U.S. patent application number 14/011157 was filed with the patent office on 2015-03-05 for method of finishing a stone surface and abrasive article.
This patent application is currently assigned to 3M INNOVATIVE PROPERTIES COMPANY. The applicant listed for this patent is 3M INNOVATIVE PROPERTIES COMPANY. Invention is credited to James L. McArdle.
Application Number | 20150065012 14/011157 |
Document ID | / |
Family ID | 51494530 |
Filed Date | 2015-03-05 |
United States Patent
Application |
20150065012 |
Kind Code |
A1 |
McArdle; James L. |
March 5, 2015 |
METHOD OF FINISHING A STONE SURFACE AND ABRASIVE ARTICLE
Abstract
A structured abrasive article comprises a structured abrasive
layer adhered to a major surface of a backing, the structured
abrasive layer comprising shaped abrasive composites adhered to the
major surface, the shaped abrasive composites comprising milled
polycrystalline ceramic abrasive particles retained in a polymeric
binder, wherein the milled polycrystalline ceramic abrasive
particles have a median particle size D.sub.50 of from 3 to 30
microns. In a method of finishing a stone surface, the structured
abrasive layer is frictionally contacting with the stone surface;
and moved relative to the stone surface under conditions sufficient
to finish the stone surface.
Inventors: |
McArdle; James L.; (Wilson,
WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
3M INNOVATIVE PROPERTIES COMPANY |
St. Paul |
MN |
US |
|
|
Assignee: |
3M INNOVATIVE PROPERTIES
COMPANY
St. Paul
MN
|
Family ID: |
51494530 |
Appl. No.: |
14/011157 |
Filed: |
August 27, 2013 |
Current U.S.
Class: |
451/41 ;
451/527 |
Current CPC
Class: |
B24D 3/14 20130101; B24B
7/22 20130101; B24D 3/20 20130101; B24D 9/08 20130101; B24B 7/18
20130101 |
Class at
Publication: |
451/41 ;
451/527 |
International
Class: |
B24B 7/22 20060101
B24B007/22; B24D 3/14 20060101 B24D003/14; B24D 9/08 20060101
B24D009/08 |
Claims
1. A method of finishing a stone surface, the method comprising:
providing a structured abrasive article comprising a structured
abrasive layer adhered to a major surface of a backing, the
structured abrasive layer comprising shaped abrasive composites
adhered to the major surface, the shaped abrasive composites
comprising milled polycrystalline ceramic abrasive particles
retained in a polymeric binder, wherein the milled polycrystalline
ceramic abrasive particles have a median particle size D.sub.50 of
from 3 to 30 microns and wherein the backing is secured to a lofty
open nonwoven backup pad mounted on a rotary floor machine, wherein
the rotary floor machine operates at a rotational speed of less
than 250 rotations per minute; frictionally contacting the
structured abrasive layer with the stone surface; and moving the
structured abrasive layer relative to the stone surface under
conditions sufficient to finish the stone surface.
2. A method according to claim 1, wherein the structured abrasive
layer has a bearing area ratio of from 40 percent to 70
percent.
3. (canceled)
4. A method according to claim 1, wherein the shaped abrasive
composites comprise hexagonal posts.
5. A method according to claim 1, wherein the milled
polycrystalline ceramic abrasive particles have an average Vickers
hardness of at least 21 gigapascals.
6. A method according to claim 1, wherein the milled
polycrystalline ceramic abrasive particles have an average fracture
toughness of at least 3 megapascals per meter.sup.0.5.
7. A method according to claim 1, wherein the stone surface
comprises at least a portion of a floor.
8. A method according to claim 1, wherein the stone surface
comprises at least a portion of a counter.
9. A method according to claim 1, wherein the stone surface
comprises at least one of a granite surface, a marble surface, a
cement surface, a terrazzo surface, a ceramic tile surface, or a
concrete surface.
10. (canceled)
11. A structured abrasive article comprising a structured abrasive
layer adhered to a major surface of a backing, wherein the
structured abrasive layer comprises shaped abrasive composites
adhered to the major surface, wherein the shaped abrasive
composites comprise milled polycrystalline ceramic abrasive
particles retained in a polymeric binder, wherein the milled
polycrystalline ceramic abrasive particles have a mean particle
size D.sub.50 of from 14 to 18 microns, and wherein the milled
polycrystalline ceramic abrasive particles comprise milled
polycrystalline alumina particles.
12. The structured abrasive article of claim 11, wherein the
structured abrasive layer has a bearing area ratio of from 40
percent to 70 percent.
13. (canceled)
14. The structured abrasive article of claim 11, wherein the
abrasive composites comprise hexagonal prisms.
15. The structured abrasive article of claim 11, wherein the milled
polycrystalline ceramic abrasive particles have an average Vickers
hardness of at least 21 gigapascals.
16. The structured abrasive article of claim 11, wherein the milled
polycrystalline ceramic abrasive particles have an average fracture
toughness of at least 3 megapascal-meter.sup.-0.5.
Description
TECHNICAL FIELD
[0001] The present disclosure broadly relates to methods of
finishing a stone surface and structured abrasive articles.
BACKGROUND
[0002] Flooring and counters made of hard composite materials are
widely used. Such hard composite materials are collectively
referred to by those engaged in the field of hard surface finishing
as "stone" or "stone surfaces". These people are involved in the
practice of producing surfaces with maximized aesthetic appearance
(e.g., high gloss and reflected image clarity); typically,
including a dry finishing process.
