Note: Descriptions are shown in the official language in which they were submitted.
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SCRUB PAD WITH PRINTED RIGID PLATES AND
ASSOCIATED METHODS
FIELD OF THE INVENTION
The present invention relates generally to
scrubbing materials. In particular, the present
invention relates without limitation to flexible ;
scrubbing pads having rigid plates for use in a
variety of household and industrial cleaning and
personal care applications.
BACKGROUND OF THE INVENTION
There are many different types and designs of
scouring and scrub pads currently available in the ,
marketplace. Metal wool pads, such as steel wool,
have long been produced and used for household and
industrial cleaning. Although these scouring pads
have excellent abrasion and scouring characteristics
due to the hardness of their metallic fibers, they
have several significant disadvantages. For example,
metallic pads are overly abrasive for surfaces that
are soft, scratch easily, or subject to oxidation.
Another problem associated with such pads is
durability since the metal fibers have a tendency to
shed and splinter while being used. Moreover, metal
wool pads ara harsh and uncomfortable for unprotected
hands to grasp, and may lead to splinters embedded in
the skin of the user. Metal wool pads also have a
relatively short useful life and often rust quite
readily.
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In order to overcome the disadvantages of metal
wool pads, many non-metallic pads have been
developed. Typically, these pads comprise a non~-
woven web of synthetic fibers such as polyester,
polyamide, polypropylene or nylon. Some examples of
this structure are disclosed in U.S. Patents No.
5,955,417, 5,786,065, and 4,949,417. Others comprise
organic material such as sponge.
These non-metallic pads avoid many of the
shortcomings of metal wool pads, but nonetheless have
other limitations. For example, they may easily
entrap food and other debris being removed from the
surface being cleaned. This may occur because the
surface of these pads is a porous non-woven web of
fibers, rather than a more impenetrable surface, such
as a tightly woven and/or liquid-resistant fabric.
The accumulation of food may have the negative
consequence of promoting bacteria growth within the
pad.
Other scrubbing pads combine a woven or non-
woven pad with cleansing agents and/or surfactant s
dispersed within the pad. One such pad is described
in U.S. Patent No. 5,955,417. The process for
manufacturing such a pad includes manufacturing a
three-dimensional, lofty pad and adding a dried,
cleansing composition to the pad. These types of
pads rely on a particular cleansing composition to
enhance their cleaning performance. Also, their
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cleaning effectiveness gradually wanes as the
cleansing composition is consumed.
Some scrub pads, such as those indicated by U.S.
Patent Nos. 3,175,331 and 4,190,550 involve the
placement of a replaceable cleansing component, such
as a bar of soap, within the pad to enhance cleansing
effectiveness. However, the user is subject to the
inconvenience of having to repeatedly replace the
cleaning component as it becomes Consumed.
Other scrubbing pad designs use synthetic fiber
protrusions to enhance scrubbing effectiveness. For
example, the scrubbing pad described in U.S. Patent
No. 5,609,431 comprises flat chisel-like tufts of
synthetic fibers protruding from a backing material.
One disadvantage of this type of pads is the
protrusions have a tendency of losing their original
shape after repeated use thereby reducing the pad's
cleansing effectiveness.
There exists a need for a scrubbing pad that
overcomes one, some or all of the disadvantages of
prior art scrubbing pads.
SUI~'~IARY OF THE INVENTION
The invention relates to a sanding, scrubbing,
or buffing material having a plurality of plates
affixed to a flexible substrate. In one aspect of
the present inventions, the scrubbing material has a
first component and a second component with different
properties. The first component comprises a
continuous flexible substrate and a second component
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comprises a discontinuous layer affixed to the
flexible substrate. The discontinuous layer is
typically embodied as a plurality of plates. The
plates comprise a resin, such as epoxy that can be
printed on one or both sides of the flexible
substrate by conventional printing methods and can be
subsequently cured.
In another aspect of the present inventions, the
substrate has two surfaces where a plurality of
plates is affixed to each surface. Each substrate
surface has a selected abrasion level associated with
various characteristics of substrate material and
affixed plates.
