U.S. patent application number 16/948163 was filed with the patent office on 2021-06-24 for synthetic surfactant-free finish, sheet having synthetic surfactant-free finish, articles having sheet with synthetic surfactant-free finish, and related methods.
The applicant listed for this patent is ATTENDS HEALTHCARE PRODUCTS, INC.. Invention is credited to Harry J. CHMIELEWSKI, Edward L. SEAMES.
Application Number | 20210186776 16/948163 |
Document ID | / |
Family ID | 1000005447728 |
Filed Date | 2021-06-24 |
United States Patent
Application |
20210186776 |
Kind Code |
A1 |
CHMIELEWSKI; Harry J. ; et
al. |
June 24, 2021 |
SYNTHETIC SURFACTANT-FREE FINISH, SHEET HAVING SYNTHETIC
SURFACTANT-FREE FINISH, ARTICLES HAVING SHEET WITH SYNTHETIC
SURFACTANT-FREE FINISH, AND RELATED METHODS
Abstract
Nonwoven (and film) topsheet and acquisition/distribution
materials treated with a hydrophilic, synthetic surfactant-free
finish, absorbent articles for infant or incontinence care that
contain these materials, and methods for apply such finishes and/or
making such absorbent articles.
Inventors: |
CHMIELEWSKI; Harry J.; (Wake
Forest, NC) ; SEAMES; Edward L.; (Rock Hill,
SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ATTENDS HEALTHCARE PRODUCTS, INC. |
Greenville |
NC |
US |
|
|
Family ID: |
1000005447728 |
Appl. No.: |
16/948163 |
Filed: |
September 4, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15707603 |
Sep 18, 2017 |
10765569 |
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16948163 |
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14941252 |
Nov 13, 2015 |
9913925 |
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15707603 |
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62079879 |
Nov 14, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 13/51113 20130101;
A61F 13/513 20130101; A61L 15/32 20130101; C09D 189/00 20130101;
A61L 15/24 20130101; A61L 15/62 20130101 |
International
Class: |
A61F 13/513 20060101
A61F013/513; A61F 13/511 20060101 A61F013/511; A61L 15/32 20060101
A61L015/32; A61L 15/24 20060101 A61L015/24; C09D 189/00 20060101
C09D189/00; A61L 15/62 20060101 A61L015/62 |
Claims
1-15. (canceled)
16. A method of imparting hydrophilic properties to a sheet of
polymeric material, the method comprising: dissolving a
water-soluble protein in water to form a 0.5-10% aqueous solution
of the water-soluble protein having a surface tension of less than
49 milliNewtons per meter (mN/m); maintaining the aqueous solution
at a temperature for a period of time sufficient to thermally
denature at least a portion of the protein; applying the aqueous
solution to a sheet of polymeric material; and drying the sheet
such that at least a portion of the protein is retained on a
surface of the sheet; where the aqueous solution is substantially
free of synthetic surfactants.
17. The method of claim 16, wherein the sheet comprises a nonwoven
fabric or a film.
18. The method of claim 16, further comprising, prior to applying
the aqueous solution to the sheet: admixing the water-soluble
protein in water; heating the water to a temperature in the range
of 40.degree. Celsius (C) to 99.degree. C.; and stirring the
admixture to dissolve the water-soluble protein in the water.
19. The method of claim 18, wherein the water is heated before
admixing the water-soluble protein.
20. The method of claim 18, wherein the temperature of the water is
maintained at a temperature of from 40.degree. C. to 99.degree. C.
during at least a portion of the stirring.
21. The method of claim 19, wherein the temperature of the water is
maintained at a temperature of from 40.degree. C. to 99.degree. C.
for a period of time sufficient to thermally denature at least a
portion of the water-soluble protein.
22. The method of claim 18, further comprising: adjusting the pH of
the admixture of water and water-soluble protein prior to heating
the admixture.
23. The method of claim 16, wherein the temperature of the solution
is in the range of 20.degree. C. to 40.degree. C. during at least a
portion of applying the aqueous solution to the sheet.
24. The method of claim 16, wherein applying the aqueous solution
to the sheet comprises: immersing the sheet a first time in the
aqueous solution; and immersing the sheet a second time in the
aqueous solution.
25. The method of claim 24, further comprising: calendaring the
sheet between immersing the sheet the first time and immersing the
sheet the second time.
26. The method of claim 16, wherein applying the aqueous solution
to the sheet is performed with at least one coating apparatus
selected from the group consisting of: a slot die, a knife coater,
a kiss coater, a gravure printer, a multiple-roller coating
apparatus, and a screen coating apparatus.
27. The method of claim 16, wherein the aqueous solution comprises
a preservative.
28. The method claim 27, wherein the preservative comprises one or
more preservatives selected from the group consisting of elemental
silver, Japanese honeysuckle, one of more tocopherols, and mixtures
thereof.
29. The method of claim 16, wherein the protein comprises soy
protein isolate (SPI).
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/707,603, filed Sep. 18, 2017, which is a
continuation-in-part of U.S. patent application Ser. No.
14/941,252, filed Nov. 13, 2015, now U.S. Pat. No. 9,913,925,
issued Mar. 13, 2018, which claims priority to U.S. Provisional
Patent Application No. 62/079,879, filed Nov. 14, 2014, each of
which are incorporated herein by reference in their entireties.
FIELD OF INVENTION
[0002] The present invention relates generally to disposable
absorbent products such as infant diapers, adult incontinence
briefs, pull-up underwear, bladder control pads, bedpads; and, more
particularly, but not by of limitation, to nonwoven topsheet and
acquisition/distribution layers (ADL's) finished with durable,
hydrophilic, synthetic surfactant-free finishes, and to absorbent
products that contain topsheets and ADL's treated with a synthetic
surfactant-free finish. The present synthetic surfactant
free-finishes, and the methods of applying it, can also be useful
for woven materials comprising hydrophobic fibers that require a
hydrophilic finish.
BACKGROUND
[0003] Absorbent articles, such as baby diapers, training pants,
adult incontinence products and other such absorbent products
include a topsheet that is closest to the wearer, an outer,
moisture-impermeable backsheet, and an absorbent core. Disposable
absorbent products have met with widespread acceptance in the
marketplace for a variety of applications, including infant and
adult incontinence care, in view of the manner in which such
products can provide effective and convenient liquid absorption and
retention while maintaining the comfort of the wearer. However,
experience has shown that a need exists for more skin-friendly
topsheet nonwovens. Examples of absorbent article constructions
with which the present sheets can be used are disclosed in United
States Patent Application Publications No. US 2006/0178650 and No.
US 2010/0280479.
[0004] The nondurable, or fugitive, nature of synthetic surfactants
used on all polyolefin topsheets and acquisition/distribution
layers in use today play a role in absorbent product acquisition
and rewet performance, but have a potential to compromise skin
health. Synthetic surfactants are used as penetration aids in
transdermal drug delivery. Synthetic surfactants washed from the
nonwoven fibers during product use can increase the permeability of
stratum corneum to all potential irritants, including the synthetic
surfactant itself. Various emollient materials have be used in an
attempt to restore barrier function to damaged skin, but a
straightforward solution to the problem is to eliminate all
synthetic surfactant from the nonwoven. In this invention we have
identified potential chemistries for imparting wettability to
polyolefin nonwovens and films, and teach how they can be applied
effectively--without the use of any conventional synthetic
surfactants and with the goal of promoting skin health.
[0005] Nonwovens made from polypropylene are hydrophobic. By
application of suitable finishing treatments, it is possible to
impart semi-durable hydrophilic properties to the nonwoven to
achieve performance in liquid strike-through and liquid runoff that
is required for their use in absorbent products. Suitable finishing
treatments are typically proprietary blends of synthetic surfactant
solutions which are commercially available, for example, from
Schill & Seilacher AG (e.g. Silastol PHP 26, Silastol PHP 90,
& Silastol 163), and Pulcra Chemicals (e.g. Stantex S 6327,
Stantex S 6087-4, & Stantex PP 602). They are typically applied
to spunbond nonwovens in the range of 0.004-0.006 gm solids/gm
nonwoven (i.e. 0.4-0.6% wt/wt). An example of a synthetic
surfactant that has been used widely used in commercially-available
topsheet finishes would be Triton GR-5M, an anionic sulfosuccinate
surfactant manufactured by Dow Chemical Company. Other types of
surfactants used are based on fatty acid polyethylene glycol
esters.
[0006] U.S. Pat. Nos. 5,938,649 and 5,944,705, Ducker, et al.,
disclosed an absorbent article containing aloe vera on the surface
of the article contacting the wearer's skin to reduce rash. A
preferred embodiment of this invention was an essentially
water-free aloe vera in a waterless lubricant that was applied to
an absorbent product independently of any surfactant finish on the
topsheet nonwoven. Procter & Gamble commercialized a baby
diaper in the late 1990's/early 2000's that contained an emollient
lotion, applied in stripes, on a conventional topsheet nonwoven.
U.S. Pat. No. 6,459,014 B1, Chmielewski and Erdman, mentions pH
control agents such as citric acid and sodium citrate that can be
added to a nonwoven topsheet in conjunction with an optional
surfactant. However, all examples in this patent included synthetic
surfactant and there was no discussion of how a nonwoven could be
successfully treated with a surfactant-free solution of citric
acid, or whether it could impart useful hydrophilic properties to
the nonwoven. Furthermore, citric acid and sodium citrate are
freely soluble in saline solution and would not provide a
sufficiently durable finish to a topsheet nonwoven. More recently,
in U.S. Pat. No. 6,936,345 B2, Wild et. al. describe a process for
finishing nonwovens in such a way to meet requirements in regard to
the permanence of the hydrophilic finish and be capable of
providing an additional benefit, in this case suppression of the
growth of bacteria. They described an aqueous antimicrobial finish
containing a monoester of glycerol, a fatty acid and chitosan. The
monoester of glycerol and the fatty acid are surface active
ingredients that facilitate spreading of the antimicrobial finish
on the nonwoven in the finishing process.