[0003] For ease of reference, the term "stone", as used
hereinafter, refers to durable naturally-occurring mineral
materials as well as rigid durable man-made composite materials
containing a predominant mineral phase. Examples include
naturally-occurring minerals (e.g., granite, limestone, travertine,
onyx, or marble) or man-made composites (e.g., cementitious
terrazzo, and resin-bonded terrazzo), ceramic tile, and
concrete).
[0004] To achieve a highly polished stone surface, the art has
relied on ultra-hard diamond particles in lofty nonwoven abrasive
constructions. Diamond abrasives are conventionally used in a
series of progressively finer particle sizes to refine stone
surfaces to high aesthetic levels (e.g. high-brightness,
high-clarity reflected image quality). Surface parameters such as,
for example, "gloss", "specular reflectivity", "haze", and/or
"distinctness of image" (DOI) are typically used to characterize
the aesthetic appearance of polished stone surfaces. These measured
surface parameters correlate well with perceived favorability of
the surface as discriminated by eye. For a floor surface, haze
(which is a measure of the cloudiness of a reflected image) and DOI
(which is a measure of the clarity or sharpness of an image
reflected off the surface) are generally the most important visual
aesthetic parameters. A high gloss value, signifying the brightness
or shininess of a surface, may not be aesthetically sufficient if
not accompanied by a high DOI value or sharp image clarity. Highly
aesthetically desirable surfaces generally exhibit very high DOI,
low haze, and at least a medium gloss level.
[0005] Diamond abrasives, as their name suggests, are typically
expensive. It would be desirable to have lower cost and/or improved
methods of finishing stone surfaces.
SUMMARY
[0006] The present disclosure provides a lower cost alternative to
diamond abrasives for finishing stone floors to high aesthetic
levels, which can surpass those achieved through conventional
diamond abrasive methods. Unexpectedly, the present disclosure
achieves these high, or even superior, aesthetic levels of
appearance using less hard and coarser abrasive materials than are
used in diamond abrasive finishing.
[0007] In one aspect, the present disclosure provides a method of
finishing a stone surface, the method comprising:
[0008] providing a structured abrasive article comprising a
structured abrasive layer adhered to a major surface of a backing,
the structured abrasive layer comprising shaped abrasive composites
adhered to the major surface, the shaped abrasive composites
comprising milled polycrystalline ceramic abrasive particles
retained in a polymeric binder, wherein the milled polycrystalline
ceramic abrasive particles have a median particle size D.sub.50 of
from 3 to 30 microns;
[0009] frictionally contacting the structured abrasive layer with
the stone surface; and
[0010] moving the structured abrasive layer relative to the stone
surface under conditions sufficient to finish the stone
surface.
[0011] In another aspect, the present disclosure provides a
structured abrasive article suitable for practicing methods of
finishing a stone surface according to the present disclosure. The
structured abrasive article comprises a structured abrasive layer
adhered to a major surface of a backing, wherein the structured
abrasive layer comprises shaped abrasive composites adhered to the
major surface, wherein the shaped abrasive composites comprise
milled polycrystalline ceramic abrasive particles retained in a
polymeric binder, wherein the milled polycrystalline ceramic
abrasive particles have a mean particle size D.sub.50 of from 3 to
30 microns.
[0012] As used herein,
[0013] "D.sub.50" refers to the median particle size (i.e.
equivalent spherical diameter) of a particle size distribution
measured consistent with ISO 13320:2009, "Particle size
analysis--Laser diffraction methods".
[0014] "Fracture toughness" is determined consistent with the
method described by P. J. Blau and B. R. Lawn, "Indentation of
Brittle Materials" in Microindentation Techniques In Materials
Science And Engineering, ASTM Special Technical Publication 889, P.
J. Blau and B. R. Lawn, Eds., 1985, pp. 26-46, ASTM Philadelphia,
Pa.;
[0015] the term "milled" means mechanically comminuted in a mill
such as, for example, a ball mill, planetary ball mill, pebble
mill, rod mill, vertical shaft impactor mill, roller mill, or jet
mill;
[0016] the term "polymeric" refers to an organic polymer; and
[0017] "Vickers hardness" is determined consistent with ASTM Test
Method E384-11 (editorially corrected March 2012), "Standard Test
Method for Knoop and Vickers Hardness of Materials".
[0018] Distinctness of Image (DOI), gloss, and haze, is determined
consistent with ASTM E430-11 (2011). "Standard Test Methods for
Measurement of Gloss of High-Gloss Surfaces by Abridged
Goniophotometry".
[0019] Features and advantages of the present disclosure will be
further understood upon consideration of the detailed description
as well as the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a schematic top-view of exemplary structured
abrasive disc 10.
[0021] FIG. 2 is a schematic cross-sectional side view of
structured abrasive disc 10 taken along plane 2-2.
[0022] Repeated use of reference characters in the specification
and drawings is intended to represent the same or analogous
features or elements of the disclosure. The figures may not be
drawn to scale. It should be understood that numerous other
modifications and embodiments can be devised by those skilled in
the art, which fall within the scope and spirit of the principles
of the disclosure.
