Note: Descriptions are shown in the official language in which they were submitted.
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
CLEANING SHEET
BACKGROUND
Dust cloths for removing dust from a surface to be cleaned, such as a table,
are
generally known. Such known dust cloths may be made of woven or nonwoven
fabrics
and are often sprayed or coated with a wet, oily substance for retaining the
dust. Such
cloths tend to leave an oily film on the surface after use and do not usually
contain any
substantial amount of surfactant.
Other known dust cloths include nonwoven entangled fibers having spaces
between the entangled fibers for retaining the dust. The entangled fibers may
be supported
by a network grid or scrim structure, which can provide additional strength to
such cloths.
Cloths of this type can become saturated with the dust during use (i.e., dust
buildup)
and/or may not be completely effective at picking up denser particles, Large
particles or
other debris. Such cloths are also typically designed to be used primarily as
a dry dust
cloth.
Cloths used as wet cleaning pads are generally known. The cloths may be formed
using woven or nonwoven fibers. Such cloths may be pre-impregnated with water
and
soap, or may be sold dry, e.g., as a soap pad. These cloths are generally
characterized by a
relatively loading of surfactant, which is released when the water contacts
the pad. The
primary use for such cloths is in wet cleaning, such as dish scrubbing. Other
wipes which
have been pre-impregnated with a cleaning solution have been reported for use
in
applications such as car washing. Soap pads and wet wipes such as these are
not usually
designed to be utilized in dry cleaning.
Accordingly, it would be advantageous to provide cleaning sheets that can both
pick-up and retain debris in dry cleaning and release surfactant to enhance
its effectiveness
when used in wet cleaning. Such a cleaning sheet would preferably be capable
of
retaining larger particulates and other debris such as hair and lint, while at
the same time
being very effective for picking up and retaining fine dust particles. Such a
cleaning sheet
would also be capable of releasing surfactant deposited on the fibers with
suitable
properties to enhance its use in wet cleaning.
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
-2-
SUMMARY OF THE INVENTION
The present invention relates generally to cleaning sheets for use in cleaning
surfaces, such as in the home or work environment. More particularly, the
invention
relates to a dry cleaning sheet with wet cleaning capabilities, used in dry
form for
collecting and retaining dust, larger particles and/or other debris and for
cleaning surfaces
while wet. The cleaiung sheet includes a surface covered with a fabric
material capable of
picking up and retaining particulate matter and other debris, such as hair and
lint. The
fabric material may optionally be treated with and/or incorporate therein a
dust adhesion
agent to enhance it effectiveness. A relatively low level of surfactant is
typically
deposited on at least some of the fibers of the fabric to enhance the ability
of the sheet to
be utilized in wet cleaning. The inclusion of the surfactant can enhance the
capability of
the cleaning sheet to use, after being wet with water, as an aid in removing
dirt, stains
and/or deposits from a surface.
The cleaning sheet includes a fabric layer which has a relatively low level of
surfactant deposited on at least a portion of the fibers. The fabric material
is selected to be
capable in dry form of picking up and retaining particulate matter and other
debris, such as
hair and lint. The sheets can also be used as wet wipes by impregnating the
sheet with
water or other cleaning solutions to facilitate the removal of troublesome
stains or
deposits. The cleaning sheets generally have a breaking strength of at least
SOOg/30 mm.
Cleaning sheets which are intended for use mounted on an implement, such as a
mop head,
generally have an elongation at a load of SOOg/30 mm of no more than about
25%.
The surfactant commonly is a paste or solid at room temperature and has a
relatively low water solubility, e.g., a water solubility of no more than
about 20 wt.% at
25°C. The latter property is often satisfied by surfactants that have
an
hydrophilic/lipophilic balance ("HLB") of about 10 to 18. Examples of
surfactants which
have such properties include a wide variety of commercially available nonionic
and
anionic surfactants.
Surfactant can deposited on the fibers of the sheet in a continuous fashion or
in
random or repeating patterns. The surfactant is generally chosen and deposited
in such an
amount that residue does not normally rub off during use of the cleaning sheet
in dry
cleaning methods. The surfactant may be applied to the fabric layer by
rolling, spraying,
or other methods. The surfactant is preferably applied to the fabric layer in
a manner that
does not impart too much stiffiiess and/or rigidity to the sheet. Depending on
the type of
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
-3-
surfactants) and manner of application, the surfactant can be deposited to
various depths
on and/or around the fibers. The result of surfactant deposit is a flexible
cleaning cloth
that is capable of releasing a portion of the surfactant when the sheet is
wet.
In one embodiment, the cleaning sheet includes a nonwoven fiber aggregate
layer
formed from a loosely entangled fibrous web. Such a fibrous web typically has
a basis
weight of 50 to 150 g/m2 and a CD initial modulus ("entanglement coefficient")
of no
more than 800 m. Surfactant is commonly deposited on no more than about 20% of
the
fibers which make up the web and, more typically, is deposited on no more than
10% of
the fibers. Preferably, the nonwoven aggregate is formed from microfibers
which have a
denier of no more than 3. To enhance the ability of the fibrous web to pick up
and retain
particulates and oils, it may be advantageous to form the nonwoven aggregate
from a
mixture of moderately fine and very fine microfibers, e.g., a mixture of
microfibers having
a denier of 1-2 and microfibers having a denier of 0.5 to 0.9.
Woven fabrics formed from microfibers, such as a sheet of ScotchbriteTM
material
(available from 3M Corporation, St. Paul, MIA, can also be treated with
surfactant and
used as the fabric layer in the present cleaning sheets. Such woven webs are
typically
formed from the same types of microfibers as the nonwoven webs described
herein. The
woven fabrics are generally formed from microfibers having a denier of no more
than
about 3.
The present cleaning sheets can be produced by imprinting a pattern of
surfactant,
e.g., either as a melt or as a mixture with a relatively volatile solvent. If
a solvent
containing mixture is employed, the treated sheet is typically subjected to a
flow of air
(either with or without exposure to a source of heat). to drive off residual
solvent.
As used herein, the term "entanglement coefficient" refers to the initial
gradient of
the stress-strain curve measured with respect to the direction perpendicular
to the fiber
orientation in the fiber aggregate (cross machine direction). The entanglement
coefficient
is also referred to herein as the "CD initial modulus." Suitable nonwoven
fiber aggregates
for use in forming the present cleaning sheets conunonly have an entanglement
coefficient
of 20 to 800 m (as measured after any reinforcing filaments or network has
been removed
from the nonwoven fibrous web) and, more typically, no more than about 300 m.