[0007] Salas, et al. in "Water-Wettable Polypropylene Fibers by
Facile Surface Treatment Based on Soy Proteins", ACS Appl. Mater.
Interfaces 2013, 5,6541-6548, reported on the modification of the
wetting behavior of polypropylene nonwovens after adsorption of
soybean proteins. Using Quartz Crystal Microgravimetry with thin,
flat films of polypropylene, they confirmed a high affinity of
adsorption for soy protein on polypropylene. A fast initial
adsorption occurred in the order of seconds. This showed that
adsorption of soy protein will indeed occur on polypropylene if the
protein solution is forced to be in contact with the polymer
surface. When extending their work to a polypropylene nonwoven,
they noted that the hydrophobic nonwoven floated on the surface of
the protein solution and prevented effective adsorption of the
protein. To overcome this issue, they first immersed the
polypropylene nonwovens in 2-propanol to clean the nonwoven,
followed by an immersion into 1 mg/mL 2-propanol solution of
cationic dioctadecyldimethylammonium bromide surfactant.
SUMMARY
[0008] A novel nonwoven or film topsheet or other
acquisition/distribution materials that has a hydrophilic,
synthetic surfactant-free finish that is useful for absorbent
products for infant or incontinence care that contain these
materials. These materials are made by intimately treating the raw
unfinished materials in the absence of air bubbles with an aqueous
solution of a hydrophilic, synthetic surfactant-free finish and
then drying the materials.
[0009] Some embodiments of the present hydrophilic, synthetic
sheets comprise: a sheet of synthetic material having a first
surface; where the sheet comprises a hydrophilic finish including
molecules of a water-soluble proteins dispersed on the first
surface; and where the finish is substantially free of synthetic
surfactants. Non-limiting examples of water-soluble proteins
include ProFam.RTM. 974 ProFam.RTM. 781, Clarisoy.RTM. 100,
Clarisoy.RTM. 150, Clarisoy.RTM. 1900, Arcon S Arcon SM, 7B Soy
Flour, Bakers Soy Flour, and Bakers Soy Flour all of which are
commercially available from Archer Daniels Midland (ADM, Decatur,
Ill.), and Prolia.RTM. defatted soy flours, commercially available
from Cargill Incorporated (Minneapolis Minn.). In some embodiments,
the finish does not include synthetic materials capable of reducing
the surface tension of water below 50 milliNewtons/m (mN/m). In
some embodiments, the sheet comprises a nonwoven fabric or a film.
In some embodiments, the sheet is a topsheet of an absorbent
article. In some embodiments, the sheet is a
distribution-acquisition layer of an absorbent article. In some
embodiments, the water-soluble protein comprises a
thermally-denatured protein. In some embodiments, a 0.4-1.2%
aqueous solution of the water-soluble protein has a surface tension
greater than 50 milliNewtons per meter (mN/m). In some embodiments,
a 0.5-10% aqueous solution of the water-soluble protein has a
surface tension less than 49 milliNewtons per meter (mN/m). In some
embodiments, a 0.5-1.2% aqueous solution of the water-soluble
protein has a surface tension less than 49 milliNewtons per meter
(mN/m). In some embodiments, at least 0.004 grams of the molecules
of the water-soluble protein are dispersed on the sheet for each
gram of sheet.
[0010] Some embodiments of the present disposable absorbent
articles comprises; a topsheet comprising an embodiment of the
present hydrophilic, synthetic sheets; a backsheet; and an
absorbent core disposed between the topsheet and the backsheet.
[0011] Some embodiments of the present disposable absorbent
articles comprise; a topsheet; a distribution-acquisition layer
comprising an embodiment of the present hydrophilic, synthetic
sheets; a backsheet; and an absorbent core disposed between the
distribution-acquisition layer and the backsheet.
[0012] Some embodiments of the present methods (e.g., of imparting
hydrophilic properties to a sheet of polymeric material) comprise:
applying an aqueous solution of a water-soluble protein to a sheet
of polymeric material in an aqueous solution; and drying the sheet
such that at least a portion of the protein is retained on a
surface of the sheet; where the aqueous solution is substantially
free of synthetic surfactants. In some embodiments, the sheet
includes less than 0.1, less than 0.05, less than 0.01, less than
0.001 wt. % synthetic surfactants, or no synthetic surfactants. In
a particular embodiment, no synthetic surfactants are included. In
some embodiments, at least a portion of the water-soluble protein
is thermally-denatured. In some embodiments, the sheet comprises a
nonwoven fabric or a film.
[0013] Some embodiments of the present methods further comprise,
prior to applying the aqueous solution to the sheet: admixing the
water-soluble protein in water; heating the water to a temperature
of between 40 degrees Celsius (.degree. C.) and 99.degree. C.; and
stirring the admixture to dissolve the protein in the water. In
some embodiments, the water is heated before admixing the
water-soluble protein. In some embodiments, the temperature of the
water is maintained between 40.degree. C. and 99.degree. C. during
at least a portion of the stirring. In some embodiments, the
temperature of the water is maintained between 40.degree. C. and
99.degree. C., or 50 to 85.degree. C. for a period of time
sufficient to thermally denature at least a portion of the protein.
Some embodiments further comprise: adjusting the pH of the
admixture of water and protein prior to heating the temperature of
the admixture.
[0014] In some embodiments of the present methods, the temperature
of the solution is between 20.degree. C. and 40.degree. C. during
at least a portion of applying the aqueous solution to the
sheet.
[0015] In some embodiments of the present methods, applying the
aqueous solution to the sheet comprises: immersing the sheet a
first time in the solution; and immersing the sheet a second time
in the solution. Some embodiments further comprise: calendaring the
sheet between immersing the sheet the first time and immersing the
sheet the second time.
[0016] In some embodiments of the present methods, applying the
aqueous solution to the sheet is performed with at least one
coating apparatus selected from the group consisting of: a slot
die, a knife coater, a kiss coater, a gravure printer, a
multiple-roller coating apparatus, and a screen coating
apparatus.
[0017] In some embodiments of the present methods, the aqueous
solution comprises a preservative. In some embodiments, the
preservative comprises one or more preservatives selected from the
group consisting of elemental silver (e.g., MicroSilver), Japanese
honeysuckle (e.g., Plantservative), one or more tocopherols (e.g.,
Nutrabiol), or mixtures thereof.
[0018] In some embodiments of the present methods, the protein
comprises soy protein isolate (SPI).
[0019] Some embodiments of the present finishes (e.g., for a
synthetic nonwoven or film) can include: an aqueous solution of a
water-soluble, thermally-denatured protein, the solution having a
surface tension greater than 50 milliNewtons per meter (mN/m). In
some embodiments, the aqueous solution comprises a preservative. In
some embodiments, the preservative comprises one or more
preservatives selected from the group consisting of:
Plantservative, MicroSilver, and Nutrabiol.
[0020] Some embodiments of the present finishes (e.g., for a
synthetic nonwoven or film) can include: an aqueous solution of a
water-soluble, thermally-denatured protein, the solution having a
surface tension less than 49 milliNewtons per meter (mN/m). In some
embodiments, the aqueous solution comprises a preservative. In some
embodiments, the preservative comprises one or more preservatives
selected from the group consisting of elemental silver (e.g.,
MicroSilver), Japanese honeysuckle (e.g., Plantservative), one or
more tocopherols (e.g., Nutrabiol),
[0021] The term "coupled" is defined as connected, although not
necessarily directly, and not necessarily mechanically; two items
that are "coupled" may be unitary with each other. The terms "a"
and "an" are defined as one or more unless this disclosure
explicitly requires otherwise. The term "substantially" is defined
as largely but not necessarily wholly what is specified (and
includes what is specified; e.g., substantially 90 degrees includes
90 degrees and substantially parallel includes parallel), as
understood by a person of ordinary skill in the art. In any
disclosed embodiment, the terms "substantially," "approximately,"
and "about" may be substituted with "within [a percentage] of" what
is specified, where the percentage includes 0.1, 1, 5, and 10
percent.
[0022] The terms "absorbent article" and "absorbent garment" are
used in this disclosure to refer to garments or articles that are
configured to absorb and contain exudates and, more specifically,
refer to garments or articles that are placed against or in
proximity to the body of a wearer to absorb and contain the
exudates discharged from the wearer's body. Examples of such
absorbent articles or absorbent garments include diapers, training
pants, feminine hygiene products, bibs, wound dressing, bed pads,
and adult incontinence products. The term "disposable" when used
with "absorbent article" or "absorbent garment" refers to garments
and articles that are intended to be discarded after a single
use.
[0023] "Absorbent core" is used in this disclosure to refer to a
structure positioned between a topsheet and backsheet of an
absorbent article for absorbing and containing liquid received by
the absorbent article. An absorbent core can comprise one or more
substrates, absorbent polymer material, adhesives, and/or other
materials to bind absorbent materials in the absorbent core.
[0024] A device or system that is configured in a certain way is
configured in at least that way, but it can also be configured in
other ways than those specifically described.
[0025] The feature or features of one embodiment may be applied to
other embodiments, even though not described or illustrated, unless
expressly prohibited by this disclosure or the nature of the
embodiments.
[0026] Some details associated with the embodiments described above
and others are described below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The following drawings illustrate by way of example and not
limitation. For the sake of brevity and clarity, every feature of a
given structure is not always labeled in every figure in which that
structure appears. Identical reference numbers do not necessarily
indicate an identical structure. Rather, the same reference number
may be used to indicate a similar feature or a feature with similar
functionality, as may non-identical reference numbers.
