Note: Descriptions are shown in the official language in which they were submitted.
CA 02305552 2005-12-30
VNU 99/20821
IPCfNS98/11967
SOFT, STRONG HYDRAULICALLY ENTANGLED NONWOVEN COMPOSITE
MATERIAL AND METHOD FOR MAKING THE SAME
s The present invention is generally directed to nonwoven composite materials.
More particularly, the present invention is directed to wiping products that
are strong,
absorbent and soft.
to Absorbent products such as industrial wipers, food service wipers, and
other
similar items are designed to combine several important attributes. For
example, the
products should have good bulk, a soft feel and should be highly absorbent.
The products
should also have good strength even when wet and should resist tearing.
Further, the
wiping products should have good stretch characteristics, should be abrasion
resistant
~s and should not deteriorate in the environment in which they are used.
In the past, many attempts have been made to enhance and increase certain
physical properties of wiping products, especially wiping products that
contain a large
.proportion of pulp or paper. Unfortunately, however, when steps are usually
taken to
increase one property of a wiping product, other characteristics of the
product may be
ao adversely affected. For instance, in pulp fiber based wiping products,
softness and bulk
can be increased by decreasing or reducing interfiber bonding within the paper
web.
Inhibiting or reducing fiber bonding by chemical and/or mechanical debonding,
however,
adversely affects the strength of the product. A challenge encountered in
designing pulp
based wiping products is increasing softness, bulk and texture without
decreasing
a5 strength and/or abrasion resistance.
One particular process that has proven to be very successful in producing
paper
towels and other wiping products is disclosed in U.S. Patent No. 3,879,257 to
Gentile, et
al. In Gentile, et al., a process is
disclosed for producing soft, absorbent, single ply fibrous webs having a
laminate-like
s o structure.
The fibrous webs disclosed in Gentile, et al. are formed from an aqueous
slurry of
principally lignocellulosic fibers under conditions which reduce interfiber
bonding. A
bonding material, such as a latex elastomeric composition, is applied to a
first surface of
the web in a spaced-apart pattern. The bonding material provides strength to
the web
3s and abrasion resistance to the surface.
The bonding material can then be similarly applied to the opposite side of the
web
for further providing additional strength and abrasion resistance. Once the
bonding
material is applied to the second side of the web, the web can be brought into
contact with
a creping surface. Specifically, the web will adhere to the creping surface
according to
4 o the pattern by which the bonding material was applied. The web is then
creped from the
creping surface with a doctor blade. Creping the web mechanically debonds and
disrupts
the fibers within the web, thereby increasing the softness, absorbency, and
bulk of the
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2
web.
In one alternative embodiment disclosed in Gentile, et al., both sides of the
paper
web are creped after the bonding material has been applied.
Although this technology has been applied to paper products, it has not been
tried
s with composites having a fibrous component and a continuous filament
component that
reinforces and strengthens the material. One disadvantage of the embodiments
disclosed
in Gentile, et al. is that the bonding material is generally cured or dried at
high
temperatures that degrade the continuous filaments.
Composite materials, which desirably combine pulp and a nonwoven layer of
io substantially continuous filaments, have desirable levels of strength but
often exhibit poor
tie-down of the fibrous component. That is, the fibrous material and/or any
fiber rich
surfaces tends to be weaker than the continuous filament component. This can
cause
undesirable levels of tinting, poor abrasion resistance and may yield a
material that has
less overall strength. Attempts to soften and/or increase the bulk of these
composite
15 materials can disrupt the tie-down or bonding of the fibrous material.
Thus, there currently remains a need for a pulp based wiping product that
includes
a continuous filament substrate. A need also exists for a pulp based wiping
product
incorporating a continuous filament substrate and having improved softness
over
conventional products while still remaining strong. A need further exists for
a pulp based
2o wiping product incorporating a continuous filament substrate that does not
become
compressed when wet and has the tactile aesthetics of a textile during use.
The deficiencies described above are addressed by the present invention which
25 provides a method for forming a softened hydraulically entangled nonwoven
composite
material. The method includes the steps: providing a hydraulically entangled
web
containing a fibrous component and a nonwoven layer of substantially
continuous filaments;
applying a bonding material to at least one side of the web; and creping said
at least one
side of the hydraulically entangled web.
so The bonding material may be a conventional adhesive such as, for example,
an
acrylate, a vinyl acetate, a vinyl chloride, or a methacrylate type adhesive.
The bonding material may contain an aqueous mixture including a curable latex
polymer, a pigment, and a cure promoter. Desirably, the aqueous mixture
includes about
100 dry parts by weight of curable latex polymer, between about 0.5 and 33 dry
parts by
s5 weight of pigment, and between about 1 and 10 dry parts by weight of cure
promoter. Even
more desirably, the aqueous mixture includes about 100 dry parts by weight of
curable latex
polymer, between about 1 and 5 dry parts by weight of pigment, and between
about 1 and 5
dry parts by weight of cure promoter.
The aqueous mixture may have a pre-cure pH adjusted to above 8 using a
fugitive
4o alkali and the mixture may be cured at a temperature below the melting
temperature of any
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WO 99/20821 PCT/US98121967
3
individual component of the hydraulically entangled web.
The curable latex polymer in the aqueous mixture may be cured prior to the
creping step. Alternatively and/or additionally , the curable latex polynmer
in the aqueous
mixture may be cured after the creping step.
The bonding material may be applied to a first side of the web and to a second
and
opposite side of the web. The bonding material may be applied to at least one
side of said
web in an amount from about 2% to about 15% by weight. It is contemplated that
less
than about 2% (e.g., about 1 %) of the bonding material may be applied to each
side of the
web.
io The web may further contain a debonding agent, the debonding agent
inhibiting at
least a portion of the fibrous component of the web from bonding together. A
friction
reducing agent may be applied to at least one side of the web.
The bonding material can be applied to the web in a pattern. For example, the
pattern may be a grid-like pattern, a fish-scale pattern, discrete points or
dots, or the like.
i5 A very wide variety of patterns are contemplated.
The present invention encompasses a method for forming a composite nonwoven
material which includes the steps of: (1 ) providing a hydraulically entangled
web including
a fibrous component and a nonwoven layer of substantially continuous
filaments, the web
having a fcrst side and a second side; (2) applying a bonding material to the
first side of
2o the web in a preselected pattern; the bonding material being added to the
first side in an
amount from about 2% to about 15% by weight of said web, the bonding material
being
used to adhere said first side of said web to a first creping surface; (3}
creping said first
side of the web from the first creping surface; (4) applying said bonding
agent to the
second side of the web in a preselected pattern, the bonding agent being added
to the
as second side in an amount from about 2% to about 15% by weight of the web,
the bonding
material being used to adhere the second side of the web to a second creping
surface;
and (5) creping said second side of the web from the second creping surface.