The entanglement coefficient (also referred to herein as "CD initial modulus")
as
used herein is a measure representing the degree of entanglement of fibers in
the fiber
aggregate. The entanglement coefficient is expressed by the initial gradient
of the stress-
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
-4-
strain curve measured with respect to the direction perpendicular to the fiber
orientation in
the nonwoven fiber aggregate, i.e., in the cross machine direction ("cross
direction" or
"CD"). A smaller value of the entanglement coefficient represents a smaller
degree of
entanglement of the fibers. The term "stress" as used herein means a value
which is
obtained by dividing the tensile load value by the chucking width (i.e. the
width of the test
strip during the measurement of the tensile strength) and the basis weight of
the nonwoven
fiber aggregate. The term "strain" as used herein is a measure of the
elongation of the
cleaning sheet material.
The term "breaking strength" as used herein refers.to the value of a load
(i.e. the
first peak value during the measurement of the tensile strength) at which the
cleaning sheet
begins to break when a tensile load is applied to the cleaning sheet.
As used herein, the term "elongation" refers to the relative increase in
length (in
percent) of a 30 mm strip of cleaning sheet material when a tensile load of
500 g is applied
to the strip. The strip is elongated at a rate of 30 mm/min in the direction
perpendicular to
the fiber orientation (i.e, in the cross machine direction).
As used herein the term "nonwoven web" means a web having a structure of
individual fibers or threads which are interlaid, but not in a regular or
identifiable manner
as in a knitted fabric. The term "nonwoven fabric" includes nonwoven webs as
well as
individual filaments and strands, yarns or tows as well as foams and films
that have been
fibrillated, apertured, or otherwise treated to impart fabric-Iike properties.
Nonwoven
fabrics or webs have been formed from many processes such as for example,
meltblowing
processes, spunbonding processes, and bonded carded web processes. Throughout
this
application, the terms "nonwoven fiber aggregate", "fibrous web", and
"nonwoven
aggregate" are used interchangeably with the term "nonwoven web".
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. Basis weights can be converted from osy to
gsm simply
by multiplying the value in 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 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
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
-5-
meters of a fiber and may be calculated as fiber diameter in microns squared,
multiplied
by the density in grams/cc, multiplied by 0.00707. A lower denier indicates a
finer fiber
and a higher denier indicates a thicker or heavier fiber. For example, the
diameter of a
polypropylene fiber given as 15 microns may be converted to denier by
squaring,
multiplying the result by .89 g/cc and multiplying by .00707. Thus, a 15
micron
polypropylene fiber has a denier of about I.42 (I52 x 0.89 x .00707 = I.4I5).
Outside the
United States the unit of measurement is more commonly the "tex", which is
defined as
the grams per kilometer of fiber. Tex may be calculated as denier/9.
As used herein, the term "average cross-sectional dimension" refers to the
average
I O dimension of a region in an outer fabric surface of the present cleaning
sheet. The
"average cross-sectional dimension" ("ACSD") is equal to one half of the sum
of the
length of the longest cross sectional axis ("Ll") of the cavity plus the cross
sectional axis
perpendicular to the longest cross sectional axis ("LS"), i.e.,
ACSD = (L1 + LS )/2.
The term "cross-sectional area" is used herein to refer to the area of a
region in the
outer plane of the fabric surface (i.e., in the cleaning surface).
It is important to note that the terms "surface" and "surface to be cleaned"
as used
in this disclosure are broad terms and are not intended as terms of
limitation. The term
surface includes substantially hard or rigid surfaces (e.g., articles of
furniture, tables,
shelving, floors, ceilings, hard furnishings, liousehold appliances, and the
like), as well as
relatively softer or semi-rigid surfaces (e.g., rugs, carpets, soft
furnishings, linens,
clothing, and the like).
It is also important to note that the term "debris" is a broad term and is not
intended as a term of limitation. In addition to dust and other fine
particulate matter, the
term debris includes relatively large-sized particulate material, e.g., having
an average
diameter greater than about 1 mm, such as large-sized dirt, soil, lint, and
waste pieces of
fibers and hair, which may not be collected with conventional dust rags, as
well as dust
and other fine dirt particles.
As employed herein, the term "melting point" is used to refer to the
temperature at
which a material transforms from a solid to a liquid, i.e., when a phase
change involving a
heat of fusion occurs. The term '.'pour point" as used herein refers to the
temperature at
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
-6-
which the material stops flowing (as measured by ASTM method D 97). Thus pour
point
is a property which may involve a phase change but generally is based on a
change in the
viscosity properties of the material.
Throughout this application, the text refers to various embodiments of the
cleaning
sheet. The various embodiments described are meant to provide illustrative
examples and
should not necessarily be construed as descriptions of alternative species.
Rather it should
be noted that the descriptions of various embodiments provided herein may be
of
overlapping scope. The embodiments discussed herein are merely illustrative
and are not
meant to limit the scope of the present invention.
BRIEF DESCRIPTION OF THE FIGURE
Figure 1 shows a plan view of a portion of a nonwoven fiber layer with
surfactant
deposited on the fibers which can be used to form a cleaning sheet.
Figure 2 shows a cross-sectional view of a portion of a nonwoven fiber layer
depicted in Figure 1.
Figure 3 shows a plan view of a portion of a woven fiber layer with surfactant
deposited on the fibers which can be used to form a cleaning sheet.
Figure 4 shows a plan view of a lattice-Iike network sheet which can be used
to
reinforce a nonwoven fiber aggregate Iayer employed to produce one example of
the
present cleaning sheet.
Figure 5 shows a cross-sectional view of a lattice-supported nonwoven fiber
aggregate layer which can be employed to produce a cleaning sheet.
Figure 6 is a graph showing a stress-strain curve for a typical nonwoven fiber
aggregate layer which can be used to form a cleaning sheet.
DETAILED DESCRIPTION
The present cleaning sheets are very effective when used as.a dry dust cloth
to
collect and retain oils, particulates, lint hair and other debris from a
surface. In addition,
the sheets are capable of being used in wet cleaning applications. For
example, the sheets
can be saturated with water to aid in removing dirt, stains and/or deposits
from a surface.
The cleaning sheet includes a fabric layer which has a relatively low level of
surfactant
deposited on at Ieast a portion of the fibers. The fabric material is selected
such that it is
capable in dry form of picking up and retaining oils, particulate matter
and/or other debris,
such as hair and Iint. The sheets can also be used as wet wipes by
impregnating the sheet
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
with water or other cleaning solutions_ where necessary to facilitate the
removal of
troublesome stains or deposits.
