U.S. patent application number 11/112684 was filed with the patent office on 2006-10-26 for cleaning sheet and method of making.
Invention is credited to Thomas E. Haskett, Scott J. Tuman.
Application Number | 20060240223 11/112684 |
Document ID | / |
Family ID | 36821519 |
Filed Date | 2006-10-26 |
United States Patent
Application |
20060240223 |
Kind Code |
A1 |
Tuman; Scott J. ; et
al. |
October 26, 2006 |
Cleaning sheet and method of making
Abstract
A cleaning sheet includes a substrate having opposed major
surfaces, an adhesive, such as an adhesive, coated onto at least a
portion of at least one of the substrate major surfaces, and loose
fibers arranged on the adhesive, wherein at least one of the
individual fibers contacts the adhesive at more than one point. A
method of making the cleaning sheet is also disclosed.
Inventors: |
Tuman; Scott J.; (Woodbury,
MN) ; Haskett; Thomas E.; (Oakdale, MN) |
Correspondence
Address: |
3M INNOVATIVE PROPERTIES COMPANY
PO BOX 33427
ST. PAUL
MN
55133-3427
US
|
Family ID: |
36821519 |
Appl. No.: |
11/112684 |
Filed: |
April 22, 2005 |
Current U.S.
Class: |
428/143 ;
428/174 |
Current CPC
Class: |
D04H 11/00 20130101;
Y10T 428/24628 20150115; A47L 13/16 20130101; D04H 1/593 20130101;
Y10T 428/24372 20150115; D04H 3/14 20130101 |
Class at
Publication: |
428/143 ;
428/174 |
International
Class: |
E01F 9/04 20060101
E01F009/04 |
Claims
1. A cleaning sheet, comprising: (a) a substrate having opposed
major surfaces; (b) an adhesive on at least a portion of at least
one of the substrate major surfaces; and (c) loose fibers arranged
on the adhesive, wherein at least one of the individual fibers
contacts the substrate or adhesive at more than one point.
2. A cleaning sheet as defined in claim 1, wherein the loose fibers
are arranged randomly.
3. A cleaning sheet as defined in claim 2, wherein the individual
loose fibers have an average length of at least about 25
millimeters.
4. A cleaning sheet as defined in claim 3, wherein a majority of
the loose fibers contact the substrate at more than one point.
5. A cleaning sheet as defined in claim 4, wherein the majority of
loose fibers contact the adhesive at more than one point.
6. A cleaning sheet as defined in claim 5, wherein the adhesive is
a pressure sensitive adhesive.
7. A cleaning sheet as defined in claim 6, wherein the region
having loose fibers defines a loose fiber layer having a basis
weight of no greater than about 20 g/m.sup.2.
8. A cleaning sheet as defined in claim 7, wherein the loose fiber
layer has an average thickness of no greater than about 3
millimeters.
9. A cleaning sheet as defined in claim 8, wherein the loose fibers
are crimped.
10. A cleaning sheet as defined in claim 9, wherein loose fibers
include a blend of fibers having different deniers.
11. A cleaning sheet as defined in claim 10, wherein both major
surfaces of the substrate are coated with adhesive.
12. A cleaning sheet as defined in claim 11, wherein the adhesive
is a continuous layer provided on the entire major surface of the
substrate.
13. A cleaning sheet as defined in claim 12, wherein at least one
major surface of the substrate has a macroscopically
three-dimensional surface topography.
14. A cleaning sheet as defined in claim 13, wherein the loose
fibers define an outward surface of the cleaning sheet that is
macroscopically planar.
15. A disposable cleaning sheet, comprising: (a) a fibrous spunbond
nonwoven substrate having a basis weight ranging from about 40
g/m.sup.2 to about 60 g/m.sup.2, the substrate including at least
one major surface having a three-dimensional surface topography;
(b) a pressure sensitive adhesive coated onto at least a portion of
at least one of the substrate major surfaces; and (c) a layer of
crimped loose fibers arranged randomly on the adhesive surface of
the substrate, wherein the layer of loose fibers has a basis weight
of no greater than about 20 g/m.sup.2, the loose fibers have an
average length of at least about 25 millimeters, the majority of
the loose fibers contact the substrate at more than one point, and
the loose fibers define a macroscopically planar outward surface of
the cleaning sheet.
16. A method of making a cleaning sheet, comprising the steps of:
(a) providing a web of material having an adhesive coated on at
least a portion the web; and (b) randomly depositing loose fibers
on the web at least in the regions of the adhesive, thereby
attaching the loose fibers to the web.
17. The method of claim 16, wherein the loose fibers are deposited
by staple fiber handling equipment.
18. The method of claim 16, further comprising the step of forcing
the loose fibers against the web.
19. The method of claim 16, wherein the loose fibers are applied to
the substrate at a generally constant thickness, and the loose
fibers define an outward surface that is macroscopically
planar.
20. A cleaning sheet made according to the process of claim 16.
Description
FIELD
[0001] The present invention relates generally to cleaning sheets
that are used, for example, to clean floors, countertops or
furniture.
BACKGROUND
[0002] Wipes and cleaning sheets are known. Japanese Kokai Patent
Application No. 2002-17639, for example, discloses a cleaning sheet
consisting of a base sheet and fiber layer provided with raised
fibers on the cleaning surface side of the base sheet. The cleaning
surface of the sheet has a structure comprising the fiber layer.
The cleaning surface has adhesive, and the spaces between the
raised fibers form free areas capable of collecting material from
the surface to be cleaned.