The present invention also encompasses a softened hydraulically entangled
composite material made according to the process described above. The
composite
ao material contains a hydraulically entangled web that includes a fibrous
component and a
nonwoven layer of substantially continuous filaments; and regions containing
bonding
material covering at least a portion of at least one side of the composite
material. Desirably,
the hydraulically entangled web includes more than about 50 percent, by
weight, of a
fibrous component, and more than about 0 up to about 50 percent, by weight, of
a
3 s nonwoven layer of substantially continuous filaments. More desirably, the
hydraulically
entangled web includes more than about 70 percent, by weight, of a fibrous
component,
and more than about 0 up to about 30 percent, by weight, of a nonwoven layer
of
substantially continuous filaments.
The substantially continuous filaments may be monocomponent filaments or they
4o may be conjugate spun filaments having at least one low-softening point
component and at
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WO 99120821 PCT/US98/21967
4
least one high-softening point component and having at least some exterior
surfaces of the
filaments composed of at least one low-softening point component.
Alternatively andlor
additionally, the conjugate spun filaments may be splittable fibers (i.e.,
fibers that may be
divided into a plurality of fibers or fibrils).
The fibrous component may be pulp. The fibrous component may further include
synthetic fibers. The nonwoven composite material may further includes a
secondary
material. The secondary material may be any suitable materials such as, for
example, clays,
fillers, starches, particulates, superabsorbent particulates and combinations
of one or more
thereof. The nonwoven composite material may have a basis weight of from about
20
io to about 200 grams per square meter.
In an aspect of the invention, the softened hydraulically entangled nonwoven
composite material incorporates a bonding material that may retain a
colorfastness above
3 when exposed to liquids with a pH befinreen about 2 and about 13. The
composite
material may incorporate a bonding material that retains a colorfastness above
3 when
is exposed to sodium hypochlorite. The composite material may incorporate a
binder material
that retains a colorfastness above 3 when exposed to alcohol.
The present invention encompasses a softened hydraulically entangled nonwoven
composite material that includes: (1 ) a hydraulically entangled web
containing a fibrous
component; and a nonwoven layer of substantially continuous filaments; and (2)
regions
2o containing bonding material covering at least a portion of at least one
side of the composite
material, wherein at least one side of the web has been creped.
The present invention further encompasses a wiping product formed from the
nonwoven composite material described above.
25 Definitions
As used herein the term "nonwoven fabric or web" means a web having a
structure of
individual fibers or threads which are interlaid, but not in an identifiable
manner as in a
knitted fabric. Nonwoven fabrics or webs have been farmed from many processes
such as
for example, meltblowing processes, spunbonding processes, and bonded carded
web
3 o processes. The basis weight of nonwoven fabrics is usually expressed in
ounces of material
per square yard (osy) or grams per square meter (gsm) and the fiber diameters
useful are
usually expressed in microns. (Note that to convert from osy to gsm, multiply
osy by 33.91 ).
As used herein the term "microfibers" means small diameter fibers having an
average
diameter not greater than about 75 microns, for example, having an average
diameter of
35 from about 0.5 microns to about 50 microns, or more particularly,
microfibers may have an
average diameter of from about 2 microns to about 40 microns. Another
frequently used
expression of fiber diameter is denier, which is defined as grams per 9000
meters of a fiber.
For example, the diameter of a polypropylene fiber given in microns may be
converted to
denier by squaring, and multiplying the result by 0.00629, thus, a 15 micron
polypropylene
4 o fiber has a denier of about 1.42 (152 x 0.00629 = 1.415}.
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As used herein the term "meltblown fibers" means fibers formed by extruding a
molten
thermoplastic material through a plurality of fine, usually circular, die
capillaries as molten
threads or filaments into converging high velocity gas (e.g. air) streams
which attenuate the
filaments of molten thermoplastic material to reduce their diameter, which may
be to
s microfiber diameter. Thereafter, the meltblown fibers are carried by the
high velocity gas
stream and are deposited on a collecting surface to form a web of randomly
disbursed
meltblown fibers. Such a process is disclosed, for example, in U.S. Patent no.
3,849,241.
Generally speaking, meltblown fibers may be microfibers which may be
continuous or
discontinuous, are generally smaller than 10 microns in diameter, and are
generally tacky
io when deposited onto a collecting surface.
As used herein the term "polymer" generally includes but is not limited to,
homopolymers, copolymers, such as for example, block, graft, random and
alternating
copolymers, terpolymers, etc. and blends and modifications thereof.
Furthermore, unless
otherwise specifically limited, the term "polymer" shall include all possible
geometrical
is configuration of the material. These configurations include, but are not
limited to isotactic,
syndiotactic and random symmetries.
As used herein the term "monocomponent" fiber refers to a fiber formed from
one or
more extruders using only one polymer. This is not meant to exclude fibers
formed from
one polymer to which small amounts of additives have been added for
coloration, anti-static
2 o properties, lubrication, hydrophilicity, etc. These additives, e.g.
titanium dioxide for
coloration, are generally present in an amount less than 5 weight percent and
more typically
about 2 weight percent.
As used herein, the term "spunbonded filaments" refers to small diameter
substantially
continuous filaments which are formed by extruding a molten thermoplastic
material as
2s filaments from a plurality of fine, usually circular, capillaries of a
spinnerette with the
diameter of the extruded filaments then being rapidly reduced as by, for
example, eductive
drawing and/or other well-known spun-bonding mechanisms. The production of
spun-
bonded nonwoven webs is illustrated in patents such as, for example, in U.S.
Patent No.
4,340,563 to Appel et al., and U.S. Patent No. 3,692,618 to Dorschner et al.,
U.S. Patent no.
30 3,802,817 to Matsuki et al., U.S. Patent nos. 3,338,992 and 3,341,394 to
Kinney, U.S.
Patent no. 3,502,763 to Hartman, U.S. Patent 3,502,538 to Levy, and U.S.
Patent no.
3,542,615 to Dobo et al. Spunbond filaments are generally not tacky when they
are
deposited onto a collecting surface. Spunbond filaments are often have
diameters larger
than 7 microns, more particularly, between about 10 and 20 microns.
3 s As used herein, the term "conjugate spun filaments" refers to spun
filaments and/or
fibers composed of multiple filamentary or fibril elements. Exemplary
conjugate filaments
may have a sheath/core configuration (i.e., a core portion substantially or
completely
enveloped by one or more sheaths) andlor side-by-side strands (i.e.,
filaments)
configuration (i.e., multiple filaments~bers attached along a common
interface). Generally
4 o speaking, the different elements making up the conjugate filament (e.g.,
the core portion, the
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6
sheath portion, and/or the side-by-side filaments) are formed of different
polymers and spun
using processes such as, for example, melt-spinning processes, solvent
spinning processes
and the like. Desirably, the conjugate spun filaments are formed from at least
two
thermoplastic polymers extruded from separate extruders but spun together to
form one
s fiber. Conjugate filaments are also sometimes referred to as multicomponent
or
bicomponent filaments or fibers. The polymers are usually different from each
other though
conjugate filaments may be monocomponent filaments. Conjugate filaments are
taught in
U.S. Patent 5,108,820 to Kaneko et al., U.S. Patent 5,336,552 to Strack et
al., and U.S.