The cleaning sheets include a relatively low level of surfactant, typically of
a type
classed as a hard surface cleaner. The surfactant may be distributed uniformly
throughout
a nonwoven fabric layer of the sheet. More commonly, the surfactant is
distributed in
discrete regions of the nonwoven Layer interspersed between regions which are
untreated
with the same level of surfactant. The discontinuous surfactant -containing
regions may be
discrete regions which can have a variety of shapes. For example, the
surfactant-
containing regions can be round ("dots"), polygon shaped or have an irregular
("amorphous") shape. Figure I depicts a section of a cleaning sheet formed
fiom a
nonwoven fiber aggregate 1.wluch has a plurality of round surfactant-
containing
regions 2. Alternatively, the discontinuous surfactant-containing regions can
have linear
shapes, e.g., curved lines 10 such as shown in Figure 3. The surfactant may
only be
deposited on the fibers on the exterior surface of the sheet. More commonly,
however, the
surfactant is applied in such a manner that the surfactant is deposited on
interior fibers as
well as fbers near the exterior surface of the web. Figure 2 depicts a fibrous
web which
includes surfactant containing regions 3 which extend from an exterior surface
into the
interior of the web. Fibrous webs of this type can be produced by applying the
surfactant
as a melt or solvent containing mixture that has a sufficiently low viscosity
to permit the
surfactant to be transported into the web. The surfactant-containing regions
may be are
arranged in a regular, repeating pattern or may be randomly distributed.
The cross sectional area of all the regions which include surfactant is
generally at
least about 2-3% of the total surface area of the exterior surface of the
fabric layer. The
total cross sectional area of these regions is commonly no more than about 25%
of the
total surface area. This allows the inclusion of sufficient surfactant to
facilitate the
removal of tough deposits and the Like without substantially altering the
overall properties
of the sheet when used as a dry dust cloth. Examples of particularly suitable
cleaning
sheets include those where the cross sectional area of all the surfactant-
containing regions
relative to the total surface area is about 5% to 10%, although in some
instances the
surfactant-containing regions may make up a larger percentage of the total
surface area of
a cleaning sheet, e.g., up to about 40% of the total area. As mentioned
elsewhere herein,
in other embodiments the low level of surfactant may be uniformly dispersed
over the
entire surface of the fabric layer.
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
_g_
Surfactant(sl
The surfactant may be printed or sprayed onto the surface to be coated.
Depending
on the design of the cleaning sheet, the surfactant may be applied as a
continuous layer,
e.g., onto one side of a fibrous web or a flexible backing layer used to form
the sheet, or
S applied in a discontinuous manner. For example, the surfactant may be rolled
or sprayed
(either as a solution or a melt) onto specific regions on the outer fabric
surface of the
sheet. In another embodiment, cleaning sheets may be form by spreading or
spraying
discontinuous patches of a surfactant onto a flexible backing layer and
brining a fibrous
web into contact with the backing layer such that at least a portion of the
surfactant is
deposited onto fibers in the web.
Specific examples of suitable types of surfactants include anionic surfactants
and
nonionic surfactants. The surfactant is chosen so that it is a paste or solid
at ordinary room
temperatures (i.e., at temperatures close to 2S°C). More commonly the
surfactant has a
melting point of at least about 3S°C and preferably at least about
40°C. The surfactant
1 S also generally has a relatively low water solubility. Tlus can accomplish
at least two
objectives. When the cleaning sheet is employed in wet state, the amount of
surfactant
wluch dissolves in the water impregnated into the sheet will be low, resulting
in a low
dosage of surfactant onto the surface being cleaned. This avoids the build up
of a
surfactant residue on the surface. In addition, if the surfactant is
relatively insoluble, not
all of the surfactant in the sheet will generally be dissolved during a single
use. This
permits the sheet to be used more than once and preferably multiple times
before disposal.
The surfactant may also be characterized in terms of its
hydrophilic/lipophilic balance
("HLB"). This is a parameter cormnonly used in the surfactant art to
characterize the
relative amount of hydrophilic and lipophilic nature in a given surfactant.
Surfactants with
2S low HLBs are more lipophilic. Surfactants with higher HLBs are more
hydrophilic arid
tend to be more water soluble. To enhance the wet cleaning capabilities of the
present
sheets, it is generally advantageous to use surfactants which have an HLB of
10 to 1 ~ and,
preferably, 13 to 16.
Examples of suitable nonionic surfactants which can be used to enhance the wet
cleaning utility of the present sheets include ethoxylated alkanols,
ethoxylated alkenols,
polyoxypropylene-polyoxyethylene block copolymers, polyethyleneglycol
monoesters,
alkylphenoxy-polyethyleneoxides, fatty acid glycol monoesters, paraffinic
ethoxylate
carboxylates, alkyldimethylamine oxides, and fatty acid hydroxyalkyl amides.
Examples
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
-9-
of suitable polyoxypropylene-polyoxyethylene block copolymers copolymers
include
copolymers having an HLB of 12 to 18. Examples of suitable polyethyleneglycol
monoesters include fatty acid monoesters and, in particular, such monoesters
where the
fatty acid has 12 to 18 carbon atoms. ethoxylated fatty alcohol having an
alkyl group with
16 to 18 carbon atoms.
As noted above, the surfactant can also include anionic surfactant. Examples
of
suitable anionic surfactants which may be utilized as part of the present
cleaning sheets
include fatty acid salts, alkanesulfonate salts, alkylbenzenesulfonate~salts,
alkanol sulfate
salts, and the like. Examples of suitable fatty acid salts include calcium
andlor magnesium
salts of fatty acids. Such salts typically iizclude salts of fatty acids
having at least 11 to 17
carbon atoms in the alkyl side chain.
Because the present cleaning sheets are often used in wet cleaning
applications
where a soiled surface is wiped or scrubbed with the wetted sheet without a
subsequent
rinse, it is generally preferable to employ surfactant which have a relatively
low foaming
character. For example, it may be particularly suitable to utilize surfactants
which have a
foam height in the Ross Miles foam test at 50°C (referred to herein as
"Ross Miles foam
height") of no more than about 100 mm and, preferably, no more than about 75
mm.
Typically, the cleaning sheet has an overall thicluZess of at least about 1 mm
and,
suitable cleaning sheets often have thicknesses of about 1.5 rnm to 3 mm or
even thicker.
Embodiments of the present cleaning sheets commonly may not include a flexible
backing
Iayer. In this instance, the fabric layer in generally somewhat thicker. For
example, such
sheets may be formed from a slightly thicker fabric layer (e.g., about 3 rnm
to 5 mm). The
flexible backing layer which is present in other embodiments of the cleaning
sheet
typically serves to provide strength and dimensional stability to the sheet.
These functions
may also be provided by a suitably designed fabric layer. Such sheets may be
suitably
thick enough to include a plurality of supporting filaments and/or a
supporting network
sheet within the layer.
