U.S. patent number 3,695,269 [Application Number 05/010,840] was granted by the patent office on 1972-10-03 for method of making absorbent products with highly absorbent cores and relatively dry facings.
Invention is credited to Frank E. Malaney.
United States Patent |
3,695,269 |
Malaney |
October 3, 1972 |
METHOD OF MAKING ABSORBENT PRODUCTS WITH HIGHLY ABSORBENT CORES AND
RELATIVELY DRY FACINGS
Abstract
Absorbent products comprising at least two fibrous layers: one
layer comprising a highly absorbent fibrous mass having excellent
absorption and retention capacity for body fluids and exudates; and
a second layer comprising a relatively dry, non-adherent, nonwoven
fabric facing made of relatively non-absorbent, hydrophobic,
synthetic fibers bonded with a hydrophobic binder material and
processed so as to be provided with increased loft and bulk
properties.
Inventors: |
Malaney; Frank E. (Somerville,
NJ) |
Family
ID: |
21747692 |
Appl.
No.: |
05/010,840 |
Filed: |
February 12, 1970 |
Current U.S.
Class: |
604/366; 604/372;
604/373; 604/375; 604/379; 604/371 |
Current CPC
Class: |
A61F
13/15577 (20130101) |
Current International
Class: |
A61F
13/15 (20060101); A61f 013/16 () |
Field of
Search: |
;128/284,287,29R,29W,296
;26/18.6 ;161/151,156,160 ;117/15,66,115,138.8,167 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Rosenbaum; Charles F.
Claims
What is claimed is:
1. A method of manufacturing an absorbent product having excellent
absorption and retention capacity for body fluids and exudates but
capable of maintaining a relatively dry surface during such
absorption and retention comprising: (1) forming a fibrous web of
overlapping, intersecting, relatively non-absorbent hydrophobic
fibers; (2) bonding said fibers with a hydrophobic, water
repellent, water insensitive binder material which does not rewet
too readily to form a bonded nonwoven fabric; (3) coating said
bonded nonwoven fabric with from about 0.3 percent to about 2
percent by weight, based on the total weight of said bonded
nonwoven fabric, of a surfactant having rewetting properties; (4)
compacting the bonded nonwoven fabric whereby the individual fibers
are crowded together into a denser and more compact configuration;
elongating the compacted, bonded nonwoven fabric whereby the bonded
nonwoven fabric is returned to within about 10 percent of its
original length prior to compacting and elongating and the bulk of
said bonded nonwoven fabric is increased from about 60 percent to
about 340 percent without materially increasing the weight per
square yard thereto; and (5) combining said bonded, bulked nonwoven
fabric with an absorbent fibrous body into a laminated absorbent
product having excellent absorption and retention capacity for body
fluids and exudates but capable of maintaining a relatively dry
surface during such absorption and retention.
Description
The present invention relates to improved absorbent products for
absorbing and retaining body fluids and exudates. More
specifically, the present invention relates to improved absorbent
products which have excellent absorption and retention capacity for
body fluids and exudates but which are capable of presenting a
relatively dry, non-absorbent, non-adherent, hydrophobic surface to
the body emitting the fluids and exudates.
There are many absorbent products, such as diapers, sanitary
napkins, surgical dressings, underpads, compresses, and the like,
which are used for the absorption and retention of body fluids and
exudates. Diapers, and particularly disposable diapers, are
representative of this very large class of absorbent products and
they will be used to illustrate more specific details of the
present inventive concept. Such, however, is not intended to limit
the broader aspects of the present inventive concept.
Disposable diapers normally comprise two or more layers of fibrous
textile materials. One of these layers is normally an absorbent
fibrous mass or core whose primary function is to absorb and retain
the bulk of the body fluids and exudates. This absorbent fibrous
mass or core is normally covered with a second layer or cover
usually referred to as a facing sheet which is in direct contact
with the body of the wearer and which is contacted first by the
body fluids and exudate. A waterproof or water impervious layer,
usually of polyethylene or the like, is frequently also used as a
backing layer which covers the outer surface of the absorbent
fibrous core and prevents the passage of the body fluids or exudate
beyond the absorbent fibrous core.