[0028] FIG. 1 depicts a plan view of one example of the present
absorbent articles.
[0029] FIG. 2-3 depict tables of various characteristics of the
present sheets and/or finishes.
[0030] FIGS. 4-5 depicts absorbance versus the square root of time
for rinse tests for one embodiment of the present sheets.
[0031] FIG. 6-15 depict tables of various characteristics of the
present sheets and/or finishes.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0032] Referring now to the drawings, and more particularly to FIG.
1, shown therein and designated with the reference numeral 1 is an
example of the present absorbent articles. In the embodiment shown,
article 1 includes a front portion 2, a rear portion 3, a core
portion 4, and band portions 5. In this embodiment, absorbent
article 1 is configured as a diaper; in other embodiments, the
present absorbent articles can be configured as pads and/or the
like.
[0033] In the embodiment shown, front portion 2 includes fasteners
6 (e.g., adhesive, hook-and-loop patches, or other fastening
structure) and band portions 5 include fasteners 6' and 7 (e.g.,
adhesive, hook-and-loop patches, or other fastening structure). In
this embodiment, article 1 comprises an absorbent core 8 with an
outer zone 9 and a middle zone 10. In the embodiment shown, article
1 also comprises a second absorbent core 12; other embodiments may
include only a single absorbent core. In this embodiment, article 1
further comprises a distribution-acquisition layer 13 that spans at
least absorbent core 8 (e.g., and absorbent core 12).
[0034] In the embodiment shown, article 1 is bounded by a back
sheet 18 (that faces outward when worn) and a top sheet 19 (that
abuts a wearer's skin when worn). In this embodiment, top sheet 19
and back sheet 18 are co-extensive and have dimensions larger than
those of the absorbent core. Back sheet 18 typically prevents
liquid absorbed and contained in the absorbent core from wetting
articles (e.g., clothing) that contact absorbent article 1. In many
(if not all) embodiments, back sheet 18 is impervious to liquids
and can comprise a thin plastic (e.g., polyethylene) film, although
other flexible liquid impervious materials may also be used. In
some embodiments, back sheet 18 may be "breathable" or configured
to permit vapors to escape from the absorbent core while preventing
exudates from passing through back sheet 18.
[0035] In the depicted embodiment, top sheet 19 is joined with and
superimposed on the back sheet 18 thereby forming the periphery of
article 1. In some embodiments, top sheet 19 is compliant, soft
feeling, and non-irritating to the wearer's skin. In many (if not
all) embodiments, top sheet 19 is liquid pervious permitting
liquids to readily penetrate through its thickness. Top sheet 19
can be manufactured from a wide range of materials such as porous
foams, reticulated foams, apertured plastic films, natural fibres
(e.g., wood or cotton fibres), synthetic fibres (e.g., polyester,
polyethen or polypropylene fibres) or from a combination of natural
and synthetic fibres. In some embodiments, top sheet 19 includes
both hydrophilic and hydrophobic material (e.g., positioned in
different zones to meet different demands, such as, for example, to
isolate a wearer's skin from liquids in the absorbent core). In
various embodiments, top sheet 19 may be woven, non-woven, spun
bonded, carded, or the like.
[0036] In the embodiment shown, fluid acquisition-distribution
layer 13 is configured to collect and temporarily hold discharged
body fluid. For example, a portion of discharged fluid may (e.g.,
depending upon the wearer's position) permeate
acquisition-distribution layer 13 and be absorbed by the absorbent
region in the area proximate to the discharge. However, since fluid
is often discharged in gushes, the portion of the absorbent core in
such area may not absorb the fluid as quickly as it is discharged,
and the acquisition-distribution layer is configured to transport
fluid from the point of initial fluid contact to other parts of the
acquisition-distribution layer for absorption by the absorbent
core.
[0037] As described below, the present finishes and methods enable
the manufacture of synthetic surfactant-free hydrophilic sheets
that are suitable for use as a topsheet (e.g., 19) and/or as an
acquisition-distribution layer (e.g., 13) in absorbent articles
(e.g., 1). As described in more detail below, the present finishes
and methods involve the application of denatured proteins to sheets
comprising hydrophobic material (e.g., films or nonwovens) to
impart hydrophilic properties. In general, the present finishes
comprise proteins in solution and the present methods involve
applying the solution to a sheet to distribute the proteins, and
subsequently drying the sheet such that the proteins are deposited
on the sheet.
I. SOLUTION PROPERTIES OF SOY PROTEIN ISOLATE (SPI)
[0038] The effects of temperature and pH were investigated on
solutions of soy protein isolate (SPI) prepared via a concentrated
pre-mix, mix, and cook protocol. Elevated temperatures were used in
an attempt to at least partially denature the protein and promote
adhesion and durability to the nonwoven finish. Properties of
proteins that promote adhesion and durability to nonwoven fibers
are related to properties that can lead to an undesirable effect of
biofouling in medical devices upon exposure of hydrophobic polymer
surfaces to protein solutions. In some embodiments, the pH of the
solution can be adjusted to be between 7.0 to 8.5, or about 7.5 to
8.0. In some embodiment, the solution containing the SPI has a pH
of 7.0 to 8.5 (for example, a solution of ProFAM.RTM. 781) so no pH
adjustment is necessary. The SPI (e.g., Clarisoy.RTM. 100) can be
dispersed either in water at room or elevated temperature to form
clear solutions while other SPIs (e.g., ProFAM.RTM. 781) can form
cloudy solutions. The examples and FIGS. described in Sections I to
IX relate to Clarisoy.RTM. 100 or other water-soluble soy proteins
however, it should be understood that the same or similar results
are expected in each section for all water-soluble soy proteins
described herein, except for ProFam.RTM. 781 surface tension
values, which are described in Section XI.
[0039] FIG. 2 shows certain properties of various mixtures made
with the Clarisoy.RTM. 100 SPI, a 100% water-soluble SPI, and the
methods by which those mixtures were made. As shown, Solution No. 1
was prepared by first premixing 0.25% solids of SPI in 90.degree.
C. distilled water at high shear until the soy powder was uniformly
dispersed in the liquid. The solution was then diluted with an
equal volume of 90.degree. C. distilled water and mixed under low
shear for about 10 minutes. Before the "cook" stage, the pH of the
mixture was adjusted to pH 8 with 0.1 N NaOH. Following the pH
adjustment, the mixture was "cooked" or maintained at an elevated
temperature with low-shear mixing for 60 minutes to simulate use of
the mixture in a commercial process. The appearance of this mixture
was cloudy at 90.degree. C. After cooling to 22.degree. C., a
precipitate settled from the mixture, indicating the presence of
undissolved solids. Formation of a precipitate was associated with
adjustment of pH while the dispersion was at an elevated
temperature. When solutions are prepared without pH adjustment, the
SPI can be dispersed either in water at room or elevated
temperature to form clear solutions. It was also determined that
comparable solution properties were achieved when the pre-mix was
eliminated and the cook time reduced to the time required to bring
the solution to temperature (see mixtures No. 3 and 4). The mixture
that formed a precipitate may not be the best for obtaining the
desired finish on nonwovens. Because of the differences in solution
properties indicated above, the investigation of the ability of SPI
to impart a hydrophilic finish to nonwovens was focused on
solutions mixed at elevated temperature both with and without prior
modification of solution pH. In experiments in which pH was
adjusted, the SPI was dispersed in water at room temperature before
mixing at elevated temperature.
II. HYDROPHILICITY AS A FUNCTION OF MIXING AND APPLICATION
TEMPERATURES OF SOLUTIONS
[0040] Heating a solution of SPI prior to application on a nonwoven
has been shown to improve the performance of the nonwoven on an
absorbent product. Heating soy proteins causes dissociation of
their quaternary structures, denatures their subunits, and promotes
the formation of protein aggregates via electrostatic, hydrophobic
and disulphide interchange mechanisms. In addition to heating, the
adjustment of pH and ionic strength, hydrolysis, and covalent
attachment of other constituents would be expected to modify the
performance of a nonwoven treated with an SPI finish. In some
embodiments, adjustment of the pH is not necessary. The
hydrophilicity of a nonwoven treated with SPI as function of mix
temperature, application temperature, and soy protein solids add-on
has been summarized in FIG. 3.
[0041] The nonwoven was a 12.5 gsm, hydrophobic (i.e., untreated),
polypropylene Spunbond-Spunbond-Spunbond (SSS) provided by Fitesa,
Simpsonville, S.C. Solutions of SPI (e.g., Clarisoy 100.RTM.) were
mixed at specified temperatures ranging from 22.degree. C. to
80.degree. C. The pH of the SPI solutions was not adjusted in these
experiments. Solution pH values ranged from 2.3 to 2.9. A
temperature of 22.degree. C. was defined as room temperature,
although in practice this could vary from about 15.degree. C. to
30.degree. C. The nonwoven was finished or treated with solutions
of Clarisoy 100.TM. at specified temperatures ranging from
22.degree. C. to 70.degree. C. using a laboratory-scale padder.
Samples were prepared using a two-stage dip-and-nip process to
ensure uniform wetting of the nonwoven.
[0042] Solutions at the specified concentrations were made in 1500
ml to 3000 ml batches with tap water of medium hardness. Clarisoy
100.RTM. powder was slowly added to vigorously-stirred water that
was held at the specified mixing temperature using a
thermocouple-equipped hotplate with temperature control. After
dispersing the powder in the heated water, mixing speed was reduced
and maintained for 30 minutes. The solution became clear after 15
to 20 minutes of mixing. About half-way through the mixing step,
0.04% n-butanol was added to reduce foaming. In some embodiments,
n-butanol is not necessary. A biobutanol such as Butamax.RTM.,
which is produced from renewable resources, can optionally be used
to reduce foaming. It is not necessary to use butanol when mixing
under less vigorous conditions. Butanol did not have a significant
effect on the surface tension of the solution. A 0.04% solution
(i.e. 0.0054 M) of n-butanol would reduce the surface tension of
water from a value of 72 mN/m only to about 62 mN/m. After mixing
at the specified temperature, the solution was allowed to cool
until reaching a specified treatment temperature. Samples were
treated .+-.5.degree. C. of a target treatment temperature.