According to a particularly suitable embodiment, the cleaning sheet includes
an
nonwoven fabric layer formed from microfibers. The nonwoven fabric layer is
typically a
Ioose aggregate of the microfibers. The denier of the fibers in the fiber
aggregate, the
length, the cross-sectional shape and the strength of the fibers used in the
nonwoven fiber
aggregate are typically also determined with an eye toward processability and
cost, among
other factors. The microfibers commonly have a denier of about 0.1 to 5 and,
more
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
- IO-
typically, about 0.5 to 2. One example of a suitable nonwoven fabric for use
as the outer
surface layer of a cleaning sheet is nonwoven fiber aggregate layer formed
from a mixture
of relatively thicker microfibers having a denier of 1 to 2 and finer fibers
having a denier
ofno more than about 0.9 and generally at least about 0.2 (preferably about
0.5 to 0.9).
Such nonwoven aggregates for use in producing the present cleaning sheets
suitably have
such thicker and finer fibers present in a weight ratio of about 50:50 to
about 20:80.
Figure 2 shows a cross=sectional view of one embodiment of the present
cleaning
sheet. The nonwoven aggregate layer of the cleaning sheet is shown made of an
entangled
network of nonwoven fibers 1 having a plurality of surfactant -containing
regions 3
therein. Pores which can also trap debris are formed by the spaces between the
entangled
fibers in the nonwoven layer (i.e., debris can be retained between the fibers
that form the
nonwoven aggregate layer). Typically, the surfactant is deposited on the
fibers in the
regions 4 such that the pores between the fibers are substantially similar to
those of the
corresponding untreated fabric.
In another embodiment, a web or lattice (shown as a scrim) may be embedded in
and support the fibers of the nonwoven layer. The scrim is commonly integrally
embedded within the fibers of the nonwoven aggregate layer to form a unitary
structure
for the layer. The scrim typically includes a net having horizontal members
attached to
vertical members arranged in a "network" configuration. Spaces (shown as
holes) are
formed between vertical members and horizontal members to give scrim a mesh or
lattice-
like structure. According to various embodiments, the horizontal and vertical
members of
the scrim may be connected together in a variety of ways such as woven, spot
welded,
cinched, tied, etc. One example of a such a lattice which may be used to
provide support
for the nonwoven layer during processing and use is shown in Figure 4.
To attach the fibers to a scrim, thereby forming nonwoven fiber aggregate
layer as
a unitary structure, the fibers may be overlaid on each side of the scrim. A
low pressure
water jet can then be applied to entangle the fibers of the nonwoven fiber
aggregate to
each other and to the scrim (i.e., hydroentanglement) to form a relatively
lose
entanglement of nonwoven fibers. Hydroentanglement of the fibers may be
further
increased during removal (e.g., drying) of the water from the water jet. The
fibers may
also be attached to the network sheet by other methods known to those of skill
in the art
{e.g., air laid, adhesive, woven). The fibers are typically entangled onto the
web to form a
unitary body, which can assist in preventing "shedding" of the fibers from the
web during
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
-11-
cleaning. Figure 5 shows one example of a scrim-supported nonwoven layer 11
which can
be utilized as the fabric layer in forming the present cleaning sheets. The
cross-sectional
view of the scrim-supported nonwoven fiber aggregate 11 shows the filaments 12
embedded within an hydroentangled nonwoven fiber web 13.
As fabric layer used to form the present cleaning sheets, a nonwoven aggregate
layer having fibers with a large degree freedom and sufficient strength is
advantageous for
effectively collecting and retaining dust and larger particulates within the
cleaning sheet.
In general, a nonwoven fabric formed by the entanglement of fibers involves a
higher
degree of freedom of the constituent fibers than in a nonwoven fabric formed
only by
fusion or adhesion of fibers. The nonwoven fabric formed by the entanglement
of fibers
can exhibit better dust collecting performance through the entanglement
between dust and
the fibers of the nonwoven fabric. The degree of the entanglement of fibers
can have a
large effect on the retention of dust. That is, if the entanglement becomes
too strong, the
freedom of fibers to move will be lower and the retention of dust is generally
decreased.
1 S In contrast, if the entanglement of the fibers is very weak, the strength
of the nonwoven
fabric can be markedly lower, and the processability of the nonwoven fabric
may be
problematic due to its lack of strength. Also, shedding of fibers from the
nonwoven fabric
is more likely to occur from a nonwoven aggregate with a very low degree of
entanglement.
A suitable nonwoven aggregate for use in producing the present cleaning sheets
can be formed by hydroentangling a fiber web (with or without embedded
supporting
filaments or a network sheet) under relatively low pressure. For example, the
fibers in a
carded polyester nonwoven web can be sufficiently entangled with a~ network
sheet by
processing the nonwoven fiber webs with water jetted at high speed under 25-50
kg/cm3
of pressure. The water can be jetted from orifices positioned above the web as
it passes
over substantially smooth non-porous supporting drum or belt. The orifices
typically have
a diameter ranging between 0.05 and 0.2 mm and can be suitably arranged in
rows beneath
a water supply pipe at intervals of 2 meters or less.
The supporting filaments and/or network sheet may be formed from a variety of
materials, such as polypropylene, nylon, polyester, etc. Exemplary webs (i.e.,
scrims) are
described in U.S. Patent No. 5,525,397, the disclosure of which is herein
incorporated by
reference. Suitable materials which may be used to form the network sheet may
be
selected from, for example, polyolefms such as polyethylene, polypropylene
axed
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
- 12-
polybutene; olefin copolymers formed from monomers such as ethylene, propylene
and
butene; olefin-vinyl ester copolymers, such as ethylene-vinyl acetate
copolymers;
acrylonitrile polymers and copolymers; polyesters such as polyethylene
terephthalate and
polybutylene terephthalate; polyamides such as nylon 6 and nylon 66;
acrylonitriles; vinyl
S polymers such as polyvinyl chloride; vinylidene polymers such as
polyvinylidene
chloride; modified polymers; and mixtures thereof.
The nonwoven aggregate layer used to form the present cleaning sheets
typically
has a relatively smooth surface apart from some gathering of the microfibers
in the
portions immediately adjacent to a supporting network (see, e.g., the cross-
sectional view
I O depicted in Figure S). This is, however, not a requirement as nonwoven
sheets having a
relatively "wavy" surface, i.e., having a plurality of peaks and valleys with
dimensions
smaller than those of the cavities in the surface, may be employed. Examples
of such
materials are described in U.S. Patent 5,310,590, International Patent
Application No.