In yet another aspect of the present inventions,
the flexible scrubbing material comprises a flexible
substrate and a compressible layer or, alternately, a
layer of soft, absorbent material such as terry
cloth. The compressible layer can be liquid
absorbent materials, such as foam or sponge. As
another aspect, the scrubbing material has a
substrate and affixed plurality of plates. The
plates are spaced apart so that a plurality of gaps
are formed between adjacent plates. The gaps are
selectively sued to provide desired characteristics
such as permeability, flexibility, and abrasion
level.
All of the embodiments may optionally have
substrate fabrics that have visually attractive
printed patterns or images that may or may not be
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seasonally appropriate. The embodiments can be used
in wet or dry applications, i.e. with or without a
liquid. The scrubbing material may be embodied as a
scrub pad, sanding pad, floor buffing pad, and
similar products providing an abrasive surface.
Finally, the inventions also relate to methods of
making the embodiments of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates an isometric view of a scrub
pad having cross-shaped. plates with substrate fabric
in a seasonal pattern.
FIG. 2 illustrates a diagrammatic view of a
plurality of plates affixed to a substrate.
FIG. 3 illustrates a diagrammatic view of a
plurality of plates in a cross pattern.
FIG. 3A is an enlarged view of a cross-shaped
plate.
FIG. 3B is a sectional view taken along line 3B-
3B in FIG. 3A.
FIG. 4 illustrates a diagrammatic view of a
plurality of plates having plates in a dot pattern.
FIG. 5 is a picture of one side of a scrub pad
having plates in a cross pattern with substrate
fabric in a seasonal snowman pattern.
~5 FIG. 5A is a picture of an enlarged portion of
the scrub pad shown in FIG. 5. ,
FIG: 6 is a picture of the opposite side of the
scrub pad shown in FIG. 5 having plates in a dot
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pattern with substrate fabric in a seasonal snowman
pattern.
FIG. 6A is a picture of an enlarged portion of
scrub pad shown in FIG. 6.
FIG. 7 illustrates an assembly view of a scrub
pad having two substrate layers with two different
plate patterns, an intermediate layer, seasonal
patterns, and sewn seams.
FIG. 8 illustrates major steps in making scrub
pad of the present invention. .
T~ETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 illustrates a flexible abrasive layer
embodied as a scrubbing, sanding or buffing material
or pad 100 on which an optional autumn pattern 102 is
printed. The flexible abrasive layer 100 comprises a
continuous flexible substrate 106 and discontinuous
abrasive layer or plates 108 adhered on the surface
110 of the substrate 106. The substrate 106 can be a
fabric or other flexible substrate. The abrasive
plates 108 can be formed from a solidified material
such as ultraviolet or thermally curable polymeric
materials, especially epoxy material, with or without
abrasive partioles embedded inside.
Plates 108 are relatively flat and rigid and are
designed to provide abrasive cleansing action. The
design of flexible abrasive layer or scrub pad 100
utilizes two independent components, abrasive
cleansing plates 108 and a flexible backing or
substrate 106, to provide a scrub pad with maximum
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design flexibility. Hence, the substrate and plate
characteristics may be chosen independently to meet
various performance requirements.
In FIG. 2, plurality of plates 108 are
positioned such that a plurality of gaps 205 are
formed between adjacent plates 108. The gaps 205 can
be relatively large compared with the dimensions of
each plate 108. Having a large gap 205 relative to
the dimensions of each plate 108 is advantageous by
providing increased flexibility and comfort and
increased permeability to soap and liquid. Also, for
most cleansing applications, plates 108 having
relatively large gaps 205 provide adequate abrasion
levels. In one embodiment, flexible substrate 106 is
liquid-permeable but impermeable to most food
particles or other debris. These characteristics
provide cleansing ability while lessening the
potential for bacteria growth from food particles or
other debris trapped within the scrubbing pad. The
flexible substrate 106 can comprise tightly woven
cotton or cotton-polyester blend fabric, but other
fabrics having similar characteristics can be used.
In FIG. 2 plates 108 are illustrated as
partially penetrating flexible substrate 106 to
securely affix plates 108 to, substrate 106. The
manufacturing process can utilize conventional
printing methods, such as, screen-printing, for
printing plates 108 on flexible substrate 106.