[0003] Japanese Kokai Patent Application No. HEI 11-253382
discloses a dust removal sheet having a sheet-like base material
and an adhesive layer formed on the base material used for trapping
dust on the floor, etc. The sheet includes a dust trapping layer
consisting of a sheet-like fiber material having voids between the
fibers that is laminated onto the adhesive layer to cover the
adhesive layer.
[0004] The industry, however, is always seeking improved wipes. It
would be desirable to provide a cleaning sheet that is easy and
inexpensive to make, is easy to handle and use, is durable, has
superior cleaning capability, and does not create unwanted noise
when moved across the surface to be cleaned.
SUMMARY OF THE INVENTION
[0005] The present invention provides a cleaning sheet including a
substrate having opposed major surfaces, an adhesive on at least a
portion of at least one of the substrate major surfaces, and loose
fibers arranged on the adhesive, wherein at least one of the
individual loose fibers contacts the substrate at more than one
point. In one aspect, the fibers are arranged randomly. In another
aspect, the loose fibers have an average length of at least about
25 millimeters. In another aspect, the loose fibers are crimped. In
yet another aspect, a majority of the loose fibers contact the
substrate and/or the adhesive at more than one point. In a more
particular aspect, the adhesive is a pressure sensitive
adhesive.
[0006] In one embodiment, the region of the cleaning sheet having
loose fibers defines a fiber layer having a basis weight of no
greater than about 20 g/m.sup.2. In another embodiment, the fiber
layer has an average thickness of no greater than about 3
millimeters.
[0007] In another embodiment, at least one major surface of the
substrate has a macroscopically three-dimensional surface
topography. In another embodiment, the loose fibers are arranged
over the macroscopically three-dimensional surface and define an
outward surface of the cleaning sheet that is macroscopically
planar.
[0008] In a specific embodiment, the present invention provides a
disposable cleaning sheet including a fibrous spunbond nonwoven
substrate having a basis weight ranging from about 40 g/m.sup.2 to
about 60 g/m.sup.2, the substrate including at least one major
surface having a three-dimensional surface topography; a pressure
sensitive adhesive coated onto at least a portion of at least one
of the substrate major surfaces; and a layer of crimped loose
fibers arranged randomly on the adhesive surface of the substrate,
wherein the layer of loose fibers has a basis weight of no greater
than about 20 g/m.sup.2, the loose fibers have an average length of
at least about 25 millimeters, the loose fibers project
perpendicularly outwardly from the substrate a distance of no
greater than about 5 millimeters, the majority of the loose fibers
contact the substrate at more than one point, and the loose fibers
define a macroscopically planar outward surface of the cleaning
sheet.
[0009] In another aspect, the present invention provides a method
of making a cleaning sheet by providing a web of material having an
adhesive coated on at least a portion the web, and randomly
depositing loose fibers on the web at least in the regions of the
adhesive, thereby attaching the loose fibers to the web. The web of
material is preferably a nonwoven web of fibrous material.
[0010] The loose fibers may be deposited using staple fiber
handling equipment such as carding equipment (e.g. a Hergeth or
Garnett card ), aerodynamic web forming equipment (e.g. a Rando
machine), or a lickerin roll in combination with a blower. In
addition, the loose fibers may be forced against the web. In a more
specific aspect, the loose fibers are applied to the substrate at a
generally constant thickness, and the loose fibers define an
outward surface that is macroscopically planar.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The present invention will be further described with
reference to the accompanying drawings, in which:
[0012] FIG. 1 perspective view of a cleaning sheet according to the
invention;
[0013] FIG. 2 is a cross-sectional view taken along line 2-2 of
FIG. 1;
[0014] FIG. 3 is a cross-sectional view of a second embodiment of
the invention;
[0015] FIG. 4 is a perspective view of a third embodiment of the
invention;
[0016] FIG. 5 is perspective view of a fourth embodiment of the
invention;
[0017] FIG. 6 is a schematic representation of an apparatus for
making the cleaning sheets of FIGS. 1-3; and
[0018] FIG. 7 is a schematic representation of an apparatus for
making the cleaning sheets of FIGS. 4 and 5.
DETAILED DESCRIPTION
[0019] Referring now to the drawings, wherein like reference
numerals refer to like or corresponding features throughout the
several views, FIGS. 1-2 show a cleaning sheet or wipe 10 including
a backing layer or substrate 12 having opposed bottom and top major
surfaces 18, 20, adhesive 14 on the top surface 20 of the substrate
12, and loose fibers 16 arranged on the adhesive 14.
[0020] FIG. 3 shows a cleaning sheet 10 similar to the cleaning
sheet of FIGS. 1-2, except in FIG. 3, the substrate 12 includes two
layers, a primary backing layer 22 and a secondary backing layer
24.
[0021] FIG. 4 shows a cleaning sheet 10 similar to the cleaning
sheet of FIGS. 1-2, except in FIG. 4, the top surface 20 of the
substrate 12 is provided with a three-dimensional surface
topography defined by a plurality of raised 26 and recessed 28
regions. The surface topography may range from a relatively fine
embossed pattern that does not significantly alter the surface
profile of the substrate 12, to a relatively large macroscopically
three-dimensional surface topography that is readily noticed by an
observer viewing the substrate 12. In addition, the surface
topography may be provided as a regular repeating pattern or the
surface topography may be completely random.