98/52458 and Japanese Laid Open Patent Document No. S-25763 (laid open on
February
1S 2, 1993), the disclosure of which is herein incorporated by reference. One
method of
forming such wavy surfaced sheets is to hydroentangle one or more layers of
nonwoven
fibers with a thermally shrinkable supporting scrim. After hydroentangling a
nonwoven
web with the supporting scrim the resulting structure can be subjected to a
heat treatment
so that the structure is dried as the scrim is simultaneously shrunk. One
example of a
20 method of producing such a sheet is set forth in and Japanese Laid Open
Patent Document
No. S-25763.
The outer cleaning surface of fabric layer 1 is a generally smooth and
compliant
(e.g., flexible) generally planar sheet for cleaning delicate surfaces (e.g.,
wood, glass,
plastic, etc.) or hard surfaces. The cleaning sheet may include a backing
layer which is
2S more rigid and/or have a greater basis weight than fabric layer to provide
support and
structure to the cleaning sheet. According to other alternative embodiments, a
spacer or
other intermediate layers may be positioned between the backing layer and the
outer fabric
layer.
A variety of materials are suitable for use as a backing.layer in the present
cleaning
30 sheets so long as this layer has the desired degree of flexibility and is
capable of providing
sufficient support to the sheet as a whole. Examples of suitable materials for
use as a
backing layer include a wide variety of lightweight (e.g., having a basis
weight of about 10
to 7S g/m2), flexible materials capable of providing the sheet with sufficient
strength to
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
- 13-
resist tearing or stretching during use. The backing layer is typically
relatively thin, e.g.,
has a thickness of about 0.05 mm to about 0.5 mm, and can be relatively non-
porous.
Examples of suitable materials include spunbond and thermal bond nonwovens
sheets
formed from synthetic and/or natural polymers. Other bacl~ing materials which
can be
utilized to produce the present cleaning sheets include relatively non-porous,
flexible
layers formed from polyester, polyamide, polyolefm or mixtures thereof. The
backing
layer could also be made of hydroentangled nonwoven fibers so long as it meets
the
performance criteria necessary for the particular application. One specific
example of a
suitable backing layer is a spun bond polypropylene sheet with a basis weight
of about 20
to 50 g/m2.
Physical Parameters of the Cleaning Sheet
The cleaning sheet typically has a relatively low overall breaking strength in
order
to preserve a relative amount of flexibility. The term "breaking strength" as
used in this
disclosure means the value of a load (i.e., the first peak value during the
measurement of
IS the tensile strength) at which the cleaning sheet begins to break when a
tensile load is
applied to the cleaning sheet. The breaking strength of the sheet should,
however, be high
enough to prevent "shedding" or tearing of the cleaning sheet during use. The
breaking
strength of the cleaning sheet is typically at least about S00 g/30 cm and
cleaning sheets
with breaking strengths of 1,500 g/30 cm to 3,000 g/30 cm are quite suitable
fox use with
the cleaning implements described herein.
The cleaning sheet typically includes an nonwoven fiber layer which has a
relatively low basis weight as the surfactant treated particle retention layer
(i.e., the
material on the cleaning surface of the sheet). According to a particularly
suitable
embodiment, the nonwoven layer has a basis weight in the range of about 30 to
250 g/m2,
preferably 50 to 150 g/ma. A low basis weight can assist in providing a
"stream-line" or
compact look and feel to the cleaning sheet.
Where intended to be used with a cleaning utensil, mounting structure or the
like,
the cleaning sheet typically has a relatively low overall elongation to assist
in resisting
"bunching" or "puckering" of the cleaning sheet. The term "elongation" as used
in this
disclosure means the elongation percentage (%) of the cleaning sheet when a
tensile load
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
- 14-
of 500 g/30 mm is applied. For example, when designed to be used in
conjunction with a
mop or similar cleaning implement where the cleaning sheet is fixedly mounted,
the
present cleaning sheets typically have an elongation of no more than about 25%
and,
preferably, no more than about 15%.
The basis weight of the nonwoven fiber aggregate generally falls within the
range
of 50 to 250 g/m~ and, typically is no more than 150 g/m2. If the basis weight
of the
nonwoven fiber aggregate layer is less than about 30 g/m2, dust may pass too
easily
through the nonwoven fiber aggregate during the cleaning operation and its
dust collecting
capacity may be limited. If the basis weight of the nonwoven fiber aggregate
is too large,
e.g., substantially greater than 250 g/m2, it can become more difficult to
sufficiently
entangle the fibers in the aggregate and the network sheet with each other to
achieve a
desirable degree of entanglement. In addition, the processability of the
nonwoven
aggregate can worsen, and shedding of the f bers from the cleaning sheet may
occur more
frequently. The denier of the fibers in the fiber aggregate, the length, the
cross-sectional
shape and the strength of the fibers used in the nonwoven fiber aggregate are
generally
determined with an eye toward processability and cost, in addition to factors
relating to
performance.
In cases where the entanglement coefficient of the fiber aggregate, which is
expressed by the initial gradient of the stress-strain curve measured with
respect to the
. direction perpendicular to the fiber orientation (i.e., "CD initial
modulus"), is to be set at a
value not greater than 800 m, as in the cleaning sheet in accordance with the
present
invention, it may be difficult for a sheet, which is constituted only of a
fiber aggregate, to
achieve the values of the breaking strength and the elongation described
above. In order
to set the entanglement coefficient at a value not larger than 800 m, a
network sheet and
the fiber aggregate can be entangled and combined with each other into a
unitary body for
use as the fabric Iayer in the cleaning sheets. By entangling the fiber
aggregate with the
network sheet into a unitary body, and the elongation of this layer is kept
low and its
processability can be enhanced. Shedding of the fibers from the cleaning sheet
in
accordance with the present invention can often be markedly prevented as
compared with
a conventional entangled sheet, which is constituted only of a fiber aggregate
in
approximately the same entanglement state as that in the fiber aggregate of
the cleaning
sheet in accordance with the present invention.
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
-15-
If the entanglement coefficient is too small, e.g., no more than about 10 to
20 m,
the fibers may not be sufficiently entangled together. In addition, the
entanglement
between the fibers and the network sheet will likely be poor as well. As a
result, shedding
of the fibers may occur frequently. If the entanglement coefficient is too
large, e.g.,
greater than about 700 to 800 m, a sufficient degree of freedom of the fibers
cannot be
obtained due to too strong entanglement. This can prevent the fibers from
easily
entangling with dust, hair and/or other debris, and the cleaning performance
of the sheet
may not be satisfactory. Preferably, the cleaning sheet is formed from a
nonwoven fiber
aggregate with an entanglement coefficient of no more than 500 m and, more
preferably,
about 50 to 300 m.
