U.S. patent application number 13/272748 was filed with the patent office on 2012-04-19 for wet wipes and methods for making same.
Invention is credited to Michael Edward Carrier, John Allen Manifold, Kevin Mitchell, Khosrow Parviz Mohammadi.
Application Number | 20120090119 13/272748 |
Document ID | / |
Family ID | 44903369 |
Filed Date | 2012-04-19 |
United States Patent
Application |
20120090119 |
Kind Code |
A1 |
Carrier; Michael Edward ; et
al. |
April 19, 2012 |
WET WIPES AND METHODS FOR MAKING SAME
Abstract
Wet wipes formed from a fibrous structure and a liquid
composition that exhibit novel properties are provided.
Inventors: |
Carrier; Michael Edward;
(Green Township, OH) ; Manifold; John Allen;
(Sunman, IN) ; Mohammadi; Khosrow Parviz; (Liberty
Township, OH) ; Mitchell; Kevin; (West Chester,
OH) |
Family ID: |
44903369 |
Appl. No.: |
13/272748 |
Filed: |
October 13, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61393098 |
Oct 14, 2010 |
|
|
|
Current U.S.
Class: |
15/209.1 |
Current CPC
Class: |
C11D 17/049
20130101 |
Class at
Publication: |
15/209.1 |
International
Class: |
A47K 7/03 20060101
A47K007/03 |
Claims
1. A wet wipe comprising a fibrous structure comprising a liquid
composition, wherein the liquid composition after extraction from
the fibrous structure exhibits a pH of less than 4.55 as measured
according to the pH Test Method described herein.
2. The wet wipe according to claim 1 wherein the fibrous structure
comprises pulp fibers.
3. The wet wipe according to claim 2 wherein the fibrous structure
comprises greater than 85% by weight on dry basis of pulp
fibers.
4. The wet wipe according to claim 3 wherein the fibrous structure
comprises about 100% by weight on a dry basis of pulp fibers.
5. The wet wipe according to claim 2 wherein the pulp fibers
comprise fibers selected from the group consisting of: softwood
fibers, hardwood fibers, and mixtures thereof.
6. The wet wipe according to claim 5 wherein the pulp fibers
comprise 100% by weight on a dry basis of softwood fibers.
7. The wet wipe according to claim 5 wherein the pulp fibers
comprise greater than 50% by weight on a dry basis of softwood
fibers and less than 50% by weight on a dry basis of hardwood
fibers.
8. The wet wipe according to claim 5 wherein the softwood fibers
are selected from the group consisting of: Northern Softwood Kraft
fibers, Southern Softwood Kraft fibers, and mixtures thereof.
9. The wet wipe according to claim 5 wherein the hardwood fibers
comprise tropical hardwood fibers.
10. The wet wipe according to claim 5 wherein the hardwood fibers
are selected from the group consisting of: Acacia, Eucalyptus,
Maple, Oak, Aspen, Birch, Cottonwood, Alder, Ash, Cherry, Elm,
Hickory, Poplar, Gum, Walnut, Locust, Sycamore, Beech, Catalpa,
Sassafras, Gmelina, Albizia, Anthocephalus, and Magnolia fibers,
and mixtures thereof.
11. The wet wipe according to claim 1 wherein the fibrous structure
is a wet-laid fibrous structure.
12. A wet wipe comprising a fibrous structure comprising a liquid
composition, wherein the fibrous structure comprises a temporary
wet strength agent.
13. The wet wipe according to claim 12 wherein the fibrous
structure comprises pulp fibers.
14. The wet wipe according to claim 12 wherein the fibrous
structure is void of any polymeric binder.
15. The wet wipe according to claim 12 wherein the fibrous
structure is a wet-laid fibrous structure.
16. A wet wipe comprising a fibrous structure comprising a surface
comprising a surface pattern imparted to the fibrous structure
during the fibrous structure making process and a liquid
composition.
17. The wet wipe according to claim 16 wherein the fibrous
structure is a wet-laid fibrous structure.
18. The wet wipe according to claim 16 wherein the surface pattern
comprises regions of different densities.
19. The wet wipe according to claim 18 wherein the surface pattern
comprises discrete, high density regions and a continuous or
substantially continuous network of a low density region
surrounding the discrete, high density regions.
20. The wet wipe according to claim 16 wherein the surface pattern
comprises a non-random, repeating pattern.
Description
CROSS REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/393,098, filed Oct. 14, 2010.
FIELD OF THE INVENTION
[0002] The present invention relates to wet wipes and more
particularly to wet wipes that comprise a fibrous structure and a
liquid composition that exhibit novel properties.
BACKGROUND OF THE INVENTION
[0003] Various fibrous structures have been used in the past as
substrates for wet wipes. For example, fibrous structures
comprising a mixture of pulp and regenerated cellulose fibers, such
as rayon and/or lyocell, with or without binding fibers, such as
polypropylene/polyester bicomponent fibers, are known to be used as
substrates for wet wipes. Further, fibrous structures comprising
100% pulp fibers are also known to be used as substrates for wet
wipes. Still further yet, fibrous structures comprising 100%
polypropylene fibers are known to be used as substrates for wet
wipes.
[0004] One important property that consumers desire is that wet
wipes must be strong enough to maintain integrity during use, which
is oftentimes 28 days or greater from the time the wet wipe is
produced. In order to maintain integrity during use, known wet
wipes utilize various technologies. For example, some wet wipes
achieve strength by using thermoplastic polymers, such as
polypropylene, to form the filaments/fibers of their fibrous
structures and then optionally, thermal bonding the fibrous
structures. Others achieve strength by the process by which they
are made, for example, hydroentangling (spunlacing). Still others
achieve strength by adding a polymeric binder to the fibrous
structures, for example an acid-insoluble, alkali-soluble
polycarboxylic acid binder and/or an ion-triggerable polymeric
binders and/or temperature-sensitive binders and/or pH sensitive
binders and/or water-soluble binder such as polyvinyl alcohol that
are typically applied to the fibrous structure prior to application
of any liquid composition. In the case of wet wipes that comprise a
100% pulp fiber fibrous structure, strength has been achieved by
employing a permanent wet strength agent, such as Kymene.RTM.,
which is commercially available from Ashland Inc. and/or Parez.RTM.
631, which is commercially available from Kemira Chemicals Inc.,
during the fibrous structure making process, which can be a
wet-laid papermaking process.
[0005] Another important property that consumers desire is that the
wet wipes need to be dispersible in order for the consumers to
dispose of by flushing in a toilet and into a sewer system, such as
a publics sewer system, and/or a septic system without creating
clogging issues. In order to achieve dispersibility, known wet
wipes have utilized wet strength technologies such as those
described above that may be triggered by some condition that causes
the wet wipe to break apart into smaller pieces. In addition some
wet wipes have used mechanical weakening to aid in dispersibility
of the wet wipe.
[0006] The challenge that has haunted formulators in the past is
balancing the in-use wet strength requirements with the
dispersibility requirements. For example, one can achieve a high
in-use wet strength in a wet wipe, but the wet wipe may exhibit
little or no dispersibility. In another example, a wet wipe may
exhibit low in-use wet strength, but the wet wipe may disperse
readily. In one example, a wet wipe may exhibit a high initial wet
strength that deteriorates over time prior to use as a result of
the wet wipe comprising its liquid composition. For example, the
wet wipe comprising its liquid composition may at the time of
packaging exhibit sufficient wet strength, but after sitting in the
package for sometime, for example 28 days or longer, the wet
strength of the wet wipe has deteriorated to an unacceptable level
for consumers.
[0007] In light of the foregoing, consumers desire a wet wipe that
exhibits sufficient wet strength during use, even 28 days after the
wet wipe has been produced, and a dispersibility that is better
than known and existing wet wipes.
[0008] Accordingly, there is a need for a wet wipe that exhibits
sufficient total wet tensile strength during use and an improved
dispersibility.
SUMMARY OF THE INVENTION
[0009] The present invention fulfills the need described above by
providing a wet wipe that exhibits a total wet tensile strength
that is acceptable to consumers during use and an improved
dispersibility compared to known wet wipes.
[0010] It has unexpectedly been found that a wet wipe that combines
a temporary wet strength agent within a fibrous structure, which
comprises a liquid composition that exhibits a pH of less than 4.55
after being extracted from the fibrous structure, provides
sufficient total wet tensile during use and improved dispersibility
compared to known wet wipes.
[0011] In one example of the present invention, a wet wipe
comprising a fibrous structure comprising a liquid composition,
wherein the liquid composition after extraction from the fibrous
structure exhibits a pH of less than 4.55 as measured according to
the pH Test Method described herein, is provided.
[0012] In another example of the present invention, a wet wipe
comprising a fibrous structure comprising a liquid composition,
wherein the fibrous structure comprises a temporary wet strength
agent, is provided.
[0013] In still another example of the present invention, a wet
wipe comprising a fibrous structure comprising a liquid
composition, wherein the fibrous structure comprises a temporary
wet strength agent and the liquid composition after extraction from
the fibrous structure exhibits a pH of less than 4.55 as measured
according to the pH Test Method described herein, is provided.
[0014] In even another example of the present invention, a wet wipe
comprising a fibrous structure comprising greater than 85% by
weight of the fibrous structure on a dry basis of pulp fibers, a
temporary wet strength agent, and a liquid composition, is
provided.
[0015] In even another example of the present invention, a wet wipe
comprising a fibrous structure comprising greater than 85% by
weight of the fibrous structure on a dry basis of pulp fibers and a
liquid composition that exhibits a pH of less than 4.55 as measured
according to the pH Test Method described herein, is provided.