[0022] The adhesive 14 may be pattern coated into the recessed
regions 28 only or coated onto one or both of the entire bottom 18
and top 20 surfaces of the substrate 12. The bottom surface 18 of
the substrate 12 is generally planar. In the illustrated
embodiment, the raised regions 26 are generally dome-shaped regions
having sloping side surfaces that are separated by a continuous
rectilinear array of recessed valleys having an exposed adhesive
therein.
[0023] Even if the adhesive 14 is applied only to the recessed
regions 28 of the substrate 12, the loose fibers 16 will be
arranged substantially over the entire top surface 20 of the
substrate because the loose fibers 16 are long enough to contact at
least one adhesive recessed region 28 and still extend over one or
more of the adjacent non-adhesive raised regions 26. Because the
loose fibers 16 act as spacers, a substrate having a low profile of
raised and recessed regions with exposed adhesive in the recessed
regions, which would otherwise experience excessive drag, may be
used. That is, if a cleaning sheet has raised and recessed regions
and has exposed adhesive in the recessed regions, and the cleaning
sheet does not have loose fibers, the adhesive free raised regions
act as the spacers to prevent excessive drag. With this
construction, the raised regions alone must be large enough to
provide sufficient spacing to prevent excessive drag when the
cleaning sheet is wiped across the surface to be cleaned. When
loose fibers are added to the surface of the cleaning sheet,
however, the raised regions can be made much smaller (i.e. the
three-dimensional surface topography of the cleaning sheet can be
made finer) without experiencing excessive drag. In addition, when
loose fibers are arranged over a cleaning sheet having a
macroscopically three-dimensional surface topography, the entire
macroscopically three-dimensional surface (i.e. including the
raised surface regions) may be coated with adhesive without
experiencing excessive drag.
[0024] Coating the entire top surface 20 of the substrate 12 (i.e.
coating both the raised 26 and recessed 28 regions of the surface
20) with adhesive 14 is advantageous because it increases the
overall holding capacity of the cleaning sheet by increasing the
surface area available to capture and retain dust, dirt and other
debris. The loose fibers 16 make it possible to coat the entire top
surface 20 with adhesive because the loose fibers 16 act as spacers
between the adhesive 14 and the surface being cleaned, thereby
reducing drag and allowing the cleaning sheet to be easily wiped
across a surface.
[0025] FIG. 5 shows a cleaning sheet 10 similar to the cleaning
sheet of FIG. 4 except that in FIG. 5, instead of the bottom
surface 18 of the substrate 12 being planar, the bottom surface 18
includes recesses 30 corresponding to and matching the raised
regions 26 on the top surface 20.
[0026] For the cleaning sheet 10 of FIGS. 4 and 5, the substrate 12
may be a unitary sheet of material, or the substrate may comprise
multiple layers, one or both of which may be a nonwoven material.
In addition, for the cleaning sheet of FIG. 5, the substrate 12 may
have a generally uniform thickness and density.
[0027] Additional details of the substrate 12, adhesive 14, and
loose fibers 16 are described separately in more detail below.
[0028] As used herein, "loose fibers" refers to a mass of fibers
that, prior to being arranged on the adhesive 14, are generally
free floating, detached, and/or unrestrained. The mass of loose
fibers has minimal tensile strength, is not self-supporting, and
does not form a separately handleable web. The fibers may contact
each other at various points but the fibers are not entangled,
fused, bonded or otherwise attached or joined in a post treatment
step to provide the fiber mass with added structural integrity
prior to being deposited on the substrate. A stream of loose fibers
is produced by staple fiber handling equipment such as carding
equipment (e.g. a Hergeth or Garnett card), aerodynamic web forming
equipment (e.g. a Rando machine), or a lickerin roll in combination
with a blower, and are deposited directly onto the adhesive surface
of the substrate.
Substrate
[0029] The substrate 12 may be formed from a variety of materials.
Suitable materials include paper, foam, sponge, a knitted or woven
fabric material, a fibrous nonwoven web, a nonwoven film such as a
thermoplastic film, or laminates thereof. The particular substrate
material is not particularly significant to the invention hereof,
so long as it provides the desired functional capabilities such as
sufficient strength for handling during processing, sufficient
strength to be used for the intended end use application, and the
ability to have the adhesive 14 transferred to at least one of its
major surfaces.
[0030] The web used to form the substrate 12 may be, for example, a
spunlace nonwoven material that is provided with a pre-formed
texture or pattern. Such a substrate may be entirely coated with
adhesive or be pattern coated with adhesive 14.
[0031] The substrate 12 may be continuous, meaning it does not
contain holes, voids, or channels extending there through in the Z
direction (i.e. the thickness or height dimension) that are larger
than the randomly formed spaces between the material itself when it
is made. Alternatively, the substrate 12 may be perforated or
otherwise be made to be discontinuous.
[0032] In the illustrated embodiment, the opposed major surfaces
18, 20 of the substrate 12 are generally planar and parallel. That
is, the opposed major surfaces 18, 20 are generally flat and
therefore generally free of any macroscopic three-dimensional
surface topography. Alternatively, one or both of the opposed major
surfaces 18, 20 may be provided with an embossed, contoured, or
otherwise macroscopically three-dimensional surface topography as
shown, for example, in FIGS. 4 and 5.