However, other methods may be used, such as roller-
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printing or ultra-violet (UV) etching, During
printing, the plates 108 may penetrate partially or
completely through substrate 106. The plates 108 are
made of a printable material 204 that can be
subsequently cured or solidified. For instance, the
printable material 204 is a paste-like resin that at
least partially penetrates and bonds with the fibers
of flexible substrate 106. One example of an
appropriate resin is heat-cured epoxy resin. Another
example is ultra-violet cured acrylate. Ultraviolet
or heat curing or some combination thereof is used to
harden plates 108. The hardened plates 108 resist
delaminating from flexible substrate 106 due to the
integral structure formed between fibers of substrate
106 and the plates 108.
The overall abrasion level of scrubbing pad 100
may be modified by the composition of printable
material 204, herein also referred to as resin.
Also, the abrasion level is influenced by the curing
process used. Therefore, selecting a particular
resin and curing process affects the abrasion level
provided by plates 108. In one embodiment, heat-
cured epoxy resin has been found to have the
necessary toughness as well as hardness for effective
household cleaning, and yet is not prone to leaving
scratch marks on many surfaces. Another example of an
appropriate resin is ultra-violet (UV) cured
acrylate.
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Optionally, abrasive particles 202, for instance
materials such as alumina or titanium dioxide, can be
added to and dispersed within printable material 204
before printing. Abrasive particles 202 tend to
elevate the pad's abrasion level and durability and
are often used for enhanced cleansing capability,
particularly when the surface to be cleansed is not
prone to scratching. Optionally, plates 108 may be
coated with a top coating 206 to reduce or increase
the abrasion level and/or otherwise modify surface
texture of plates 108. For example, a top coating of
silicone reduces the abrasion level of the plates
108.
Other variables for controlling abrasion levels
of plates 108 include shape, aspect ratio, gap size,
and coverage area of plates 108. The possible shapes
of each plate 108 include a hexagon, dot, cross and
other geometric and non-geometric shapes. FIG. 3
illustrates a plurality of plates 300 where each
plate 302 has a cross shape and the plates 302 are
arrayed in horizontal and vertical rows in a
repeating pattern. Some shapes, such as cross-shaped
plates 302 have been found to provide a higher
abrasion level than many other shapes, such as
plurality of plates 400, where each plate 402 is
elongated and dot-shaped. Plates 402 are illustrated
in a repeating pattern in FIG. 4. It is noted that
each plate 402 may be identical but oriented
differently. For example, some plates 402 may be
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flipped over and/or rotated so that plates 402 form a
repeating pattern, such as plurality of plates 400.
It is believed that cross-shaped plate 302 has a
relatively higher abrasion level due to the plurality
of sharp corners 308 on arms 306 as illustrated in
FIG. 3A which is an enlarged view of plate 302.
Further, in plates 302 the abrasion level also
increases as the ratio of arm length 305 to arm width
303 increases. However, if the arm length 305 to arm
width 303 becomes too_large, plates 302 will tend to
delaminate from the substrate. Therefore, selecting
particular shapes for plates 108 will also vary the
overall abrasion level of scrub pad 100.
One embodiment having two surfaces 500, 600 with
different abrasion levels in a seasonal snowman
pattern is shown in approximate full sire in FIGS . 5
and 6. FIGS. 5A and 6A are enlarged views of
portions 502, 602 of surfaces 500, 600 of scrub pad
shown in FIGS. 5 and 6, respectively. FIGS. 5A and
6A show the detail of the abrasive plates having
different shapes and abrasion levels affixed to a
substrate. It is noted that other embodiments
include abrasion levels that may be equal on both
sides, such as a pad 100, 500, 600, 700 having the
same pattern of plates 108, 302, 402, 708 printed on
both sides of pad 100, 500, 600, 700. In FIG. 5,
higher abrasion side 500 is shown with cross-shaped
plates in a repeating pattern similar or the same to
the pattern shown in FIGS. 3 and 5A. Lower abrasion
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side 600 has dot-shaped plates 402 in a repeating
pattern similar or the same to the pattern shown in
FIGS. 4 and 6A. Substrate material is shown with a
snowman pattern. Providing high abrasion side 500
and low abrasion side 600 within one scrubbing pad is
advantageous due to increased flexibility in use for
various situations because a user would be able to
scrub one surface not particularly prone to
scratching with high abrasion side 500 and turn the
scrub pad over to scrub a more delicate surface .with
low abrasion side 600. However, in other situations
having two abrasion levels that are the same is
advantageous, such as when the pad will be used for
the same scrubbing purpose with both sides. In these
cases, having two equal abrasion levels is believed
to extend the useful life of the pad.