[0016] In even still another example of the present invention, a
wet wipe comprising a fibrous structure comprising a surface
pattern imparted to the fibrous structure during the fibrous
structure making process and a liquid composition, is provided.
[0017] In yet another example of the present invention, a method
for making a wet wipe comprising the steps of: [0018] a. providing
a fibrous structure; and [0019] b. contacting the fibrous structure
with a liquid composition such that the pH of the liquid
composition after being extracted from the fibrous structure is
less than 4.55 as measured according to the pH Test Method to
produce a wet wipe, is provided.
[0020] In still yet another example of the present invention, a
method for making a wet wipe comprising the steps of: [0021] a.
providing a fibrous slurry comprising a plurality of fibers and a
temporary wet strength agent; [0022] b. depositing the fibrous
slurry onto a forming wire to form an embryonic web; [0023] c.
transferring the embryonic web to a patterned belt to impart a
surface pattern to the embryonic web; [0024] d. drying the
embryonic web to form a fibrous structure; and [0025] e. contacting
the fibrous structure with a liquid composition to form a wet wipe,
is provided.
[0026] Accordingly, the present invention provides novel wet wipes
comprising a fibrous structure and a liquid composition and methods
for making same.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is a schematic representation of an example of a
fibrous structure in accordance with the present invention;
[0028] FIG. 2 is a cross-sectional view of FIG. 1 taken along line
2-2;
[0029] FIG. 3 is a schematic representation of another example of a
fibrous structure in accordance with the present invention;
[0030] FIG. 4 is a cross-sectional view of FIG. 3 taken along line
4-4;
[0031] FIG. 5 is a schematic representation of an example of a
fibrous structure in accordance with the present invention; and
[0032] FIG. 6 is a cross-sectional view of FIG. 5 taken along line
6-6.
DETAILED DESCRIPTION OF THE INVENTION
Definitions
[0033] "Fibrous structure" as used herein means a structure that
comprises one or more filaments and/or fibers. In one example, a
fibrous structure according to the present invention means an
orderly arrangement of filaments and/or fibers within a structure
in order to perform a function. Non-limiting examples of fibrous
structure of the present invention include paper, fabrics
(including woven, knitted, and non-woven), and absorbent pads (for
example for diapers or feminine hygiene products).
[0034] Non-limiting examples of processes for making fibrous
structures include known wet-laid papermaking processes, air-laid
papermaking processes, and other nonwoven making processes such as
meltblowing, spunbonding, and carding. Such wet-laid and/or
air-laid papermaking processes typically include steps of preparing
a fiber composition in the form of a suspension in a medium, either
wet, more specifically aqueous medium, or dry, more specifically
gaseous, i.e. with air as medium. The aqueous medium used for
wet-laid processes is oftentimes referred to as a fiber slurry. The
fibrous slurry is then used to deposit a plurality of fibers onto a
forming wire or belt such that an embryonic fibrous structure is
formed, after which drying and/or bonding the fibers together
results in a fibrous structure. Further processing the fibrous
structure may be carried out such that a wet wipe is formed.
[0035] The fibrous structures of the present invention may be
homogeneous or may be layered. If layered, the fibrous structures
may comprise at least two and/or at least three and/or at least
four and/or at least five layers.
[0036] The fibrous structures of the present invention may be
co-formed fibrous structures.
[0037] "Co-formed fibrous structure" as used herein means that the
fibrous structure comprises a mixture of at least two different
materials wherein at least one of the materials comprises a
filament, such as a polypropylene filament, and at least one other
material, different from the first material, comprises a solid
additive, such as a fiber and/or a particulate. In one example, a
co-formed fibrous structure comprises solid additives, such as
fibers, such as wood pulp fibers, and filaments, such as
polypropylene filaments.
[0038] "Solid additive" as used herein means a fiber and/or a
particulate.
[0039] "Particulate" as used herein means a granular substance or
powder.
[0040] "Fiber" and/or "Filament" as used herein means an elongate
particulate having an apparent length greatly exceeding its
apparent width, i.e. a length to diameter ratio of at least about
10. In one example, a "fiber" is an elongate particulate as
described above that exhibits a length of less than 5.08 cm (2 in.)
and a "filament" is an elongate particulate as described above that
exhibits a length of greater than or equal to 5.08 cm (2 in.).
[0041] Fibers are typically considered discontinuous in nature.
Non-limiting examples of fibers include wood pulp fibers and
synthetic staple fibers such as polyester fibers.
[0042] Filaments are typically considered continuous or
substantially continuous in nature. Filaments are relatively longer
than fibers. Non-limiting examples of filaments include meltblown
and/or spunbond filaments. Non-limiting examples of materials that
can be spun into filaments include natural polymers, such as
starch, starch derivatives, cellulose and cellulose derivatives,
hemicellulose, hemicellulose derivatives, and synthetic polymers
including, but not limited to polyvinyl alcohol filaments and/or
polyvinyl alcohol derivative filaments, and thermoplastic polymer
filaments, such as polyesters, nylons, polyolefins such as
polypropylene filaments, polyethylene filaments, and biodegradable
or compostable thermoplastic fibers such as polylactic acid
filaments, polyhydroxyalkanoate filaments and polycaprolactone
filaments. The filaments may be monocomponent or multicomponent,
such as bicomponent filaments.
[0043] In one example of the present invention, "fiber" refers to
papermaking fibers. Papermaking fibers useful in the present
invention include cellulosic fibers commonly known as wood pulp
fibers. Applicable wood pulps include chemical pulps, such as
Kraft, sulfite, and sulfate pulps, as well as mechanical pulps
including, for example, groundwood, thermomechanical pulp and
chemically modified thermomechanical pulp. Chemical pulps, however,
may be preferred since they impart a superior tactile sense of
softness to tissue sheets made therefrom. Pulps derived from both
deciduous trees (hereinafter, also referred to as "hardwood") and
coniferous trees (hereinafter, also referred to as "softwood") may
be utilized. The hardwood and softwood fibers can be blended, or
alternatively, can be deposited in layers to provide a stratified
web. U.S. Pat. No. 4,300,981 and U.S. Pat. No. 3,994,771 are
incorporated herein by reference for the purpose of disclosing
layering of hardwood and softwood fibers. Also applicable to the
present invention are fibers derived from recycled paper, which may
contain any or all of the above categories as well as other
non-fibrous materials such as fillers and adhesives used to
facilitate the original papermaking. Non-limiting examples of
suitable hardwood pulp fibers include eucalyptus and acacia.
Non-limiting examples of suitable softwood pulp fibers include
Southern Softwood Kraft (SSK) and Northern Softwood Kraft
(NSK).
[0044] "Hardwood pulp fiber" as used herein means pulp fibers
obtained from deciduous trees. Non-limiting examples of deciduous
trees include Northern hardwood trees and tropical hardwood trees.
Non-limiting examples of hardwood pulp fibers include hardwood pulp
fibers obtained from a fiber source selected from the group
consisting of Acacia, Eucalyptus, Maple, Oak, Aspen, Birch,
Cottonwood, Alder, Ash, Cherry, Elm, Hickory, Poplar, Gum, Walnut,
Locust, Sycamore, Beech, Catalpa, Sassafras, Gmelina, Albizia,
Anthocephalus, Magnolia, and mixtures thereof. In one example, the
hardwood pulp fiber of the present invention is obtained from
Eucalyptus.
[0045] "Tropical hardwood pulp fiber" as used herein means pulp
fibers obtained from a tropical hardwood tree. Non-limiting
examples of tropical hardwood trees include Eucalyptus trees and/or
Acacia trees.
[0046] In addition to the various wood pulp fibers, other
cellulosic fibers such as cotton linters, rayon, lyocell and
bagasse can be used in this invention. Other sources of cellulose
in the form of fibers or capable of being spun into fibers include
grasses and grain sources.
[0047] In addition, trichomes such as from "lamb's ear" plants and
seed hairs can also be utilized in the fibrous structures of the
present invention.
[0048] In one example, the fibrous structure may comprise 100% by
weight on a dry fiber basis of softwood fibers, such as NSK fibers.
In another example, the fibrous structure may comprise a mixture of
softwood fibers, such as NSK fibers, and hardwood fibers, such as
Eucalyptus fibers. In still another example, the fibrous structure
may comprise less than 100% and/or less than 90% and/or less than
80% and/or to about 70% by weight on a dry fiber basis of softwood
fibers, such as NSK fibers, and greater than 0% and/or greater than
10% and/or greater than 20% and/or to about 30% by weight on a dry
fiber basis of hardwood fibers, such as Eucalyptus fibers.
[0049] In one example, the fibrous structure may comprise greater
than 50% and/or 70% or greater by weight on a dry basis of softwood
fibers and less than 50% and/or 30% or less by weight on a dry
basis of hardwood fibers.
[0050] In still another example, the fibrous structure may comprise
greater than 0% and/or greater than 5% and/or greater than 10%
and/or greater than 20% and/or greater than 30% and/or to about 50%
by weight on a dry fiber basis of fibers, such as pulp fibers, that
exhibit a mean fiber length of from less than 1 mm and/or less than
0.9 mm and/or less than 0.8 mm and/or to about 0.5 mm and/or to
about 0.6 mm and/or to about 0.7 mm.
[0051] "Wet wipe" as used herein means a fibrous structure that
contains greater than 20% and/or greater than 40% and/or greater
than 50% and/or greater than 75% by weight of the wet wipe of a
liquid composition. In one example, the fibrous structure of the
present invention comprises a % saturation of greater than 50%
and/or greater than 75% and/or greater than 100% and/or greater
than 125% and/or greater than 150% and/or to about 1000% and/or to
about 500% and/or to about 400% and/or to about 300% and/or to
about 250% and/or to about 200%.