It is to be readily appreciated that if all the body fluids and
exudates were to rapidly pass through the relatively non-absorbent,
non-adherent hydrophobic facing sheet of the diaper and be absorbed
and retained substantially completely by the inner absorbent
fibrous core, the facing sheet would remain relatively dry. This
would increase the absorptive effectiveness of the diaper and would
decrease the incidence of diaper rash and related irritation which
could be created by the presence of body fluids and exudates if
they were permitted to remain in the facing in continual contact
with the body of the wearer of the diaper.
The principal purpose and object of this invention is therefore to
provide a facing material for absorbent products which is capable
of rapidly passing the body fluids and exudates through to the
inner absorbent core whereby the facing material remains relatively
dry and thus possesses anti-rash and anti-irritation
properties.
It has been discovered that such purpose and object, as well as
other purposes and objects which will become clear from a reading
of this disclosure, may be accomplished by (1) manufacturing the
facing material in the form of a fibrous web made substantially
completely of relatively non-absorbent, non-adherent hydrophobic,
synthetic fibers; (2) bonding the fibrous web into a bonded
nonwoven fabric by means of a hydrophobic binder material; (3)
applying a rewetting surfactant to the bonded nonwoven fabric; (4)
increasing the bulk of the bonded nonwoven fabric without
materially increasing the weight per square yard thereof; and then
(5) using the bonded, bulked nonwoven fabric as the facing material
for an absorbent product.
The present invention will be further described in greater detail
by reference to the following specification and claims and the
accompanying drawings wherein there is described and illustrated a
preferred embodiment of the invention.
In the drawings,
FIG. 1 is a fragmentary, partially cutaway, perspective view of a
portion of a diaper, representing a preferred embodiment of the
absorbent products of the present invention; and
FIG. 2 is a diagrammatic, schematic showing of a process for
manufacturing the absorbent products of the present invention.
With reference to the drawings and particularly FIG. 1 thereof,
there is shown an absorbent product such as a diaper 10 which
comprises a nonwoven fabric facing sheet 12, a centrally located
highly absorptive fibrous body or core 14, and a waterproof or
water impervious backing sheet 16, made of polyethylene or similar
material.
The nonwoven fabric which is the basis of the facing sheet 12 may
be made by any of the well-known processes for making such nonwoven
fabrics. Typical of such nonwoven fabrics are the so-called
"KEYBAK" bundled rearranged nonwoven fabrics wherein the individual
fibers are more or less predominantly oriented in one direction but
are also reorganized and rearranged in predetermined, regularly
repeating designs or patterns comprising a plurality of fabric
openings and fiber bundles. Such fabrics are described in greater
detail in U. S. Pat. Nos. 2,862,251, 3,025,585 and 3,033,721.
Another type of nonwoven fabric suitable as the facing sheet of the
present invention is the so-called "MASSLINN" nonwoven fabric
derived from carded fibrous webs wherein the individual fibers are
predominantly oriented in one direction. Such fabrics are described
in greater detail in U. S. Pat. Nos. 2,705,498, 2,705,687 and
2,705,688.
Still another type of nonwoven fabric suitable as the facing sheet
of the present invention is the so-called "isotropic" nonwoven
fabric wherein the individual fibers are disposed at random and are
not predominantly oriented in any one direction. Such fabrics are
described in greater detail in U. S. Pat. Nos. 2,676,363 and
2,676,364.
A still further type of nonwoven fabric suitable as the facing
sheet of the present invention is the more recently developed
rearranged nonwoven fabric described in greater detail in British
Pat. No. 1,088,376.
The synthetic fibers which are used to make up the fibrous web are
relatively non-absorbent and hydrophobic. Typical of such synthetic
fibers are the polyester, acrylic, modacrylic, polyamide nylon,
polyolefin, polyurethane spandex, polyvinylidene chloride saran,
fluorocarbon, and like fibers.
