Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02293906 2000-02-08
000104 RV6 1 MAGL 3.0-300
METHOD OF MAKING, CLEANING, SCOURING, SANDING AND/OR
POLISHING PADS AND THE IMPROVED PAD PRODUCED THEREBY
FIELD OF THE INVENTION
Domestic foam based cleaning pads, including household and
5 commercial scrubbers and sanders normally used wet and abrasive and
sanding blocks normally used dry.
BACKGROUND OF THE INVENTION
The combination of synthetic foams, particularly urethane forms, with
10 at least one abrasive surface is well-known and pads of this type have been
on the market for at least 20 years.
Processes for making such pads may be found, for example, in US
Patent 4,111,666 to Kalbow and US Patent 4,263,337 to Fenster, et al.
15 Nevertheless, the art always seeks methods of making such devices more
economically and with the ability to provide a large variety of abrasive
surfaces without major changes in the equipment required to build the
same.
20 The foams utilized for such pads are usually polyurethane foams of
open-celled structure. Conventionally; the abrasive quality of the abrading
surface of such pads has been controlled solely by the nature of the
abrasive material, which has been applied to the surface of the pad selected
for this purpose.
25
SUMMARY OF THE INVENTION
It has been found that the aggressiveness of the abrading surface of
a scrubbing pad can be affected by the way that the surface of the pad is
cut. This approach leads to a substantial cost saving of materials utilized
for
30 the abrading, as well as giving excellent control over is abrading nature.
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The basis of Applicants' invention lies in their finding that if, contrary
to general cu«ent practice, the surface of the foam substrate which is to be
used as an abrasive surface is not cut smoothly, but is slightly torn,
suitably
to a random depth of at feast 1-1/2 but not more than 9 cell diameters
relative to the surface made by a substantially planar cut, there remains in
that surface a desirable number of fiber-like residues from the cells. The
torn surface is then coated, suitably with an adhesive which may, if desired,
contain an abrasive material. If desired, the adhesive material can be
applied per se, and thereafter the abrasive is applied to the surface of the
adhesive, which is then cured. The coating, without abrasive content, may
be applied to the torn surface.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The starting material for the present invention is a block of
substantially open-celled urethane foam with an I.L.D. of at least 30 pounds
or more, preferably 50 pounds, with good tear resistance, which is
conventionally utilized for sponge material. A particularly suitable sponge
material is disclosed in Applicants' PCT Patent Application No.
PCT/US98/08605, filed April 27, 1998, although any commercial urethane
foam or other foams, including rubber foams may be used. The blocks of
foam are treated to provide at least one roughened surface, the treatment
may be carried out with an abrasive cutting tool on a given surface.
Preferably, the block may be cut with a knurled wire, such as that
manufactured by Albrecht Baumer KG, Freudenberg, Germany. These wires
have angled toothing set with broaching tooth.
Utilizing either of the aforementioned means, there is produced a
single surface or a double surface, or up to six surfaces which are randomly
torn (relative to an original planar cut), suitably of at least 1.5 and not
more
than 9 cell diameters. A less aggressive cut generally does not leave a
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sufficient number of hair-like projections or jagged cell membranes to
provide the optimum effect and a deeper cut has a similar effect.
The jagged cell membrane residues and hairline-like projections, with
5 a cured coating, which may originally be adhesive, but does not need to be,
have a mild abrasive quality of their own, particularly in a household
scrubber sponge. More importantly, these projections increase the available
surface area for the application of abrasive materials, which allow more
effective loading of the abrasives.
10
After cutting, the abrasive surface is coated, suitably with a curable
adhesive. Such adhesives are well-known in the art. A suitable example is
Swift 22005, manufactured by Reichhold Chemical. Similar adhesives are
described in US Patents 4,264,337 and 4,111,666.
15
There are many possible methods of applying the adhesive coating,
namely by spray knife or roller, the latter being preferred. The actual
amount applied is dependent on the foam cell size and the ultimate
properties desired but for the best results the coating is applied so as to
20 fully coat each projection and beyond to a depth of at least 2 cell
diameters.
Care is taken so that the porosity of the foam is minimally reduced and
preferably the coating does not pool between the projections. In this way,
the scrubber or sanding sponge produced has a brush-like quality to its
surface and the bristle-like protuberances are stiffened and reinforced.
25
Abrasives can be added to the adhesive and/or added as a surface
treatment after application of the adhesive, but prior to cure by vibratory or
other feeding devices. The coated scrubber is conveyed under a vibratory
feeder a nd the abrasive is °sprinkled on", coating each bristle or
ruptured
30 cell wall. The scrubber is cured and the excess abrasive vacuumed off and
recycled
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Depending upon the final application, a variety of abrasives known to
those skilled in the art can be useful, suitably in a Mohr hardness range of
3-9. A non-scratch scrubber suitable for non-stick cookware or counter-
tops, may use no abrasive or incorporate an amount of calcium carbonate,
suitably about 1-400 mesh, preferably 200 mesh in the adhesive. A
spackling sponge rubber may use a glass microspheres, suitably #3000
(Potters Industry), surfaced coated on the uncured foam at the rate of, say
50-300, suitably 120 gms per square yard. A barbecue grill scrubber might
use a 180-mesh silicon carbide, suitably 100-300 mesh, preferably 180
mesh abrasive at the rate of 200 gms per square yard. Silica sand and
aluminum oxide may also be used. Adhesive amount, abrasive type , mesh
size, and amount, if any, are very dependent on the foam cell size and
aggressiveness desired.