[0043] The laboratory padder had two rubber-coated, vertical, 8 in.
diameter rolls. Sufficient nip pressure was applied to target a wet
pick up on the nonwoven in the range of 1.0 g. of solution/g. of
nonwoven. Each 430 mm.times.430 mm section of nonwoven was immersed
in a volume of about 1500 ml of solution at a specified treatment
temperature before being calendared between the padder rolls. A
two-stage dip-and-nip process was used to treat the nonwoven.
Solution was not absorbed uniformly on the hydrophobic nonwoven
after the first dip-and-nip cycle. Immediately after the first
cycle, the nonwoven sample was re-immersed in the solution and
calendared or nipped a second time. This two-stage dip-and-nip
process produced a uniformly wet nonwoven and helped to distribute
the dissolved solid uniformly over the fiber surfaces. The wet
weight of the sample was recorded to determine wet pick-up of
solution before hanging the sample in an oven at 107.degree. C. for
15 min. to dry.
[0044] Drop values in FIG. 3 were measured using a 4-Hole Drop Test
to provide a measure of the hydrophilicity of the treated nonwoven.
Solids add-on was calculated from the solution concentration and
the wet pick-up of solution on the nonwoven (expressed as g. of
solution per g. of nonwoven). Average wet pick-up was calculated
from the wet and dry weights of each of three handsheets as they
were treated. The pooled standard deviation for wet-pick was 0.07
g/g. In the 4-Hole Drop Test a plastic plate with dimensions of 75
mm.times.75 mm.times.13 mm with four evenly spaced holes each of 15
mm diameter was placed on a sample of nonwoven which was resting on
one piece of Whatman No. 4 filter paper (90 mm diameter). Using an
eye dropper, four drops of tap water were dropped into one hole
from a height equal to the thickness of the plastic plate. A Drop
Value of 2, 1, or 0 was assigned according to how quickly the drop
penetrated the nonwoven and was absorbed by the filter paper. A
Drop Value of 2 was used to indicate that the liquid was
spontaneously absorbed by the nonwoven within five seconds. A Drop
Value of 1 indicated that the liquid was absorbed when the assembly
of filter paper, nonwoven sample, and plastic plate was softly
shaken after five seconds. A Drop Value of 0 indicated that the
liquid was not absorbed. Average Drop Values were calculated from
the average values obtained from each of four holes on four samples
of nonwoven for a total of 16 measurements.
[0045] An untreated, hydrophobic nonwoven had average Drop Values
in the range of 0 to 0.5. Drop Values of 2.0 were measured for
hydrophilic SSS and Spunbond-Meltblown-Spunbond (SMS) nonwoven
topsheets that had been treated with conventional finishes. An
average Drop Value of greater than about 1.2 provided adequate
hydrophilicity for liquid acquisition in an absorbent product. Drop
Values less than 1.2 are shaded in FIG. 3. FIG. 3 shows that
average Drop Values greater than 1.2 were achieved for solids
add-on greater than 0.5% (or 0.005 g. of solids per g. of nonwoven)
when the solution mixing temperature was equal to or greater than
about 50.degree. C. to 70.degree. C. Drop Values were not affected
by the application temperature of the solution, i.e. Drop Values
greater than 1.2 were achieved when a nonwoven was treated with a
solution at ambient temperature, or about 22.degree. C., as long as
that solution was mixed at a temperature equal to or greater than
50.degree. C. The pooled standard deviation for the average Drop
Values was 0.9.
III. WETTABILITY OF PROTOTYPE NONWOVENS USING GRAVIMETRIC ABSORBENT
TEST SYSTEM
[0046] Samples were produced for testing on a Gravimetric
Absorbency Test System (GATS) to characterize the absorption of
saline by the nonwoven over successive absorption cycles. The GATS
test was used to assess the durability of the finish to multiple
doses of saline solution. After each test, the nonwoven was removed
from the apparatus and rinsed by immersion in 100 ml of 0.9% saline
solution at room temperature for 1 minute, then blotted dry with a
paper towel. The sample was immediately retested after each rinse.
FIG. 4 shows the weight (g) of saline absorbed by three layers of
nonwoven as a function of the square root of time (sec.sup.0.5).
The liquid was absorbed through a single aperture with the nonwoven
sample supported by a finned plate. The finned plate reduced the
amount of spurious liquid that could be absorbed between the
nonwoven sample and the plate. Results in FIG. 4 were obtained
using a commercial 12.5 gsm spunbond nonwoven that had been treated
with a commercially-available, proprietary, semi-durable
finish.
[0047] As shown in FIG. 4, liquid was absorbed more slowly after
each of the four rinses. This was the expected result for wetting
of a nonwoven that had a semi-durable finish. Note, however, that
the induction time for absorption increased after each of the first
three rinses while the actual rate of absorption after the
induction period remained fairly constant. The induction time for
wetting after the fourth rinse was very long, greater than 300 sec,
and the rate of absorption after the onset of wetting much
decreased.
[0048] As shown in FIG. 5, a nonwoven with an SPI add on of 0.006
g. SPI/g. nonwoven showed much different behavior in this test.
This nonwoven was finished on a pilot line described in Section V
below. Liquid absorption of the unrinsed nonwoven with the SPI
finish was comparable to that of the commercially available
nonwoven with a conventional synthetic surfactant finish. After the
first rinse there was a clear increase in the induction time of
wetting and a modest decrease in the rate of wetting after the
induction period, compared to the unrinsed sample. However, in
contrast to the nonwoven with the commercially available synthetic
surfactant finish, liquid absorption, performance of the nonwoven
with a synthetic surfactant-free SPI finish improved after both the
second and third rinses. Performance after the third rinse was
typically as good or better than that of an unrinsed sample. This
was an unexpected result, but can be explained by a finish that was
extremely durable and improved as it hydrated during use.
IV. SPREADING OF SPI SOLUTION WITHIN A NONWOVEN USING A CALENDAR
NIP
[0049] As shown in Section V below, a high-surface-tension saline
solution (i.e. synthetic urine) will spread on and be imbibed by a
polypropylene nonwoven that has been treated with a hydrophilic
finish comprised of SPI. However, a high-surface-tension SPI
solution will not readily spread on a hydrophobic polypropylene
nonwoven. The nonwoven can be treated by immersing it in a solution
of SPI and forcibly removing entrained air to ensure intimate
contact between solution and nonwoven fibers. Once the solution
comes in contact with the hydrophobic polypropylene fiber of the
nonwoven, the protein adsorbs on the fiber surface and renders the
nonwoven more hydrophilic, but the protein cannot adsorb to fiber
in areas of the nonwoven that solution cannot spread.
[0050] Water with a surface tension of 72.8 mN/m does not spread on
a low-surface-energy solid like polypropylene. Conventional
nonwoven finishes that are in widespread use today are comprised of
synthetic surfactants that lower the surface tension of water to a
range of about 30-37 mN/m (see Table 1 below). These surfactant
solutions of low surface tension spread on polypropylene fibers and
provide a uniform distribution of surfactant finish upon drying. A
0.1% solids solution of Clarisoy.RTM. 100 SPI had a surface tension
of 64 mN/m. This solution will not readily spread in a
polypropylene nonwoven. Classes of materials that can be used to
make a synthetic surfactant-free nonwoven finish described in this
invention are hydrophilic, but solutions of these materials do not
reduce the surface tension of water below 49 mN/m. These solutions
are not spontaneously imbibed by hydrophobic nonwovens, and require
special processing to uniformly distribute the finish throughout
the nonwoven structure.
[0051] The surface tensions of solutions of Clarisoy.RTM. 100 SPI
at concentrations in the range of 0.4%-1.2% solids were in the
range of 49-68 mN/m at 22.degree. C. The mean value was 58.+-.9.9
mN/m. At these concentrations the surface tension was independent
of solution concentration. Surface tension was measured using a
method of capillary rise. Capillary rise was measured after raising
and lowering the liquid in the capillary and measuring the values
at equilibrium after 10 min.
TABLE-US-00001 TABLE 1 Surface Tensions of Liquids and Solutions
Liquid Surface Tension (mN/m) Water 72 SPI solution (0.4%-1.2%)
49-68 0.1% 7B Soy Flour 61 Silastol 163 (0.4%-6%) 35-37 Silastol
PHP 26 (0.4%) 30 Stantex S6757 (0.4%-6%) 31-36 0.1% Triton X-100 33
Isopropyl alcohol 22
[0052] The Silastol and Stantex materials in Table 1 are surface
finishes comprised of proprietary mixtures of synthetic surfactants
that are used to render polypropylene spunbond nonwoven
hydrophilic. Silastol 163 is a silicone-free, anionic finish for
the production of durable hydrophilic polyolefin nonwovens,
especially topsheets. Silastol PHP 26 is a cationic/amphoteric
finish for the production of durable hydrophilic polyolefin staple
and spunbond fibers suitable for topsheet. Stantex S 6757 is
durable hydrophilic finish for polypropylene spunbond materials,
especially for hygienic applications. These surfactants are often
applied to nonwoven using solution concentrations in the range of
6%. At solids in the range of 0.4%-6%, solutions of these materials
had a surface tension in the range of 31-37 mN/m. The low surface
tension of these solutions promotes wetting of the hydrophobic
polypropylene nonwoven and enables the nonwoven to spontaneously
imbibe the surfactant solution.