[0033] Depending on the particular surface topography of the
substrate 12, the loose fibers 16 may either follow the contour of
the substrate or they may overlay and be generally unaffected by
the surface topography of the underlying substrate. For example, if
the substrate 12 includes relatively large raised and recessed
regions (e.g., having a height differential of 10 millimeters and a
peak to peak distance of 10 millimeters), or includes other
significant three-dimensional surface characteristics, the loose
fibers 16 may, at least to some degree, mirror or follow the
surface topography of the substrate 12. In this case, the loose
fibers 16 will create an outward cleaning surface having a surface
topography that is also macroscopically three-dimensional working
face. On the other hand, if the substrate 12 is, for example,
embossed with a fine surface pattern, the loose fibers 16 will tend
to lay across the embossed pattern and will be generally unaffected
by the surface topography of the underlying substrate. In this
case, the loose fibers 16 will create an outward cleaning surface
having a surface topography that is macroscopically planar, that
is, the surface of the cleaning sheet will appear generally flat
with little or no three-dimensionality to an observer.
[0034] In addition, if the substrate includes raised and recessed
regions with adhesive exposed only in the recessed regions as shown
and described in U.S. Patent Application Publication No. US
2003/0171051 (Bergsten), the entire contents of which are hereby
incorporated by reference, the loose fibers may be deposited and
retained in the recessed regions, thereby "filling" the recessed
regions to create a cleaning sheet having a generally flat or
planar outward surface that is generally free of macroscopic
three-dimensionality.
[0035] One or both opposed major surfaces 18, 20 of the substrate
12 may also optionally include printing. The substrate 12, for
example, may be printed with graphics, logos, or other indicia. The
substrate may also be printed to give a generally planar substrate
the appearance of having a macroscopically three-dimensional
surface topography.
[0036] The substrate 12 is preferably formed from a fibrous
nonwoven web. The nonwoven web may be prepared by any suitable melt
forming or mechanical forming operation. For example, the nonwoven
web may be carded, spunbonded, spunlaced, melt blown, air laid,
creped, or made by other processes known in the art.
[0037] Preferred webs include nonwoven webs made from one or more
of a variety of thermoplastic polymers that are known to form
fibers. Suitable thermoplastic polymers can be selected from
polyolefins (such as polyethylenes, polypropylenes, and
polybutylenes), polyamides (such as nylon 6, nylon 6/6, and nylon
10), polyesters (such as polyethylene terephthalate), copolymers
containing acrylic monomers, and blends and copolymers thereof.
Semi-synthetic fibers (such as acetate fibers), natural fibers
(such as cotton), regenerated fibers (such as rayon), and other
non-thermoplastic fibers can also be blended with the thermoplastic
fibers.
[0038] In a preferred embodiment, the web includes a blend of
fibers and one of the fibers is a binder fiber. In one embodiment,
the binder fibers are activated by heat. Such binder fiber may
comprise from about 5% to about 90% of the web weight and more
generally from about 30% to about 50%. A suitable binder fiber is
available under the trade designation CELBOND T254 12 denier fiber
available from Kosa Incorporated, Wichita, Kans.
[0039] The fibers used to form the web typically have a minimum
denier of at least about 1, more typically at least about 2, and
even more typically at least about 5, and a maximum denier of no
greater than about 50, more typically no greater than about 30, and
even more typically no greater than about 15.
[0040] The web typically has a minimum basis weight of at least
about 5 grams per square meter (g/m.sup.2), more typically at least
about 10 g/m.sup.2, and even more typically at least about 20
g/m.sup.2, and a maximum basis weight of no greater than about 150
g/m.sup.2, more typically no greater than about 100 g/m.sup.2, and
even more typically no greater than about 75 g/m.sup.2.
[0041] The web typically has a minimum uncompressed thickness of at
least about 0.1 mm, more typically at least about 0.2 mm, and even
more typically at least about 0.5 mm, and a maximum uncompressed
thickness of no greater than about 25 mm, more typically no greater
than about 8 mm, and even more typically no greater than about 5
mm.
[0042] A particularly suitable substrate 12 is a carded web formed
of a blend of two sizes of polyester fibers, the first fibers
having a denier of about 2-4 and the second having a denier of
about 10-15. The web has a basis weight of about 50 g/m.sup.2 and a
thickness of about 3 mm.
[0043] As shown in FIG. 3 the substrate 12 may include a secondary
backing layer 24 arranged adjacent the primary backing layer 22.
The secondary backing layer 24 may be, for example, a net, scrim,
foam, a knitted or woven fabric, filament strands, a nonwoven web,
paper, a plastic film, or laminates thereof. If the secondary
backing layer 24 is a nonwoven layer or a knitted or woven fabric,
it may optionally serve as a second wiping surface.
[0044] If the secondary backing layer 24 is a plastic film, a
polyolefin (such as polypropylene or polyethylene), a polyamide, a
polyester, or other film may be used. The thickness of the film
maybe from about 0.012 mm (0.5 mils) to about 0.075 mm (3 mils). If
the film is extrusion bonded to a nonwoven web, then it is
preferable that the nonwoven web and the film layer be of
compatible materials so that adequate bonding between the two
members is obtained.
Adhesive Layer
[0045] The adhesive 14 serves to bond the loose fibers 16 to the
substrate 12. In addition, if the adhesive 14 remains tacky after
being applied to the substrate 12, the adhesive 14 also serves to
retain dust, dirt, debris and other particles during the cleaning
process. The adhesive 14 may be applied uniformly over one or both
of the entire first and second major surfaces 18, 20 of the
substrate 12, or the adhesive 14 may be applied discontinuously to
selected regions of one or both of the first and second major
surfaces 18, 20. For example, the adhesive 14 may be applied to the
surfaces 18, 20 as dots or strips, or may be applied only in the
recessed regions of a cleaning sheet having raised and recessed
regions. The adhesive may be applied by a variety of methods such
as roll coating, curtain coating, stripe coating, pattern coating,
spray coating, screen printing, etc., as is known in the art.