[0052] The liquid composition may be added to the fibrous structure
to form a wet wipe prior to and/or after packaging and/or prior to
and/or after folding, if any, and/or prior to and/or after any post
processing operation, such as embossing, tuft generating, printing,
combining with other fibrous structure plies and mixtures thereof.
The wet wipe is typically packaged in a moisture impervious
container and/or wrapper. The wet wipe may be in the form of one or
more individual sheets, such as a stack of sheets, which may be
interleaved. In another example, the wet wipes of the present
invention may be in the form of wet wipe rolls. Such wet wipe rolls
may comprise a plurality of connected, but perforated sheets of
fibrous structure, that are separably dispensable from adjacent
sheets.
[0053] The fibrous structure, as described above, may be utilized
to form a wet wipe. "Wet wipe" may be a general term to describe a
piece of material, generally fibrous structure, used in cleansing
hard surfaces, food, inanimate objects, toys and body parts. In
particular, many currently available wet wipes may be intended for
the cleansing of the perianal area after defecation. Other wet
wipes may be available for the cleansing of the face or other body
parts. Multiple wipes may be attached together by any suitable
method to form a mitt.
[0054] The fibrous structure from which a wet wipe is made should
be strong enough to resist tearing during normal use, yet still
provide softness to the user's skin, such as a child's tender skin.
Additionally, the fibrous structure should be at least capable of
retaining its form for the duration of the user's cleansing
experience.
[0055] Wet wipes may be generally of sufficient dimension to allow
for convenient handling. Typically, the wipe may be cut and/or
folded to such dimensions as part of the manufacturing process. In
some instances, the wipe may be cut into individual portions so as
to provide separate wipes which are often stacked and interleaved
in consumer packaging. In other embodiments, the wipes may be in a
web form where the web has been slit and folded to a predetermined
width and provided with means (e.g., perforations) to allow
individual wipes to be separated from the web by a user. Suitably,
an individual wipe may have a length between about 100 mm and about
250 mm and a width between about 140 mm and about 250 mm. In one
embodiment, the wipe may be about 200 mm long and about 180 mm
wide. The material of the wipe may generally be soft and flexible,
potentially having a structured surface to enhance its cleaning
performance.
[0056] The wet wipes may also be treated to improve the softness
and texture thereof by processes such as hydroentanglement or
spunlacing. The wet wipes may be subjected to various treatments,
such as, but not limited to, physical treatment, such as ring
rolling, as described in U.S. Pat. No. 5,143,679; structural
elongation, as described in U.S. Pat. No. 5,518,801; consolidation,
as described in U.S. Pat. Nos. 5,914,084, 6,114,263, 6,129,801 and
6,383,431; stretch aperturing, as described in U.S. Pat. Nos.
5,628,097, 5,658,639 and 5,916,661; differential elongation, as
described in WO Publication No. 2003/0028165A1; and other solid
state formation technologies as described in U.S. Publication No.
2004/0131820A1 and U.S. Publication No. 2004/0265534A1 and zone
activation and the like; chemical treatment, such as, but not
limited to, rendering part or all of the substrate hydrophobic,
and/or hydrophilic, and the like; thermal treatment, such as, but
not limited to, softening of fibers by heating, thermal bonding and
the like; and combinations thereof.
[0057] The wet wipe may have a basis weight of at least about 40
grams/m.sup.2. In one example, the wipe may have a basis weight of
at least about 45 grams/m.sup.2. In another example, the wet wipe
basis weight may be less than 120 grams/m.sup.2. In another
example, wet wipe may have a basis weight of from about 45
grams/m.sup.2 to about 90 grams/m.sup.2 and/or from about 50
g/m.sup.2 to about 80 g/m.sup.2.
[0058] In one example of the present invention the surface of wet
wipe may be essentially flat. In another example of the present
invention the surface of the wet wipe may optionally contain raised
and/or lowered portions. These can be in the form of logos,
indicia, trademarks, geometric patterns, images of the surfaces
that the substrate is intended to clean (i.e., infant's body, face,
etc.). They may be randomly arranged on the surface of the wipe or
be in a repetitive pattern of some form.
[0059] In another example of the present invention the wet wipe may
be biodegradable. For example the wet wipe could be made from a
biodegradable material such as a polyesteramide, or high wet
strength cellulose.
[0060] "Liquid composition" as used herein means any liquid
including, but not limited to a pure liquid such as water, an
aqueous composition, a colloid, an emulsion, a suspension, a
solution and mixtures thereof. The term "aqueous composition" as
used herein refers to a composition that comprises at least 20%
and/or at least 40% and/or at least 50% and/or to about 98% and/or
to about 95% and/or to about 93% and/or to about 90% by weight
water.
[0061] In one example, the liquid composition comprises water or
another liquid solvent. Generally the liquid composition is of
sufficiently low viscosity to impregnate the entire structure of
the fibrous structure. In another example, the liquid composition
may be primarily present on a surface of the fibrous structure
surface and to a lesser extent in the inner structure of the
fibrous structure. In a further example, the liquid composition is
releasably carried by the fibrous structure, that is the liquid
composition is carried on or in the fibrous structure and is
readily releasable from the fibrous structure by applying some
force to the fibrous structure, for example by wiping a surface,
such as a human skin, with the fibrous structure.
[0062] The liquid composition of the present invention may comprise
an oil-in-water emulsion. In one example, the liquid composition of
the present invention comprises at least 80% and/or at least 85%
and/or at least 90% and/or at least 95% by weight water.
[0063] When present on and/or in the fibrous structure of the
present invention, the liquid composition may be present at a level
of from about 10% to about 1000% of the basis weight of the fibrous
structure and/or from about 100% to about 700% of the basis weight
of the fibrous structure and/or from about 200% to about 400% of
the basis weight of the fibrous structure.
[0064] The liquid composition may comprise an acid. Non-limiting
examples of acids that can be used in the liquid composition of the
present invention are adipic acid, tartaric acid, citric acid,
maleic acid, malic acid, succinic acid, glycolic acid, glutaric
acid, malonic acid, salicylic acid, gluconic acid, polymeric acids,
phosphoric acid, carbonic acid, fumaric acid and phthalic acid and
mixtures thereof. Suitable polymeric acids can include
homopolymers, copolymers and terpolymers, and may contain at least
30 mole % carboxylic acid groups. Specific examples of suitable
polymeric acids useful herein include straight-chain poly(acrylic)
acid and its copolymers, both ionic and nonionic, (e.g.,
maleic-acrylic, sulfonic-acrylic, and styrene-acrylic copolymers),
those cross-linked polyacrylic acids having a molecular weight of
less than about 250,000, preferably less than about 100,000
poly(.alpha.-hydroxy) acids, poly(methacrylic) acid, and naturally
occurring polymeric acids such as carageenic acid, carboxy methyl
cellulose, and alginic acid. In one example, the liquid composition
comprises citric acid and/or citric acid derivatives.
[0065] The liquid composition may also contain salts of the acid or
acids, which may help to lower the pH of the liquid composition, or
another weak base to impart buffering properties to the fibrous
structure. The buffering response is due to the equilibrium which
is set up between the free acid and its salt. This allows the
fibrous structure to maintain its overall pH despite encountering a
relatively high amount of bodily waste as would be found post
urination and/or defecation in a baby or adult. In one embodiment
the acid salt comprises sodium citrate. The amount of sodium
citrate present in the liquid composition in one example may be
between 0.01 and 2.0%, alternatively 0.1 and 1.25%, or
alternatively 0.2 and 0.7% by weight of the liquid composition.
[0066] In addition to the above ingredients, the liquid composition
may comprise additional ingredients. Non-limiting examples of
additional ingredients that may be present in the liquid
composition of the present invention include: skin conditioning
agents (emollients, humectants) including, waxes such as
petrolatum, cholesterol and cholesterol derivatives, di and
tri-glycerides including sunflower oil and sesame oil, silicone
oils such as dimethicone copolyol, caprylyl glycol and
acetoglycerides such as lanolin and its derivatives, emulsifiers;
alcohols; preservatives; stabilizers; surfactants including
anionic, amphoteric, cationic and non ionic surfactants, colorants,
chelating agents including EDTA, sun screen agents, solubilizing
agents, perfumes, opacifying agents, vitamins, viscosity modifiers;
such as xanthan gum, astringents and external analgesics.
[0067] In one example, the liquid composition comprises an alcohol,
such as benzylalcohol.
[0068] In one example, the liquid composition comprises a
perfume.
[0069] In one example, the liquid composition comprises a
preservative. In another example, the liquid composition is void of
a preservative.
[0070] The liquid composition prior to contacting the fibrous
structure of the present invention may exhibit a pH of greater than
5 and/or greater than 5.2 and/or greater than 5.5 and/or greater
than 6 and/or less than 10 and/or less than 9 and/or less than 8
and/or less than 7 as measured according to the pH Test Method
described herein prior to contacting the fibrous structure.
[0071] The pH of the liquid composition may be impacted by the
fibrous structure, for example the fiber composition of the fibrous
structure. The liquid composition may exhibit a pH of less than
4.55 and/or less than 4.3 and/or less than 4.1 and/or less than 4
and/or less than 3.8 and/or greater than 2 and/or greater than 2.5
and/or greater than 3 and/or greater than 3.5 as measured according
to the pH Test Method described herein after being extracted from
the fibrous structure.
[0072] Table 1 below shows the pH of the liquid composition after
being extracted from the fibrous structure of the present invention
and known wet wipes.