[0053] To achieve spreading and contact between an SPI solution and
a hydrophobic nonwoven, the nonwoven was immersed in an SPI
solution and calendared to eliminate entrained air and promote
intimate contact, even for a short period, between nonwoven fiber
and solution. A laboratory calendar with an adjustable nip was used
simulate what could be achieved using a flooded nip or size press
on a commercial production line. Table 2 shows how the solution
concentration of SPI was increased to compensate for a reduced wet
pick up of solution after calendaring. A critical nip dimension of
about 0.150 (in arbitrary units) was required to achieve uniform
wetting of the nonwoven in this calendar. There was a large
reduction in wet pick up for calendared nonwoven, but no meaningful
change in wet pick up for small changes in nip dimension near the
critical value.
TABLE-US-00002 TABLE 2 Properties of Certain of Methods of Making
the Present Sheets Solution Dry Wt. of Concentration Wet Pick Up
SPI Add On Nonwoven (g. SPI/ Nip (g. soln/ (g. SPI/ Sample g. NW)
Dimension g. NW) g. NW) 0.08 0.001 None 6.0 0.006 0.08 0.001 0.200
2.3 0.002 0.08 0.002 None 6.4 0.013 0.08 0.002 0.200 2.8 0.006 0.08
0.002 0.150 3.0 0.006 0.08 0.002 0.125 3.0 0.006 0.08 0.004 0.125
3.0 0.012
[0054] Runoff tests were used to assess the ability of a stream of
liquid to penetrate a topsheet nonwoven and to be absorbed by an
absorbent core before the liquid could run over the surface of the
topsheet nonwoven to the end or side of an absorbent article. Two
runoff tests were used in this work. One test utilized a model
absorbent core and the other used absorbent cores from actual baby
diapers. In this section the test with the model absorbent core, as
described in Section X.C below, was used. The other test will be
discussed in a later section to evaluate the properties of nonwoven
prototypes that had been made on a pilot line and evaluated on baby
diapers.
[0055] As shown in FIG. 6, performance of 12-13 gsm spunbond
nonwovens finished with a synthetic surfactant-free topsheet finish
at 0.006 g. SPI/g. nonwoven was compared to that obtained for a
commercially available nonwoven finished with a semi-durable
synthetic surfactant. The data clearly show comparable performance
for the synthetic surfactant-free topsheet finish. There was a
modest reduction or improvement in Liquid Runoff for the nonwoven
with the surfactant-free finish, even though the liquid travel may
have been somewhat greater than that measured for the commercial
nonwoven topsheet with a semi-durable surfactant finish.
V. SYNTHETIC SURFACTANT-FREE NONWOVEN FINISHES APPLIED ON A PILOT
LINE
[0056] A high-surface-tension aqueous solution of SPI will not
readily spread on a hydrophobic polypropylene nonwoven. In earlier
sections it has been shown that lab prototypes can be prepared
successfully by immersing a sample in a solution and calendaring it
to evenly distribute solution throughout the nonwoven. A pilot line
with a flooded nip size press at North Carolina State University
was used to validate this approach. Identification of a process
that does not require spontaneous spreading of the aqueous
synthetic surfactant-free solution on the hydrophobic, untreated
nonwoven was considered to be important for commercial use of at
least some of the present embodiments. The flooded nip on the pilot
line was set up and adjusted to achieve uniform wetting of the web
in machine- and cross-directions. The nonwoven was successfully
processed using a steel on rubber roll configuration where the
Durometer Hardness of the rubber roll had a value of 72. Roll
pressure was adjusted until the wet pick up of the solution on
nonwoven was qualitatively uniform in appearance and touch in both
MD and CD directions. Variability in wet pick up was checked by
weighing samples that had been cut from the web. After adjustment,
wet pick up on nonwoven varied less than 10%. A uniform wet pick up
of solution could not be achieved using a harder rubber roll with a
Durometer Hardness of 90.
[0057] Preparation of SPI solution for pilot line runs was done as
closely as possible to lab protocol described above. SPI powder was
mixed with distilled water (<10 .mu.mho conductivity) in a five
gallon pail using a high-shear mixer at 6000-7000 rpm for 15
minutes at room temperature. The solution was adjusted from its
natural pH of 2.7-3.0 to a pH of 8.0.+-.0.2 before being placed in
a steam-jacketed reservoir on the pilot line. It took about 15
minutes for the solution to reach temperature in the pilot line.
The solution was maintained at a temperature of about 90.degree. C.
in the reservoir to ensure an application temperature of 80.degree.
C. in the flooded nip. Wet pick up of solution on the pilot line
was less than that achieved using the laboratory calendar.
Prototypes made in the lab had a wet pick up of about 3 g.
solution/g. nonwoven, but only about 1 g. solution/g. nonwoven
remained on the nonwoven on the pilot line after the roll pressure
in the flooded nip had been increased to achieve uniform wetting.
Solution concentration was adjusted upward during the pilot line
trials to achieve a target add on of SPI in the range of
0.006-0.008 g. SPI/g. nonwoven. Steam can rolls were maintained at
110.degree. C. on the pilot line to dry the nonwoven at a line
speed of 30 feet/minute. Prototypes made on the pilot line are
listed in Table 3 below.
TABLE-US-00003 TABLE 3 Pilot Line Prototypes Solution Conc. Wet
Pick Up SPI Add On Prototype Base (g. SPI/ (g. soln/ (g. SPI/ No.
Nonwoven g. soln) g. NW) g. NW) 1 12 gsm SSS 0.0025 1.0 0.003 2
0.0050 1.2 0.006 3 0.0025 1.1 0.003 4 15 gsm SMS 0.0050 1.0 0.005 5
0.0100 0.8 0.008
[0058] As described below, several of these prototypes were
incorporated into baby diapers for testing, and certain
characteristics and test results are summarized in FIG. 7. The
testing methods are described in the "Experimental Methods" section
below.
A. Example No. 1
[0059] This example shows the lab performance of a leading private
label baby diaper (Size 4) reconstructed with a 12 gsm SSS spunbond
nonwoven topsheet that had been treated with a synthetic
surfactant-free SPI finish (Prototype No. 2 above, with 0.006 g.
SPI/g. nonwoven). The topsheet of the commercially available diaper
was carefully removed by gentle heating with a forced air hair
dryer and replaced with the prototype topsheet. All other
materials, including the 60 gsm acquisition/distribution layer used
on the commercial diaper remained the same. To minimize the effect
of diaper reconstruction on interpretation of test results,
especially for runoff tests, the topsheet of the control or
commercial diaper was also removed and then replaced in its
original position. The topsheet of the commercial diaper comprised
a 15 gsm nonwoven.
[0060] A diaper containing an unfinished hydrophobic spunbond
topsheet was included for reference in FIG. 7. This hydrophobic
topsheet generated poorer performance in third and fourth dose
liquid acquisition time (ACQ3 & ACQ4) and poorer performance in
side leakage in this test. Higher side leakage in the
ACQ(uistion)/REW(etting) test was related to the very high runoff
volumes exhibited by the hydrophobic nonwoven. In comparison,
performance of the diaper that contained the nonwoven topsheet that
had been treated with the synthetic surfactant-free finish was
comparable to that of the diaper containing the original, synthetic
surfactant-finished topsheet. The synthetic surfactant-free,
hydrophilic SPI finish had imparted useful properties to the
initially hydrophobic topsheet nonwoven. In the Anarewet Test,
there was a notable advantage in side leakage for the diaper
containing the synthetic surfactant-free topsheet. Runoff improved
after each successive dose for the diaper that contained the
synthetic surfactant-free topsheet. Mannequin leakage, expressed as
absorption before leakage (ABL) was significantly improved from 206
g. to 250 g. for the diaper containing a topsheet nonwoven with a
synthetic surfactant-free finish.
B. Example No. 2
[0061] This example shows the lab performance of a leading private
label baby diaper (Size 4) reconstructed with a 15 gsm SMS nonwoven
topsheet that had been treated with a synthetic surfactant-free SPI
finish (0.008 g. SPI/g. nonwoven). The synthetic surfactant-free
topsheet used with this diaper was Prototype No. 5 that was made in
the pilot line trial described above. The topsheet of the
commercially available diaper was carefully removed by gentle
heating with a forced air hair dryer and replaced with the
prototype topsheet. All other materials, including the 60 gsm
acquisition/distribution layer used on the commercial diaper
remained the same. To minimize the effect of diaper reconstruction
on interpretation of test results, especially for runoff tests, the
topsheet of the reference diaper was also removed and then replaced
in its original position.
[0062] A diaper containing an unfinished hydrophobic SMS topsheet
was included for reference in FIG. 7. The diaper containing the SMS
topsheet with the synthetic surfactant-free finish showed
comparable performance to the commercially available diaper, but
provided a significant advantage in side leakage in the Anarewet
Test. Runoff also improved after each successive dose for the
diaper that contained the synthetic surfactant-free topsheet. The
synthetic surfactant-free SPI treatment had imparted an effective
hydrophilic finish to the topsheet nonwoven.
[0063] Further optimization of the performance of topsheet and
acquisition/distribution layer (ADL) nonwovens finished with SPI,
as well as other materials, can proceed using solution
concentration, solution pH, solution mixing temperature, nonwoven
treatment temperature, calendaring to promote liquid spreading, and
drying temperature. The invention can be extended to include other
hydrophilic, but non-surface active, materials. Examples of these
will be discussed in a later section.