Other techniques for varying the abrasion level
of each side are discussed below. However, it should
be noted that plates 108 may be identical or non-
identical, and therefore, combinations of shapes can
also be provided on the same side. Also, plates 108
may be arrayed in a repeating pattern, a non-
repeating pattern, or positioned randomly on
substrate 106.
As mentioned above, shape and aspect ratio of
plates 108 also influence the abrasion level of
plates 108. FIGS. 3A and 3B illustrate enlarged top
and sectional views, respectively, of cross-.shaped
plate 302. A scrub pad 100 with plates 108, 302
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having a relatively high aspect ratio is associated
with a higher abrasion level. The abrasion level of
scrub pad 100 can be modified by selecting a
different aspect ratio of plates 108, 302, 402.
A plate's aspect ratio, as defined in the
present application, is the ratio of the plate's
maximum linear dimension to the plate's nominal
height, where the maximum linear dimension is defined
as the greatest linear distance between two points on
a corresponding surface.
Therefore, for plate 302, the aspect ratio, as
the term is used in the present application, is the
ratio of maximum linear dimension 307 to the plate's
nominal height 309. In the case of plate 302, the
maximum linear dimension 302 is the distance between
opposing corners 308 as illustrated in FIG. 3A. In
some embodiments, the aspect ratio for plates 302 is
approximately 1 to 20 although other aspect ratios
can also be used. However, the nominal height of
plates 302 generally does not exceed the maximum
linear dimension 307 due to the greater tendency of
plates 302 to delaminate as height increases.
The abrasion level of scrub pad 100 can also be
adjusted by varying the coverage area of plates 108
on surface 110. In FIG. 3, surface area coverage is
computed by dividing total surface area of all
plates 302 by a particular substrate surface area 304
including the substrate area beneath plates 302.
Higher coverage areas are associated with higher
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abrasion levels. In this embodiment, coverage areas
range from 5% to 80o although other coverage areas
can be used.
Gap size 205, 301 (shown in FIGS. 2 and 3) also
affects the abrasion level of scrub pad 100. Gap
size is the closest distance between adjacent plates
108, 302. In one embodiment illustrated in FIGS. 2~
and 3, gap 205, 301 is greater than 1/3 the maximum
linear dimension 307 which is defined above. For
example, for a cross-shaped plate 302 having four
arms 306, the maximum linear dimension is illustrated
by reference numbers 307 in FIG. 3A. In other
embodiments, the gap 205, 301 may be 1/2, equal to,
or greater than twice, three-times, five-times, and
ten-times the maximum linear dimension 307. The
features described above such as abrasive particles,
resin composition, aspect ratio, coverage area, and
gap size allow the abrasion level of the scrub pad to
be modified as required by specific application.
Hence, variations of the present scrub pad may be
marketed as heavy-duty, normal, or non-scratch scrub
pads for industrial and household cleaning. Also, it
is contemplated that the scrub pads of the present
invention can be made gentle enough. for human use
such as cleansing skin and removing make-up.
Another desirable feature of scrub pads of the
present invention is flexibility. Scrub pad
flexibility, like its abrasion level, is influenced
at least by plate shape and size, aspect ratio,
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coverage area, resin composition, gap size, and
substrate fabric. Therefore, gap sire and placement
as well as the substrate fabric may be selected to
manufacture a scrub pad having flexibility to meet
performance requirements.
One benefit of gaps 205, 301 (shown in FIGS. 2
and 3) between plates 108, 302 is a relatively large
area of surface 110, 304 is left exposed and visible.
Therefore, it is possible to print a visually
attractive pattern or image on surface.110, 304 or
select a commercially available preprinted fabric.
For example, scrub pad 100, 700 is illustrated in an
autumn pattern in FIG. 1 and a snowman image is shown
in FIGS. 5 through 7. Substrate 106, 706 can be
printed in various colors, patterns, and images to be
visually appealing to consumers. The designs can be
seasonal, such as autumn leaves or a winter snowman
pattern, or be appropriate for holidays, such as
Christmas or Thanksgiving.