The following examples are given for purposes of illustration and not
limitation.
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EXAMPLES
In the foregoing examples the starting material is a polyurethane foam
of average density of 1-1.3 and average cell size of 10-100 cells per inch.
The abrasive surface was obtained by cutting with a #15 cutting wire,
5 manufactured by Albrecht Baumer KG, Freudenberg, Germany. This wire
having a tooth size of 1.5 ml.
XSORB SCRUBBERS
FORMULATION OF TOP COATING
MATERIAL PART BLUE GREEN SPACKLING
# ALL HEAVY SPONGE
PURPOSE DUTY AMOUNT
AMOUNT AMOUNT
Swift-22005 058390030.OIbs.30.OIbs 30.OIbs.
C-55 Camel 05131009.0 Ibs.9.0 Ibs. 6.0 Ibs.
Carb
Milliken Blue0584700140 gms.)(40 gms.)(159 gms.)
X-3
Milliken Yellow0585000-- (34 gms.)(41 gms.)
X-15
TOTAL 39.1 39.2 Ibs.36.4 Ibs.
Ibs.
Procedure for All Purpose and Heavy Dutx
To a 5-gallon pail, add Swift 22005 and C-55; mix for approximately
3-5 minutes. Add dye and mix for 5 minutes. Charge roller coater with
coating compound and set coater for maximum penetration and an
15 application rate of 91 gms. per foam sheet of 22-1/2 x 34. Pass foam sheet
through coater two times. Final coating weight is 190-210 gms. per sheet.
The blue all-purpose scrubber coated sheets are placed in racks and air
cured for 48 hours. The green heavy-duty sheets are run through the
abrasive applicator and 115 gms. of Arrowblast 100 grit is applied, and the
sheets are placed in racks and air cured for 48 hours.
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Procedure for Spacklin_g Sponge
To a 5-gallon pail, add Swift 2205 and dye, mix for approximately 5
minutes. Charge roller coater with coating compound and set coater for
maximum penetration at an application rate as follows:
Sheet Dimension - 1 " x 27" x 34-1 /2" - 120 gms./sheet
- 1-3/4" x 23" x 34-1/2" - 100 gms./sheet Pass foam
through coater two times for a final coating of:
Sheet Dimension - 1 " x 27" x 34-1 /2" - 260 gms.lsheet
- 1-3/4" x 23" x 34-1/2" - 280 gms./sheet
10 The sheets are run through the abrasive applicator and Microspheres 3000,
Potters Ind. is applied per the following schedule:
Sheet Dimension - 1 " x 27" x 34-1 /2" - 104 gms.
- 1-3/4" x 23" x 34-1/2" - 90 gms.
The sheets are placed in racks and air-cured for 48 hours.
Procedure for a Sanding Block
Sanding blocks of various grades may use an aluminum oxide
abrasive of 30 mesh, 60 mesh, 80 mesh, 100 mesh, 120 mesh, 150 or 200
mesh. One suitable foam would be polyurethane foam of 1.835/cu.ft., an
I.L.D. of 55 and cell size of 55 cells per linear inch.
Charge roller coater with Swift 20026, a urethane moisture cure
adhesive by Reichold Chemical and set coater for maximum penetration at
an application rate as follows:
Sheet Dimension - 1 " x 18" x 18"
Sample A - 145 gms
Sample B - 130 gms
The sheets are run through the abrasive applicator and Microspheres 3000,
Potters Ind., is applied per the following schedule:
Sample A - 100 mesh aluminum oxide - 80 gms/sheet
Sample B - 80 mesh aluminum oxide - 160 gmslsheet
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The sheets are placed in racks and air-cured for 48 hours.
On curing, the sheets are cut into pieces 5" x 3" x 1 ". When
sanding, it is observed that the wood flour produced does not remain on the
5 abrasive face but penetrates into the surface of the foam to a depth to
which the form was originally torn/cut. A light tap of the abrasive block
discharges the wood flour from the foam block. Commercial sanding
sponges utilize urethane foam having a relatively smooth surface. This
surface being adhesive coated. The abrasive applied to this surface yields a
10 non-porous, essentially one-dimensional surface. In use, these sanding
sponges while effective, allow the buildup of wood flour or debris on the
abrasive surface reducing their efficiency. The debris is difficult to remove.
Sample A was found to have a very open surface structure and very
15 abrasive feel due to the rough foam surface and abrasive coating.
Comparable sanding blocks are relatively smoother feeling in comparison.
Sample B was found to have an open structure less than A due to a
heavier abrasive loading.
20
It should be noted that foams of various cell sizes are useful. Foams
of large pore sizes or less cells per inch to better accommodate abrasives of
larger particle size and still maintain the advantages of open structure and
vice versa, although it should be noted that foams of large pore size and
25 fine abrasives and foams of small pore size and coarse abrasives have
utility
in some applications.
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