VI. ADDITIONAL EXAMPLES
[0064] Examples 3-6 show liquid acquisition and rewet performance
of diapers that had been reconstructed with topsheet nonwoven that
had been finished using a laboratory padder as described in the
earlier section "Hydrophilicity as a Function of Mixing and
Application Temperatures of Solutions." A reconstructed diaper is a
machine-made diaper that has had its original topsheet nonwoven
dissected and replaced with test material. Control diapers for this
experiment had the original topsheet also dissected and replaced to
reproduce any differences in liquid communication within the diaper
that may have been introduced by the reconstruction process. Size
Large diapers from a leading private label producer were used to
evaluate the topsheets. The absorbent core of the diaper was
comprised of 45% fluff and 55% SAP. There was about 11.5 g. of SAP
in the absorbent core of the diaper. A partial core length, 50 gsm
through-air-bonded acquisition layer was used between the topsheet
and the core. Examples 3-6 provide results from the Liquid
Acquisition and Rewet (ACQ/REW) Test for diapers reconstructed with
SSS topsheet nonwovens that had been finished using various
combinations of solution concentrations of SPI, types of SPI, SPI
add-on levels, solution mixing temperatures, and solution
application temperatures. The pH of the SPI solutions used to make
these samples was not adjusted. Their natural pH was in the range
of 2.2-2.9. The Drop Values for the topsheet nonwovens used in
these examples ranged from 1.4-2.0. Example 7 provides a
comprehensive assessment of a machine-made diaper that had been
produced with a machine-made SSS topsheet nonwoven finished with
SPI.
[0065] The SPI-finished topsheet nonwoven in Example 3 (1.2%
Clarisoy.RTM. 100 solution mixed at 80.degree. C. and applied at
22.degree. C.), as indicated in Table 4, as evaluated in a
lab-reconstructed diaper. Results of testing of Example 3 are shown
in FIG. 8.
TABLE-US-00004 TABLE 4 Properties of Example 3 Clarisoy 100 .RTM.
SPI Add-On Solution (g solids/g Mix Application 4-Hole
Concentration nonwoven .times. Temperature Temperature Drop (%)
100%) (.degree. C) (.degree. C) Value 1.2% 2.0% 80.degree. C.
22.degree. C. 2.0
[0066] Example 4 included a lab-made SPI-finished nonwoven
evaluated in a lab-reconstructed diaper (1.2% Clarisoy.RTM. 150
solution mixed at 80.degree. C. and applied at 22.degree. C.), as
indicated in Table 5. Results of testing of Example 4 are shown in
FIG. 9.
TABLE-US-00005 TABLE 5 Properties of Example 4 Clarisoy 150 .RTM.
SPI Add-On Solution (g solids/g Mix Application 4-Hole
Concentration nonwoven .times. Temperature Temperature Drop (%)
100%) (.degree. C) (.degree. C) Value 1.2% 2.0% 80.degree. C.
22.degree. C. 2.0
[0067] Example 5 included a lab-made SPI-finished nonwoven
evaluated in a lab-reconstructed diaper (0.8% Clarisoy.RTM. 100
solution mixed at 80.degree. C. and applied at 50.degree. C.), as
indicated in Table 6. Results of testing of Example 5 are shown in
FIG. 10.
TABLE-US-00006 TABLE 6 Properties of Example 5 Clarisoy 100 .RTM.
SPI Add-On Solution (g solids/g Mix Application 4-Hole
Concentration nonwoven .times. Temperature Temperature Drop (%)
100%) (.degree. C) (.degree. C) Value 0.8% 1.1% 80.degree. C.
50.degree. C. 2.0
[0068] Example 6 included a lab-made SPI-finished nonwoven
evaluated in a lab-reconstructed diaper (0.8% Clarisoy.RTM. 100
solution mixed at 50.degree. C. and applied at 22.degree. C.), as
indicated in Table 7. Results of testing of Example 6 are shown in
FIG. 11.
TABLE-US-00007 TABLE 7 Properties of Example 6 Clarisoy 100 .RTM.
SPI Add-On Solution (g solids/g Mix Application 4-Hole
Concentration nonwoven .times. Temperature Temperature Drop (%)
100%) (.degree. C) (.degree. C) Value 0.8% 0.7% 50.degree. C.
22.degree. C. 1.4
[0069] Examples 3-6 show that the SPI-treated nonwovens are
suitable for use in an absorbent product and can provide a
meaningful improvement in Surface Wetness over a conventional
nonwoven finished with synthetic surfactant. Saline was maintained
at 22.degree. C. for tests in Examples 3-6. Overall, the diapers
containing the SPI-treated nonwovens had somewhat lower (i.e.,
better) liquid acquisition times and higher (i.e., poorer) rewet
values after the first dose. This behavior is consistent with SPI
providing a more durable hydrophilic finish than synthetic
surfactant. Synthetic surfactant used in the conventional finish is
washed from the nonwoven in use, and the nonwoven becomes less
hydrophilic after each dose. This results in higher acquisition
times and lower rewet on subsequent doses of liquid compared to the
performance of the diaper made with the SPI-treated nonwoven. The
reduction in liquid acquisition times for diapers with the
SPI-treated nonwoven topsheets were not statistically significant
at p=0.05, but consistent and directional with p values generally
less than 0.20. There were meaningful reductions in Surface Wetness
for diapers made with the SPI-treated nonwoven topsheets. For
example, after the fourth dose, Surface Wetness for the diapers
with the SPI-treated topsheets ranged from 0.000-0.027 g. compared
to a value of 0.050 g. for the diaper with the conventional
topsheet. Surface Wetness is a measure of small amounts of saline
that can remain trapped between a wearer's skin and the nonwoven on
the surface of the product. It is important because synthetic
surfactant from a nondurable nonwoven finish can dissolve in urine
and contact skin. The presence of synthetic surfactant on skin may
be associated with skin irritation and transient erythema, as well
as an increase in the permeability of the skin to any irritant that
may be present. Side leakage for diapers with the SPI-treated
topsheets was less than for diapers with the conventional,
synthetic surfactant-treated topsheet.
[0070] Example 7 included a machine-made SPI-treated nonwoven
evaluated in a machine-made diaper (solution mixed at 80.degree. C.
and applied at 65.degree. C.), as indicated in Table 8. Results of
testing of Example 7 are shown in FIG. 12.
TABLE-US-00008 TABLE 8 Properties of Example 7 Clarisoy 100 .RTM.
SPI Add-On Solution (g solids/g Mix Application 4-Hole
Concentration nonwoven .times. Temperature Temperature Drop (%)
100%) (.degree. C) (.degree. C) Value 1.4% 0.6% 80.degree. C.
65.degree. C. 2.0
[0071] A commercial-scale textile finishing line at TSG Finishing
(Hickory, N.C.) was used to produce 5,000 lineal meters of a
SPI-treated nonwoven for making prototype diapers on a
commercial-scale converting machine. The base nonwoven was a
hydrophobic (i.e., unfinished), 12.5 gsm Fitesa SSS spunbond
nonwoven. The padder process was modified to finish the topsheet
using a two-stage dip and nip process at 50 yd./min. with a
solution of Clarisoy 100 maintained at 60.degree.-70.degree. C. The
solution was prepared at 1.2 wt. % of Clarisoy.RTM. 100 and 0.04
wt. % of n-butanol, however due to evaporative losses during the
trial run, the average solution concentration was about 1.4%. Tap
water was heated to a temperature of 80.degree. C. before adding
the Clarisoy 100 and mixing for 30 min. The solution was used at
its natural pH in the range of 2.2-2.9. Solids add-on calculated
from wet pick-up of solution on the nonwoven was 0.006 g. solids
per g. of nonwoven. The nonwoven was dried on a tenter frame in an
air impingement oven at 225.degree. F. Rolls of the SPI-treated
nonwoven were used to make infant diapers on a commercial-scale
converting machine at Domtar Personal Care in Delaware, Ohio. Size
Large diapers used for this evaluation were made with a 45%
fluff/55% superabsorbent polymer (SAP) absorbent core comprised of
11.5 g. of SAP. A 50 gsm acquisition/distribution layer (Shalag
Nonwovens, Oxford, N.C.) of through-air-bonded synthetic fiber was
placed in the diaper between the absorbent core and topsheet.
Diapers were made with both a conventional 13.5 gsm SMS topsheet
nonwoven and at 12.5 gsm SPI-treated topsheet nonwoven, and were
evaluated using 4-Hole Drop, Conventional Liquid Acquisition/Rewet,
Anarewet Liquid Acquisition, Liquid Runoff, and Mannequin Leakage
Tests.
[0072] This SPI-treated topsheet nonwoven was uniformly wettable
and suitable for use as a topsheet nonwoven in an absorbent
product. Drop values obtained using the 4-Hole Drop Test were
2.0.+-.0.01 for SPI-treated nonwoven produced both at the beginning
and at the end of the trial run.
[0073] Values of Liquid Acquisition and Rewet for diapers made with
a conventional nonwoven topsheet and the SPI-treated topsheet were
generally comparable (FIG. 12). Tests were run using saline
solutions at 22.degree. C. and 37.degree. C. There were
statistically significant (i.e., p<0.05) improvements in liquid
acquisition times at 22.degree. C. for all doses for the diaper
made with the SPI-treated nonwoven. At 37.degree. C., due to higher
variability in the acquisition times, there was only a directional
improvement in fourth dose acquisition time with p=0.14. There were
directionally poor Rewet values after the third and fourth doses
for the SPI-treated nonwoven. These increases in Rewet were small
and not statistically significant. As noted in earlier testing,
Surface Wetness and Side Leakage were better for the diaper made
with the SPI-treated topsheet.