The degree of the entanglement of the fibers depends on the entanglement
energy
applied to the fiber web during the entanglement process. For example, in the
water
needling process, the entanglement energy applied to the fiber web can be
controlled from
the view point of the type of fibers, the basis weight of the fiber web, the
number and
positioning of the water jet nozzles, the water pressure and the line speed
among other
factors.
In cases where the network sheet is a net foamed from filaments of
thermoplastic
material, such as shown in Figure 4, the mesh, the fiber diameter, the
distance between
fibers (and consequently the size of the holes) and the configuration of the
holes are
generally determined from the view point of the local entanglement with the
nonwoven
fiber aggregate. Specifically, the diameter of the holes ("gaps") typically
falls within the
range of 5 mm to 30 mm. Stated otherwise, the distance between adjacent
parallel rows of
fibers commonly falls within the range of 5 mm to 30 mm, and more preferably
falls
within the range of 10 mm to 20 mm.
The fibers used to form the fiber aggregate are suitably made from any of a
number
of thermoplastic fibers such as polyesters (e.g., polyethylene terephthalate
and/or
polylactate), polyamides (e.g., nylon) and polyolefms (e.g., polypropylene);
composite
fibers thereof, divided fibers thereof, and ultra thin fibers thereof, such as
produced by a
melt blown process; semi-synthetic fibers such as acetate fibers; regenerated
fibers such as
rayon; and natural fibers such as cotton and blends of cotton and other
fibers. The fibers
typically have a denier of no more than about 5 and, more preferably, 0.5 to
3.
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
- 16-
Dust Adhesion Agent
In accordance with the performance functions typically required for the
present
cleaning sheet, it may be advantageous to incorporate some form of dust
adhesion agent in
the fabric layer to enhance the dust collecting capabilities of the cleaning
sheet when it is
employed as a dry cleaning cloth. Herein, agents which enhance the dust
collecting
capabilities of the cleaning sheet in some manner are referred to as "dust
adhesion agents."
For example, the fabric layer may be a nonwoven fiber aggregate layer which
includes a
lubricant and/or surface-active agent. The surface active agent can improve
the surface
physical properties of the fiber aggregate and enhance the cleaning sheet's
ability to
absorb dust. The inclusion of lubricant can also impart gloss to a surface
being cleaned
with the sheet as well as enhancing the dust collecting efficiency of the
cleaning sheet.
Generally, the entire fabric layer will be treated with the dust adhesion
agent.
Although the dust adhesion agent and surfactant treatments may be applied in
any order,
commonly dust adhesion agent is applied to the entire fabric layer and the
surfactant The
dust adhesion agents are commonly added in an amount of 0.1 to 20 wt.% (add-on
wt.%
based on the weight of the fabric layer being treated). More typically, no
more than about
10 wt.% (add-on basis) of the dust adhesion agent is added to the fabric
layer. Particularly
suitable embodiments of the present cleaning sheets include a fabric layer
which has been
treated with about 3 to about 10 wt.% (add-on basis) of the dust adhesion
agent. As will
be understood by those skilled in the art, the amount of dust adhesion agent
utilized will
depend on the specific type of fabric material being treated, the specific
dust adhesion
agent employed and the type of application the cleaning sheet is designed to
be utilized
for, among other factors.
Suitable lubricants for use as dust adhesion agents in the present cleaning
sheets
include mineral oils, synthetic oils, silicone oils. Examples of mineral oils
which may be
employed include paraffin hydrocarbons, naphthenic hydrocarbons, and aromatic
hydrocarbons. Suitable synthetic oils include allcylbenzene oils, polyolefin
oils,
polyglycol oils and the like. Suitable silicone oils include acrylic dirnethyl
polysiloxane,
cyclic dimethyl polysiloxane, methylhydrogen polysiloxane, and various
modified silicone
oils.
The mineral oils, synthetic oils and silicone oils generally have a viscosity
of 5 to
1000 cps, particularly 5 to 200 cps (at 25°C). If the viscosity is
lower than about 5 cps, the
dust-adsorbing property can be decreased. If the viscosity is greater than
about 1000 cps,
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
- 17-
the lubricant can sometimes fail to spread uniformly on the fibers. In
addition, friction
coefficient to the surface to be cleaned may increase, possibly causing damage
of the
surface to be cleaned. The mineral oils, synthetic oils and silicone oils
commonly have a
surface tension of 15 to 45 dyn/cm, particularly 20 to 35 cyn/cm (at
25°C). If the surface
tension is lower than 15 dynlcm, the dust-adsorbing property of the treated
fabric can
become worse, and if it is higher than 45 dyn/cm, the lubricant sometimes
fails to spread
uniformly on the fibers constituting the nonwoven fabric.
As indicated above, the dust adhesion agents may include a surfactant. This
surfactant can be in addition to and/or different from the surfactant which is
present in the
sheet to enhance its wet cleaning capability. The surfactant component of the
dust
adhesion agent typically includes cationic and/or nonionic surfactant(s). The
surfactant
component generally makes up no more than 5-10 wt.% of the dust adhesion
agent. Thus,
a typical cleaning sheet which includes 5 wt.% dust adhesion agent (add-on
wt.% based on
the dry weight of the fabric layer being treated) generally contains no more
than about 0.5
wt.% surfactant which is present as a component of the dust adhesion agent.
Examples of
suitable cationic surfactants include rnono(long-chain
alkyl/alkenyl)trimethylammonium
salts, di(long-chain alkyl/alkenyl)dimethyl-ammonium salts, and mono(long-
chain
alkyl/alkenyl)dimethylbenzylammonium salts, each having an alkyl or alkenyl
group
containing 10 to 22 carbon atoms. Examples of suitable nonionic surfactants
for inclusion
as a dust adhesion agent include polyethylene glycol ethers, e.g.,
polyoxyethylene (6 to 35
mol) primary or secondary long-chain (C8 - C22) alkyl or alkenyl ethers,
polyoxyethylene
(6 to 35 mol) (C8 - Cl8) alkyl phenyl ethers, polyoxyethylene polyoxypropylene
bloclc
copolymers, and those of polyhydric alcohol type, e.g., glycerol fatty acid
esters, sorbitan
fatty acid esters, and alkyl glycosides. It is preferred that the surface
active agent contains
5% by weight or less of water to enhance effective cleaning.
The dust adhesion agents typically include a minor amount of a surfactant
together
with a lubricant. Typically, the dust adhesion agents include at least about
70 wt.% and,
preferably, at least about 80 wt.% of a lubricant made up of mineral oil,
synthetic oil
and/or silicone oil. One example of a suitable dust adhesion agent is made up
of 90-95
wt.% of a mineral oil such as petrolatum or a related paraffmic hydrocarbon
together with
5-10 wt.% of a nonionic surfactant, e.g., a polyoxyethylene allcyl ether such
as a
polyoxyethylene (C1z-Ci4) alkyl ether having an average of 3-5 oxyethylene
subunits.