The terms "non-absorbent" and "hydrophobic" are, of course,
relative terms and, as such, require definition. Such terms are
defined in many ways but it is believed that one of the most
commonly accepted forms is the percentage of water absorbed by the
fibers at 70.degree. F. and 65 percent relative humidity. As used
herein, the terms "non-absorbent" and "hydrophobic" are intended to
include those fibers having water absorbencies less than about 41/2
percent by weight and preferably less than about 1 percent by
weight.
Another accepted form of determining the lack of absorption
desirable in the fibers of the present invention is the percent
water of imbibition which is the water content of a fiber when
brought to equilibrium from the wet side at 100 percent relative
humidity and 70.degree. F. Under such conditions, the percent of
water imbibition should be less than about 10 percent and
preferably less than about 2 percent by weight.
In the following description, the polyester fiber will be used as
the relatively non-absorbent, hydrophobic fiber to illustrate the
invention but such is by way of example and is not limitative of
the broader aspects of the present invention.
As used herein, the term "polyester" conforms with the Federal
Trade Commission's Rules and Regulations under the Textile Fiber
Products Identification Act and is a manufactured fiber in which
the fiber-forming substance is any long chain synthetic polymer
composed of at least 85 percent by weight of an ester of a dihydric
alcohol and terephthalic acid (p-HOOC--C.sub.6 H.sub.4 --COOH).
Other fiber terms such as "acrylic," "modacrylic," "rayon,"
"nylon," "olefin," etc., as used herein, are used as defined by
Federal Trade Commisiion's Rules and Regulations under the Textile
Fiber Products Identification Act.
The most common polyester fiber used herein is polyethylene
terephthalate derived from a reaction between ethylene glycol and
terephthalic acid. Such a fiber is sold by various companies under
various trademarks such as "Dacron," "Kodel," "Encron," "Vycron,"
"Quintess," "Trevira," "Fortrel," "Avlin," "Blue C," etc.
The denier of the relatively non-absorbent, hydrophobic fibers may
be selected from a relatively wide range of from about 1 denier to
about 15 denier, depending upon the needs and requirements of the
particular situation. Preferably, however, a range of from about
11/4 denier to about 3 denier has been found most desirable from a
commercial viewpoint.
The weight of the fibrous web may be varied relatively widely
depending on the uses for which it is intended. Weights as low as
about 150 grains per square yard are useful for some purposes,
whereas heavier weights up to about 1,000 grains per square yard
are required for other uses. Within the more commercial fields, a
range is preferred of from about 250 grains per square yard to
about 550 grains per square yard.
In some uses and applications wherein the needs and requirements
are not too rigorous, it is possible to include a minor percentage,
up to about 25 percent by weight of the total weight of the fibrous
web, of fibers which are not relatively non-absorbent or
hydrophobic. Typical of such fibers are the natural and synthetic
cellulosic fibers, such as cotton and rayon.
The fibrous web W may be manufactured by any desired apparatus 20
(see FIG. 2) such as described or referred to previously, and is
then forwarded, if so desired, through fibrous web reorganizing and
rearranging apparatus 24 referred to hereinbefore. The fibrous web
is preferably, however, reorganized and rearranged by passage
through apparatus illustrated in FIGS. 7-10 of U. S. Pat. No.
2,862,251 whereby the familiar fabric openings and fiber bundles of
a typical "KEYBAK" bundled rearranged nonwoven fabric are
obtained.
Although the present invention will be described with special
emphasis on the use of a "KEYBAK" bundled rearranged nonwoven
fabric as the facing sheet, such is for illustrative purposes and
is not to be construed as limitative of the broader aspects of the
present invention.
The fibrous web is then bonded into a bonded nonwoven fabric F in
suitable web bonding apparatus 28 which may comprise spraying
techniques, overall impregnation bonding techniques or intermittent
print pattern bonding techniques, such as described in the patents
relating to the manufacture of the so-called "MASSLINN" nonwoven
fabrics.