[0074] Similarly, there were directional indications of improved
Anarewet Liquid Acquisition times at both 22.degree. C. and
37.degree. C. for the SPI-treated nonwoven that were not
statistically significant (FIG. 13). The rate of liquid acquisition
in the Anarewet Test depends more on demand absorbency than it does
in a conventional ACQ/REW liquid acquisition test. Acquisition rate
in the Anarewet Test would be expected to be more sensitive to the
hydrophilicity and durability of the topsheet finish. For saline
solutions at 22.degree. C., there were: statistically significant
(p<0.05) reductions in Liquid Acquisition time at all doses for
the diaper with the SPI-treated nonwoven, directionally higher
Rewet after the 4th dose for the diaper with the SPI-treated
nonwoven but not statistically significant (p=0.152), comparable
surface wetness, and higher side leakage for the diaper with
conventional topsheet. For saline solutions at 37.degree. C., there
were: no statistically significant differences in Liquid
Acquisition time, directionally lower 4th dose Liquid Acquisition
time for diaper with the SPI-treated nonwoven (p=0.138),
directionally higher Rewet after 4th dose for the diaper with the
SPI-treated nonwoven but not statistically significant (p=0.402),
comparable Surface Wetness, and higher Side Leakage for the diaper
with conventional topsheet.
[0075] Liquid Run-Off performance for the diaper containing the
SPI-treated nonwoven was significantly better than that of the
control diaper that contained the conventional nonwoven (FIG. 14).
The saline in the Liquid Run-Off Test was adjusted to a surface
tension of 60 mN/m with isopropyl alcohol and maintained at
37.degree. C. After the first dose, there was a meaningful
reduction in Run-Off for the diapers containing the SPI-treated
nonwoven. Reductions in liquid run-off and liquid acquisition time
over multiple doses are the result of a more durable hydrophilic
nonwoven finish imparted by the SPI treatment.
[0076] Reductions in liquid run-off would be expected to reduce
urine leakage in absorbent products. Evidence of reduced urine
leakage has been demonstrated in an Infant Mannequin Leakage Test.
There was a statistically significant (p=0.015) increase (i.e.,
improvement) in Absorption Before Leakage (ABL) of the infant
diapers made with the SPI-treated nonwoven. ABL values of 226 g.
and 200 g. were obtained for the diapers with the SPI-treated and
conventional nonwoven topsheets, respectively. ABL for an absorbent
product can generally be increased by increasing core capacity, as
well as by improving containment related to product design and fit,
however it was an unexpected result of this invention to measure a
13% increase in ABL with use of an SPI-treated topsheet nonwoven
alone.
VII. PRESERVATIVES FOR SPI SOLUTIONS
[0077] Soy protein can provide nutrients for yeast and bacterial
growth when sufficient moisture is present. There is little concern
for microbial growth on an SFT-finished nonwoven under normal
conditions of storage and use. When aqueous solutions of soy
protein are prepared and stored prior to manufacture of an SFT
nonwoven it may be necessary to add a preservative to the solution
to provide adequate shelf life. Peracetic acid can be used to
sterilize the solution, and conventional preservatives such as
sulfites, benzoic acid and sodium benzoates can be effective.
Preservatives such as ascorbic acid, sorbic acid, Natamycin,
taurine, aspartame, nisin, polyhexamethylene biguanide
hydrochloride, and elemental silver may also be effective. It is
important to assure that the preservative does not impair the
hydrophilicity or durability of the SFT nonwoven finish.
Plantservative WSr (BioOrganic Concepts, Santa Fe Springs, Calif.),
derived from Japanese honeysuckle, and Nutrabiol T30 WD (Food
Ingredient Solutions LLC, Teterboro, N.J.), a tocopherol
derivative, maintain 4-Hole Drop values >1.2 for nonwovens with
SPI add-on in the range of 0.02-0.020 g. SPI/g. of nonwoven when
the preservatives are incorporated into the SPI finish such that
the ratio of preservative to SPI does not exceed a value of about
0.08 to 1, or the preservative amounts to no more than about 8% of
SPI on the nonwoven.
VIII. OTHER HYDROPHILIC, NON-SURFACE ACTIVE MATERIALS FOR NONWOVEN
FINISHES
[0078] A. Examples of Other Soy Materials
[0079] ProFam.RTM. 974 is another soy protein isolate. Arcon S and
Arcon SM are soy protein concentrates with better water
dispersibility than soy protein isolates. 7B Soy Flour, Bakers Soy
Flour, and Bakers Soy Flour are defatted soy flours. In addition to
these materials produced by ADM, Cargill Incorporated produces
Prolia defatted soy flours.
[0080] Solutions of other soy materials were made using 0.001 g.
powder/g. solution and mixed at 80.degree. C. for 60 minutes. All
of these materials were more easily dispersed in water than
Clarisoy 100. No pH adjustments were made. The pH of the solutions
are shown in FIG. 15. Hydrophobic spunbond was treated by immersion
in the solution at 80.degree. C. for 30 seconds and dried in an
oven at 120.degree. C. A drop test discussed in a previous section
was used to assess the hydrophilicity of the treated nonwovens,
results of which are shown in FIG. 15. As indicated, all of the
nonwovens treated with the soy materials performed as well as the
commercially available topsheet made with a semi-durable surfactant
finish. There was some evidence after a warm tap water rinse that
these synthetic surfactant-free soy-finishes were more durable than
the commercial surfactant finish. The good performance of these
other soy materials suggests that many other natural and synthetic
materials may fall within the teaching of this invention.
[0081] B. Hydrolyzed Proteins and Gelatin
[0082] Various plant- and animal-derived biopolymers may provide
additional examples for the present finishes. For example,
hydrolyzed collagen, hydrolyzed albumen, hydrolyzed barley protein,
hydrolyzed casein, hydrolyzed cottonseed protein, hydrolyzed
gelatin, hydrolyzed hemp seed protein, hydrolyzed whey protein,
casein, hydrolyzed silk, glutelin proteins, silk sericin, gum
arabic, bovine serum albumin, and various vegetable proteins. Of
particular interest are the Peazazz.RTM. pea protein and
Supertein.RTM. canola protein isolates produced by Burcon
NutraScience Corporation and zein produced by Flo Chemical
Corporation.
[0083] C. Polyvinylpyrrolidone (PVP)
[0084] PVP is a water-soluble, nonionic polymer that adheres to a
variety of substrates. BASF (Kollidon.RTM.), Harke Group and
International Specialty Products (ISP) produce PVP polymers in
several viscosity grades, ranging from low to high molecular
weight. PVP is mainly used as a binder in wet granulation and hair
spray products. Copolymers of vinyl pyrrolidone and vinyl acetate
are also commercially available. PVP will crosslink in air at
150.degree. C. and become insoluble in water. Crosslinking would
impart exceptional durability to a nonwoven finish comprised of
PVP. These properties suggest that PVP would function particularly
well as a hydrophilic nonwoven finish, as well as an inert scaffold
for the incorporation of microsilver or skin wellness
ingredients.
[0085] D. Other Hydrophilic Polymers
[0086] Hydrophilic, water-soluble polymers like carboxymethyl
cellulose (and other cellulosic polymer derivatives), starches,
polyvinyl alcohol, and polyethylene and polypropylene glycols for
providing less durable nonwoven finishes. Many polysaccharides may
also provide examples of this invention.
IX. DURABLE, SYNTHETIC SURFACTANT-FREE FINISHES AS CARRIER FOR SKIN
WELLNESS INGREDIENTS
[0087] The durable, synthetic surfactant-free finishes described in
this invention can also be used as a carrier or scaffold for
incorporation of skin wellness ingredients in a nonwoven finish for
application in absorbent products. The durability of the finish can
be adjusted to accommodate the desired rate of delivery of any
particular active ingredient to wet skin. Examples of skin wellness
ingredients include anti-infective agents such as silver powder
(e.g., MicroSilver), silver sulfadiazine, povidone iodine, and
PVP-stabilized peroxides; anti-viral agents such as citric acid,
copper oxide, and Zn salts; anti-microbial (e.g., plantservative)
and, various skin-rejuvenation ingredients widely used in the
cosmetic industry. A synthetic-surfactant-free SPI finish provides
a novel, skin-friendly vehicle for incorporating biopolymers such
as 2-methacryloyloxyethyl phosphorylcholine (MPC) and its
derivatives into a nonwoven finish to impart bioinert properties
and form a hydration shell of water around nonwoven fibers.
X. EXPERIMENTAL METHODS
[0088] A. Liquid Acquisition and Rewet (ACQ/REW)
[0089] A conventional liquid acquisition and rewet test was
performed according to the following procedure. The liquid
acquisition is the time in seconds for a section of core to absorb
a known volume (usually 75 or 100 ml) of 0.9% saline through a 48
mm diameter dosing head. Products were equilibrated overnight and
tested in a room maintained at 22.degree. C. and 50% relative
humidity (RH). The saline solution was used at a room temperature
of 22.degree. C. The dosing head was weighted and had a screen on
one end to apply an even pressure of 0.5 pounds per square inch
(psi) to the core at the point of liquid dosing. The remainder of
the core was restrained under a 150 mm.times.300 mm plate that
weighed 600 g. The dosing head extended through a hole drilled
through the core restraining plate and was positioned over the
center of the acquisition layer used on the absorbent core. A 75 ml
dose was metered to the dosing head at a rate of approximately 20
ml/sec and the time to absorb the liquid was recorded as the
acquisition time (.+-.0.1 sec). After 30 minutes of equilibration,
the restraining plate was removed, and a stack of ten filter papers
(Whatman 4, 70 mm) were placed on the dosing area under a
cylindrical brass weight of 60 mm diameter. The weight applied a
pressure of 0.8 psi. After two minutes the weight was removed and
rewet was determined from a difference in weight between the wet
and dry filter papers (.+-.0.01 g). The acquisition and rewet test
was repeated for 4 doses.
[0090] Surface Wetness and Side Leakage were also determined in
this test. Surface Wetness was determined when the restraining
plate was removed from the core. A paper towel was used to collect
liquid still attached to the plate after the plate had been removed
from the core. A single paper towel was used to remove liquid from
three to five plates used for replicate samples. The mass of the
liquid from the plates was determined from a difference in weight
between the wet and dry paper towel (.+-.0.01 g.). An average
Surface Wetness for each replicate was determined by dividing the
total mass of liquid collected from the plates by the number of
replicates. The steps were repeated for four doses of 75 ml of
liquid.