Patent 5,382,400 to Pike et al. For two component filaments, the polymers may
be present
io in ratios of 75/25, 50/50, 25175 or any other desired ratios. Alternatively
and/or additionally,
the conjugate spun filaments may be splittable fibers (i.e., fibers that may
be divided or
separated into a plurality of fibers or fibrils). Such filaments or fibers are
taught in U.S.
Patent 4,369,156 to Mathes et al. and U.S. Patent 4,460,649 to Park et al.
As used herein, the term "softening point' refers to a temperature near the
melt
i5 transition of a generally thermoplastic polymer. The softening point occurs
at a temperature
near or just below the melt transition and corresponds to a magnitude of phase
change
and/or change in polymer structure sufficient to permit relatively durable
fusing or bonding of
the polymer with other materials such as, for example, cellulosic fibers
andlor particulates.
Generally speaking, internal molecular arrangements in a polymer tend to be
relatively fixed
2 o at temperatures below the softening point. Under such conditions, many
polymers are
difficult to soften so they creep, flow and/or othennrise distort to integrate
or merge and
ultimately fuse or bond with other materials. At about the softening point,
the polymer's
ability to flow is enhanced so that it can be durably bonded with other
materials. Generally
speaking, the softening point of a generally thermoplastic polymer can be
characterized as
2s near or about the Vicat Softening Temperature as determined essentially in
accordance with
ASTM D 1525-91. That is, the softening point is generally less than about the
polymer's
melt transition and generally about or greater than the polymer's Vicat
Softening
Temperature.
As used herein, the term "low-softening point component" refers to one or more
a o thermoplastic polymers composing an element of a conjugate spun filament
(i.e., a sheath,
core and/or side-by-side element) that has a lower softening point than the
one or more
polymers composing at least one different element of the same conjugate spun
filament
(i.e., high-softening point component) so that the low-softening point
component may be
substantially softened, malleable or easily distorted when at or about its
softening point while
35 the one or more polymers composing the at least one different element of
the same
conjugate spun filament remains relatively difficult to distort or reshape at
the same
conditions. For example, the low-softening point component may have a
softening point that
is at least about 20°C lower than the high-softening point component.
As used herein, the term "high-softening point component" refers to one or
more
4 o polymers composing an element of a conjugate spun filament (i.e., a
sheath, core and/or
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WO 99/20821 PCTNS98/21967
7
side-by-side) that has a higher softening point than the one or more polymers
composing at
least one different element of the same conjugate spun filament (i.e., low-
softening point
component) so that the high-softening point component remains relatively
undistortable or
unshapeable when it is at a temperature under which the one or more polymers
composing
at least one different element of the same conjugate spun filament (i.e., the
low-softening
point component) are substantially softened or malleable (i.e., at about their
softening point).
For example, the high-softening point component may have a softening point
that is at least
about 20°C higher than the low-softening point component.
As used herein the term "biconstituent filaments" refers to filaments or
fibers which
io have been fomled from at least two polymers extruded from the same extruder
as a blend.
The term "blend" is defined below. Biconstituent filaments do not have the
various polymer
components arranged in relatively constantly positioned distinct zones across
the cxoss-
sectional area of the filament and the various polymers are usually not
continuous along the
entire length of the filament, instead usually forming fibrils or protofibrils
which start and end
is at random. Biconstituent filaments are sometimes also referred to as
multiconstituent
filaments. Fibers~laments of this general type are discussed in, for example,
U.S. Patent
5,108,827 to Gessner. Conjugate and biconstituent fibers~laments are also
discussed in
the textbook Polymer Blends and Composites by John A. Manson and Leslie H.
Sperling,
copyright 1976 by Plenum Press, a division of Plenum Publishing Corporation of
New York,
ao IBSN 0-306-30831-2, at pages 273 through 277.
As used herein the term "blend" means a mixture of two or more polymers while
the
term "alloy" means a sub-class of blends wherein the components are immiscible
but have
been compatibilized. "Miscibility" and "immiscibility" are defined as blends
having negative
and positive values, respectively, for the free energy of mixing. Further,
"compatibilization"
2s is defined as the process of modifying the interfacial properties of an
immiscible polymer
blend in order to make an alloy.
As used herein "thermal point bonding" refers to a bonding technique that
involves
passing a fabric or web of fibers to be bonded between a heated calender roll
and an anvil
roll. The calender roll is usually, though not always, patterned in some way
so that the
3 o entire fabric is not bonded across its entire surface. As a result,
various patterns for
calender rolls have been developed for functional as well as aesthetic
reasons. One
example of a pattern has points and is the Hansen Pennings or "H&P" pattern
with about a
30% bond area with about 200 bonds/square inch as taught in U.S. Patent
3,855,046 to
Hansen and Pennings. The H&P pattern has square point or pin bonding areas
wherein
3 s each pin has a side dimension of 0.038 inches (0.965 mm), a spacing of
0.070 inches
(1.778 mm) between pins, and a depth of bonding of 0.023 inches (0.584 mm).
The
resulting pattern has a bonded area of about 29.5%. Another typical point
bonding pattern
is the expanded Hansen and Pennings or "EHP" bond pattern which produces a 15%
bond
area with a square pin having a side dimension of 0.037 inches (0.94 mm), a
pin spacing of
40 0.097 inches (2.464 mm) and a depth of 0.039 inches (0.991 mm). Another
typical point
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s
bonding pattern designated "714" has square pin bonding areas wherein each pin
has a side
dimension of 0.023 inches, a spaang of 0.062 inches (1.575 mm) between pins,
and a
depth of bonding of 0.033 inches (0.838 mm). The resulting pattern has a
bonded area of
about 15%. Yet another common pattern is the C-Star pattern which has a bond
area of
s about 16.9%. The C-Star pattern has a cross-directional bar or "corduroy"
design
interrupted by shooting stars. Other common patterns include a diamond pattern
with
repeating and slightly offset diamonds and a wire weave pattern looking as the
name
suggests, e.g. like a window screen. Typically, the percent bonding area
varies from around
10% to around 30% of the area of the fabric laminate web. The spot bonding
holds the
io laminate layers together as well as imparts integrity to each individual
layer by bonding
filaments and/or fibers within each layer.
As used herein, the term °food service wiper" means a wiper used
primarily in the food
service industry, i.e., restaurants, cafeterias, bars, catering, etc. but
which may be used in
the home as well. Food service wipers may be made from woven and/or nonwoven
fabrics.
is These wipers are usually used to wipe up food spills on countertops,
chairs, etc., and in
Geanup of grease, oil, etc., from splatters or spills in the cooking or
serving areas, with a
variety of cleaning solutions. Cleaning solutions typically used in food
service area clean up
can vary widely in pH from highly acidic to highly alkaline and may be solvent
solutions as
well.
2o The term "pulp" as used herein refers to fibers from natural sources such
as woody
and non-woody plants. Woody plants include, for example, deciduous and
coniferous trees.