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
- 18-
The present cleaning sheets typically are capable of picking up and retaining
at
least about at least about 15 g/m2 of dust. Stated otherwise, the cleaning
sheet has a
particle retention capacity of at least about 15 g/m2. Preferably, the
cleaning sheet has a
particle retention capacity of at least about 20 g/m2, more preferably at
least about 25
S g/m2.
The cleaning sheet may be used alone (e.g., as a rag) or in combination with
another implements) to clean a surface. Examples of suitable cleaning
implements which
can include the present cleaning sheet include mops, gloves, dusters, rollers,
or wipes. For
example, the cleaning sheet may be attached to a mounting structure, such as
the head of a
mop. The head typically includes a carriage providing fasteners for mounting
the sheet.
An elongate rigid member (such as a segmented handle) may be attached to
carriage by a
mounting structure. The mounting structure can include a yoke having a y-
shaped end
pivotally mounted to a socket (e.g., a ball joint). An adapter can be
threadably attached to
an arm of a handle. According to alternative embodiments, the cleaning utensil
may be a
broom, brush, polisher, handle or the like adapted to secure the cleaning
sheet.
The cleaning sheet may be attached to a head of a cleaning utensil, such as a
dust
mop. The cleaning pad typically includes a layer of nonwoven microfibers which
has a
discontinuous pattern of regions in which a surfactant has been deposited on
the
microfibers to enhance the wet cleaning capability of the sheet. Debris can be
forced
20. and/or drawn into the pores in the outer cleaning surface and become
entrapped between
the fibers of the nonwoven aggregate layer when the pad is moved along a
surface to be
cleaned. As discussed elsewhere herein, the cleaning sheet is generally
somewhat flexible
to permit surfaces with different contours (e.g., smooth, irregular, creviced,
etc.) to be
cleaned. According to an alternative embodiment, the cleaning sheet may be
semi-rigid,
e.g., where it is designed to be utilized for cleaning planar surfaces.
The cleaning sheet may be attached to the cleaning utensil by any of a variety
of
fasteners (e.g., friction clips, screws, adhesives, retaining fingers, etc.)
as are known to one
of skill that reviews this disclosure. According to other alternative
embodiments, the
cleaning sheet may be attached as a single unit, or as a plurality of sheets
(e.g., strips or
"hairs" of a mop).
According to another embodiment, the components of the cleaning utensil,
namely
the mounting structure, adapter and handle may be provided individually or in
combinations as a kit or package. The components of the cleaning utensil may
be readily,
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
- 19-
easily and quickly assembled and disassembled in the field (e.g., work site,
home, office,
etc.) for compactablity and quick replacement. The components of the cleaning
utensil
may also be provided in a pre-assembled and/or unitary condition. In one
particularly
suitable embodiment, the cleaning sheet is configured for use with the
Pledge° Grab-ItTM
S sweeper commercially available from S.C. Johnson & Son, Inc. of Ravine,
Wisconsin.
To clean a surface, a cleaning sheet can be secured to the head of a mop. The
sheet
may be brought into contact with surface and moved along this surface (e.g.,
in a
horizontal direction, vertical direction, rotating motion, linear motion,
etc.). Debris from
surface is commonly entrained within the cavities in the fabric layer. Finer
particulate
material can become entrapped in pores between the fibers of the fabric. After
use, the
sheet may be removed from mop for disposal or cleaning (e.g., washing,
shaking,
removing debris, etc.) prior to reuse. According to an alternative embodiment,
the
cleaning sheet may be used alone (e.g., hand held) to clean the surface.
Test Methods:
1S (1) Breaking strength (cross machine direction)
From each of the sheets, samples having a width of 30 mm were cut out in the
direction perpendicular to the fiber orientation.in the sheet, i.e., in the
cross machine
direction. The sample was chucked with a chuck-to-chuck distance of 100 mm in
a tensile
testing machine and elongated at a rate of 300 mm/min in the direction
perpendicular to
the fiber orientation. The value of load at which the sheet began to break
(the first peak
value of the continuous curve obtained by the stress/strain measurement) was
taken as the
breaking strength.
(2) Elongation at a load of S00 g/30 rnln
The elongation of the sample, at a load of S00 g in the measurement of the
2S breaking strength in the cross machine direction described above, was
measured. For the
purposes of this application, "elongation" is defined as the relative increase
in length (in
%) of a 30 mm strip of cleaning sheet material when a tensile load of S00 g is
applied to
the strip.
(3) Entanglement coefficient
The network sheet is removed from the nonwoven fiber aggregate. Where the
network sheet has a lattice-like net structure, this is typically accomplished
by cutting the
fibers which make up the network sheet at their junctures and carefully
removing the
fragments of the network sheet from the nonwoven fiber aggregate with a
tweezers. A
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
- 20 -
sample having a width of 15 mm is cut out in the direction perpendicular to
the fiber
orientation in the sheet (i:e., in the cross machine direction). The sample is
chucked with a
chuck-to-chuck distance of 50 mm in a tensile testing machine, and elongated
at a rate of
30 mmlmin in the direction perpendicular to the fiber orientation (in the
cross machine
direction). The tensile load value F (in grams) with respect to the elongation
of the sample
is measured. The value, which is obtained by dividing the tensile load value F
by the
sample width (in meters) and the basis weight of the nonwoven fiber aggregate
W (in
g/m2), is taken as the stress, S (in meters). A stress-strain curve is
obtained by plotting
stress ("S") against the elongation ("strain" in %).
Stress S [m]=(F/0.015)/W
For a nonwoven fiber aggregate, which is held together only through the
entanglement of the fibers, a straight-line relationship is generally obtained
at the initial
stage of the stress-strain (elongation) curve. The gradient of the straight
line is calculated
as the entanglement coefficient E (in meters). For example, in the
illustrative stress-strain
curve shown in FIG. 6 (where the vertical axis represents the stress, the
horizontal axis
represents the strain, and O represents the origin), the limit of straight-
line relationship is
represented by P, the stress at P is represented by Sp, and the strain at P is
represented by
yp. In such cases, the entanglement° coefficient is calculated as
E=Sp/yp. For example,
when Sp=60 m and yp=~6%, E is calculated as E=60/0.6=70 m. It should be noted
that
the line OP is not always strictly straight. In such cases, the line OP is
approximated by a
straight line.
The articles and methods of the present invention may be illustrated by the
following examples, which are intended to illustrate the present invention and
to assist in
teaching one of ordinary skill how to make and use the invention. These
examples are not
intended in any way to limit or narrow the scope of the present invention.