DETAILED DESCRIPTION
[0023] Without wishing to be bound by theory, the present inventor
believes that in processes according to the present disclosure, the
stone surface undergoes a brittle to ductile state transition due
to action of the structured abrasive article. This results from the
physical properties (e.g., hardness, toughness, and few cutting
points) of the milled polycrystalline ceramic abrasive particles in
combination with the structured abrasive article construction. Once
in the ductile state, the material smears and then reverts to the
brittle state thereby resulting in a smooth high clarity surface
finish. This contrasts with diamond abrasives, which are typically
single crystal and have numerous points per crystal.
[0024] Materials with surfaces that can be finished according to
the methods of the present disclosure include durable
naturally-occurring mineral materials as well as rigid durable
man-made composite materials containing a predominant mineral
phase. Examples include granite, limestone, travertine, onyx,
marble, cementitious terrazzo, resin-bonded terrazzo, ceramic tile,
concrete, and combinations thereof.
[0025] The materials may be in any form such as, for example, in
the form of a floor, counter, wall, pillar, monument, plaza, table
top, sculpture, or patio. In such cases, the surfaces finished are
generally exposed to viewing by a user.
[0026] Characterization of stone surfaces before, during, and/or
after finishing may be characterized by any suitable technique.
Examples of useful parameters include gloss, specular reflectivity,
distinctness of image (DOI), and haze. Suitable measurement
techniques for these parameters are known in the art (e.g., as
available from standards organizations such as ASTM International,
West Conshohocken, Pa.).
[0027] In typical use, structured abrasive articles according to
the present disclosure are affixed to a backup/driver pad mounted
on a tool, although this not a requirement. Examples of suitable
tools include: (a) for stone floors; floor machines having a driven
lofty nonwoven driver pad, low-speed 180 rpm swing machine, a
battery electric ride-on or walk-behind floor machine, or a
high-speed >1400 rpm (e.g., propane) floor machine operated at
travel speed in excess of normal use; and (b) for non-floor stone
surfaces; handheld random orbital tool, handheld rotary tool, and
handheld, planetary tools. With floor machines, the driver pad is
typically a lofty open nonwoven disc such as, for example, that
available as 3M 4100 WHITE SUPER POLISH PAD or 5100 RED BUFFER PAD
from 3M Company.
[0028] In some embodiments, it may be useful to employ one or more
grinding and/or honing steps prior to finishing the stone surface
according to the present disclosure. Such techniques are well known
to those of ordinary skill in the art.
[0029] Unexpectedly, when using methods and structured abrasive
articles according to the present disclosure, floor machines having
a rotational speed of 180 to 300 revolutions per minute (rpm),
preferably less than 200 rpm, typically outperform high speed
finishing machines in terms of aesthetic appearance if used for
comparable times under normal use conditions.
[0030] An exemplary structured abrasive disc 10, useful for
practicing the method of the present disclosure, is shown in FIGS.
1 and 2.
[0031] FIG. 1 shows exemplary structured abrasive disc 10, which
has an array of hexagonal-post-shaped abrasive composites 18
separated from adjacent shaped abrasive composites by a network
valley region 28. The structured abrasive article can be, for
example, in the form of an abrasive disc (as shown) or other common
converted form such as an endless belt.
[0032] As shown in FIG. 2, structured abrasive layer 14 includes a
plurality of shaped abrasive composites 18 that are bonded to
backing 12. Backing 12 has first side 12a and second side 12b.
Shaped abrasive composites 18 comprise abrasive particles 15
dispersed and retained in polymeric binder matrix 16. Second side
12b of backing 12 is attached to optional foam layer 20 on first
side 20a of foam layer 20 by optional first adhesive layer 22.
Optional attachment layer 26 (shown as one part of a two-part
mechanically interlocking fastener system), to attach the structure
abrasive disc 10 to a platen of a grinding or finishing machine, is
affixed to second side 20b of foam layer 20 by second adhesive
layer 24. Instead of one part of a two-part interlocking fastener
system (e.g. hook and loop) to attach the abrasive article to a
grinding tool, other attachment systems such as adhesives, or other
types of interlocking and/or mechanical fasteners can also be
used.
[0033] Exemplary suitable shaped abrasive composite shapes include,
without limitation: rods, cones, truncated cones; rhomboid,
triangular, rectangular, hexagonal, or square posts; and rhomboid,
triangular, rectangular, hexagonal, or square truncated pyramids.
In one embodiment, the top of each shaped abrasive composite is
planar such that the shaped abrasive composite does not come to a
peak or a tip; however, pyramidal or conical shaped abrasive
composites can be used in some applications.
[0034] The spacing of the shaped abrasive composites may vary from
about 0.3 shaped abrasive composites per linear cm to about 100
shaped abrasive composites per linear cm, or about 0.4 to about 20
shaped abrasive composites per linear cm, or about 0.5 to 10 shaped
abrasive composites per linear cm, or about 0.6 to 3.0 shaped
abrasive composites per linear cm. In one aspect of the abrasive
article, there are at least about 1 shaped abrasive composite per
square centimeter (cm.sup.2) or at least about 5 shaped abrasive
composites per square centimeter (cm.sup.2). In a further
embodiment of the disclosure, the area spacing of shaped abrasive
composites ranges from about 1 to about 200 shaped abrasive
composites/cm.sup.2, or from about 2 to about 10 shaped abrasive
composites/cm.sup.2.