Non-woody plants include, for example, cotton, flax, esparto grass, milkweed,
straw, jute
hemp, and bagasse.
The term "average fiber length" as used herein refers to a weighted average
length of
25 pulp fibers determined utilizing a Kajaani fiber analyzer model No. FS-100
or 200 available
from Kajaani Oy Electronics, Kajaani, Finland. According to the test
procedure, a pulp
sample is treated with a macerating liquid to ensure that no fiber bundles or
shives are
present. Each pulp sample is disintegrated into hot water and diluted to an
approximately
0.001 % solution. Individual test samples are drawn in approximately 50 to 100
ml portions
3 o from the dilute solution when tested using the standard Kajaani fiber
analysis test procedure.
The weighted average fiber length may be expressed by the following equation:
k
S (x, * n,)/n
x;=0
35 where k = maximum fiber length
x; = fiber length
n, = number of fibers having length x;
n = total number of fibers measured.
The term "low-average fiber length pulp" as used herein refers to pulp that
contains a
4 o significant amount of short fibers and non-fiber particles. Many secondary
wood fiber pulps
may be considered low average fiber length pulps; however, the quality of the
secondary
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WO 99/20811 PCTlUS98/21967
9
wood fiber pulp will depend on the quality of the recycled fibers and the type
and amount of
previous processing. Low-average fiber length pulps may have an average fiber
length of
less than about 1.2 mm as determined by an optical fiber analyzer such as, for
example, a
Kajaani fiber analyzer model No. FS-100 (Kajaani Oy Electronics, Kajaani,
Finland). For
s example, low average fiber length pulps may have an average fiber length
ranging from
about 0.7 to 1.2 mm. Exemplary low average fiber length pulps include virgin
hardwood
pulp, and secondary fiber pulp from sources such as, for example, office
waste, newsprint,
and paperboard scrap.
The term "high-average fiber length pulp" as used herein refers to pulp that
contains a
io relatively small amount of short fibers and non-fiber particles. High-
average fiber length pulp
is typically formed from certain non-secondary (i.e., virgin) fibers.
Secondary fiber pulp
which has been screened may also have a high-average fiber length. High-
average fiber
length pulps typically have an average fiber length of greater than about 1.5
mm as
determined by an optical fiber analyzer such as, for example, a Kajaani fiber
analyzer model
i5 No. FS-100 (Kajaani Oy Electronics, Kajaani, Finland). For example, a high-
average fiber
length pulp may have an average fiber length from about 1.5 mm to about 6 mm.
Exemplary high-average fiber length pulps which are wood fiber pulps include,
for example,
bleached and unbleached virgin softwood fiber pulps.
As used herein, the term "coforfastness" refers to the transfer of a colored
material
2 o from a sample as determined by a colorfastness to crocking test.
Colorfastness to crocking
is measured by placing a 5 inch by 7 inch (127 mm by 178 mm) piece of the
material to be
tested into a Crockmeter model cm-1 available fram the Atlas Electric Device
Company of
4114 Ravenswood Ave., Chicago, IL 60613. The crockmeter strokes or rubs a
cotton cloth
back and forth across the sample a predetermined number of times (in the tests
herein the
2 s number was 30) with a fixed amount of force. The color transferred from
the sample onto
the cotton is then compared to a scale wherein 5 indicates no color on the
cotton and 1
indicates a large amount of color on the cotton. A higher number indicates a
relatively more
colorfast sample. The comparison scale is available from the American
Association of
Textile Chemists and Colorists (AATCC), PO Box 12215, Research Triangle Park,
NC
3 0 27709. This test is similar to the AATCC Test Method 8 except the AATCC
test procedure
uses only 10 strokes across the cloth and uses a different sample size. The
inventors
believe their 30 stroke method is more rigorous than the AATCC 10 stroke
method.
FIG. 1 is an illustration of an exemplary embodiment of a process for forming
a
hydraulically entangled web.
FIG. 2 is a schematic diagram of one embodiment of a process for double
creping
a paper web in accordance with the present invention;
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io
petailed Descrip~p
It has been discovered that hydraulically entangled composite materials
having good absorbing properties but are generally stiff, thin and flat (i.e.,
lacking texture)
may be improved by printing a binding material on at least one side of the
composite and
s compacting the web to impart texture. Also of significance, it has been
further
unexpectedly discovered that the process of the present invention not only
increases
softness but also does not adversely affect the strength of the web in
comparison to
similarly made composite materials. In some applications, the strength of the
web is
actually increased. It has also been found that the fiber tie-down may be
improved. This
io phenomena can result in greater:abrasion resistance and lower lint values.
Better fiber tie
down also helps the performance of the composite fabric when subjected to
mechanical
softening such as creping by keeping the fibrous material joined to the
continuous filament
component.
Referring now to FIG. 1, there is shown an exemplary hydraulic entangling
process
is used to make composite materials. Hydraulically entangled composites
materials
containing, for example, a fibrous component such as pulp and a nonwoven layer
of
substantially continuous filaments are described at, for example, U.S. Patent
No.
5,389,202 to Everhart, et al..
Generally speaking, suitable hydraulically entangled composite materials may
be
2o made by supplying a dilute suspension of pulp to a head-box 12 and
depositing 'tt via a
sluice 14 in a uniform dispersion onto a forming fabric 16 of a conventional
papermaking
machine. The suspension of pulp fibers may be diluted to any consistency which
is typically
used in conventional papermaking processes. Water is removed from the
suspension of
pulp fibers to form a uniform layer of pulp fibers 18.
2 s The pulp frbers may be any high-average fiber length pulp, low-average
fiber length
pulp, or mixtures of the same. Exemplary high-average fiber length wood pulps
include
those available.Mfrrm the Kimberly-Clark Corporation under the trade
designations Longlac
19, Coosa Rivet: ~6, and Coosa River 57.
The low-auerage fiber length pulp may be, for example, certain virgin hardwood
pulps
3 o and secondary (i.e. recyGed) fiber pulp from sources such as, for example,
newsprint,
reclaimed paperboard, and office waste.
Mixtures of high-average fiber length and low-average fiber length pulps may
contain
a significant proportion of low-average fiber length pulps. Other fibrous
materials, such as,
for example, synthetic fibers, staple length fibers, and the like may be added
to the pulp
3 5 fibers.
These otherftbrous materials may be "non-bonding fibers° which
generally refers to
fibers that do not undergo hydrogen bonding during formation of the web. Non-
bonding
fibers can include, for instance, polyolefin fibers, polyester fibers, nylon
fibers, polyvinyl
acetate fibers, and mixtures thereof. The non-bonding fibers can be added to
the web in
4 o an amount from about 5% to about 30% by weight. Fibrous material such as,
for example,
CA 02305552 2000-04-03
WO 99120821 PCT1US98/Z1967
11
meltblown fibers may also be used. The meltblown fibrous material may be in
the form of
individualized fibers or a web of meltblown fibers. In one embodiment of the
invention, the
meltblown fibrous material may be sandwiched between two or more nonwoven
layers of
substantially continuous filaments. Various combinations of meltblown fibers,
staple fibers,
pulp and/or substantially continuous filaments are contemplated.