Example 1
A scrim supported polyester fiber nonwoven cloth can be formed by
hydroentangling a polypropylene scrim sandwiched between two carded polyester
fiber
webs. The polypropylene scrim is a grid of 0.2 mm diameter fibers with a 9 mm
spacing
between adjacent fibers and had a basis weight 5 g/m2. The two carded
polyester webs
are formed from 1.5 denier polyethylene terephthalate ("PET") fibers 51 mm in
length.
Each of the carded polyester webs has a basis weight of 24 g/m2. The
combination of the
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
-21-
polypropylene scrim and the two carded polyester webs is subjected to water
needling
("hydroentanglement") under low energy conditions to produce a unitary
nonwoven sheet
having a breaking strength of 1500 to 2500 g/30 mm (CD) and an elongation (at
SOOg/30
mm) of 4%. The hydroentanglement is conducted such that after removal of the
S supporting scrim from the unitary nonwoven sheet, the remaining
hydroentangled
polyester web has an entanglement coefficient of 6S-70 m.
A dust adhesion agent (viscosity: 12S cps, surface tension: 30 dyn/cm)
consisting
of 9S% of liquid paraffin and S% of nonionic surfactant (polyoxethylene
(average moI
number: 3.3) (Cl2-Cis) alkyl ether) is then applied to the reinforced nonwoven
aggregate
to enhance its dust collecting capabilities. The dust adhesion agent is
commonly applied
uniformly to one surface of the nonwoven aggregate in an amount which results
in S wt.%
(based on the dry weight of the fiber aggregate) dust adhesion agent being
deposited on
the fibers of the aggregate.
A mixture of a volatile solvent, such as ethanol, and polyoxypropylene-
1 S polyoxyethylene block copolymer (available under the tradename
Pluronic° P l OS from
BASF Corp., Mount Olive, NJ) is then imprinted onto one surface of the fabric
in a
discontinuous pattern of dots, such as depicted in Figure 1. The amount of the
mixture
applied to the fabric is such that 3 wt.% copolymer (based on the dry weight
of the
nonwoven fabric) is present in the sheet after the volatile solvent has been
removed. The
"dotted regions" typically contains the copolymer deposited on fibers in the
interior of the
fabric layer as well as on fibers on the surface of the aggregate (e.g., as
depicted in Figure
2). The solvent is removed by passing a stream of air over the surfaces of the
fabric.
Example 2
Another example of a cleaning sheet can be produced by imprinting a mixture of
2S volatile solvent such as ethanol and a hydroxyalkyl amide surfactant, e.g.,
lauramide DEA
(available under the tradename Ninol° 96-SL from Stepan Co.,
Northfield, IL) onto a
woven microfiber fabric, such as a sheet of ScotchbriteTM material (available
from 3M
Corporation, St. Paul, MN). An amount of a SO wt.% solution of Ninol" 96-SL
sufficient
to result in a sheet with S wt.% Ninol° 96-SL (based on the dry weight
of the woven
fabric) is imprinted onto one surface of the fabric in a regular pattern of
wavy lines, such
as depicted in Figure 3. The volatile solvent (ethanol) can be removed by
passing a stream
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
-22-
of air over the sheet until the weight of the fabric has been reduced by an
amount
corresponding to the amount of ethanol applied. If desired, the treated fabric
layer may be
heated as well to speed the removal of the ethanol.
Example 3
Polyester fiber web having a basis weight of 10 g/m2 can be prepared by a
conventional carding maclune from polyester fiber 51 mm in length and 1.5
denier in
diameter. The fiber web is lapped in 3 layers (30 g/m2) and layers of the
lapped fiber web
are overlaid on the upper and lower sides, respectively, of a biaxially
shrinlcable
polypropylene net (mesh: 5, fiber diameter: 0.215 mm). The resulting
combination is
subjected to a water needling process to entangle the fiber webs and the net.
The water
pressure used in the water needling process is about 35-40 kg/cm2 at a nozzle
pitch of 1.6
mm while the combination of fiber web and polypropylene net is moved past the
nozzles
at a line speed of Sm/min. The hydroentangled combination is then subjected to
heat
treatment with hot air (130°C) for about 1-2 minutes to simultaneously
dry the web and
shrink the polypropylene net. This produces a reinforced nonwoven aggregate
having an
area shrinkage coefficient of 10% in which depressions and projections are
formed over
the major surfaces. If desired, 5 wt.% (based on the dry weight of the fiber
aggregate) of a
dust adhesion agent (viscosity: 125 cps, surface tension: 30 dyn/cm)
consisting of 95% of
liquid paraffin and 5% of nonionic surfactant (polyoxethylene (average mol
number: 3.3)
(C12-Ci3) alkyl ether) can be applied to the reinforced nonwoven aggregate to
enhance its
dust collecting capabilities. A 60°C melt of PEG-20 stearate (mp -
41°C; HLB 15.7;
available from Stepan Co., Northfield, IL) is then applied to one surface of
the web in a
discontinuous regular pattern of dots covering 6% of the surface. The
surfactant is applied
in an amount such that the surfactant makes up 5 wt.% of the total weight of
the nonwoven
web.
INDUSTRIAL APPLICABILITY_
The cleaning sheet of the present invention can be manufactured using
commercially available techniques, equipment and material. In addition, the
cloth may be
used on a variety of surfaces such as plastic, wood, carpet, fabric, glass and
the like.
Cleaning implements and methods of cleaning surfaces using the cleaning sheet
are
also provided herein. The cleaning implement may be produced as an intact
implement or
in the form of a cleaning utensil kit. Intact implements include gloves,
dusters and rollers.
Kits according to the present invention, which are designed to be used for
cleaning
CA 02413892 2002-12-23
WO 02/00819 PCT/USO1/20074
-23-
surfaces, commonly include a cleaning head and a cleaning sheet capable of
being coupled
to the cleaning head. In addition, the kit can include a yoke capable of
installation on the
cleaning head and an elongate handle for attachment to the yoke. Whether
provided as a
completely assembled cleaning implement or as a kit, the cleaning implement
may include
a cleaning head that allows the cleaning sheet to be removably attached to the
cleaning
head.
While the making and using of various embodiments are discussed in some detail
herein, it should be appreciated that the present invention provides inventive
concepts
which can be embodied in a wide variety of specific contexts. The specific
embodiments
discussed herein are merely illustrative of specific ways to make and use
cleaning sheets
and are not meant to limit the scope of the invention. Various modifications
and
combinations of the illustrative embodiments, as well as other embodiments of
the
invention, will be apparent to persons skilled in the art upon reference to
the description.