[0035] The height of the abrasive composites as measured from the
top of the valley between adjacent shaped abrasive composites to
the top of the shaped abrasive composite is constant across
structured abrasive article, but it is possible to have shaped
abrasive composites of varying heights. The height of the shaped
abrasive composites may be a value from about 10 microns to about
25,000 microns (2.5 cm), or about 25 to about 15,000 microns, or
from about 100 to about 10,000 microns, or from about 500 to about
4,000 microns.
[0036] In various embodiments, the bearing area ratio can be
between about 20 percent to about 80 percent, or between about 40
percent to about 70 percent, or between about 50 percent to about
70 percent. The bearing area ratio, expressed as a percentage, is
the ratio of the total area of the shaped abrasive composites 18 to
the total area of the abrasive article including the area of the
network valley region 28. Depending on the application or the
workpiece, a larger or smaller bearing area ratio may desirable
depending on the grade of abrasive, the work piece material, the
unit loading pressure, and the desired cut rate and finish.
[0037] Suitable backings include those known useful in abrasive
articles, such as polymeric film, cloth including treated cloth,
paper, foam, nonwoven, treated or primed versions thereof, and
combinations thereof. Examples include polyester films, polyolefin
films (e.g., polyethylene and propylene film), polyamide films, and
polyimide films. A thin backing can be reinforced using another
layer for support, such as a thicker film, or a polycarbonate
sheet, for example. In addition, the abrasive article can be
attached to a base or sheet or directly to a finishing apparatus or
machine via any known route, for example, adhesives including
pressure sensitive adhesives are useful.
[0038] The backing serves the function of providing a support for
the shaped abrasive composites. The backing should be capable of
adhering to the polymeric binder matrix after exposure of binder
precursor to curing conditions, and be strong and durable so that
the resulting abrasive article is long lasting. In some
embodiments, the backing may be sufficiently flexible so that the
articles used in the inventive method may conform to surface
contours, radii, and irregularities in the workpiece. In other
embodiments, the backing may be rigid.
[0039] As mentioned, the backing may be a polymeric film, paper,
vulcanized fiber, a molded or cast elastomer, a treated nonwoven
backing, or a treated cloth. Examples of polymeric films include
polyester films, co-polyester films, polyimide films, and polyamide
films. Porous backings (e.g., woven, knit, or nonwoven (including
paper) backings) may be saturated with a thermosetting and/or
thermoplastic material to provide the desired properties. Any of
the above backing materials may further include additives such as,
for example, fillers, fibers, dyes, pigments, wetting agents,
coupling agents, and plasticizers. In one embodiment, the backing
is about 0.05 millimeter (mm) to about 5 mm thick.
[0040] If present, the optional foam layer may be open cell and/or
closed cell, and may be stiff or soft. Preferably, the optional
foam layer has a thickness of less than 1 centimeter (cm), more
preferably less than 0.5 cm. In some embodiments, the foam layer is
substantially uniform in thickness.
[0041] The milled polycrystalline ceramic abrasive particles will
now be discussed in greater detail.
[0042] First of all, the milled polycrystalline ceramic abrasive
particles are milled. During the milling process, cutting points
are successively reduced by mechanical comminution in a mill,
resulting in blocky abrasive particles with few or no cutting
points (e.g., in contrast to diamond crystals which have many
cutting points).
[0043] Second, the milled polycrystalline ceramic abrasive
particles are polycrystalline ceramics. That is, the ceramic
material in each abrasive particle comprises a plurality of
discrete crystallites characterized by discrete boundaries. In some
embodiments, a separate, compositionally distinct, crystalline
phase may be present throughout the milled polycrystalline ceramic
abrasive particles, which serves to inhibit crack propagation.
Preferably, the crystallites have an average size of less than 0.5
micron, more preferably less than 0.3 micron, and more preferably
less than 0.1 micron.
[0044] Alumina-based polycrystalline ceramic abrasive particles may
comprise only alumina, or alternatively alumina in combination with
one or more metal oxides other than alumina such as rare earth
oxide, yttria, iron oxide, titania, including materials of or
containing complex Al.sub.2O.sub.3-metal oxides (e.g.
Dy.sub.3Al.sub.5O.sub.12, Y.sub.3Al.sub.5O.sub.12, or
CeAl.sub.11O.sub.18). The Al.sub.2O.sub.3 source may also include,
for example, minor amounts of silica, iron oxide, titania, and
carbon.
[0045] Preferably, the shaped abrasive composites are essentially
free of ceramic abrasive particles other than the milled
polycrystalline ceramic abrasive particles, although secondary
ceramic abrasive particles that are less hard than the milled
polycrystalline ceramic abrasive particles may be acceptable in
some applications where the workpiece is harder than the secondary
ceramic abrasive particles. Preferably, the shaped abrasive
composites contain less than 5 percent by weight, preferably less
than 1 percent by weight, and more preferably less than 0.1 percent
by weight of ceramic particles other than the milled
polycrystalline ceramic abrasive particles.
[0046] Any milled polycrystalline ceramic material may be used
including, for example, alumina-based ceramics, and zirconia-based
ceramics. Preferably, the milled polycrystalline ceramic material
comprises at least 70 percent by weight, 80 percent by weight, 90
percent by weight, 95 percent by weight, 99 percent by weight, or
even 100 percent by weight of polycrystalline ceramic alumina.