Besides non-bonding fibers, thermomechanical pulp can also be added.
Thermomechanical pulp refers to pulp that is not cooked during the pulping
process to the
same extent as conventional pulps. Thermomechanical pulp tends to contain
stiff fibers
and has higher levels of lignin. Thermomechanical pulp can be added to the
base web of
io the present invention in order to create an open pore structure, thus
increasing bulk and
absorbency.
When present, the thermomechanical pulp can be added to the base web in an
amount from about 10% to about 30% by weight. When using thermomechanical
pulp, a
wetting agent is also preferably added during formation of the web. The
wetting agent
can be added in an amount less than about 1 % and, in one embodiment, can be a
sulphonated glycol.
Small amounts of wet-strength resins and/or resin binders may be added to
improve
strength and abrasion resistance. Cross-linking agents andlor hydrating agents
may also be
added to the pulp mixture. Debonding agents may be added to the pulp mixture
to reduce
2 o the degree of hydrogen bonding if a very open or loose nonwoven pulp fiber
web is desired.
The addition of certain debonding agents in the amount of, for example, 1 to 4
percent, by
weight, of the composite also appears to reduce the measured static and
dynamic
coefficients of friction and improve the abrasion resistance of the continuous
filament rich
side of the composite fabric. The de-bonder is believed to act as a lubricant
or friction
reducer.
A continuous filament nonwoven substrate 20 is unwound from a supply roll 22
and
travels in the direction indicated by the an-ow associated therewith as the
supply roll 22
rotates in the direction of the arrows associated therewith. The nonwoven
substrate 18
passes through a nip 24 of a S-roll arrangement 26 formed by the stack rollers
28 and 30.
a o The nonwoven substrate 20 may be formed by known continuous filament
nonwoven
extrusion processes, such as, for example, known solvent spinning or melt-
spinning
processes, and passed directly through the nip without first being stored on a
supply roll.
Desirably, the continuous filament nonwoven substrate is a nonwoven web of
conjugate
spun filaments. More desirably, the conjugate spun filaments are conjugate
melt-spun
filaments such as, for example, conjugate spunbond filaments. Such filaments
may be
shaped filaments, sheath/core filaments, side-by-side filaments or the like.
The conjugate
melt-spun filaments may be splittable filaments.
The spunbond filaments may be formed from any melt-spinnable polymer, co
polymers or blends thereof. Desirably, the conjugate spun filaments are
conjugate melt-spun
4o filaments. More desirably, the conjugate spun filaments are conjugate melt-
spun filaments
CA 02305552 2000-04-03
_ wo ~noszi rc~rius9am~~
12
composed of at least one low-softening point component and at least one high-
softening
point component (in which at least some of the exterior surfaces of the
filaments are
composed of at least one low-softening point component). One polymeric
component of the
conjugate melt-spun filaments should be a polymer characterized as a low-
softening point
s thermoplastic material (e.g., one or more low-softening point polyolefins,
low-softening point
elastomeric block copolymers, low-softening point copolymers of ethylene and
at least one
vinyl monomer [such as, for example, vinyl acetates, unsaturated aliphatic
monocarboxylic
acids, and esters of such monocarboxylic acids] and blends of the same). For
example,
polyethylene may be used as a low-softening point thermoplastic material.
io Another polymeric component of the conjugate melt-spun filaments should be
a
polymer characterized as a high-softening point material. (e.g., one or more
polyesters,
polyamides, high-softening point polyolefins, and blends of the same). For
example,
polypropylene may be used as a high-softening point thermoplastic material.
In one embodiment of the invention, the nonwoven continuous filament substrate
may
i5 have a total bond area of less than about 30 percent and a uniform bond
density greater
than about 100 bonds per square inch. For example, the nonwoven continuous
filament
substrate may have a total bond area from about 2 to about 30 percent (as
determined by
conventional optical microscopic methods) and a bond density from about 250 to
about 500
pin bonds per square inch.
2o Such a combination total bond area and bond density may be achieved by
bonding
the continuous filament substrate with a pin bond pattern having more than
about 100 pin
bonds per square inch which provides a total bond surface area less than about
30 percent
when fully contacting a smooth anvil roll. Desirably, the bond pattern may
have a pin bond
density from about 250 to about 350 pin bonds per square inch and a total bond
surface
2 s area from about 10 percent to about 25 percent when contacting a smooth
anvil roll..
Although pin bonding produced by thermal bond rolls is described above,
embodiments of the present invention contemplate any form of bonding which
produces
good tie down of the flaments with minimum overall bond area. For example,
ultrasonic
bonding, thermal bonding, a combination of thermal bonding, ultrasonic bonding
and/or latex
3 o impregnation may be used to provide desirable filament tie down with
minimum bond area.
Alternatively and/or additionally, a resin, latex or adhesive may be applied
to the nonwoven
continuous filament web by, for example, spraying or printing, and dried to
provide the
desired bonding. If splittable filaments/fibers are used, hydraulic entangling
may be used to
provide the desired level of bonding alone or in combination with other
bonding techniques.
35 When conjugate spun filaments are used to form the nonwoven substrate 20 or
are
included in the nonwoven substrate 20, the nonwoven substrate may be
relatively lightly
bonded or even unbonded prior to entanglement with the pulp layer.
The pulp fiber layer 18 is then laid on the nonwoven substrate 20 which rests
upon a
foraminous entangling surface 32 of a conventional hydraulic entangling
machine. It is
4o preferable that the pulp layer 18 is between the nonwoven substrate 20 and
the hydraulic
CA 02305552 2005-12-30
WO 99821 PCTNS98/Z1967
13
entangling manifolds 34. The pulp fiber layer 18 and nonwoven substrate 20
pass under
one or more hydraulic entangling manifolds 34 and are treated with jets of
fluid to entangle
the pulp fibers with the filaments of the continuous filament nonwoven
substrate 20. The
jets of fluid also drive pulp fibers into and through the nonwoven substrate
20 to form the
s composite material 36.
Alternatively, hydraulic entangling may take place while the pulp fiber layer
18 and
nonwoven substrate 20 are on the same foraminous scxeen (i.e., mesh fabric)
which the
wet-laying took place. The present invention also contemplates superposing a
dried pulp
sheet on a continuous filament nonwoven substrate, rehydrating the dried pulp
sheet to a
i o specified consistency and then subjecting the rehydrated pulp sheet to
hydraulic entangling.
The hydraulic entangling may take place while the pulp fiber layer 18 is
highly
saturated with water. For example, the pulp fiber layer 18 may contain up to
about 90
percent by weight water just before hydraulic entangling. Alternatively, the
pulp fiber layer
i s may be an air-laid or dry-laid layer of pulp fibers.
The hydraulic entangling may be accomplished utilizing conventional hydraulic
entangling equipment such as may be found in, for example, in U.S. Patent No.