TABLE-US-00001 TABLE 1 pH of Liquid Composition Wet Wipe Extracted
from Wet Wipe Invention Example1 4.3 Invention Example 2 4.3
Invention Example 3 4.3 Invention Example 4 4.3 Invention Example 5
4.3 Invention Example 6 4.3 Charmin Freshmates (currently marketed)
4.62 Kleenex Cottonelle Fresh 5.03 Walgreens Flushable Moist Wipes
5.09 Walmart Natural Choice Flushable Moist 5.19 Wipes Kroger Nice
n Soft Flushable Moist Wipes 5.05 Meijer Flushable Moist Wipes 5.23
Target Up&Up Flushable Moist Wipes 5.04 Scott Wipes 5.08
[0073] In one example, the liquid composition comprises an alcohol.
In another example, the liquid composition comprises a perfume. In
still another example, the liquid composition comprises a
preservative.
[0074] "% Saturation" also equivalently referred to as "saturation
loading" as used herein means the amount of a liquid composition
applied to a fibrous structure to form a wet wipe. In general, the
amount of the liquid composition applied to a fibrous structure
according to the present invention may be chosen in order to
provide maximum benefits to the wet wipe. Saturation loading, often
expressed as percent saturation, is defined as the percentage of
the dry fibrous structure's mass that the liquid composition mass
represents. For example, a saturation load of 1.0 (equivalently
100% saturation) indicates that the mass of the liquid composition
contained in/on the fibrous structure is equal to the fibrous
structure mass whereas a saturation load of 1.5 (equivalently 150%
saturation) indicates that the mass of the liquid composition
contained in/on the fibrous structure is 1.5 times the fibrous
structure mass.
[0075] The wet wipes and/or fibrous structures of the present
invention may exhibit a basis weight of greater than 15 g/m.sup.2
(9.2 lbs/3000 ft.sup.2) to about 120 g/m.sup.2 (73.8 lbs/3000
ft.sup.2) and/or from about 15 g/m.sup.2 (9.2 lbs/3000 ft.sup.2) to
about 110 g/m.sup.2 (67.7 lbs/3000 ft.sup.2) and/or from about 20
g/m.sup.2 (12.3 lbs/3000 ft.sup.2) to about 100 g/m.sup.2 (61.5
lbs/3000 ft.sup.2) and/or from about 30 (18.5 lbs/3000 ft.sup.2) to
90 g/m.sup.2 (55.4 lbs/3000 ft.sup.2). In addition, the wet wipes
and/or fibrous structures of the present invention may exhibit a
basis weight between about 40 g/m.sup.2 (24.6 lbs/3000 ft.sup.2) to
about 120 g/m.sup.2 (73.8 lbs/3000 ft.sup.2) and/or from about 50
g/m.sup.2 (30.8 lbs/3000 ft.sup.2) to about 110 g/m.sup.2 (67.7
lbs/3000 ft.sup.2) and/or from about 55 g/m.sup.2 (33.8 lbs/3000
ft.sup.2) to about 105 g/m.sup.2 (64.6 lbs/3000 ft.sup.2) and/or
from about 60 (36.9 lbs/3000 ft.sup.2) to 100 g/m.sup.2 (61.5
lbs/3000 ft.sup.2).
[0076] The wet wipes of the present invention may exhibit an
initial total wet tensile strength of less than 3000 g/in and/or
less than 2500 g/in and/or less than 2000 g/in and/or less than
1800 g/in and/or less than 1500 g/in and/or less than 1250 g/in
and/or greater than 300 g/in and/or greater than 400 g/in and/or
greater than 500 g/in and/or greater than 600 g/in as measured
according to the Wet Tensile Strength Test Method described herein.
In one example, the wet wipes of the present invention may exhibit
a total wet tensile strength after 28 days of less than 2000 g/in
and/or less than 1800 g/in and/or less than 1500 g/in and/or less
than 1250 g/in and/or less than 1000 g/in and/or greater than 100
g/in and/or greater than 200 g/in and/or greater than 300 g/in
and/or greater than 400 g/in as measured according to the Wet
Tensile Strength Test Method described herein.
[0077] The wet wipes of the present invention may exhibit a density
(measured at 95 g/in.sup.2) of less than about 0.60 g/cm.sup.3
and/or less than about 0.30 g/cm.sup.3 and/or less than about 0.20
g/cm.sup.3 and/or less than about 0.10 g/cm.sup.3 and/or less than
about 0.07 g/cm.sup.3 and/or less than about 0.05 g/cm.sup.3 and/or
from about 0.01 g/cm.sup.3 to about 0.20 g/cm.sup.3 and/or from
about 0.02 g/cm.sup.3 to about 0.10 g/cm.sup.3.
[0078] The wet wipes of the present invention may be in the form of
wet wipe rolls. Such wet wipe rolls may comprise a plurality of
connected, but perforated sheets of fibrous structure, that are
separably dispensable from adjacent sheets.
[0079] The wet wipes of the present invention may comprises
additives such as softening agents such as silicones and/or
quaternary ammonium compounds, temporary wet strength agents,
permanent wet strength agents, bulk softening agents, lotions,
silicones, wetting agents, latexes, especially
surface-pattern-applied latexes, dry strength agents such as
carboxymethylcellulose and starch, and other types of additives
suitable for inclusion in and/or on wet wipes.
[0080] In one example, the wet wipe is void (less than 5% and/or
less than 3% and/or less than 1% and/or less than 0.5% and/or less
than 0.1% by weight of the wet wipe) of any post fibrous structure
making applied polymeric binder.
[0081] "Weight average molecular weight" as used herein means the
weight average molecular weight as determined using gel permeation
chromatography according to the protocol found in Colloids and
Surfaces A. Physico Chemical & Engineering Aspects, Vol. 162,
2000, pg. 107-121.
[0082] "Basis Weight" as used herein is the weight per unit area of
a sample reported in lbs/3000 ft.sup.2 or g/m.sup.2 and is measured
according to the Basis Weight Test Method described herein.
[0083] "Caliper" as used herein means the macroscopic thickness of
a fibrous structure. Caliper is measured according to the Caliper
Test Method described herein.
[0084] "Bulk" as used herein is calculated as the quotient of the
Caliper, expressed in microns, divided by the Basis Weight,
expressed in grams per square meter. The resulting Bulk is
expressed as cubic centimeters per gram. For the products of this
invention, Bulks can be greater than about 3 cm.sup.3/g and/or
greater than about 6 cm.sup.3/g and/or greater than about 9
cm.sup.3/g and/or greater than about 10.5 cm.sup.3/g up to about 30
cm.sup.3/g and/or up to about 20 cm.sup.3/g. The products of this
invention derive the Bulks referred to above from the basesheet,
which is the sheet produced by the tissue machine without post
treatments such as embossing. Nevertheless, the basesheets of this
invention can be embossed to produce even greater bulk or
aesthetics, if desired, or they can remain unembossed. In addition,
the basesheets of this invention can be calendered to improve
smoothness or decrease the Bulk if desired or necessary to meet
existing product specifications.
[0085] "Density" as used herein is calculated as the quotient of
the Basis Weight expressed in grams per square meter divided by the
Caliper expressed in microns. The resulting Density is expressed as
grams per cubic centimeters (g/cm.sup.3 or g/cc). In one example,
the Densities can be greater than 0.05 g/cm.sup.3 and/or greater
than 0.06 g/cm.sup.3 and/or greater than 0.07 g/cm.sup.3 and/or
less than 0.10 g/cm.sup.3 and/or less than 0.09 g/cm.sup.3 and/or
less than 0.08 g/cm.sup.3. In one example, a fibrous structure of
the present invention exhibits a density of from about 0.055
g/cm.sup.3 to about 0.095 g/cm.sup.3.
[0086] "Machine Direction" or "MD" as used herein means the
direction parallel to the flow of the fibrous structure through the
fibrous structure making machine and/or wet wipe manufacturing
equipment.
[0087] "Cross Machine Direction" or "CD" as used herein means the
direction parallel to the width of the fibrous structure making
machine and/or wet wipe manufacturing equipment and perpendicular
to the machine direction.
[0088] "Ply" as used herein means an individual, integral fibrous
structure.
[0089] "Plies" as used herein means two or more individual,
integral fibrous structures disposed in a substantially contiguous,
face-to-face relationship with one another, forming a multi-ply
fibrous structure and/or multi-ply wet wipe. It is also
contemplated that an individual, integral fibrous structure can
effectively form a multi-ply fibrous structure, for example, by
being folded on itself.
[0090] "Embossed" as used herein with respect to a fibrous
structure means a fibrous structure that has been subjected to a
process which converts a smooth surfaced fibrous structure to a
decorative surface by replicating a design on one or more emboss
rolls, which form a nip through which the fibrous structure passes.
Embossed does not include creping, microcreping, printing or other
processes that may impart a texture and/or decorative pattern to a
fibrous structure.
Fibrous Structure
[0091] In one example of the present invention, the fibrous
structure of the wet wipe comprises greater than 20% and/or greater
than 40% and/or greater than 50% and/or greater than 75% and/or
greater than 90% and/or to about 100% by weight on a total dry
fiber basis of pulp fibers, such as hardwood and/or softwood pulp
fibers.
[0092] The fibrous structure may comprise a surface comprising a
surface pattern. The surface pattern may comprise a non-random,
repeating pattern. The surface pattern may comprise a formed
surface pattern such as resulting from a patterned belt and/or
belt/fabric combination. In another example, the fibrous structure
may be an embossed fibrous structure that comprises one or more
embossments, such as imparted by passing the fibrous structure
(prior to and/or after application of a liquid composition) through
an embossing nip. The one or more embossments may comprise line art
embossments and/or dot embossments and/or other non-line art
embossments.