[0047] The milled polycrystalline ceramic abrasive particles have a
median particle size D.sub.50 of from 3 to 30 microns; preferably
from 5 to 25, more preferably from 10 to 20, and still more
preferably from 14 to 18 microns. Smaller sizes are too small; they
may be difficult to retain and abrasive action may be adversely
affected, while larger sizes may result in noticeable
scratches.
[0048] The milled polycrystalline ceramic abrasive particles
preferably have an average Vickers hardness of at least 18 GPa,
more preferably at least 20 GPa, more preferably at least 22 GPa,
more preferably at least 24 GPa, and still more preferably at least
26 GPa.
[0049] The milled polycrystalline ceramic abrasive particles
preferably have an average fracture toughness of at least 2.2
MPa/m.sup.1/2, more preferably at least 2.4 MPa/m.sup.1/2, more
preferably at least 2.6 MPa/m.sup.1/2, more preferably at least 2.8
MPa/m.sup.1/2, more preferably at least 3.0 MPa/m.sup.1/2, more
preferably at least 3.2 MPa/m.sup.1/2, more preferably at least 3.4
MPa/m.sup.1/2, more preferably at least 3.6 MPa/m.sup.1/2, and even
more preferably at least 3.8 MPa/m.sup.1/2. Lesser fracture
toughness values may result in fracture of the abrasive particles
and generation of cutting edges which cause scratches that reduce
the image clarity of the stone surface.
[0050] Suitable alumina-based polycrystalline ceramic abrasive
particles and methods for their manufacture are described in, for
example, in U.S. Pat. No. 4,314,827 (Leitheiser et al.); U.S. Pat.
No. 4,518,397 (Leitheiser et al.); U.S. Pat. No. 4,623,364
(Cottringer et al.); U.S. Pat. No. 4,744,802 (Schwabel); U.S. Pat.
No. 4,770,671 (Monroe et al.); U.S. Pat. No. 4,881,951 (Wood et
al.); U.S. Pat. No. 4,960,441 (Pellow et al.); U.S. Pat. No.
5,139,978 (Wood); U.S. Pat. No. 5,201,916 (Berg et al.); U.S. Pat.
No. 5,366,523 (Rowenhorst et al.); U.S. Pat. No. 5,429,647
(Larmie); U.S. Pat. No. 5,547,479 (Conwell et al.); U.S. Pat. No.
5,498,269 (Larmie); U.S. Pat. No. 5,551,963 (Larmie); U.S. Pat. No.
5,725,162 (Garg et al.); U.S. Pat. No. 6,878,456 (Castro et al.);
and in U.S. Pat. Appl. Publ. Nos. 2005/0132656 A1, 2005/0137077 A1,
and 2005/0132657 A1.
[0051] The abrasive particles are dispersed and retained within the
polymeric binder matrix to form shaped composites of the structured
abrasive article. Polymeric binder matrix is typically derived from
a binder precursor. During the manufacture of the structured
abrasive article, the binder precursor is exposed to an energy
source which aids in the initiation of the polymerization or curing
of the binder precursor. Examples of energy sources include thermal
energy and radiation energy, the latter including electron beam,
ultraviolet light, and visible light. During this polymerization
process, the binder precursor is polymerized and/or cured and
thereby converted into a solidified binder. Upon solidification of
the binder precursor, the polymeric binder matrix is formed.
[0052] Examples of suitable binder precursors include amino resins,
alkylated urea-formaldehyde resins, melamine-formaldehyde resins,
alkylated benzoguanamine-formaldehyde resins, acrylate resins
(including acrylates and methacrylates) such as vinyl acrylates,
acrylated epoxies, acrylated urethanes, acrylated polyesters,
acrylated acrylics, acrylated polyethers, vinyl ethers, acrylated
oils, and acrylated silicones, alkyd resins such as urethane alkyd
resins, polyester resins, reactive urethane resins, phenolic resins
such as resole and novolac resins, phenolic/latex resins, epoxy
resins such as bisphenol epoxy resins, isocyanates, isocyanurates,
polysiloxane resins (including alkylalkoxysilane resins), reactive
vinyl resins, and phenolic resins (resole and novolac). The resins
may be provided as monomers, oligomers, polymers, or combinations
thereof. Typically, the resins may have multiple cure sites, which
results upon curing in a crosslinked polymeric binder matrix.
[0053] The binder precursor can be a condensation curable resin, an
addition polymerizable resin, a free-radically-curable resin,
and/or combinations and blends of such resins. One binder precursor
is a resin or resin mixture that polymerizes via a free-radical
mechanism. The polymerization process is initiated by exposing the
binder precursor, along with an appropriate catalyst, to an energy
source such as thermal energy or radiation energy. Examples of
radiation energy include electron beam, ultraviolet light, or
visible light.
[0054] Examples of free-radically-curable resins include acrylated
urethanes, acrylated epoxies, acrylated polyesters,
ethylenically-unsaturated monomers, aminoplast monomers having
pendant unsaturated carbonyl groups, isocyanurate monomers having
at least one pendant acrylate group, isocyanate monomers having at
least one pendant acrylate group, and mixtures and combinations
thereof. When used generically herein, the term "acrylate"
encompasses acrylates and/or methacrylates.
[0055] One binder precursor comprises a urethane acrylate oligomer,
or a blend of a urethane acrylate oligomer and an
ethylenically-unsaturated monomer. Useful ethylenically-unsaturated
monomers include, for example, monofunctional acrylate monomers,
difunctional acrylate monomers, trifunctional acrylate monomers,
acrylate oligomers, and combinations thereof.