3,485,706 to
Evans, The hydraulic
entangling of the present invention may be carried out with any appropriate
working fluid
z o such as, for example, water.
The fluid impacts the pulp fiber layer 18 and the nonwoven substrate 20 which
are
supported by a foraminous surface which may be, for example, a single plane
mesh having
a mesh size of from about 8 X 8 to about 100 X 100. The foraminous surtace may
also be a
multi-ply mesh having a mesh size from about 50 X 50 to about 200 X 200.
25 The wire mesh pattern may be selected to provide a textile-like appearance
on the
hydraulically entangled product. For example, coarse mesh fabrics tend to
produce
noticeable ridges and valleys on the hydraulically entangled fabric. One
desirable mesh
material may be obtained from Albany International of Portland, Tennessee
under the
TM
designation FormTech i4 Wire. The wire may be described as a 14-C Flat Warp 14
x 13
3 o mesh, single layer ~Neave. The warp strands are 0.88 x 0.57 mm polyester.
The shuts
strands ane 0.89 mm polyester. The average caliper is 0.057 inch, Air
Permeability 725 cfm
(cubic feet per minute); and the open area is 27.8 percent.
As is typical in rnany-water jet treatment processes, vacuum slots 38 may be
located
directly beneath the hydro-needling manifolds or beneath the foraminous
entangling surface
35 32 downstream of the entangling manifold so that excess water is withdrawn
from the
hydraulically entangled composite material 36.
After the fluid jet treatment, the composite fabric 36 may be transferred to a
non-
compre:~sive drying operation. A differential speed pickup roll 40 may be used
to transfer
the material from the hydraulic needling belt to a non-compressive drying
operation.
4 o Alternatively, conventional vacuum-type pickups and transfer fabrics may
be used. If
CA 02305552 2005-12-30
WO 99!10821 PCTNS98r2196?
14
desired, the composite fabric may be wet-aeped before being transferred to the
drying
operation. Non-compressive drying of the web may be accomplished utilizing a
conventional rotary drum through-air drying apparatus shown in FIG. 1 at 42.
The through-
dryer 42 may be an outer rotatable cylinder 44 with perforations 46 in
combination with an
outer hood 48 for receiving hot air blown through the perforations 46. A
through~lryer belt
50 carries the composite fabric 36 over the upper portion of the through-dryer
outer cylinder
40. The heated air fond through the perforations 46 in the outer cylinder 44
of the
through-dryer 42 removes water from the composite fabric 36. Other useful
through-drying
methods and apparatus may be found in, for example, U.S. Patent Nos. 2,666,369
and
i o 3,821,068, It should be
understood, however, that other drying devices may be used in the process. -
For
instance, it is believed that during some applications, a Yankee dryer may be
used in
place of or in addition to the through-drying operation.
The fabric may contain various materials such as, for example, scouring
agents,
i5 abrasives, activated charcoal, clays, starches, and superabsorbent
materials. For example,
these materials may be added to the suspension of pulp fibers used to form the
pulp fiber
layer. These materials may also be deposited on the pulp fiber layer prior to
the fluid jet
treatments so that they become incorporated into the composite fabric by the
action of the
fluid jets. Alternatively and/or additionally, these materials may be added to
the composite
2 o fabric after the fluid jet treatments.
A binder material may be applied to the hydraulically entangled composite
fabric 36
either prior to the drying operation or after the drying operation. The binder
material may be
applied utilizing any conventional technique. Desirably, the binder material
is printed onto
the composite material. The printing method may be any which is known in the
art to be
a 5 effective such as, for example, flexographic printing, gravure printing ,
ink jet printing, spray
printing andlor screen printing.
Generally speaking, the binder material may be latex based . They may contain
a
latex base and a cure promoter and a, if desired, a pigment. A cure promoter
may be added
to a latex base in order to allow curing of the composition at ambient
temperatures, well
s o below that which would melt the polymer components of a nonwoven web which
generally
indudes a polyolefln like polypropylene if it is considered desirable to avoid
such
temperatures. -The curing process may be triggered by the loss of a fugitive
alkali which
may be made past of the fom~ulation. Altematively,=latex polymers with
internal curing
agents may be used.
35 A viscosity modifier or additional water may also be part of the
formulation if the
viscosity is not in the proper range for printing after the addition of all
ingredients.
An acceptable latex polymer system for use in this invention should be cxoss-
linkable
at room temperature or at slightly elevated temperatures and should be stable
to ambient
weather conditions and be flexible when cured. Examples include potymen; of
ethylene
4 o vinyl acetates, ethylene vinyl chlorides, styrene-butadiene, acrylates,
and styrene-acrylate
CA 02305552 2005-12-30
wo ~nosz~ rcrn~s9snm~
copolymers. Such latex polymers generally have a Tg in the range of -15 to +20
°C. One
such suitable latex r composition is known as HYCAR~ 26084 from the B.F.
Goodrich Company of Cleveland, OH. Other suitable latexes include HYCAR~ 2671,
26445, 26322 and 26469 from B.F. Goodrich, RHOPLEX~ B-15, HA-8 and NW-1715
from
s Rohm 8 Haas, DUR-O-SET~ E-646 from National Starch & Chemical Co. of
Bridgewater,
NJ and BUTOFAN~ 4261 and STYRONAL~ 4574 from BASF of Chattan~ga, TN.
An acceptable pigment for use in this invention (if pigment is desired) must
be
compatible with the latex and crosslinker used. Generally speaking, pigments
refer to
compositions having particulate color bodies, not liquid as in a dye.
Commercially available
i o pigments for use in this invention inGude those manufactured by the Sandoz
Chemical
Company of Charlotte, NC, under the trade designation GRAPHTOL~. Particular
pigments
inGude GRAPHTOL~ 1175-2 (red), GRAPHTOL~ 6825-2 (blue), GRAPHTOL~ 5869-2
(green), and GRAPHTOL~ 4534-2 (yellow). Combinations of pigments may be used
to
provide various colors.
is In addition to or perhaps in place of some pigment, a filler such as clay
may be used
as an extender. The clay appears to have an effect of reducing the
colorfastness of the
composition and will not provide the color of a pigment of course, but it
represents a cost
saving measure as it a less expensive than pigments. A clay which may be used
is, for
example, Ultrawhite 90Tavailable from the Englehard Corp., 101 Wood Ave,
Iselin, NJ
a o 08830.
Useful cure promoters should cause or result in the crosslinking of the latex
polymer in
the composition. Desirably, the cure promoters should allow the latex based
composition to
cure at room temperature or slightly above so that the composite material does
not need to
be heated to~a temperature at which it may begin to melt in order to cure the
latex. The cure
promoter may become active at a pH which is neutral or acidic so that the
binder
composition is kept at a pH of above 8 during mixing and application. The pre-
cure pH is
kept above 8 by the use of a fugitive alkali such as, for example, ammonia.