[0093] In one example, the fibrous structure of the present
invention may comprise two or more regions that are different from
one another with respect to their specific level of wet tensile
strength and/or resistance to disperse.
[0094] As shown in FIGS. 1 and 2, a fibrous structure 10 according
to the present invention may comprise a surface 12 comprising a
surface pattern 14. The surface pattern 14 may include two or more
different regions. In one example, the surface pattern 14 includes
discrete, higher density regions 16 and a lower density region 18
compared to the discrete, higher density regions 16. The lower
density region 18 may be in the form of a continuous or
substantially continuous network surrounding the discrete, higher
density regions 16. In one example, the discrete, higher density
regions 16 comprise greater than 6% to about 65% of the surface
pattern. In another example, the surface pattern 14 comprises from
about 8 to about 400 discrete, higher density regions 16. The
discrete, higher density regions 16 may comprise any shape or
combination of shapes, for example, circles, triangles, diamonds,
trapezoids, squares, rectangles, parallelograms, rhombuses, stars,
pentagons, hexagons, and octagons. Without wishing to be bound by
theory, it is believed that the lower density region 18 disperses
more readily than the higher density regions 16. However, as shown
in FIGS. 3 and 4, the fibrous structure 10 of the present invention
may comprise a surface 12 having a surface pattern 14 that includes
discrete, lower density regions 20, sometimes referred to as
"pillows" and a higher density region 22, sometimes referred to as
a "knuckle." The higher density region 22 may be in the form of a
continuous or substantially continuous network surrounding the
discrete, lower density regions 20.
[0095] In another example of the present invention as shown in
FIGS. 5 and 6, a fibrous structure 10 may comprise a surface 12
having a surface pattern 14. The surface pattern 14 may comprise
discrete, higher density regions 24 and discrete, lower density
regions 26.
[0096] In another example of the present invention, the fibrous
structure comprises two or more regions that exhibit different
values of a common intensive property, for example different
densities (a region of higher density relative to a region of lower
density) and/or different basis weights.
[0097] The fibrous structure may be a creped fibrous structure or
an uncreped fibrous structure. The fibrous structure may be a
fabric and/or belt creped fibrous structure. In addition, the
fibrous structure may be a wet molded and/or a wet microcontracted
fibrous structure. Further, the fibrous structure may be a
through-air-dried fibrous structure or a compressively dewatered
fibrous structure, such as a conventional papermaking processed
fibrous structure. In one example, the fibrous structure is a
non-hydroentangled (non-spunlaced) fibrous structure.
[0098] The fibrous structure may comprise a temporary wet strength
agent. Suitable temporary wet strength agents include materials
that can react with hydroxyl groups, such as on cellulosic pulp
fibers, to form hemiacetal bonds that are reversible in the
presence of excess water. Suitable temporary wet strength agents
are known to those of ordinary skill in the art. Non-limiting
examples of temporary wet strength agents suitable for the fibrous
structures of the present invention include glyoxylated
polyacrylamide polymers, for example cationic glyoxylated
polyacrylamide polymers. In one example, the temporary wet strength
agent comprises Hercobond.RTM. commercially available from Ashland
Inc. In another example, the temporary wet strength agent comprises
Parez.RTM. 750 and/or 745 commercially available from Kemira
Chemicals, Inc.
[0099] In one example, the temporary wet strength agent exhibits a
pH of less the 7 and/or less than 6.5 and/or less than 6 and/or
less than 5.5 and/or less than 5 and/or less than 4.5 and/or to
about 2.5 and/or to about 3 and/or to about 3.5. In one example,
the pH of the temporary wet strength agent is about 4.
[0100] Non-limiting examples of temporary wet strength agents made
by the methods of the present invention generally have weight
average molecular weights of from about 20,000 to about 400,000
and/or from about 50,000 to about 400,000 and/or from about 70,000
to about 400,000 and/or from about 70,000 to about 300,000 and/or
from about 100,000 to about 200,000.
[0101] The temporary wet strength agents of the present invention
impart wet tensile strength properties and wet tensile decay
properties to the fibrous structures and/or wet wipes of the
present invention.
[0102] It has been found that temporary wet strength agents with
high weight average molecular weights (i.e. those in excess of
300,000) may decay unacceptably slow for consumer purposes.
Further, it has been found that temporary wet strength agents with
extremely low weight average molecular weights (i.e. those less
than 70,000) may have very low wet strength and may not be optimal
as temporary wet strength agents for fibrous structures and/or wet
wipes.
[0103] Non-limiting examples of temporary wet strength agents in
accordance with the present invention include temporary wet
strength agents having the formula:
##STR00001##
wherein: A (the moiety present on the co-crosslinking monomeric
unit) is independently an electrophilic moiety, non-limiting
examples of which include the following:
##STR00002##
Z (the moiety present on the reversible, homo-crosslinking
monomeric unit) is independently a nucleophilic moiety capable of
forming an unstable covalent bond with the electrophilic moiety,
non-limiting examples of which include the following:
##STR00003##
and X is independently --O--, --NH--, or --NCH.sub.3--; and R.sub.1
is a substituted or unsubstituted aliphatic group; Y.sub.1,
Y.sub.2, and Y.sub.3 are independently --H, --CH.sub.3, or a
halogen; Q is a cationic moiety; and W is a non-nucleophilic moiety
or a nucleophilic moiety that does not form a stable covalent bond
with the electrophilic moiety. Non-limiting examples of moieties
for W include water-soluble N,N-dialkyl acrylamide moieties and/or
water-soluble carboxylic acid moieties.
[0104] The mole percent of a ranges from about 1% to about 20%,
preferably from about 2% to about 15%, the mole percent of b ranges
from about 0% to about 60%, preferably from about 0% to about 45%,
the mole percent of c ranges from about 10% to about 90%,
preferably from about 30% to about 80%, and d ranges from about 1%
to about 40%, preferably from about 2% to about 20%, more
preferably from about 5% to about 12%.
[0105] Unless otherwise expressly specified, values for a, b, c,
and d shall be mole percentage values based upon the average number
of monomeric units in the polymer backbone of the temporary wet
strength agent of the present invention.
[0106] The monomeric units of the polymer backbone of the temporary
wet strength agent of the present invention may be randomly
distributed throughout the polymer in ratios corresponding to the
mole percentage ranges described herein.
[0107] Each class of monomeric units may include a single monomer
or may include combinations of two or more different monomers
within that class. The mole percent of each monomeric unit within a
class of monomeric units may be independently selected.
[0108] In one example, the fibrous structure comprises greater than
5% and/or greater than 10% and/or greater than 25% and/or greater
than 40% and/or greater than 50% and/or to about 90% and/or to
about 80% and/or to about 70% by weight of the liquid
composition.
Wet Wipe
[0109] The fibrous structures of the present invention may be
saturation loaded with a liquid composition to form a wet wipe. The
loading may occur individually, or after the fibrous structures are
placed in a stack, such as within a liquid impervious container or
packet. In one example, the fibrous structures may be saturation
loaded with from about 1.5 g to about 6.0 g and/or from about 2.5 g
to about 4.0 g of liquid composition per g of fibrous
structure.
[0110] The wet wipes of the present invention may be placed in the
interior of a container, which may be liquid impervious, such as a
plastic tub or a sealable packet, for storage and eventual sale to
the consumer. The wet wipes may be folded and stacked. The wet
wipes of the present invention may be folded in any of various
known folding patterns, such as C-folding, Z-folding and
quarter-folding. Use of a Z-fold pattern may enable a folded stack
of wet wipes to be interleaved with overlapping portions.
Alternatively, the wet wipes may include a continuous strip of
fibrous structure which has perforations between each wet wipe and
which may be arranged in a stack or wound into a roll for
dispensing, one after the other, from a container, which may be
liquid impervious.
[0111] The wet wipes of the present invention may further comprise
prints, which may provide aesthetic appeal. Non-limiting examples
of prints include figures, patterns, letters, pictures and
combinations thereof.
[0112] In one example, the wet wipe of the present invention
exhibits an in-use total wet tensile strength of greater than 300
g/in and/or greater than 400 g/in and/or greater than 500 g/in
and/or greater than 600 g/in and/or less than 2500 g/in and/or less
than 2000 g/in and/or less than 1500 g/in and/or less than 1000
g/in as measured by the Wet Tensile Strength Test Method described
herein.
[0113] In another example, the wet wipe of the present invention
exhibits a 12.5 mm Screen Retention Value at 3 hours of less than
50% and/or less than 40% and/or less than 30% and/or 20% and/or
less than 15% and/or less than 10% and/or less than 5% as measured
according to the Shake Flask Test Method described herein.
[0114] In another example, the wet wipe of the present invention
exhibits a 3 mm Screen Retention Value at 3 hours of less than 50%
and/or less than 40% and/or less than 30% and/or less than 25%
and/or less than 20% and/or less than 15% and/or less than 10%
and/or less than 5% as measured according to the Shake Flask Test
Method described herein.
[0115] Table 2 below shows the Screen Retention Values for several
invention example wet wipes that comprised 7 pounds/ton of
temporary wet strength agent (Hercobond.RTM. 1194), a first
prototype (Prototype 1) that was similar to the invention example
wet wipes except it contained 12 pounds/ton temporary wet strength
agent (Hercobond.RTM. 1194), two prototypes (Prototypes 2 and 3)
that were similar to the invention example wet wipes except they
contained a permanent wet strength agent (Kymene.RTM.) rather than
a temporary wet strength agent, and known wet wipes.