[0091] Side leakage tests were also performed in conjunction with
the Liquid Acquisition and Rewet testing. Side leakage can occur by
liquid running off of the surface of the core, as well as by moving
through the core itself and leaking from the side. In this test, a
disposable absorbent bed pad was cut to a width that was 50 mm
wider (i.e., 25 mm on each side) than the diaper and placed under
the diaper at the beginning of the test. This mat was used to
contain any test liquid that was not absorbed by the diaper core
during the test. At the end of the test, the bed pad material was
re-weighed to determine the amount of leakage that occurred during
the test. Values of Side Leakage obtained for each replicate were
combined to provide an average value of Side Leakage for the
test.
[0092] B. ANAREWET Test
[0093] The Anarewet test was used to find acquisition times for
products without forming a hydrostatic head over the dosing area.
In particular, the Anarewet apparatus doses the liquid only when a
product being tested can absorb it. A 75 ml dose of 0.9% saline
solution at 22.degree. C. was applied to the product at a pressure
of 20 millibars (mb) and the acquisition or absorption time
(without hydrostatic head) was measured.
[0094] C. Runoff Test Procedure for FIG. 6
[0095] This runoff test simulates the washing/rinsing off (or lack
thereof) of surfactants or other nonwoven treatments which often
occurs under subsequent insults of saline solution over the top of,
or through, a nonwoven top-sheet. This run-off test was performed
with an absorbent core and topsheet that were secured on a
plexiglass plate that was inclined 20.degree. above horizontal such
that the liquid would flow laterally across the surface of the
product. A tray was positioned under the lower end of the sample to
collect runoff. Six 75 ml doses of 0.9% saline at 22.degree. C.
were then applied at 420 ml/min at 5 minute intervals from a tube
with its end disposed 1 cm above the core and dispensing liquid at
an angle parallel to the incline of the product in a direction from
the front toward the back of the product. For each dose, the saline
that immediately ran off the topsheet (not leaking from the core
over time) was collected in the tray and the change in weight
measured.
[0096] D. Runoff Test Procedure for FIG. 14
[0097] This run-off test was performed with whole diapers. Diapers
were secured on a plexiglass plate that was inclined 33.degree.
above horizontal, and oriented such that liquid from a nozzle would
flow under gravity from the front to the back of the diaper. A
nozzle was centered over the acquisition layer in the diaper in a
vertical orientation 1 cm from the surface of the diaper. For each
dose, the volumetric liquid flow rate was held constant at 420
ml/min for respective doses of 35, 70, and 105 ml. The diameter of
the nozzle orifice was selected to provide a maximum liquid stream
velocity of 200 cm/sec at a flow rate of 1200 ml/min. The test
liquid was a 0.9% saline solution that had its surface tension
reduced to 60 mN/m (at 22.degree. C.) with isopropanol. The
solution was heated such that the temperature of the solution at
the nozzle exit was 35.degree. C. After each dose, liquid that was
not absorbed by the diaper core was collected at the base of the
incline. Two additional doses at the same dose volume were
administered at an interval of two minutes. Run-off was determined
as a function of dose volume using dose volumes of 35, 70, and 105
ml per dose.
[0098] E. Mannequin Testing
[0099] For the mannequin testing, Large Size 4 diapers were
constructed to include topsheets according to the present
embodiments. These diapers were tested on a Size 4 prone Courtray
mannequin diaper tester commercially available from SGS Courtray
EURL, Douai, France, using the Courtray absorption before leakage
(ABL) protocol provided with the apparatus.
[0100] The mannequin is made of a soft silicone rubber and has
appropriate dimensions for a Large Size 4 infant. In this test a
diaper was fitted to the mannequin and stressed until leakage with
multiple doses of 0.9% saline test liquid supplied by Lab Chem
Inc., Cat. No. 07933, which had a specification of 0.9%
Wt./Vol..+-.0.005% sodium chloride. Products were equilibrated
overnight and tested in a room maintained at 22.degree. C. and 50%
relative humidity. The saline solution used was at a room
temperature of 22.degree. C. Absorption Before Leakage (ABL) was
defined as the mass of liquid that the diaper absorbed (.+-.0.01
g.) under conditions of the test before a leak occurred. Higher
values of ABL=(Final Weight of Diaper after Leakage)-(Initial Dry
Weight of Diaper) are preferred. The mannequin was provided with
female and male dosing tubes. The male mode was used in all tests.
The liquid was pumped to the mannequin at a rate of 7 ml/sec using
a Masterflex L/S Digital Drive, Model No. HV-07523-80 and a
Masterflex L/S Easy-Load II Pump Head, Model No. EW-77200-62. The
mannequin was placed on a rectangular foam pad that had a
waterproof cover. Leakage was detected visually on a sheet of
tissue placed under the mannequin. Times were measured using a
stopwatch.+-.1 sec.
[0101] General instructions for fitting a diaper on the mannequin
follow. The diaper should be folded in the longitudinal direction
forming a pouch, concave inward, between the legs of the mannequin.
The standing gathers of the product need to come to rise while
applying it to the mannequin, paying close attention to how they
lie in the groin. Correct position is achieved when the standing
gathers remain extended and surround the male adapter evenly. The
outer leg elastics are folded outwardly in the crotch region so
that the inner face of the product remains in contact with the skin
of the mannequin. The tabs of the diaper are unfolded and put on
smoothly. The diaper is spread flatly on front and backside to
ensure an even fit. The diaper is then fixed in place with the tape
tabs. The tabs should be centered on the landing zone. On a Size 4
Large diaper the ends of the tabs should nearly touch (1 mm.+-.0.5
mm) in the middle of the landing zone. The front and back ends of
the diaper should remain at equal height on the torso of the
mannequin. Small adjustments can be made to align the front and
back ends of the diaper, if necessary. Differences in diaper
dimensions can affect the tightness of fit of the diaper around the
waist of the mannequin. In the testing described below, folded
multi-layer cores were tested in commercially-available diaper
chassis.
[0102] The protocol for liquid dosing of the product is given in
the table below. An initial dose of 75 ml of liquid was delivered
at t=0 with the mannequin lying on its belly. At t=4 min. the
mannequin was turned on its back. At t=5 min. a dose of 25 ml was
delivered with the mannequin lying on its back. At t=9 min. the
mannequin was turned onto its belly, rotating the torso in the same
direction as turned initially. At t=10 min. a dose of 75 ml was
delivered with the mannequin lying on its belly. The mannequin
remained on its belly for the remainder of the test and was dosed
with 25 ml every 2 min. (e.g., t=12, 14, 16 min., etc.) until
leakage occurred. Saline solution that leaks out of the diaper will
be absorbed and spread by the tissue layer that covers the pad and
will present a visible dark spot. After a leak occurred, the diaper
was removed and weighed. The difference between the wet and initial
dry weights of the diaper was defined as Absorption Before Leakage
(ABL).
TABLE-US-00009 Time (min) Position Dose No. Dose Vol. (ml) 0 Belly
1 75 4 Back -- -- 5 Back 2 25 9 Belly -- -- 10 Belly 3 75 After 10
min. the mannequin remains on its belly and is dosed with 25 ml
every 2 min. until a leak occurs.
[0103] The diaper chassis used for making diapers containing the
present topsheets was a commercially available, private label
disposable diaper. The diapers were placed on the Courtray
mannequin and the ABL was measured and recorded per the procedure
supplied by the manufacturer of the mannequin.
XI. SOY PROTEIN ISOLATE WITH SURFACE TENSION OF LESS THAN 49
MN/M
[0104] The surface tensions of solutions of Profam.RTM. 781 SPI
were tested. Surface tension of solutions at concentrations in the
range of 0.05 wt. % to 10 wt. % were in the range of 40 to 49 mN/m
at 22.degree. C. The mean value was 43.+-.1.3 mN/m. In contrast to
Clarisoy.RTM. 100, a 0.5 wt. % to 10 wt. % solids solution of
ProFAM.RTM. 781 SPI can reduce the surface tension of water to less
than 49 mN/m. ProFAM.RTM. 781 containing solutions are not
spontaneously imbibed by hydrophobic nonwovens, and require special
processing (e.g., heating process described in Section IV and
below) to uniformly distribute the finish throughout the nonwoven
structure. The solutions were prepared by adding with agitation dry
powder SPI to distilled water at 75 to 85.degree. C., or about
80.degree. C. The solution was agitated at 80.degree. C. for about
20 to 50 minutes, or about 30 minutes. The solution were added to
the fabric using a two-stage dip-and-nip process. The treated
fabric was dried and tested using the 4-Hole Drop test described
above. The material has an average drop value of 1.5. Surface
tension was measured using a Kibron (Parrish, Fla.) Ez Pi Plus
instrument which uses the DuNouy maximum pull force method. Table 9
lists the surface tension of the Profam.RTM. 781 samples at various
weight percentages.
TABLE-US-00010 TABLE 9 wt. % Profam .RTM. 781 Surface Tension
(mN/m) 0.001 70.5 0.01 61.8 0.1 55.6 0.5 48.6 1.0 45.2 2.0 43.9 4.0
42.7 6.0 42.5 8.0 42.0 10.0 42.0
[0105] From the foregoing, it will be observed that numerous
modifications and variations can be effected without departing from
the true spirit and scope of the novel concept of the present
invention. It is to be understood that no limitation with respect
to the specific embodiments disclosed herein is intended or should
be inferred. The disclosure is intended to cover, by the appended
claims, all such modifications as fall within the scope of the
claims.
* * * * *