Fugitive alkalis
remain in solution until driven off by drying at room temperature or
alternatively, heating
them a small amount to incxease the evaporation rate. The loss of the alkali
causes a drop
3 o in the pH of the composition which triggers the action of the cure
promoter.
Suitable cure promoters are for example, XAMA~-2 and XAMA~-7 and are available
commercially from the B.F. Goodrich Company of Cleveland, OH. Another
acceptable cure
promoter is Chemitite PZ-33Tavaitable from the Nippon Shokubai Co. of Osaka,
Japan.
These materials are aziridine~oligimers with at least two aziridine functional
groups.
A viscosity modifier, though~generally not necessary, may be used if the
viscosity of
the printing composition is not suitable for the method of printing desired.
One such suitable
viscosity modifier is known as ACRYSOL~ RM-8 and is available from the Rohm~&
Haas
Company of Philadelphia, PA. If it is desired to reduce the viscosity of the
printing
composition of this invention, water may simply be added to the mixture.
4 o Other suitable bonding materials that may be used in the present invention
include
CA 02305552 2000-04-03
WO 99/20821 PCT/US98/21967
16
latex compositions, such as acrylates, vinyl acetates, vinyl chlorides, and
methacrylates.
Other bonding materials that may also be used include polyacrylamides,
polyvinyl
alcohols, and carboxymethyl cellulose.
In one embodiment, the bonding material used in the process of the present
s invention comprises an ethylene vinyl acetate copolymer. In particular, the
ethylene vinyl
acetate copolymer may be cross-linked with N-methyl acrylamide groups using an
acid
catalyst. Suitable acid catalysts include ammonium chloride, citric acid, and
malefic acid.
The bonding agent should have a glass transition temperature of not lower than
about -
10°F and not higher than +10°F.
io As noted above, the bonding material is applied to the composite fabric 36
in a
preselected pattern. In one embodiment, for instance, the binder material can
be applied
to the composite fabric 36 in a reticular pattern, such that the pattern is
interconnected
forming a net-like design on the surface. For example, the binder material can
be applied
according to a diamond shaped grid. The diamonds, in one embodiment, can be
square
is having a length dimension of 1/8 inch. In an alternative embodiment, the
diamonds
comprising the grid can have length dimensions of 6 x 10'3 inch and 9 x 10'3
inch.
In another embodiment, the binder material may be applied to the fabric in a
pattern that represents a succession of discrete dots. This particular
embodiment may be
well suited for use with lower basis weight wiping products. Applying the
bonding agent in
2 o discrete shapes, such as dots, provides sufficient strength to the fabric
without covering a
substantial portion of the surface area of the web. In some situations,
applying the binder
material to the surfaces of the fabric can adversely affect the absorbency of
the fabric.
Thus, in some applications, it is preferable to minimize the amount of binder
material
applied.
2s In a further alternative embodiment, the binder material can be applied to
the
fabridweb 36 according to a reticular pattern in combination with discrete
dots. For
example, in one embodiment, the binder material can be applied to the fabric
according to
a diamond shaped grid having discrete dots applied to the web within the
diamond
shapes.
3 o The binder material agent can be applied to each side of the fabric so as
to cover
almost any amount of surface area. For example, the binder material may be
applied to
cover from about 10% to about 60% of the surface area. Desirably, the binder
material
will cover from about 20% to about 40% of the surface area of each side of the
fabric. The
total amount of binder material applied to each side of the fabric/web will
preferably be in
3 s the range of from about 2% to about 15% by weight, based upon the total
weight of the
web. Thus, when the binder material is applied to each side of the fabric, the
total add on
will be from about 4% to about 30% by weight.
Referring now to FIG. 2, there is shown an exemplary embodiment of a process
in
which a bonding material is applied to both sides of a web 36 and both sides
of the web
4 o are creped.
CA 02305552 2000-04-03
WO 99/Z0821 PCT/US98/21967
17
A nonwoven composite fabric or web 36 made according to the process
illustrated
in FIG. 1 or according to a similar process, is passed through a first bonding
agent
application station generally 50. Station 50 includes a nip formed by a smooth
rubber
press roll 52 and a patterned rotogravure roll 54. Rotogravure roll 54 is in
communication
with a reservoir 56 containing a first bonding agent 58. Rotogravure roll 54
applies
bonding agent 58 to one side of web 36 in a preselected pattern.
The web 36 is then pressed into contact with a first creping drum 60 by a
press roll
62. The web adheres to creping drum 60 in those locations where the bonding
agent has
been applied. If desired, creping drum 60 can be heated for promoting
attachment
io between the web and the surface of the drum and for partially drying the
web. Care
should be taken so the temperature of the drum is not hot enough to degrade
the strength
of the web.
Once adhered to creping drum 60, web 36 is brought into contact with a creping
blade 64. Specifically, the web 36 is removed from creping roll 60 by the
action of creping
i5 blade 64, performing a first controlled pattern crepe on the web.
Once creped, the web 36 can be advanced by pull rolls 66 to a second bonding
agent application station generally 68. Station 68 includes a transfer roll 70
in contact with
a rotogravure roll 72, which is in communication with a reservoir 74
containing a second
bonding agent 76. Similar to station 50, second bonding agent 76 is applied to
the
20 opposite side of the web 36 in a preselected pattern. Once the second
bonding agent is
applied, web 20 is adhered to a second creping roll 78 by a press roll 80. The
web 36 is
carried on the surface of creping drum 78 for a distance and then removed
therefrom by
the action of a second creping blade 82. Second creping blade 82 performs a
second
controlled pattern creping operation on the second side of the web.
25 Once creped for a second time, the web 36, in this embodiment, is pulled
through
a curing or drying station 84. The drying station 84 can include any form of a
heating unit,
such as an oven energized by infrared heat, microwave energy, hot air or the
like. The
drying station 84 may be necessary in some applications to dry the web and/or
cure the
first and second bonding agents. Depending upon the bonding agents selected,
however,
3o in other applications drying station 84 may not be needed. Care should be
taken so the
temperature of the web at the drying station does not get high enough to
degrade the
strength of the web. Desirably, the bonding material is adapted to cure at low
temperatures so a curing station is not required.
Once drawn through the drying station 84, the web 3fi can be transferred to
35 another location for further processing or can be cut into commercial size
sheets for
packaging as a cloth-like wiping product.
The bonding agents applied to each side of the web 36 are selected for not
only
assisting in creping the web but also for adding dry strength, wet strength,
stretchability,
and teat resistance to the paper. The bonding agents also prevent lint from
escaping
4o from the wiping products during use.
CA 02305552 2005-12-30
wo ~nos2 ~ pcnus9s3m ~~
is
After the bonding material is applied to the web and the web is creped, the
web is
ready for use as a cloth-like wiping product in accordance with the present
invention.
Alternatively, however, further processing steps can be performed on the web
as desired.
It is contemplated that the web 36 may be rolled up with relatively high
levels of
stretch imparted to the web by the creping process. This results in a web
having a high
level of texture which may enhance wiping, scrubbing and/or cleaning.