TABLE-US-00002 TABLE 2 12.5 mm Screen 3 mm Screen Retention
Retention Value (%) Value (%) Wet Wipe After 3 hours After 3 hours
Invention Example 1 0 19 Invention Example 2 0 0 Invention Example
3 0 0 Invention Example 4 0 5.5 Invention Example 5 0 0 Invention
Example 6 2.4 20.1 Charmin Freshmates 83.2 70 (currently marketed)
Prototype 1 -- 70 Prototype 2 92 92 (permanent wet strength agent)
Prototype 3 95 95 (permanent wet strength agent) Kleenex Cottonelle
0 28 Fresh Walgreens Flushable 90.6 0 Moist Wipes Walmart Natural
-- -- Choice Flushable Moist Wipes* Kroger Nice n Soft 90.8 0
Flushable Moist Wipes Meijer Flushable -- -- Moist Wipes* Target
Up&Up -- -- Flushable Moist Wipes* Scott Natural Wipes 23.0 5.1
Unicharm Wipes -- 12 *Expect the values for these products to be
consistent with the values of the Walgreens and the Kroger products
since their fibrous structures are apparently supplied by the same
supplier; namely Rockline Industries.
Method for making Fibrous structure
[0116] Any suitable process known in the art may be used to make
the fibrous structure of the present invention. In one example, the
fibrous structure of the present invention is made using a wet-laid
fibrous structure making process.
[0117] The fibrous structure of the present invention may be made
by any suitable process known in the art so long as the fibrous
structure meets the wet tensile strength and/or dispersibility
requirements described herein. In one example, the fibrous
structure of the present invention is made using a wet-laid fibrous
structure making process.
[0118] In one example, a method for making a wet wipe comprising
the steps of: [0119] a. providing a fibrous structure, for example
a fibrous structure according to the present invention; and [0120]
b. contacting the fibrous structure with a liquid composition, for
example a fibrous structure according to the present invention such
that a wet wipe, for example a wet wipe according to the present
invention is produced.
[0121] In still another example, a method for making a wet wipe
comprising the steps of: [0122] a. providing a fibrous structure,
for example a fibrous structure according to the present invention;
and [0123] b. contacting the fibrous structure with a liquid
composition, for example a liquid composition according to the
present invention such that the pH of the liquid composition after
being extracted from the fibrous structure is less than 4.55 as
measured according to the pH Test Method to produce a wet wipe, for
example a wet wipe according to the present invention.
[0124] In yet another example, a method for making a wet wipe
comprising the steps of: [0125] a. providing a fibrous slurry
comprising a plurality of fibers and a temporary wet strength
agent; and optionally, a dry strength agent; [0126] b. depositing
the fibrous slurry onto a forming wire to form an embryonic web;
[0127] c. transferring the embryonic web to a patterned belt to
impart a surface pattern to the embryonic web; [0128] d. drying the
embryonic web to form a fibrous structure, for example a fibrous
structure according to the present invention; and [0129] e.
contacting the fibrous structure with a liquid composition, for
example a liquid composition according to the present invention to
form a wet wipe, for example a wet wipe according to the present
invention.
[0130] In yet another example, a method for making a wet wipe
comprising the steps of: [0131] a. providing a fibrous slurry
comprising a plurality of fibers and a temporary wet strength
agent; and optionally, a dry strength agent; [0132] b. depositing
the fibrous slurry onto a forming wire to form an embryonic web;
[0133] c. transferring the embryonic web to a patterned belt to
impart a surface pattern to the embryonic web; [0134] d. drying the
embryonic web to form a fibrous structure, for example a fibrous
structure according to the present invention; and [0135] e.
contacting the fibrous structure with a liquid composition, for
example a liquid composition according to the present invention to
form a wet wipe, for example a wet wipe according to the present
invention wherein the pH of the liquid composition after being
extracted from the fibrous structure is less than 4.55 as measured
according to the pH Test Method, is provided.
[0136] The fibrous structure may be any suitable fibrous structure.
In one example, the fibrous structure comprises a wet-laid fibrous
structure.
[0137] In another example, the fibrous structure comprises greater
than 75% and/or greater than 80% and/or greater than 90% and/or
greater than 95% and/or to about 100% by weight of pulp fibers.
[0138] The patterned belt of the present invention may be a molding
member. A "molding member" is a structural element that can be used
as a support for an embryonic web comprising a plurality of
cellulosic fibers and a plurality of synthetic fibers, as well as a
forming unit to form, or "mold," a desired microscopical geometry
of the wet wipe of the present invention. The molding member may
comprise any element that has fluid-permeable areas and the ability
to impart a microscopical three-dimensional pattern to the
structure being produced thereon, and includes, without limitation,
single-layer and multi-layer structures comprising a stationary
plate, a belt, a woven fabric (including Jacquard-type and the like
woven patterns), a band, and a roll. In one example, the molding
member is a deflection member. The molding member may comprise a
surface pattern according to the present invention that is imparted
to the wet wipe during the wet wipe making process.
[0139] A "reinforcing element" is a desirable (but not necessary)
element in some embodiments of the molding member, serving
primarily to provide or facilitate integrity, stability, and
durability of the molding member comprising, for example, a
resinous material. The reinforcing element can be fluid-permeable
or partially fluid-permeable, may have a variety of embodiments and
weave patterns, and may comprise a variety of materials, such as,
for example, a plurality of interwoven yarns (including
Jacquard-type and the like woven patterns), a felt, a plastic,
other suitable synthetic material, or any combination thereof.
[0140] In one example of a method for making a wet wipe of the
present invention, the method comprises the step of contacting an
embryonic fibrous web with a deflection member (molding member)
such that at least one portion of the embryonic fibrous web is
deflected out-of-plane of another portion of the embryonic fibrous
web. The phrase "out-of-plane" as used herein means that the wet
wipe comprises a protuberance, such as a dome, or a cavity that
extends away from the plane of the wet wipe. The molding member may
comprise a through-air-drying fabric having its filaments arranged
to produce linear elements within the wet wipes of the present
invention and/or the through-air-drying fabric or equivalent may
comprise a resinous framework that defines deflection conduits that
allow portions of the wet wipe to deflect into the conduits thus
forming linear elements within the wet wipes of the present
invention. In addition, a forming wire, such as a foraminous member
may be arranged such that linear elements within the wet wipes of
the present invention are formed and/or like the through-air-drying
fabric, the foraminous member may comprise a resinous framework
that defines deflection conduits that allow portions of the wet
wipe to deflect into the conduits thus forming linear elements
within the wet wipes of the present invention.
[0141] The step of contacting the fibrous structure with a liquid
composition may comprise spraying, dipping, extruding, and/or
printing the liquid composition onto the fibrous structure.
[0142] In one example, the liquid composition exhibits a pH of
greater than 5 and/or greater than 5.2 and/or greater than 5.5
and/or greater than 6 and/or less than 10 and/or less than 9 and/or
less than 8 and/or less than 7 as measured according to the pH Test
Method described herein prior to contacting the fibrous
structure.
[0143] The liquid composition may exhibit a pH of less than 4.55
and/or less than 4.3 and/or less than 4.1 and/or less than 4 and/or
less than 3.8 and/or greater than 2 and/or greater than 2.5 and/or
greater than 3 and/or greater than 3.5 as measured according to the
pH Test Method described herein after being extracted from the
fibrous structure.
[0144] In one example, the liquid composition comprises an alcohol.
In another example, the liquid composition comprises a perfume. In
still another example, the liquid composition comprises a
preservative.
[0145] Any suitable level of the liquid composition may be
delivered to the fibrous structure. In one example, the fibrous
structure comprises greater than 5% and/or greater than 10% and/or
greater than 25% and/or greater than 40% and/or greater than 50%
and/or to about 90% and/or to about 80% and/or to about 70% by
weight of the liquid composition.
[0146] Any suitable level of the temporary wet strength agent may
be added to the fibrous slurry. In one example, the temporary wet
strength agent is added to the fibrous slurry at a level of greater
than 0.1 and/or greater than 0.5 and/or greater than 1 and/or
greater than 3 and/or greater than 5 and/or greater than 6 and/or
to less than 12 and/or less than 10 and/or less than 8 pounds/ton
of fiber.
[0147] Before or after the contacting step, the fibrous structure
may converted into a wet wipe.
[0148] The fibrous structure may be in a roll form, such as a
parent roll from the fibrous structure making process. A roll of
fibrous structure may be converted into rolls of wet wipes and/or
individual sheets of wet wipes.
[0149] In one example a roll of fibrous structure may be unwound
and slit into smaller widths of fibrous structures that may then be
wound into smaller width rolls, for example 188 mm width rolls.
[0150] The rolls of fibrous structure may be loaded into a
converting line's unwind stand. The unwind stand may be a center
driven unwind stand capable of controlling the tension via speed
control through a series of dancers. In one example, the line speed
at this stage in the converting line is about 34 m/min. The fibrous
structure then may pass over the dancers and a tensiometer device
that monitors tension of the fibrous structure inline while being
converted with real time feedback to the center drive unwind stand
to control in process tension monitoring and control. In one
example, the inline converting tension of the fibrous structure may
be about 1 N.
[0151] The fibrous structure may then pass over a liquid
composition bar (also referred to as a lotion bar) with minimal
contact such that the lotion bar delivers the liquid composition
through openings in the lotion bar to a surface of the fibrous
structure.
[0152] The fibrous structure may then be folded into any suitable
fold configuration, such as a Z-fold. This folding step may occur
prior to the fibrous structure passing over the liquid composition
bar.