[0046] In one embodiment, the adhesive 14 is a tacky polymer, more
particularly an adhesive and, even more particularly, a
pressure-sensitive adhesive. Suitable adhesives include those that
are capable of being tacky at room temperature, including those
adhesives that are initially tacky and either remain tacky or
become non-tacky after drying or curing, and those that are
initially non-tacky but which can be activated to become tacky.
[0047] Suitable adhesives include any pressure-sensitive adhesives,
including materials based on acrylates, silicones,
poly-alpha-olefins, polyisobutylenes, rubber block copolymers (such
as styrene/isoprene/styrene and styrene/butadiene/styrene block
copolymers), styrene butadiene rubbers, synthetic isoprenes,
natural rubber, and blends thereof. The pressure-sensitive
adhesives may be coated from solvent, from water, radiation
polymerized, or hot melt processed. The pressure-sensitive
adhesives may or may not be crosslinked. Crosslinking can be done
by well-known methods, including chemical, ionic, physical, or
radiation-induced processes. To improve the cohesive strength of
the adhesive once it is deposited onto the substrate, some
crosslinking may be used.
[0048] To allow for low viscosity for easy processing while
providing for good cohesive strength, adhesives with physical
crosslinking, ionic crosslinking, or some form of post-crosslinking
are preferred. Post-crosslinking can be carried out by exposing the
adhesive to radiation, such as electron-beam or high intensity
ultraviolet (UV) radiation. For UV crosslinking, it may be
desirable to incorporate a photo-receptive group into the polymer
backbone to facilitate the crosslinking reaction.
[0049] U.S. Pat. No. 4,737,559 (Kellen et al.) discloses examples
of such UV-crosslinked adhesives. Physical or ionic crosslinking
provide the advantage that the process is thermally reversible,
making it particularly preferred for hot-melt processing.
Physically crosslinked adhesives include those based on rubber
block copolymers. Examples of synthetic rubber block copolymers
include Kraton.TM. commercially available from Kraton Polymers of
Houston, Tex., and Vectorm.TM. commercially available from
Exxon-Mobil of Houston, Tex. These block copolymers are typically
formulated into pressure-sensitive adhesives by compounding them
with tackifiers and/or oils. Other physically crosslinked adhesives
include macromer grafted polymers as disclosed in U.S. Pat. No.
5,057,366 (Husman et al.).
[0050] The adhesives useful in this invention may be tacky under
both dry and wet conditions. Adhesives with high tack under wet
conditions are disclosed in a PCT Publication Number WO 00/56828.
The pressure-sensitive adhesives may also be coated from water in
the form of a latex or dispersion. These adhesives may be based on
polymers like natural rubber, acrylates, styrene-butadienes, and
vinyl ethers. Especially when coated directly on a porous, woven,
or nonwoven substrate, the latex adhesives may not be viscous
enough to prevent excessive penetration into the substrate. Whereas
the viscosity and flow of the latex adhesive may be controlled by
the solids content of the material, it may be more beneficial to
formulate the latex with thickening agents. Thickening agents are
typically categorized as water-soluble polymers or associative
thickeners. In the case of pressure-sensitive adhesives, particular
care has to be taken in the selection of the thickening agent so it
does not interfere with the adhesive properties.
[0051] A suitable adhesive is a 95% iso-octyl acrylate, 5% acrylic
acid hot melt pressure-sensitive adhesive. Such adhesives are
described in U.S. Pat. No. 5,753,768, the entire contents of which
are hereby incorporated by reference.
[0052] The substrate 12 will typically include from about 2 weight
% to about 50 weight % of adhesive, more typically from about 10
weight % to about 20 weight % of adhesive, based on the weight of
substrate. Also, if the substrate 12 is pattern coated, the planar
ratio between areas of the substrate that have adhesive and those
that have no adhesive may range from about 80:20 to about
20:80.
[0053] The adhesive is typically coated onto the web at a minimum
weight of about 1 gram/m.sup.2, more typically at least about 2.5
grams/m.sup.2, and even more typically at least about 4
grams/m.sup.2, and at a maximum weight of no more than about 25
grams/m.sup.2, more typically no more than about 15 grams/m.sup.2,
and even more typically no more than about 10 grams/m.sup.2.
Loose Fibers
[0054] The loose fibers 16 act as a spacer between the surface
being cleaned and the adhesive 14. By acting as a spacer, the
fibers 16 prevent excessive drag that could make wiping difficult
or cause the adhesive to be transferred to the surface being
cleaned. Due to their openness, however, the loose fibers also
allow dust, dirt, debris, and other particles to effectively travel
through the layer of loose fibers and into contact with the
adhesive 14 where they are captured and held, thereby improving the
holding capacity and cleaning ability of the cleaning sheet 10. The
loose fibers 16 themselves also serve to trap dust, dirt, debris,
and other particles during use of the sheet. The loose fibers 16
are preferably selected to minimize the amount of noise generated
by the cleaning sheet as it is moved across the surface being
cleaned.
[0055] The loose fibers 16 are arranged randomly on the substrate
12 such that the majority of the loose fibers 16 contact the
substrate 12 at more than one point. That is, the majority of the
loose fibers 16 are not standing on end or otherwise extending
perpendicularly outwardly from the surface of the substrate 12, but
are tipped over and laying down on their sides. As the loose fibers
16 are deposited onto the substrate, preferably, they are generally
allowed to settle into their natural positions on the substrate 12.