Scrub pad flexibility is also influenced by
substrate 106, 706 particularly the type and
thickness of fabric material selected. Some
potential, fabric types include without limitations
woven, non-woven, or knit fabrics but having the
ability to permit at least partial penetration of
resin during printing. Fabric materials include
without limitations cotton and cotton-polyester
blends and other natural and man-made~fabrics having
similar properties.
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In one embodiment, the fabric is a tightly woven
cotton-polyester blend. In this embodiment, this
type of fabric is used because heat-cured epoxy resin
has been found to seep into and bond well with this
substrate fabric. The tightly-woven cotton-polyester
blend.also resists penetration by food particles and
other debris but permits soap and liquid to permeate
through the substrate fabric for cleansing
effectiveness. Finally, colorful patterns can be
printed on this fabric because it absorbs ink, the
ink does not tend to bleed when exposed to water, and
printed patterns have relatively good resolution due
partly to the fabric's tight-woven flat surface.
Tightly woven cotton-polyester also does not readily
shrink when washed.
FTG. .7 illustrates a diagrammatic assembly of a
scrub pad 700. As in FIG. 1, scrub pad 700 has a
substrate 106 and a plurality of plates 108 shown as
a separate layer. Plates 108 are affixed to
substrate 106 by printing as discussed above. Scrub
pad 700 further comprises a second substrate 706
illustrated in a falling leaf pattern. Plates 708 are
shown in a dot pattern similar to the pattern shown
in FIGS. 6 and 6A. Plates 708 are affixed to
substrate 706 by the printing process described for
substrate 106 and plates 108, 302 above.
Intermediate layer 702 is inserted and sandwiched
between substrate 106 and substrate 706. In one
embodiment, intermediate layer 702 is a compressible,
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liquid absorbent. material that is flexible and soft,
such as foam or sponge. Substrate 106 and substrate
706 can be loosely coupled to intermediate layer 702
by means such as sewing 104 or conventional heat
sealing (not shown) along perimeter edge portions
701, 703. In another embodiment, substrates 106, 706
can be tightly coupled to intermediate layer 702 by
means such as lamination..
In another embodiment, intermediate layer 702
may be joined with only one substrate 106.
Intermediate layer 702 may be a soft, liquid
absorbent material, but not necessarily compressible,
such as but not limited to, woven or non-woven fabric
with or without loops such as found in terry cloth.
Another example includes flannel. Substrate 106 can
be loosely or tightly coupled to intermediate layer
702, such as terry cloth, by means such as sewing or
lamination but other means for coupling may be used.
In one embodiment, the substrates 106, 706 are
tightly woven cotton-polyester generally permeable to
liquid but impermeable to most food particles. The
abrasive plates 108, 708 comprise heat-cured epoxy
which are printed on both side of pad 700. Heat-cured
epoxy resin inherently inhibits bacterial growth,
further reducing potential bacteria growth on the pad
and hence the need for a separate anti-bacterial
formulation. The structure of the scrub pad 700
allowssoap and liquid to soak through substrates
106, 706 and be absorbed by intermediate layer 702.
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The scrub pad structure is easy to rinse and clean
after use. The substrates 106, 706 may be printed
with attractive patterns, prints and colors. Also,
they can be stitched together along their perimeter
edge portions 701, 703 to enclose compressible layer
702. In another embodiment, substrate 106 can be
folded over intermediate layer 702 thereby enveloping
intermediate layer 702. Substrate 106 can be loosely
coupled to the enveloped intermediate layer 702 by
sewing along edge portion 701.
It is noted that .the embodiment illustrated in
FIG. 7 is not intended to be limiting. Other
embodiments can be constructed with some or all of
the structural elements shown in FIGS. 7 and affixed
by means other than sewing or heat sealing. For
instance, a scrub pad may have one substrate 106
laminated to intermediate layer 702. A scrub pad may
have both substrates 106 and 706 laminated to
opposite sides of intermediate layer 702:
Intermediate layer 702, substrate 706, and plates 708
are features that may be eliminated as necessary for
performance standards as well as cost considerations.
Intermediate layer 702 may or may not be
compressibl e. ~ Substrate 106 can be loosely or
tightly coupled to intermediate layer 702, substrate
706 or both. Similarly, patterns and images printed
on substrates 106 and 706 are variable and optional.