[0056] Examples of useful acrylated urethanes include those known
by the trade designations: "PHOTOMER" (for example, PHOTOMER 6010
aliphatic urethane acrylate oligomer) available from IGM Resins,
Waalwijk, The Netherlands; "EBECRYL" (for example, EBECRYL 220
hexafunctional aromatic urethane acrylate of molecular weight 1,000
g/mol, EBECRYL 284 aliphatic urethane diacrylate of 1,200 molecular
weight diluted with 1,6-hexanediol diacrylate, EBECRYL 4827
aromatic urethane diacrylate of 1,600 g/mol molecular weight,
EBECRYL 4830 aliphatic urethane diacrylate of 1,200 g/mol molecular
weight diluted with tetraethylene glycol diacrylate), EBECRYL 6602
(trifunctional aromatic urethane acrylate of 1,300 g/mol molecular
weight diluted with trimethylolpropane ethoxy triacrylate), and
EBECRYL 840 aliphatic urethane diacrylate of 1,000 g/mol molecular
weight), available from Cytec Industries Inc., Smyrna, Ga.; and
SARTOMER (for example, SARTOMER 9635, SARTOMER 9645, SARTOMER 9655,
SARTOMER 963-B80, and SARTOMER 966-A80), commercially available
from Sartomer Company, Exton, Pa.
[0057] Ethylenically-unsaturated monomers or oligomers, or acrylate
monomers or oligomers, may be monofunctional, difunctional,
trifunctional, tetrafunctional, or even of higher functionality.
Ethylenically-unsaturated binder precursors include both monomeric
and polymeric compounds that contain atoms of carbon, hydrogen, and
oxygen, and optionally, nitrogen and the halogens.
Ethylenically-unsaturated monomers or oligomers preferably have a
molecular weight of less than about 4000 g/mol, and are preferably
esters made from the reaction of compounds containing aliphatic
monohydroxy groups or aliphatic polyhydroxy groups and unsaturated
carboxylic acids, such as acrylic acid, methacrylic acid, itaconic
acid, crotonic acid, isocrotonic acid, and maleic acid.
Representative examples of ethylenically-unsaturated monomers
include methyl methacrylate, ethyl methacrylate, styrene,
divinylbenzene, hydroxyethyl acrylate, hydroxyethyl methacrylate,
hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl
acrylate, hydroxybutyl methacrylate, vinyl toluene, ethylene glycol
diacrylate, polyethylene glycol diacrylate, ethylene glycol
dimethacrylate, hexanediol diacrylate, triethylene glycol
diacrylate, trimethylolpropane triacrylate, glycerol triacrylate,
pentaerythritol triacrylate, pentaerythritol trimethacrylate,
pentaerythritol tetraacrylate and pentaerythritol
tetramethacrylate. Other ethylenically-unsaturated monomers or
oligomers include monoallyl, polyallyl, and polymethallyl esters
and amides of carboxylic acids, such as diallyl phthalate, diallyl
adipate, and N,N-diallyladipamide. Still other nitrogen containing
compounds include tris(2-acryloxyethyl)isocyanurate,
1,3,5-tri(2-methacryloxyethyl)-s-triazine, acrylamide,
methacrylamide, N-methylacrylamide, N,N-dimethylacrylamide,
N-vinylpyrrolidone, and N-vinylpiperidone. Further examples of
ethylenically-unsaturated diluents or monomers can be found in U.S.
Pat. No. 5,236,472 (Kirk) and U.S. Pat. No. 5,580,647 (Larson et
al.).
[0058] In general, the ratio between these acrylate monomers will
depend on the weight percent of abrasive particles and any optional
additives or fillers desired in the final abrasive article.
Typically, these acrylate monomers range from about 5 parts by
weight to about 95 parts by weight urethane acrylate oligomer to
about 5 parts by weight to about 95 parts by weight
ethylenically-unsaturated monomer. Additional information
concerning other potential useful binders and binder precursors can
be found in U.S. Pat. No. 4,773,920 (Chasman et al.) and U.S. Pat.
No. 5,958,794 (Bruxvoort et al.).
[0059] Acrylated epoxies are diacrylate esters of epoxy resins such
as, for example, the diacrylate esters of bisphenol A epoxy resin.
Examples of acrylated epoxies include those available as EBECRYL
3500, EBECRYL 3600, and EBECRYL 3700 from Cytec Industries Inc.;
and as CN103, CN104, CN111, CN112, and CN114 from Sartomer
Company.
[0060] Examples of polyester acrylates include those available as
EBECRYL 80, EBECRYL 657, and EBECRYL 830 from Cytec Industries
Inc.
[0061] Aminoplast monomers have at least one pendant alpha,
beta-unsaturated carbonyl group. These unsaturated carbonyl groups
may be acrylate, methacrylate or acrylamide type groups. Examples
of such materials include N-(hydroxymethyl)acrylamide,
N,N'-oxydimethylene-bisacrylamide, ortho- and
para-acrylamidomethylated phenol, acrylamidomethylated phenolic
novolac, and combinations thereof. These materials are further
described in U.S. Pat. No. 4,903,440 (Kirk) and U.S. Pat. No.
5,236,472 (Kirk).