Preferably, the loose fibers 16 free-fall onto the substrate under
the own weight only and are not otherwise positioned or arranged on
the substrate in any sort of orderly, systematic or controlled
manner. If the adhesive 14 is coated on the entire surface of the
substrate 12, the majority of the loose fibers 16 will also contact
the adhesive 14 at more than one point.
[0056] The loose fibers 16 are individually arranged in a random
manner with no discernable alignment or orientation among the
individual fibers. However, the loose fibers 16 may, as an
aggregate, be arranged in a pattern on the surface of substrate 12
such that selected regions of the substrate 12 are provided with
loose fibers 16 and other regions are essentially free of loose
fibers 16. This pattern coating of the loose fibers 16 may be
accomplished regardless of whether the adhesive 14 is coated over
the entire surface of the substrate or pattern coated onto only
selected regions of the substrate by placing a shield in the stream
of loose fibers 16 as they are deposited onto the substrate 12,
thereby to direct the loose fibers onto certain regions of the
substrate 12.
[0057] Suitable fibers for the loose fibers 16 include natural
fibers such as cotton, synthetic fibers such as thermoplastic
polymer fibers, semi-synthetic fibers such as acetate fibers,
regenerated fibers such as rayon, or other non-thermoplastic
fibers, and combinations thereof. Suitable thermoplastic polymers
can be selected from polyolefins (such as polyethylenes,
polypropylenes, and polybutylenes), polyamides (such as nylon 6,
nylon 6/6, and nylon 10), polyesters (such as polyethylene
terephthalate), copolymers containing acrylic monomers, and blends
and copolymers thereof.
[0058] The loose fibers 16 are affixed to the substrate 12 by the
adhesive 14. Thus, if the adhesive 14 is coated over the entire
surface of the substrate 12, the loose fibers 16 will form a
fibrous layer over the entire surface of the substrate 12, and if
the adhesive 14 is pattern coated onto only selected regions of the
substrate 12, the loose fibers 16 will be adhered to the substrate
12 only in the regions coated with the adhesive 14.
[0059] The loose fibers 16 typically have a minimum denier of at
least about 1, more typically at least about 5, and even more
typically at least about 10, and a maximum denier of no greater
than about 100, more typically no greater than about 70, and even
more typically no greater than about 50. The loose fibers 16 may
optionally include a blend of fibers having different deniers. In
addition, the individual loose fibers 16 typically have an average
length of at least about 15 mm, more typically at least about 25
mm, and even more typically, at least about 35 mm. Loose fibers of
this length are generally too long to stand on end (i.e. too long
to project outwardly in a generally perpendicular direction from
the surface of the substrate) and therefore tend to lay generally
horizontally on the substrate.
[0060] The fiber mass defined within a region adhered to the
substrate 12 (that is, excluding any area that is generally free of
loose fibers), typically has a maximum basis weight of no greater
than about 40 grams per square meter (g/m.sup.2), more typically no
greater than about 25 g/m.sup.2, and even more typically no greater
than about 15 g/m.sup.2.
[0061] The thickness of the layer of loose fibers 16 is typically
no greater than about 7 mm, more typically no greater than about 5
mm, and even more typically no greater than about 3 mm.
[0062] The loose fibers 16 may be produced and deposited on the
substrate 12 using conventional staple fiber handling equipment
such as carding equipment (e.g. a Hergeth or Garnett card ),
aerodynamic web forming equipment (e.g. a Rando machine), or a
lickerin roll in combination with a blower. The loose fibers 16 are
preferably deposited on the substrate 12 in a random manner, that
is, the fibers are not purposely oriented or aligned in any regular
fashion. In one aspect of the invention, at least some of the
fibers are non-linear. That is, at least some of the fibers are
curled, bent, crimped, and the like. In another aspect, the fiber
layer may include a blend of polarized fibers, such as polyester
fibers, and non-polarized fibers, such as polyolefin fibers.
[0063] The cleaning sheet 10 may be die cut in a variety of shapes
and sizes depending on the need. The cleaning sheet 10 may be used
alone as a dust cloth or in combination with a cleaning implement
or tool such as a mop, a duster, a roller, and the like. The
cleaning sheet 10 may also be formed into a mitt or glove that fits
over the user's hand to facilitate hand cleaning. The cleaning
sheets can be packaged as a stack of sheets that can be
individually dispensed from a package, or may be provided in roll
form similar to paper towels with perforations separating
individual sheets. The cleaning sheets may be used for general
purpose cleaning of hard surfaces such as tile or wood, or they may
be used on cloth, upholstery, and carpet. The cleaning sheet may
also be provided in relatively large sheets that can be used as a
floor mat to protect floors or used as a floor mat for automobiles.
The cleaning sheet may also be used as a tack cloth.
[0064] Additives may also be applied to the cleaning sheet to
provide improved performance or other desirable properties.
Additives include waxes, polishes, pest control ingredients,
antimicrobial agents, disinfectants, oils, dyes, colorants,
fragrant powders, soaps, detergents, abrasives and the like, and
other ingredients. The additive may be provided on the substrate 12
or between the primary 22 and secondary backing 24 layers so the
additive can act on a surface over which the cleaning sheet is
moved. In a particular embodiment, the cleaning sheet may include
an encapsulated fragrance such that the capsules rupture during use
and release the fragrance. In addition, the loose fibers may be
electrostically charged to enhance dust pickup.
[0065] The fibers of the substrate may be hydrophilic or may be
hydrophilically modified (for example with a surfactant) so that
both dry and damp wiping applications are possible.