[0153] In one example, the folded fibrous structure may be cut to
desired dimensions to form individual wet wipes. A plurality of the
individual wet wipes may be stacked together and then packaged in a
container and/or wrapper.
[0154] In another example, the folded fibrous structure may be
perforated and then wound into a roll of perforated wet wipes,
which may be dispensed from the roll as individual wet wipes upon
tearing along a perforation.
[0155] A container and/or wrapper containing a stack of wet wipes
or a roll of wet wipes forms an article of manufacture that may be
sold to consumers.
[0156] In one example, the fibrous structure making process may be
directly coupled or close coupled to the converting line.
[0157] In another example, the fibrous structure making process may
comprise slitting the fibrous structure prior to moving to the
converting line.
Non-Limiting Example
[0158] One example of a process for making a wet wipe is as
follows. A wet wipe in accordance with the present invention is
prepared using a fibrous structure made by a fibrous structure
making machine having a non-layered headbox.
[0159] A conventional pulper is used to prepare the hardwood stock
chest with eucalyptus fiber having a consistency of about 3.0% by
weight to form a thick stock. Separately, a conventional pulper is
used to prepare the softwood stock chest with northern softwood
kraft (NSK) fiber having a consistency of about 3.0% by weight to
form a thick stock. The NSK fiber is passed through a refiner and
is refined to a Canadian Standard Freeness (CSF) of about 650.
After refining, a temporary wet strength agent, Hercules
Hercobond.RTM. 1194 at 1% solids, is added to the NSK thick stock
at a rate of about 6.1 pounds per ton of fiber. The refined NSK
thick stock and the Eucalyptus thick stock are then combined into a
common stock line at an in-line mixer to form a homogeneous thick
stock at a proportion of 70% NSK and 30% Eucalyptus.
[0160] The homogeneous thick stock is pumped to the fan pump where
it is diluted from about 3% consistency to about 0.1% to about 0.2%
consistency with process water having a pH of about 5.2 to about
5.5. Once diluted, the homogeneous slurry is pumped to the headbox
where the fiber slurry is evenly distributed onto a forming wire
(84.times.78, Albany International) traveling at a velocity of 220
feet per minute to form an embryonic web. The vacuum slots located
on the wire table vacuum are used to dewater the embryonic web to a
consistency of about 20% to about 25% before entering the
wire-to-press transfer zone.
[0161] A pickup shoe is used to transfer the embryonic web from the
forming wire to a patterned drying belt. The speed of the patterned
drying belt is about 200 feet per minute. The drying belt is
designed to mold a pattern of substantially discrete high density
regions surrounded by a continuous network of low density regions
into the embryonic web. The drying belt is formed by casting an
impervious resin surface onto a fiber mesh supporting fabric. The
supporting fabric is a 98.times.62 filament, dual layer mesh. The
thickness of the resin cast is about 22 mils above the supporting
fabric.
[0162] While remaining in contact with the patterned drying belt,
the web is pre-dried by air blow-through pre-dryers to a fiber
consistency of about 60% by weight.
[0163] After the pre-dryers, the semi-dry web is transferred to the
Yankee dryer via pressure roll nip and adhered to the surface of
the Yankee dryer with a sprayed a creping adhesive coating. The
creping adhesive is an aqueous dispersion with the actives
consisting of Georgia Pacific's Unicrepe 457T20 and Vinylon Works'
Vinylon 8844 at a blend of about 25%/75%, respectively. The fiber
consistency is increased to about 97% before the web is dry-creped
from the Yankee with a doctor blade.
[0164] The doctor blade has a bevel angle of about 45 degrees and
is positioned with respect to the Yankee dryer to provide an impact
angle of about 101 degrees. The Yankee dryer is operated at a
temperature of about 350.degree. F. (177.degree. C.) and a speed of
about 200 feet per minute. The fibrous structure is wound into a
parent roll using a surface driven reel drum having a surface speed
of about 191 feet per minute.
[0165] The parent roll width is slit to a width of 188 millimeters
as it rewound into a "chip" roll. The "chip" is placed onto the
unwind stand and the fibrous web is threaded through a wet wipe
converting line. The speed of the fibrous web through the process
is 34 meters per minute while the fibrous web tension is controlled
to about 1 Newton. The fibrous web then passes over a lotion bar
(liquid composition bar) where the fibrous web absorbs the lotion
(liquid composition) at a saturation level of about 150% to about
200%.
[0166] The lotion-saturated fibrous web is then folded in a Z-fold
configuration (ribbon), cut to length, stacked, and optionally
interleaved to form a stack of wet wipes, which then are placed
into a wrapper or container, such as a tub.
Test Methods
[0167] Unless otherwise indicated, all tests described herein
including those described under the Definitions section and the
following test methods are conducted on samples that have been
conditioned in a conditioned room at a temperature of 23.degree.
C..+-.2.2.degree. C. and a relative humidity of 50%.+-.10% for 2
hours prior to the test. All tests are conducted in such
conditioned room.
pH Test Method
[0168] In order to measure the pH of a liquid composition present
on a wet wipe, the following procedure is used. First, secure a
C-clamp's frame in the jaws of a 6 inch table vise. Tighten the
table vise so that the C-clamp does not move. The C-clamp should
not shift within the table vise as compression is formed between
the stationary foot and the adjustable foot of the C-clamp. The
feet of the C-clamp have a 1 inch diameter.
[0169] Calibrate a digital pH meter (Oakton pH 5, Acorn Series,
WD-35613-00 or equivalent) according to the manufacturer's
instruction manual. Measurements are made according to the
manufacturer's instruction manual.
[0170] Wearing latex or rubber gloves, dispense a single sheet of
wet wipe from a package or tub of wet wipes being sure that the wet
wipe has not dried out too much. Fold the single wet wipe sheet
five times (resulting in a 32-ply implement).
[0171] Place the folded wet wipe sheet onto the stationary foot of
the C-clamp. Turn the adjustment screw for the adjustable foot of
the C-clamp until the stationary and adjustable foot of the C-clamp
contact the folded wet wipe sheet.
[0172] Position a 50 ml beaker under the folded wet wipe sheet and
then turn the adjustment screw of the C-clamp to begin compressing
the folded wet wipe sheet to cause the liquid composition to flow
from the folded wet wipe sheet and collect the liquid composition
into the 50 ml beaker.
[0173] Repeat the steps of this procedure with additional wet wipes
from the package or tub until the level of extricated liquid
composition in the 50 ml beaker is sufficient for measuring pH per
the pH meter manufacturer's instruction manual.
[0174] Measure and record the resulting pH for the wet wipe.
[0175] One of ordinary skill in the art will understand how to
measure the pH of a liquid composition prior to contacting a
fibrous structure and/or a temporary wet strength agent.
Shake Flask Test Method
[0176] To determine the dispersibility of a wet wipe, the following
Shake Flask Test is performed. The results of this test show the
Screen Retention Value of a wet wipe at various size screens.
[0177] Sample Preparation: Weigh a wet wipe to be tested. Incubate
a wet wipe sample in a 2800 mL baffled Fernbach flask with tap
water on a rotary shaker at 150 rpm. After 3 hours the contents of
the flask is passed through a sequential series of different sized
perforated plates with openings of 12.5 mm, 6 mm, 3 mm, and 1.5 mm.
Material retained on each plate is recovered, dried at 40.degree.
C., and weighed. The percent of material retained is calculated
based on the initial weight of the wet wipe. The overall loss of
the wet wipe is also calculated.
Basis Weight Test Method
[0178] Basis weight of a fibrous structure and/or wet wipe sample
is measured by selecting twelve (12) usable units (also referred to
as sheets) of the fibrous structure and/or wet wipe and making two
stacks of six (6) usable units each. Perforation, if any, must be
aligned on the same side when stacking the usable units. A
precision cutter is used to cut each stack into exactly 8.89
cm.times.8.89 cm (3.5 in..times.3.5 in.) squares. The two stacks of
cut squares are combined to make a basis weight pad of twelve (12)
squares thick. The basis weight pad is then weighed on a top
loading balance with a minimum resolution of 0.01 g. The top
loading balance must be protected from air drafts and other
disturbances using a draft shield. Weights are recorded when the
readings on the top loading balance become constant. The Basis
Weight is calculated as follows:
Basis Weight ( lbs / 3000 ft 2 ) = Weight of basis weight pad ( g )
.times. 3000 ft 2 453.6 g / lbs .times. 12 ( usable units ) .times.
[ 12.25 in 2 ( Area of basis weight pad ) / 144 in 2 ] ##EQU00001##
Basis Weight ( g / m 2 ) = Weight of basis weight pad ( g ) .times.
10 , 000 cm 2 / m 2 79.0321 cm 2 ( Area of basis weight pad )
.times. 12 ( usable units ) ##EQU00001.2##
Caliper Test Method
[0179] To measure the caliper (thickness) of a wet wipe, the
following procedure is used. Identify a minimum of 5 different
locations on the wet wipe to measure the caliper. Cut the 5 or more
portions (replicates) in a dimension greater than the foot of the
Caliper Tester (Ono Sokki GS--503 Linear Gauge Sensor with an Ono
Sokki DG3610 display or equivalent. May be obtained from
Measure-All, Inc. 447 Nilles Road, Fairfield, Ohio 45014). to
contact the sample. When testing finished wet wipe product, open a
package of wet wipes and randomly select 5 finished wet wipe
products and measure immediately in their normal wet state. Place
package with remaining product in a resealable plastic bag and
seal.