[0062] Isocyanurates having at least one pendant acrylate group and
isocyanate derivatives having at least one pendant acrylate group
are further described in U.S. Pat. No. 4,652,274 (Boettcher). One
preferred isocyanurate material is a triacrylate of
tris(hydroxyethyl) isocyanurate.
[0063] Depending upon how the free-radically-curable resin is cured
or polymerized, the binder precursor may further comprise a curing
agent (e.g., a thermal initiator or a photoinitiator). When the
curing agent is exposed to the appropriate energy source, it will
generate a free-radical source that will start the polymerization
process.
[0064] Another useful binder precursor comprises an epoxy resin.
Epoxy resins have an oxirane ring and are polymerized by a ring
opening reaction. Such epoxide resins include monomeric epoxy
resins and polymeric epoxy resins. Exemplary epoxy resins include
diglycidyl ethers of bisphenol A or F such as, for example, those
available as EPON 828, EPON 1004, and EPON 1001F from Momentive
Specialty Chemicals, Columbus, Ohio, and as DER-331, DER-332, and
DER-334, commercially available from Co. Midland, Mich. Other
suitable epoxy resins include cycloaliphatic epoxies, glycidyl
ethers of phenol formaldehyde novolacs (for example, as available
under the trade designations DEN-431 and DEN-428 from Dow Chemical
Co.). Examples of usable multi-functional epoxy resins include EPON
HPT 1050 and EPON 1031 from Momentive.
[0065] Blends of free-radically-curable resins and epoxy resins may
be used and are further described in U.S. Pat. No. 4,751,138 (Tumey
et al.) and U.S. Pat. No. 5,256,170 (Harmer et al.).
[0066] In one embodiment, the polymeric binder, when incorporated
with the abrasive particles in the structured abrasive article, has
high thermal resistance. Specifically, the cured binder has a glass
transition temperature (i.e., T.sub.g) of at least 150.degree. C.,
or at least 160.degree. C., or even at least 175.degree. C. is
desired, or at least 200.degree. C.
[0067] The polymeric binder matrix and the backing of this
disclosure may contain additives such as, for example, abrasive
particle surface modification additives (e.g., coupling agents),
fillers, expanding agents, fibers, pore formers, antistatic agents,
curing agents, suspending agents, wetting agents, photosensitizers,
lubricants, surfactants, pigments, dyes, UV stabilizers, and
antioxidants. The amounts of these materials are selected to
provide the properties desired.
[0068] Examples of useful fillers for this disclosure include:
metal carbonates (such as calcium carbonate-chalk, calcite, marl,
travertine, marble, and limestone; calcium magnesium carbonate,
sodium carbonate, and magnesium carbonate), silica (such as quartz,
glass beads, glass bubbles, and glass fibers), silicates (such as
talc, clays-montmorillonite; feldspar, mica, calcium silicate,
calcium metasilicate, sodium aluminosilicate, sodium silicate,
lithium silicate, and hydrous and anhydrous potassium silicate),
metal sulfates (such as calcium sulfate, barium sulfate, sodium
sulfate, aluminum sodium sulfate, aluminum sulfate), gypsum,
vermiculite, wood flour, aluminum trihydrate, carbon black, metal
oxides (such as calcium oxide-lime; aluminum oxide; tin oxide--for
example, stannic oxide; titanium dioxide) and metal sulfites (such
as calcium sulfite), thermoplastic particles (such as
polycarbonate, polyetherimide, polyester, polyethylene,
polysulfone, polystyrene, acrylonitrile-butadiene-styrene block
copolymer, polypropylene, acetal polymers, polyurethanes, nylon
particles) and thermosetting particles (such as phenolic bubbles,
phenolic beads, polyurethane foam particles). The filler may also
be a salt such as a halide salt. Examples of halide salts include
sodium chloride, potassium cryolite, sodium cryolite, ammonium
chloride, potassium tetrafluoroborate, sodium tetrafluoroborate,
silicon fluorides, potassium chloride, and magnesium chloride.
Examples of metal fillers include, tin, lead, bismuth, cobalt,
antimony, cadmium, iron, and titanium. Other miscellaneous fillers
include sulfur, organic sulfur compounds, graphite, and metallic
sulfides. Fillers generally have an average particle size range of
0.1 to 50 microns, typically 1 to 30 microns.
[0069] An example of a suspending agent is an amorphous silica
particle having a surface area less than 150 meters square/gram,
commercially available from DeGussa Corp. Ridgefield Park, N.J.,
under the trade designation OX-50. The addition of the suspending
agent may lower the overall viscosity of the abrasive slurry. The
use of suspending agents is further described in U.S. Pat. No.
5,368,619 (Culler).
[0070] A coupling agent may provide an association bridge between
the binder and the abrasive particles, and any filler particles.
Examples of coupling agents include silanes, titanates, and
zircoaluminates. The coupling agent can be added directly to the
binder precursor, which may have about 0 to 30 percent by weight,
preferably 0.1 to 25 percent by weight coupling agent.
Alternatively, the coupling agent can be applied to the surface of
any particles, typically about 0 to 3% by weight coupling agent,
based upon the weight of the particle and the coupling agent.
Examples of commercially available coupling agents include SILQUEST
A-174 (gamma-methacryloxypropyltrimethoxysilane) coupling agent,
commercially available from GE Advanced Materials, Wilton, Conn.
Still another example of a commercial coupling agent is an
isopropyl triisostearoyl titanate, available as KR-TTS from Kenrich
Petrochemicals, Bayonne, N.J.