Application of the bonding material may be accomplished, for
example, by any conventional saturation coating or impregnating
apparatus, such as by having the fibrous web pass in rolling
contact with an applicator roll 29 or the like having a suitably
prepared surface and which dips into a trough or bath 30 containing
a supply of the bonder material 31 which is transferred to the
fibrous web. Nip rolls 32, 33 or other suitable devices may be used
to control the amount of binder material which is added.
The binder material must naturally be inert, non-toxic,
non-allergenic, and non-irritating to the skin of the user. It must
have very little and preferably no affinity for water and
specifically no affinity for body fluids and exudates or any other
fluids with which it may come in contact in use. It should be used
in an amount and in a fashion as not to stiffen or reduce the
softness of the fibrous web, either immediately or upon ageing. It
should be colorless and odorless.
The binder material should be hydrophobic and water repellent and
of the type which is water insensitive and which does not re-wet
too readily. Typical of such binder materials are the solution or
emulsion polymerized resins which are usually in the form of solid
resin particles dispersed in a liquid which is normally water.
Suitable examples of such resins are the polyvinyl chlorides and
particularly plasticized polyvinyl chloride; polyvinyl acetates and
polyvinyl chloride-polyvinyl acetate copolymers; polyacrylates such
as ethyl acrylates and other alkyl acrylates; polymethacrylates
such as methyl methacrylate, ethyl methacrylate, etc.; polyacrylate
copolymers such as ethyl acrylate-methyl methacrylate copolymers;
polyvinyl chloride-alkyl acrylate copolymers such as vinyl
chloride-ethyl acrylate copolymers; polyvinyl acetate-alkyl
acrylate copolymers such as vinyl acetate-methyl acrylate
copolymers; polyurethanes; synthetic rubber latexes; etc.
The amount of binder material which is applied to the fibrous web
may be varied within relatively wide limits. A range of from about
15 percent to about 45 percent by weight, based on the total weight
of the bonded fibrous web is suitable, with a preferred range of
from about 25 percent to about 35 percent by weight, based on the
total weight of the bonded fibrous web.
The bonded nonwoven fabric F is then dried by any suitable drying
apparatus 34, such as a series of rotating heated drying cans, or
by passage through a heated drying chamber or oven. Elevated
temperatures of from about 220.degree. F. to about 330.degree. F.
are normally employed for the heating step which may also perform a
curing function for the binder material, if necessary.
Subsequent to the drying step, the bonded nonwoven fabric F is
impregnated in conventional coating or impregnating apparatus 36
with a surfactant having rewetting properties.
The surfactant may be anionic, cationic, or nonionic. Specific
classes of suitable surfactants include: sodium and potassium salts
of saturated fatty acids containing 5-18 carbon atoms; sodium alkyl
sulfates containing 6-18 carbon atoms; sodium alkyl sulfonates
containing 6-18 carbon atoms; sodium alkyl benzene sulfonates
containing 6-18 carbon atoms; sodium 1-methyl alkyl benzene
sulfonates in which the methyl alkyl group contains 12-18 carbon
atoms; sodium di-alkyl sulfosuccinates in which each group contains
4-12 carbon atoms; sodium polyoxyethylene ether alcohol sulfates in
which the alcohol contains 12-18 carbon atoms; triethanolamine
salts of fatty acids; alkyl amine hydrochlorides; alkyl trimethyl
ammonium bromides; di-alkyl dimethyl ammonium chlorides;
polyoxyethylene mono alkyl ethers in which the alkyl group contains
12 to 18 carbon atoms; polyoxyethylene nonyl phenyl ethers; methoxy
polyoxyethylene decanoates and dodecanoates; etc.
Particular preferred species within the above-mentioned classes of
surfactants include: anionic surfactants such as "Aerosol OT"
(dioctyl sodium sulfosuccinate); "Aerosol OS" (isopropyl
naphthalene sodium sulfosuccinate); "Deceresol OS" (sodium
di-isopropyl naphthalene sulfonic acid); "Emulgator K-30" (sodium
alkyl C.sub.10 -C.sub.14 sulfonate); "Triton X-405" (polyethylene
glycol nonyl phenyl ether (40 moles ethylene oxide); "Hyamine"
(tertiary aryl dialkyl amine).