[0066] The substrate 12 may also be provided with the adhesive 14
pre-applied such that the loose fibers 16 can be deposited onto a
pre-coated substrate. For example, the substrate 12 may comprise an
adhesively coated film similar to conventional tape. The loose
fibers can then be deposited directly onto the adhesive surface of
the film. Additional suitable substrates are described in, for
example, U.S. Patent Application Publication No. US 2003/0171051
(Bergsten), and in 3M Patent Docket No. 60452US002, application
Ser. No. 11/025,388, the entire contents of which are each hereby
incorporated by reference.
Method and Apparatus for Making
[0067] FIG. 6 schematically illustrates a method and apparatus 100
for making the cleaning sheet 10 described above in reference to
FIGS. 1-3. The apparatus 100 generally includes a dispenser 102, a
transfer roll 108, a backup roll 110, and a fiber depositing device
112. The dispenser dispenses adhesive 104, such as a pressure
sensitive adhesive, onto the outer surface of the transfer roll
108. The transfer roll 108, in turn, rotates counter-clockwise into
contact with a web of material 106, which is conveyed past the
transfer roll 108, and thereby applies the adhesive 104 onto a
surface of the web of material 106. After the adhesive 104 is
applied to the web 106, the fiber depositing device 112 deposits
loose fibers 114 onto the adhesively coated surface of the web
106.
[0068] Other known methods of applying the adhesive 104 to the
outer surface of the transfer roll 108, such as spraying the
adhesive directly onto the outer surface of the transfer roll 108
or using gravure coating to coat the outer surface of the transfer
roll with the adhesive, may also be used and are considered within
the scope of the present invention.
[0069] In addition, the adhesive may be applied to either the
transfer roll 108 or the web 106 in strips using known pattern
coating techniques to produce regions having the adhesive applied
thereto and adjacent regions free of the adhesive. Alternatively,
the adhesive 104 may be applied directly to the web 106, for
example, by curtain coating or spraying.
[0070] In the illustrated embodiment, a doctor blade 116 is
provided adjacent the outer surface of the transfer roll 108 to
spread the adhesive 104 uniformly over the entire outer surface of
the transfer roll 108. The blade 116 evenly distributes the
adhesive 104 and produces a smooth layer having a generally uniform
and constant thickness.
[0071] The device 112 may be a piece of staple fiber handling
equipment such as carding equipment (e.g. a Hergeth or Garnett card
), aerodynamic web forming equipment (e.g. a Rando machine), or a
lickerin roll in combination with a blower. The loose fibers 114
are deposited directly onto the substrate in-line. The apparatus
100 may further include a device (not shown) to force the loose
fibers 114 against the adhesive 104 to more securely bond the
fibers 114 to the web 106. This may be accomplished, for example,
using pressurized air, rollers, heat, ultra-sonically, and the
like.
[0072] In an alternative embodiment, a web having the adhesive
pre-applied may be provided, and the loose fibers 114 may be
deposited directly onto the surface of the web having the
adhesive.
[0073] FIG. 7 schematically illustrates a method and apparatus 100
for making the cleaning sheet 10 described above in reference to
FIGS. 4 and 5. The apparatus is similar to the apparatus of FIG. 6
except the apparatus of FIG. 7 includes a patterned roll 118. The
patterned roll 118 is arranged to rotate into contact with the
transfer roll 108. It will be recognized that the patterned roll
118 may come in a wide variety of patterns depending on the desired
pattern of the adhesive 104 to be applied to the web 106 and the
desired topography of the processed web. The apparatus 100 is
similar to the apparatus shown and described in 3M Patent Docket
No. 60452US002, application Ser. No. 11/025,388, the entire
contents of which are hereby incorporated by reference, except that
the apparatus 100 in FIG. 7 includes the fiber depositing device
112. Other useful processes are disclosed in 3M Patent Docket No.
60072US002, application Ser. No. 10/920,473, and 3M Patent Docket
No. 60092US002, application Ser. No. 10/920,953.
[0074] In order that the invention described herein can be more
fully understood, the following examples are set forth. It should
be understood that these examples are for illustrative purposes
only, and are not to be construed as limiting this invention in any
manner.
EXAMPLES
Test Methods
Sand Pickup Test
[0075] The sand pickup test measures the quantity of sand that can
be picked up by a given cleaning sheet attached to a flat mop
head.
[0076] 1.5 grams of sand (sieved to particle size diameter of 177
to 250 microns) was weighed (designated as W.sub.3) and was spread
as evenly as possible over the entire cleaning surface of a piece
of vinyl flooring measuring 0.90.times.2.67 meters. The cleaning
surface area (which was marked off with a permanent marker) was
0.61.times.2.43 meters. A sample of the cleaning sheet to be tested
was attached to a flat mop head (no handle) with the working
surface of the sheet facing away from the head. The flathead mop
with the cleaning sheet attached was then weighed (designated as
W.sub.1). The flathead mop used was a ScotchBrite.TM. High
Performance Sweeper (available from 3M Company, St. Paul, Minn.)