FIG. 8 illustrates steps of a typical
manufacturing process 800 for manufacturing
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embodiments of the scrubbing or sanding pad of the
present invention. Step 802 involves selecting
fabric for one or both of substrates 106, 706 shown
on FIGS. 1 and 7. The selected fabric has a texture
that is liquid permeable, generally resistant to food
particle penetration, and allows adequate physical
penetration of plate resin into substrate fabric to
develop a strong adhesive bond with the fabric.
Typically, suitable substrate fabrics include tightly
woven cotton or cotton-polyester blends, but other
fabrics with similar properties are contemplated may
be used. The fabric may be printed in various colors
with attractive prints and images., Step 804 includes
selecting appropriate resin material that forms
plates 108, 708 with adequate abrasion levels. The
selected resin has properties that allow plates to
form that have a suitable shape and size, aspect
ratio, gap size, coverage area, resolution, abrasion
level and liquid and bacteria resistance as discussed
2 0 above .
In one embodiment, the selected resin is the
family of one-part heat-curable epoxy resins
available from Fielco Industries, Inc. of Huntingdon
Valley, Pennsylvania. One-part heat-curable epoxy
does not cure at room temperature but must be heat-
cured. Heat curing is advantageous over room
,temperature curing due to the longer shelf life of
unused resin. The one-part formulation is also
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advantageous because it can eliminate the need for
mixing prior to printing.
The resin material of one embodiment has an
approximate viscosity of 1.61x106 cps at a shear rate
of 0.6 sec-' measured using a viscometer at a
temperature of 87° F. This material is highly shear-
thinning since at a shear rate of 12.6 sec-' the
viscosity drops more than one order of magnitude to
approximately 1.5x105 cps. At rest, it has an apparent
yield stress of approximately 75 Pa. This resin
material can be printed using conventional screen
printing techniques with good definition in a variety
of patterns, si2es,_and shapes.
Step 804 also includes selecting abrasive
particles 202 illustrated in FIG. 2 to increase the
abrasion level and/or durability of the scrubbing
pad, if desired. Also included in step 804 is
selecting coating 206, if any, shown in FIG. 2 that
may modify the surface texture of plates 108, 708
shown in FIG. 7.
Step 806 is the step of printing the plates 108,
708 onto substrates 106, 706 shown in FIG. 7. A
conventional screen-printing technique can be used
but other techniques, such as. W etching and roller-
printing can also be used. An adhesive, such as
commercially available off-the-shelf spray mount
adhesive, (not shown) is sprayed on the fabric. In
conventional screen-printing, a template or screen
(not shown) having shapes punched out is placed over
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each of substrates 106, 706. The punched out shapes
leave voids identical in size, shape, and spacing as
plates 108, 708. Paste-like resin, such as heat-
curable epoxy or W-curable acrylate, is spread over
the screen to produce plates with thickness generally
around 10-20 mils. The screen can use a 200-micron
capillary film to develop the print pattern, and in
one embodiment produces abrasive plates of thickness
around 10 mils. The screens may be made of capillary
films or polyester meshes. For mass production,
roller printing may also be used. Printing can be on
one or both sides of the substrate.
Step 808 is the step of curing the resin 'by
heat, ultra-violet radiation, or a combination
thereof. The resin plates solidify and harden on the
substrate fabric during the curing process. In one
embodiment, the printed resin is first individually
pre-cured in an oven at 120° C for 4-5 minutes. After
pre-curing, individual substrate layers are stacked
and fully cured at 120° C for approximately one hour.
Step 810 involves assembly of individual
elements into a complete scrub pad. One or two
substrate layers 106, 706 with abrasive plates can be
combined with an intermediate layer such as foam or a
sponge to make a scrubbing pad. Alternately, a. soft,
liquid absorbent material such as terry cloth or a
wash cloth may be used as an intermediate layer
instead of the compressible layer. Typical examples
of a compressible material include polyurethane or
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regenerated cellulose. A scrubbing pad can be
assembled by stitching or sealing two~substrates 106,
706 together to enclose intermediate layer 702.
Alternately, one or two abrasive substrates 106, 706
may be laminated on one or both sides of intermediate
layer 702 to form a scrub pad. Substrate 106 can be
stitched to an intermediate layer such as terry cloth
to form a scrubbing cloth.
Although the present invention has been
described with reference to preferred embodiments,
workers skilled in the art will recognize that
changes may be made in form and detail without
departing from the spirit and scope of the invention.