The surfactant must naturally be inert, non-toxic, non-allergenic,
and non-irritating to the skin of the user. It should be used in an
amount and in a fashion as not to stiffen or reduce the softness of
the nonwoven fabric, either immediately or upon ageing. It should
preferably be colorless and odorless and should not significantly
reduce the wet or dry strength of the material to which it is
applied.
Application of the surfactant may be accomplished by any
conventional method such as by having the nonwoven fabric pass in
rolling contact with a coating or impregnating roller 37 or the
like, the surface of which has been suitably prepared and which
dips into a trough or receptacle 38 containing a supply of the
surfactant material 39 and transfers the same to the nonwoven
fabric.
The amount of rewetting surfactant which is applied to the bonded
nonwoven fabric F must be controlled within specified limits in
order that just the right kind of rewetting properties and
characteristics are obtained. It has been established that the
addition of from about 0.1 percent by weight to about 2 percent by
weight, based on the total weight of the bonded nonwoven fabric, is
suitable. Less than about 0.1 percent by weight does not create
sufficient rewetting characteristics and more than 2 percent by
weight causes the body fluids and exudates to tend to flow back
into the facing sheet from the absorbent core whereby the facing
sheet loses its relatively dry hand. Within the narrower aspects of
the present invention, a range of from about 0.3 percent to about 1
percent by weight is preferred.
After the rewetting surfactant has been applied to the bonded
nonwoven fabric, drying takes place in conventional drying
apparatus 42 comprising a series of rotating heated drying cans or
a heated oven maintained at an elevated temperature of from about
220.degree. F. to about 300.degree. F.
The bonded nonwoven fabric is then passed through suitable bulking
apparatus 44 which may take the form of any conventional bulking of
lofting apparatus presently available. An example of a typical
bulking apparatus are the forms of apparatus described particularly
in FIGS. 1-5 of U. S. Pat. Nos. 2,765,513 and 2,765,514.
Such apparatus creates a crepe or a crimp in the nonwoven fabric
whereby its bulk or loft is increased manyfold. The action is
somewhat like a scuffing or piling action which fluffs up and
crinkles the fibers of the nonwoven fabric, primarily in their
direction of travel through the bulking apparatus. As a result of
such scuffing and bulking action, the fibers no longer lay
generally flat in substantially a single plane but are more erect
and extend in many cases from one surface to the other surface of
the nonwoven fabric.
Such bulking action, however, basically also yields a compaction of
the fibrous structure whereby the individual fibers are crowded
together into a denser and more compact configuration. The nonwoven
fabric is therefore drafted or elongated, such as by means of
positively driven drafting rollers positioned at the exit of the
bulking apparatus and capable of rotating at a desired speed
whereby the nonwoven fabric is stretched and returned substantially
to its original length. The loft of the nonwoven fabric, however,
is maintained whereby the density or compaction of the fibers is
reduced considerably.
The speed of the drafting rolls is so adjusted that they are
capable of bringing the nonwoven fabric back substantially to its
original length, or at least to within 5 percent or 10 percent
thereof.
The retention of the high loft even after the drafting of the
nonwoven fabric is due to many factors. The internal bonding and
holding action of the binder material has been sufficiently
disrupted during the bulking action whereby it does not hold the
fibrous structure as it did previously to the bulking action and
thus the bulk or loft remains. Additionally, the type of fiber
used, and this is particularly true for the polyester species,
possesses considerable resilience and spring-back and will tend to
remain in its bulked and lofty condition and not to return to its
flattened planar condition.
The increase in bulk or loft depends upon many processing factors
such as the severity and intensity of the bulking action, the type
of fibers present, the type and amount of binder material and
surfactant applied, the degree of subsequent drafting action, etc.
Under normal circumstances, increases in bulk or loft range from
about 60 percent to about 340 percent. Couched in other terms, it
may be stated, for example, that a fibrous web having an original
thickness of about 6 or 7 mils may be increased in thickness to a
range of from about 12 mils to 17 or 18 mils and even 25 mils or
more, without substantial loss in length or increase in weight per
square yard.