[0180] Before using the Caliper Tester, make sure that the pressure
foot (a stainless steel circular foot Area: 2500 mm.sup.2.+-.50
mm.sup.2 (56 mm Diameter) and Foot Pressure: 0.501 kPa.+-.0.021)
and anvil surfaces are clean, that the calibration of the
instrument has been done per the manufacturer's instruction manual,
and that the instrument is mounted on a solid level surface free
from noticeable vibration, for example a granite base with mounting
arm (Chicago Dial Indicator Co. Part No. 608-12-1R or equivalent),
which may be obtained from Measure-All, Inc. 447 Nilles Road,
Fairfield, Ohio 45014. Calibration should include verification of
0.501 kPa.+-.0.021 (0.073 PSI.+-.0.003) pressure with a balance,
verification that the presser foot is level to the base .+-.0.05
mm, and readings of steel gauge blocks accurate to .+-.0.05 mm.
Zero the thickness gauge as described by the manufacturer.
[0181] With the Caliper Tester foot in the up-position, center the
sample portion underneath. Lower the foot with the handle at a rate
of approximately 3 mm per second. After the foot contacts the
sample, wait 5 seconds and record the caliper (thickness) result
for each sample portion (replicate).
[0182] 1) Calculate the Mean for replicates used for measured
sample.
[0183] 2) Report Thickness in mm to the nearest 0.01 mm.
[0184] Do not use sample portions cut with a die. Do not make
thickness readings on creases resulting from folds. Do not make
thickness readings on samples with obvious defects such as
wrinkles, tears, and holes. Do not handle in areas to be measured.
Do not test the same area of a sample portion more than once.
Elongation, Tensile Strength, TEA and Modulus Test Methods
[0185] To test wet wipes, open a package of wet wipes and remove 8
wet wipes. Place the opened package of wet wipes in a resealable
plastic bag and seal. Using a 50 mm wide by 500 mm long precision
sample cutter (JDC-50M-12, Thwing-Albert Instrument Company 10960
Dutton Road Philadelphia, Pa.) cut 4 replicates of each sample in
the MD and CD directions to a length greater than 250 mm. If sample
available does not allow for the greater than 250 mm length report
the length as a deviation and set the instrument gage length
accordingly (see Instrument Settings). The sample should be gripped
by at least 25 mm at each end. For finished product wipes, test
samples immediately. Cut samples for their unfolded position
whenever possible. The total wet tensile strength of a wet wipe is
measured by this procedure also.
a. Testing Apparatus
[0186] Tensile Tester to be used and settings are as follows:
[0187] Tensile Tester Constant Rate of Elongation (CRE) Tensile
Tester, capable of performing the test profile as described.
[0188] Recommended Thwing-Albert Instruments:
[0189] EJA Vantage (preferred), EJA, or Intelect II STD Tensile
Testers from Thwing-Albert Instrument Company, 10960 Dutton Road
Philadelphia, Pa. 19154 USA (215) 637-0100.
[0190] Recommended MTS Instruments:
[0191] MTS Synergie 200/L, MTS Alliance RT/1 Tensile Testers from
MTS, 1001 Sheldon Drive, Cary, N.C. 27513, or equivalent. Refer to
Analytical Method GCAS 58007265 "Testing and Calibration of
Instruments--The Tensile Tester". [0192] Tensile Tester Load
Cell--Cell should be chosen such that the normally measured force
is between 20% and 95% of the range in use. Obtain from Tensile
Tester Manufacturer. [0193] Calibration Weights--Refer to Tensile
Tester Manufacturer. [0194] Tensile Tester Grips Flat face, air
operated, at least 50 mm wide purchased via the manufacturer of the
tensile tester. b. Instrument Settings [0195] 1. For MTS
Instruments set the tensile tester to the following parameters:
[0196] (For Thwing-Albert see Section 2 under "Instrument Settings"
for all others instruments check with the manufacturer for
equivalent instrument/software set up.)
[0197] Test Speed . . . 100 mm/min+2 mm/min
[0198] Gauge Length . . . 200 mm most preferred (EDANA)--or 50 mm
acceptable if sample size requires a shorter gauge length, as long
as such deviation is reported.
[0199] Slack Compensation . . . A) 0.10N most preferred B) Non-use
of slack compensation is acceptable only on instruments that do not
have slack compensation functionality--such deviation must be
reported.
[0200] Pre-test Path (no data) . . . None
[0201] Test path (data collected) . . . "Go Forever Until
Break"
[0202] Post-test Path (no data) . . . None
[0203] Break Detection . . . 95% drop from Peak
[0204] Break Threshold . . . 0.25N (break detection inactive until
this force is reached)
[0205] Data Acquisition Rate . . . 100 Hz
[0206] Measured Variables . . . Tensile Strength (Peak Force) and
Load at 5% Elongation--reported in Newtons to 1 decimal place (i.e.
33.5). Additionally, report % Elongation at Peak % of adjusted
gauge length to 2 decimal places (i.e. 10.44%). [0207] 2. For
Thwing-Albert Instruments with APS Software set the tensile tester
to the following parameters: [0208] Test Units--Elongation Units .
. . mms [0209] Test Units--Curve Units . . . load/elongation %
[0210] Test Units--Load Units . . . N [0211] Set Mode . . . Tension
[0212] Test Over . . . Fail [0213] Set Range . . . 100% [0214] At
Test End . . . Return [0215] Speeds--Pre-Test . . . 100.000 mms/min
[0216] Speeds--At Start of Test . . . 100.000 mms/min [0217]
Speeds--For a distance of . . . 1.000 mms [0218] Speeds--Then
crosshead will travel at . . . 100.000 mms/min [0219]
Speeds--Return . . . 1015.998 mms/min [0220] Sample Rate . . . 100
readings/sec [0221] Collision . . . Yes [0222] Gauge Length . . .
200 mm most preferred (EDANA)--50 mm acceptable if sample size
requires a shorter gauge length, as long as such deviation is
reported. [0223] Adj. GL . . . Adjusted [0224] Break Sensitivity .
. . 2 N [0225] Pre-tension . . . 0.10 N [0226] Load Divider . . . 1
[0227] Sample shape/size--Sample Shape . . . Rectangular [0228]
Sample shape/size--Width . . . 50.000 mms [0229] Sample
shape/size--Thickness . . . 10.000 mms [0230] Tag Results--El Trp
Load: [0231] Load Units . . . N [0232] Add'l Parameters . . .
5.000% [0233] Tag Results--Tangent Modulus: [0234] Elong. Units . .
. cm [0235] Load Units . . . grams [0236] Add'l Parameters . . .
Load [0237] Load Trap gms . . . 75.000 [0238] Measured Variables .
. . Tensile Strength (Peak Force) and Load at 5%
Elongation--reported in Newtons to 1 decimal place (i.e. 33.5).
Additionally, report % Elongation at Peak in % of adjusted gauge
length to 2 decimal places (i.e. 10.44%). Also in this test set up
Tangent Modulus @ 15 gm/cm is shown and may be additionally
reported if desired.
[0239] Check tensile tester calibration according to manufacturer's
instructions. Check the load cell for zero reading and adjust if
necessary. Clamp the sample in the grips of the tensile tester,
mounting the sample without any pretension (<0.05N). Begin the
test by depressing the start (i.e., test) button. When the test is
complete, record the values, remove the tested sample from the
grips and discard. Check the load cell for zero reading and repeat
this procedure until all samples are tested. Discard the results of
any sample where the sample 1) slips during the test, 2) the break
occurs in or at either grip or 3) where any break reaches the
grips.
c. Calculations [0240] Record each of the following variables for
each replicate: [0241] Peak Load (in Newtons to the nearest 0.1).
[0242] Load at 5% Elongation (in Newtons to the nearest 0.1).--this
quantity is not specifically mentioned by EDANA 20.2-89, but it a
useful measure for process-development. [0243] % Elongation at
Peak--EDANA 20.2-89 states to measure % Elongation at break, but
"break" is not clearly defined by EDANA (i.e. 50% drop from peak,
75% drop, 95% drop?). Additionally, these samples often fail in
different ways leading to highly variable elongation data (if
"break" is defined as complete failure of the sample). This method
measures % Elongation at Peak.Option for Thwing-Albert Instruments:
[0244] Tangent Modulus @ 15 g/cm.
[0245] Any of the units can be converted to other units for example
g/in for tensile by appropriate conversion factors known in the
art.
d. Reporting Results
[0246] Report mean and standard deviation for each measured
quantity expressed in N (Newtons) and report any deviation (i.e.
shorter gauge length due to short sample length, no slack
compensation available, etc). Report the number of replicates used
for testing.
[0247] The dimensions and values disclosed herein are not to be
understood as being strictly limited to the exact numerical values
recited. Instead, unless otherwise specified, each such dimension
is intended to mean both the recited value and a functionally
equivalent range surrounding that value. For example, a dimension
disclosed as "40 mm" is intended to mean "about 40 mm."
[0248] Every document cited herein, including any cross referenced
or related patent or application, is hereby incorporated herein by
reference in its entirety unless expressly excluded or otherwise
limited. The citation of any document is not an admission that it
is prior art with respect to any invention disclosed or claimed
herein or that it alone, or in any combination with any other
reference or references, teaches, suggests or discloses any such
invention. Further, to the extent that any meaning or definition of
a term in this document conflicts with any meaning or definition of
the same term in a document incorporated by reference, the meaning
or definition assigned to that term in this document shall
govern.
[0249] While particular embodiments of the present invention have
been illustrated and described, it would be obvious to those
skilled in the art that various other changes and modifications can
be made without departing from the spirit and scope of the
invention. It is therefore intended to cover in the appended claims
all such changes and modifications that are within the scope of
this invention.
* * * * *