Alternatively, much
of the texture or stretch may be pulled out of the sheet by stretching or
pulling the sheet.
This may be done immediately after creping or it may be done during a
rewinding
operation or the like. Such a stretched or pulled sheet tends to have a
smooth, soft
io appearance that provides a wiper that readily conforms to surfaces.
In one embodiment, the web can be calendered and then treated with a friction
reducing agent in order to provide a resulting wiping product having a smooth,
low friction
surface. It should be understood, however, that calendering step can be
eliminated from
the process if it is important to preserve as much bulk as possible in web.
i5 The friction reducing composition may be sprayed onto the web or it may
also be
printed on the web using a lithographic printing fountain. The friction
reducing
composition can be applied to either a single side of the web or to both sides
of the web.
Once applied to web, the friction reducing composition increases the
smoothness
of the surface of the web and lowers friction. Some examples of friction
reducing
2 o compositions that may be used in the process of the present invention are
disclosed in
U.S. Patent No. 5,558,873 to Funk. et al..
In one embodiment, the friction reducing composition applied is a quaternary
lotion, such as a quaternary silicone spray. For instance, the composition can
include a
silicone quaternary ammonium chloride. One commercially available silicone
glycol
25 quaternary ammonium chloride suitable for use in the present invention is
ABI~MSW
marketed by Goldschmidt Chemical Company of Essen, Germany.
In another embodiment, the friction reducing composition is applied to one
side of
the web in an amount from about 0.4% to about 2% by weight and particularly
from about
0.4% to about 1.4% by weight, based upon the weight of the web.
3o After being sprayed with the friction reducing composition, the web may be
fed to a
dryer, such as an infrared dryer, to remove any remaining moisture within the
web.
The web can then be wound into a roll of material, which can be transferred to
another location and cut into commercial size sheets for packaging as a wiping
product.
The textured composite nonwoven materials made according to the above-
a5 described process provide many advantages and benefits over many wiping
products
made in the past. Of particular advantage, the wiping products of the present
invention
have the appearance and feel of a textile product.
In comparison to conventionally made untextured hydraulically entangled
composite materials, the textured materials of the present invention have much
more
4 o conformability and stretch. The textured materials may also provide better
wiping or
CA 02305552 2000-04-03
WO 99/20821 PCT/US98I21967
19
scrubbing properties because of the texture. Also, the better tie-down or
bonding of the
fibrous material provides greater abrasion resistance, lower levels of tinting
and better
strength. Further, the textured composite materials of the present invention
have
improved wet bulk due to the texture and the latex printing.
s The basis weight of softened hydraulically entangled nonwoven composite
materials made according to the present invention can generally range from
about 20 to
about 200 grams per square meter (gsm), and particularly from about 35 gsm to
about
100 gsm. In general, lower basis weight products are well suited for use as
light duty
wipers while the higher basis weight products are better adapted for use as
industrial
io wipers.
The present invention may be better understood with reference to the following
example.
is lE)CAIVIPLE
Softened hydraulically entangled nonwoven composite materials were made from
a hydraulically entangled composite material. Two different bonding materials
were
applied and during the creping operation. The resulting products were compared
with an
untreated (i.e., unprinted and uncreped) wiping product made of essentially
the same
zo hydraulically entangled composite material.
Three different wiping products were produced and tested. The results of the
tests
are contained in Table 1 below. The base web used to make the samples was
identical
and was formed by wet-depositing a paper web onto a nonwoven web of
substantially
continuous filaments and then through dried. The base web is available from
Kimberly-
z5 Clark Corporation as Workhorse~ Manufactured Rags and had a basis weight of
approximately 55 gsm. The material contained about 75%, by weight, Northern
Softwood
Kraft pulp and about 25%, by weight, polypropylene spunbond. Results of
testing this
material are reported in Table 1 under the heading Sample 1.
The two creped samples were printed with a latex bonding material on both
sides.
ao In each case, the latex bonding material was applied according to a'/< inch
diamond
pattern in combination with an over pattern of dots. The latex bonding
materials were
mixed to contain 33% latex solids and were printed at a print pressure of 30
pounds per
square inch. The latex bonding material was applied to each surface of the
base web in
an amount of 5% by weight. The samples were creped on each side according to
the
35 procedure shown at FIG. 2 utilizing creping dryers set at 210°F, 10
degree creping blade,
18 degree shelf angle to achieve approximately a 15% crepe.
One creped sample was printed with a latex available from Air Products under
the
designation Airflex A-105. This sample required curing in a cure oven set at
280°F for less
than one second. Results of testing this material are reported in Table 1
under the
4o heading Sample 2.
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Another creped sample was printed with a latex available from B.F. Goodrich of
Cleveland, OH, as HYCAR~ 26469 latex. The material is a carboxylated acrylic.
The latex
was mixed with about 5%, by weight, of a cure promoter available from B.F.
Goodrich
designation XAMA~-7. This material is an aziridine derivative. Approximately
0.5%, by
s weight, of an ammonium chloride catalyst was added to the XAMA~-7 cure
promoter. A
small amount of defoamer was also added. This sample required no additional
curing.
Results of testing this material are reported in Table 1 under the heading
Sample 3.
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21
Sample No.
1 2 3 4
Basis Weight (gsm) 55.8 63.6 62
Bulk 450 517 530
Machine Direction Tensile 122 >160 155
Strength
(oz)
Machine Direction Stretch 27 - 42
(%)
Cross-Direction Tensile 58 85 80
Strength
(oz)
Cross-Direction 134 140 137
Stretch (%)
Cross-Direction - 69 75.6
Wet Tensile Strength (oz/in)
Taber (cycles) 41 50 50
Wipe Dry (cmz) - 400 25
Z dir wick - 0.917 0.626
(g water/g fiber/sec)
XY dir wick - 0.295 0.401
(g water/g fiber/sec)
Lint 318 80 79
(No. of particles/10 micron
screen)
Machine Direction Tear 4.7 4.9 4.9
(Ibs)
Cross-Direction Tear (Ibs)3.2 3.4 3.6
Total Water Capacity 4.67 2.95 3.16
(g water/g product)
Bending Modulus 3.8 3.32 3.97
Machine Direction
Bending Modulus 2.23 2.5 2.77
Cross-Direction
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22
The above tests performed on the samples were done according to conventional
methods which are well known in the art. From the above table, Taber refers to
an
abrasion test that determines how many cycles it takes for a paper wiping
product to
develop a %2 inch hole. The wipe dry test above determines the area of a 1.5
mil pool of
water that will be absorbed by a sheet of a paper wiping product having a
particular size.
These and other modifications and variations to the present invention may be
practiced by those of ordinary skill in the art, without departing from the
spirit and scope of
the present invention, which is more particularly set forth in the appended
claims. In
io addition, it should be understood that aspects of the various embodiments
may be
interchanged both in whole or in part. Furthermore, those of ordinary skill in
the art will
appreciate that the foregoing description is by way of example only, and is
not intended to
limit the invention so further described in such appended claims.