having a width of 10.2 centimeters and a length of 25.4
centimeters. The mop handle was attached to the mop head and the
floor surface was cleaned where the sand had been spread. The mop
was pushed with minimal pressure applied to the mop handle,
lengthwise from one end of the cleaning surface to the opposite
end. When the end was reached, the mop was lifted carefully and
positioned without turning over the sand that had been pushed by
the first pass. The mop was again pushed with minimal pressure to a
new position beside its original placement. The reason for making
these steps without turning the mop was to avoid sand accumulation
on only one edge of the cleaning tool and to use the entire
available cleaning surface of the cleaning sheet. Three lengthwise
passes were made to clean the floor (depending on the size of the
mop head), trying to maintain the same speed for all the tests. The
handle was carefully removed from the mop head and the weight of
the mop head+cleaning sheet+sand picked up was recorded (designated
as W.sub.2). The entire test area was then cleaned using a slightly
damp microfiber dust cloth and was allowed to dry. The test was
carried out three times for each type of sample tested. The weight
percent of the sand picked up from the cleaning surface by the
cleaning sheet was calculated using the following formula. The
average of the three tests was reported. % Sand
Pick-up=[(W.sub.2-W.sub.1)/W.sub.3].times.100 Static and Kinetic
Coefficient of Friction Test
[0077] The static and kinetic coefficient of friction values were
measured in accordance with ASTM D1894-01.
Thickness Measurement
[0078] A model M034A Digital Thickness Gauge (available from SDL
America, Charlotte, N.C.) was used to determine the thickness of
the cleaning sheet samples. The pressure foot (measuring 10.00 cm
diameter, 78.54 cm.sup.2) was elevated, using the joystick control
if necessary, to give sufficient clearance to insert the sample and
the sample was then placed on the platform. The measuring platform
was zeroed using the zero control knob located under the digital
load display. The sample was then removed, and the indicator showed
a negative value. Using the fast speed, the pressure foot was
lowered until it was approximately 2 mm above the measuring
platform. The speed was switched to slow, and the pressure foot was
lowered, using the joystick, until it came into contact with the
platform and a load of 0.20 grams was displayed. The digital height
gauge was then zeroed by gently pressing the zero button once. At
that point the thickness gauge was zeroed to the platform after the
required load had been applied and the weight of the sample had
been taken into account. The sample thickness was then measured by
raising the pressure foot and placing the sample on the platform,
then lowering the pressure foot using the slow speed until a load
of 0.20 grams was obtained. The thickness (in mm) was then read
from the digital thickness gauge.
Materials
Fiber Materials
[0079] Fiber materials used in the examples are described in Table
1. TABLE-US-00001 TABLE 1 Fiber Fiber Length Fiber Diameter Type
Manufacturer (inches) Description (denier) 1 3M 2 Amber 50
(41-1500-7645-7) 2 Invista 2 T295 15 (Wichita, KS) Pentalobal 3
Wellman 1.5 Type 25 25 (Shrewsbury, NJ) 4 Wellman 1.5 Type 25 25
(Shrewsbury, NJ) 5 Wellman 1.5 Type 25 25 (Shrewsbury, NJ) 6
Invista 3 T293 32 (Wichita, KS) 7 Invista 3 T293 32 (Wichita, KS) 8
Invista 3 T293 32 (Wichita, KS)
Examples 1-8
[0080] For each example, staple fibers (Fiber Types 1-8) were
deposited onto an adhesive coated backing material (3M.TM.
Micropore.TM. Jumbo, 51 inch, coated tape--Product No.
41-9100-4735-0) available from 3M Company, St. Paul, Minn., by
using a lickerin roll in combination with a blower. The lickerin
roll conditions were: [0081] Saber to conveyor distance: 6.5''
[0082] Saber gap: 0.5'' [0083] Lickerin speed: 2000 RPM [0084]
Blower speed: 500 RPM
[0085] The conveyor speed was adjusted to achieve the desired fiber
basis weight. The basic weights and the thickness of the staple
fiber layer for each cleaning sheet are in Table 2. TABLE-US-00002
TABLE 2 Fiber Basis Weight Fiber Layer Thickness Example Fiber Type
(grams/m.sup.2) (mm) 1 1 15 1.55 2 2 12 2.23 3 3 8 2.15 4 4 11 1.95
5 5 14 2.06 6 6 8 2.69 7 7 11 2.07 8 8 14 1.85
[0086] Each of the eight cleaning sheet examples was tested for
sand pick-up and coefficient of friction as described above. The
data is summarized in Table 3. TABLE-US-00003 TABLE 3 Example Sand
Pick-up Static COF Kinetic COF 1 92% 0.56 0.51 2 85% 0.66 0.62 3
98% 1.28 0.7 4 84% 0.92 0.61 5 84% 0.68 0.66 6 92% 0.74 0.63 7 89%
0.72 0.59 8 94% 0.6 0.57
Example 9
[0087] A cleaning sheet was constructed using a spunlaced nonwoven
substrate available from Shanghai Mascot, Shanghai, China (Product
No. V 580C03W-CET) comprising a combination of 50% polyester and
50% rayon fibers having a basis weight of 80 g/m.sup.2 having a
macroscopically three-dimensional surface topography. The adhesive
was a 95% iso-octyl acrylate, 5% acrylic acid hot melt
pressure-sensitive adhesive coated at a weight of 8 g/m.sup.2.
Loose fibers comprising 90% 25 denier polyester and 10% CELBOND
T254 12 denier fiber available from Kosa Incorporated, Wichita,
Kans. at a total basis weight of 9 g/m.sup.2 using the process
shown in FIG. 7.
[0088] Various modifications and alterations to this invention will
become apparent to those skilled in the art without departing from
the scope and spirit of this invention. It should be understood
that this invention is not intended to be unduly limited by the
illustrative embodiments and examples set forth herein and that
such examples and embodiments are presented by way of example only
with the scope of the invention intended to be limited only by the
claims set forth herein as follows.
* * * * *