It also varies depending upon the size and intended use of
the sanitary napkin. Expressed in this manner, it may be stated
that from about 0.05 gram to about 0.4 gram of hydrocolloidal
material is used per sanitary napkin. Within the preferred
commercial ranges, however, it may be stated that from about 0.11
gram to about 0.2 gram is used per sanitary napkin.
The hydrocolloidal materials may be selected from a relatively
large group of such materials, including both synthetic and
naturally occurring hydrocolloids. Examples of such materials
include cellulose ethers such as sodium carboxymethyl cellulose and
methyl cellulose, guar gums, gum karaya, gum tragacanth, algin,
polysaccharides, starches, gelatin, agar agar, proteins such as
blood or egg albumin, etc.
If merely one tissue layer is used, the hydrocolloidal material is
applied thereto in the ranges indicated. If two or more tissue
layers are used, and such construction is preferred, the
hydrocolloidal material is applied either merely to one tissue, or
to all tissues, but the total amount applied still falls within the
range of from about 0.002 to about 0.03 gram per square inch, based
on the area of the absorbent product. To illustrate specifically,
the total area of a sanitary napkin is in the range of from about
17 to about 25 square inches and normally from about 20 to about 22
square inches. The applied hydrocolloidal material add-on is
calculated on such an area.
When two or more tissue layers are used, the hydrocolloidal
material is preferably so applied and the tissues are so used that
the hydrocolloidal material is located between the tissue layers,
rather than being on an outer surface thereof.
In FIG. 4, there is illustrated a diaper 26 which represents
another specific embodiment of the application of the principles of
the present invention. The diaper 26 comprises: a soft, fluid
permeable, top facing surface 34 which may be a nonwoven fabric, a
nonwoven or woven scrim, a woven fabric such as gauze, or the like;
a centrally-located, highly absorbent fibrous body or core 32,
primarily or completely of cellulosic materials; and a waterproof
or fluid impervious barrier sheet 28 comprising a repellent treated
tissue and a hydrocolloidal material deposited thereon.
Such a waterproof or fluid impervious barrier sheet 28 is, of
course, fundamentally similar in construction, operation and
function to the waterproof or fluid impervious barrier sheet 18
which has been described previously.
If desired, an additional backing or supporting sheet 36 may be
added to reinforce or strengthen the fluid impervious barrier sheet
28. Such a backing sheet 36 may be similar to the facing sheet and
may also be a nonwoven fabric, a nonwoven or woven scrim, a woven
fabric such as gauze, or the like.
The water repellent material and the hydrocolloidal material are
preferably applied to the tissue in a finely divided particulate
form. Such application may be in a liquid carrier such as an
aqueous dispersion of the particulate materials wherein they are
applied by spraying, padding, dipping, or other techniques. Or, if
desired, the application may be dry and the particulate materials
applied by spraying, dusting, brushing, sprinkling, or other
techniques.
The particle size of the particulate material is not a critical
consideration. Relatively small particle sizes are preferred
inasmuch as such is more conducive to more uniform and more
efficient and economical application and coverage.
The invention will be more specifically described by reference to
the following Examples wherein particular materials and
constructions are used. Such specific examples, however, are
employed to illustrate selected embodiments of the inventive
concept and are not to be construed as limitative of the broader
aspects thereof.
EXAMPLE I
Highly absorbent, cellulosic tissue material having a basis weight
of approximately 14 pounds is treated with a cationic starch water
repellent material ("Aquapel" Fancourt) so as to render it water
repellent. The dry add-on of the cationic starch is 0.25 percent by
weight, based on the dry weight of the treated tissue. One ply of
the treated tissue is tested for water repellency, using the
previously described standard test. The test results are as
follows:
Sample No. Time In Seconds 1 25 2 90 3 120 4 150 5 270 6 20 7 25 8
35 9 90 10 120 11 15 12 50 13 60 14 70 15 80
These values are to be compared to the water repellency time for
the original, untreated tissue of one-half second.
The repellent tissue is then treated with a guar gum (Stein-Hall)
hydrocolloidal material in an amount sufficient to deposit 0.11
gram (dry) on an area measuring 21/4 .times. 87/8 inches
(approximately 20 square inches) for inclusion as a double
thickness sandwich of two tissues in a standard napkin such as
illustrated in FIG. 1. This is equivalent to a deposition of
approximately 0.0055 gram of guar gum hydrocolloidal material per
square inch of repellent tissue.
Upon deposition of body fluid upon the sanitary napkin and contact
thereof with the guar gum, swelling of the guar gum takes place
immediately and the treated repellent tissue becomes waterproof or
water impervious. "Strike-through" is prevented and the sanitary
napkin performs satisfactorily in use. Subsequent to use it is
discarded and disposed of readily inasmuch as the absorbent
cellulosic core, the cellulosic nonwoven fabric cover and the
barrier sheet are biodegradable.
EXAMPLES II - III
The procedures of example I are followed substantially as set forth
therein except that the add-on of the "Aquapel" water repellent
material is changed from 0.25 percent by weight to 0.15 percent by
weight and 0.35 percent by weight. The results are comparable.
EXAMPLES IV - V
The procedures of Example I are followed substantially as set forth
herein except that the "Aquapel" water repellent material is
replaced by a fluorocarbon (PTFE) and by a silicone ("Dri-Film
1042" - General Electric). The results are comparable.
EXAMPLE VI
The procedures of Example I are followed substantially as set forth
therein with the exception that the "Aquapel" water repellent
material is replaced by "Dri-Film 1040" (General Electric).
EXAMPLE VII
The procedures of Example I are followed substantially as set forth
therein with the exception that the "Aquapel" water repellent
material is replaced by "Dri-Film 1043" (General Electric).
EXAMPLES VIII - X
The procedures of Example I are followed substantially as set forth
therein except that the add-on of the guar gum is changed from 0.11
gram to 0.05 gram, 0.20 gram and 0.40 gram. This is equivalent to
the deposition of approximately 0.0025, 0.01, and 0.02 gram per
square inch of repellent tissue, respectively. The results are
comparable.
EXAMPLES XI - XIV
The procedures of Example I and II are followed substantially as
set forth therein except that the guar gum is replaced by sodium
carboxymethyl cellulose (DuPont - Code CS-5702-Grade P-75-H) in
similar amounts of 0.05 gram, 0.11 gram, 0.20 gram, and 0.40 gram.
The results are comparable.
Although the present invention has been described and illustrated
with reference to preferred embodiments thereof, it is to be
appreciated that such is merely for the purpose of disclosing the
invention and is not to be construed as limitative of the broader
aspects of the inventive concept, except as defined by the appended
claims.
* * * * *