The thickness of the nonwoven fabric or the fibrous web may be
determined by any suitable measuring apparatus, such as a Randall
and Stickney Gauge made in Waltham, Mass.
The nonwoven fabric is forwarded to a product formation zone 48
whereat it is laminated with suitable absorbent structures as the
facing sheet thereof, as desired or required. In the case of the
absorbent product illustrated in FIG. 1, the absorbent structure
comprises a heavier layer of absorbent fibers such as wood pulp,
cotton and/or rayon, and a waterproof or water impervious backing
sheet made of polyethylene, regenerated cellulose (cellophane),
polyvinylidene chloride (saran), polyvinyl chloride, or other
natural or synthetic material having like properties and
characteristics.
The invention will be further illustrated in greater detail by the
following specific examples. It should be understood, however,
that, although these examples may describe in particular detail
some of the more specific features of the invention, they are given
primarily for purposes of illustration and the invention in its
broader aspects is not to be construed as limited thereto.
EXAMPLE I
An oriented card web weighing about 350 grains per square yard and
comprising 100 percent Eastman Kodak "Kodel" polyethylene
terephthalate polyester fibers having a denier of 1.5 and a staple
length of 11/2 inches is used as the starting fibrous web material.
The water absorbency of such fibers is about 0.4 percent.
This fibrous web material is passed through "KEYBAK" rearranging
apparatus such as illustrated in FIGS. 7-10 of U. S. Pat. No.
2,862,251, wherein the forming drum is provided with 225 holes per
square inch, with each hole having a diameter of 0.045 inch,
whereby the open area is about 37 percent.
The resulting rearranged fibrous web is then bonded with Rohm &
Haas "Rhoplex HA-8" which is essentially a self-crosslinking ethyl
acrylate synthetic polymeric resin binder material. Drying takes
place at a temperature of about 280.degree. F. on a series of
rotating heated dry cans. The amount of dry add-on of resin binder
is approximately 30 percent by weight of the total weight of the
bonded nonwoven fabric.
The bonded nonwoven fabric is then treated with American Cyanimid's
"Aerosol OT" (dioctyl sodium sulfosuccinate) in a saturation
impregnating bath and is dried at a temperature of about
260.degree. F. on a series of rotating heated drying cans. The
amount of dry add-on of the surfactant is about 0.5 percent by
weight rf the total weight of the bonded, surfactant-treated
nonwoven fabric.
The bonded, surfactant-treated nonwoven fabric is then bulked in
apparatus illustrated in FIGS. 1-5 of U. S. Pat. Nos. 2,765,513 and
2,765,514 and then passed through the nip of rotating drafting
rolls, the speed of which is so adjusted as to bring the length of
the nonwoven fabric back to within 5 percent of its length prior to
bulking. The thickness of the nonwoven fabric prior to bulking is
about 7 mils. Subsequent to bulking, the thickness of the nonwoven
fabric is about 17 mils which represents an increase in bulking or
loft of about 143 percent, with a decrease in length of only about
5 percent.
The bulked, bonded nonwoven fabric is then laminated with a heavier
absorbent core of comminuted wood pulp fibers which is backed up
with a 1-mil polyethylene water-impervious film. The resultant
composite absorbent product is useful as a disposable diaper, or as
an underpad, a surgical dressing, or a compress, and is capable of
absorbing and retaining substantial amounts of body fluids and
exudates, while presenting a relatively dry, non-absorbent,
non-adherent, hydrophobic surface to the body of the wearer.
EXAMPLES II-IV
The procedures of Example I are followed substantially as set forth
therein except that the relative speeds of the fast and slow rolls
of the bulking apparatus are varied as to provide for changes in
the increase of the bulking effect. The original thickness of 7
mils, rather than being increased to 17 mils, as in Example I, is
increased to (II) 12 mils, (III) 18 mils, and (IV) 25 mils,
representing increases in loft and bulk of (II) 71 percent, (III)
157 percent, and (IV) 258 percent, respectively. All three bulked
bonded nonwoven fabrics are found suitable as facing materials on
diapers, sanitary napkins, surgical dressings, underpads and
compresses.
EXAMPLES V-VIII
The procedures of Example I are followed substantially as set forth
therein except that the dry add-on of the surfactant is changed
from 0.5 percent as in Example I to (V) 0.2 percent, (VI) 1.0
percent, (VII) 1.5 percent, and (VIII) 5 percent by weight. Results
comparable to those obtained in Example I are obtained for the
first three absorbent products but it is noted that the fourth
absorbent product wherein 5 percent of surfactant is applied, there
is a tendency for the body fluids and exudate to wet back from the
absorbent fibrous mass into the facing sheet whereby it does not
remain as dry as desired.
EXAMPLES IX -XIV
The procedures of Example I are followed substantially as set forth
therein except that the following fibers are used to replace the
polyester fibers of Example I: (IX) polyamide nylon 66
(hexamethylene tetramine-adipic acid), water absorbency -- 4
percent; (X) polyamide nylon 610 (hexamethylene tetramine-sebacic
acid), water absorbency--4percent; (XI) polyamide nylon 6
(caprolactam), water absorbency--4 percent; (XII) polypropylene,
water absorbency, 0.1 percent; (XIII) "Acrilan" acrylic fiber
having more than 85 percent by weight of acrylonitrile units, water
absorbency, 1.5 percent; and (XIV) "Dynel" modacrylic fibers
containing between 35 percent and 85 percent by weight of
acrylonitrile units, water absorbency, 0.4 percent. The results are
generally comparable to those obtained in Example I. The absorbent
products containing the polypropylene fibers are particularly
non-absorptive with the water of imbibition being only about 0.1
percent.
EXAMPLES XV-XVIII
The procedures of Example I are followed substantially as set forth
therein except that the ethyl acrylate resin binder of Example I is
replaced by: (XV) plasticized polyvinyl chloride; (XVI) polyvinyl
acetate; (XVII) polyurethane; and (XVIII) vinyl acetate-butyl
acrylate copolymer. The results are comparable to those obtained in
Example I.
EXAMPLES XIX-XXIII
The procedures of Example I are followed substantially as set forth
therein except that the rewetting surfactant used rather than being
"Aerosol OT" as in Example I is: (XIX) "Aerosol OS" (isopropyl
naphthalene sodium sulfosuccinate); (XX) "Deceresol OS" (sodium
di-isopropyl naphthalene sulfonic acid); (XXI) "Emulgator K-30"
(sodium alkyl C.sub.10 -C.sub.14 sulfonate); (XXII) "Triton X-405"
(polyethylene glycol nonyl phenyl ether (40 moles ethylene oxide);
and (XXIII) "Hyamine" (tertiaryaryl dialkyl amine).
EXAMPLES XXIV-XXVI
The procedures of Example I are followed substantially as set forth
therein with the exception that the fibrous web used is not an
oriented rearranged card web as in Example I but is: (XXIV) an
oriented card web which has not been rearranged and in which 25
percent of the polyester fibers are replaced by 1.5 denier, 1 9/16
inch staple length rayon fibers, water absorbency, 11 percent;
(XXV) a 550-grain weight all-polyester oriented card web; and
(XXVI) a 450-grain weight all-polyester fiber isotropic fibrous
web. The results are generally comparable to those obtained in
Example I.
EXAMPLES XXVII-XXVIII
The procedures of Example I are followed substantially as set forth
therein except that the "Kodel" polyester fibers of Example I are
replaced by (XXVII) "Fortrel" (Fiber Industries) and (XXVIII)
"Dacron" (Du Pont) polyethylene glycol terephthalate polyester
fibers are used. The water absorbencies of such fibers are both 0.4
percent. The results are comparable to those obtained in Example I.
The water of imbibition of such fibers is less than about 2
percent.
Although the present invention has been described and illustrated
with specific regard to particular embodiments thereof in the
preceding examples, such is not to be construed as limitative of
the broader aspects of the inventive concept, except as defined and
limited by the appended claims.
* * * * *