[0071] The binder precursor may further comprise a curing agent. A
curing agent is a material that helps to initiate and complete the
polymerization or crosslinking process such that the binder
precursor is converted into a binder. The term "curing agent"
encompasses initiators (e.g. thermal initiators and
photoinitiators), catalysts, and activators. The amount and type of
the curing agent will depend largely on the chemistry of the binder
precursor.
[0072] Polymerization of ethylenically-unsaturated monomer(s) or
oligomer(s) occurs via a free-radical mechanism. If the energy
source is an electron beam, or ionizing radiation source (gamma or
x-ray), free-radicals which initiate polymerization are generated.
However, it is within the scope of this disclosure to use
initiators even if the binder precursor is exposed to an electron
beam. If the energy source is heat, ultraviolet light, or visible
light, an initiator may have to be present in order to generate
free-radicals. Examples of initiators that generate free-radicals
upon exposure to ultraviolet light or heat include, but are not
limited to, organic peroxides, azo compounds, quinones, nitroso
compounds, acyl halides, hydrazones, mercapto compounds, pyrylium
compounds, imidazoles, chlorotriazines, benzoin, benzoin alkyl
ethers, diketones, phenones, and mixtures thereof. Examples of
commercially available photoinitiators that generate free-radicals
upon exposure to ultraviolet light include those available as
IRGACURE 651, IRGACURE 184, IRGACURE 369, and DAROCUR 1173 from
Ciba Specialty Chemicals, Tarrytown, N.Y. Examples of initiators
that generate free-radicals upon exposure to visible light may be
found in U.S. Pat. No. 4,735,632 (Larson et al.).
[0073] Typically, the initiator is used in amounts ranging from 0.1
to 10 percent by weight, preferably 2 to 4 percent by weight, based
on the total weight of the binder precursor. Additionally, it is
preferred to disperse, preferably uniformly disperse, the initiator
in the binder precursor prior to the addition of any particulate
material, such as the abrasive particles and/or filler
particles.
[0074] In general, it is preferred that the binder precursor be
exposed to radiation energy, preferably ultraviolet light or
visible light. In some instances, certain abrasive particles and/or
certain additives will absorb ultraviolet and visible light, which
makes it difficult to properly cure the binder precursor. This
phenomenon is especially true with ceria abrasive particles and
silicon carbide abrasive particles. It has been found, quite
unexpectedly, that the use of phosphate-containing photoinitiators,
in particular acylphosphine oxide containing photoinitiators, tends
to overcome this problem. An example of such a photoinitiator is
2,4,6-trimethylbenzoyldiphenylphosphine oxide, commercially
available from BASF Corporation, Charlotte, N.C., as LUCIRIN TPO.
Other examples of commercially available acylphosphine oxides
include those available as DAROCUR 4263 and DAROCUR 4265 from Ciba
Specialty Chemicals.
[0075] Optionally, the curable compositions may contain
photosensitizers or photoinitiator systems which affect
polymerization either in air or in an inert atmosphere, such as
nitrogen. These photosensitizers or photoinitiator systems include
compounds having carbonyl groups or tertiary amino groups and
mixtures thereof. Among the preferred compounds having carbonyl
groups are benzophenone, acetophenone, benzil, benzaldehyde,
o-chlorobenzaldehyde, xanthone, thioxanthone, 9,10-anthraquinone,
and other aromatic ketones which may act as photosensitizers. Among
the preferred tertiary amines are methyldiethanolamine,
ethyldiethanolamine, triethanolamine, phenylmethylethanolamine, and
dimethylaminoethyl benzoate. In general, the amount of
photosensitizer or photoinitiator system may vary from about 0.01
to 10% by weight, more preferably from 0.25 to 4.0 percent by
weight, based on the weight of the binder precursor. Examples of
photosensitizers include those available as QUANTICURE ITX,
QUANTICURE QTX, QUANTICURE PTX, and QUANTICURE EPD from Biddle
Sawyer Corp., New York, N.Y.
[0076] In one embodiment, the binder precursor is cured with the
aid of both a photoinitiator (e.g., as described hereinabove) and a
thermal initiator acting on the same functional type. Examples of
thermal initiators include organic peroxides (e.g., benzoyl
peroxide), azo compounds, quinones, nitroso compounds, acyl
halides, hydrazones, mercapto compounds, pyrylium compounds,
imidazoles, chlorotriazines, benzoin, benzoin alkyl ethers,
diketones, phenones, and mixtures thereof. Examples of suitable azo
compound thermal initiators include those available as VAZO 52,
VAZO 64, and VAZO 67 from E.I. du Pont de Nemours and Co.,
Wilmington, Del.
[0077] Structured abrasive articles according to the present
disclosure can be made using known methods for making structured
abrasive articles having shaped abrasive composites. Useful methods
are described in U.S. Pat. No. 5,152,917 (Pieper et al.); U.S. Pat.
No. 5,672,097 (Hoopman); U.S. Pat. No. 5,681,217 (Hoopman et al.);
and U.S. Pat. No. 5,435,816 (Spurgeon et al.); U.S. Pat. No.
5,454,844 (Hibbard et al.), U.S. Pat. No. 5,851,247 (Stoetzel et
al.); U.S. Pat. No. 6,139,594 (Kincaid et al.); and U.S. Pat. No.
5,304,223 (Pieper et al.); and in U.S. Pat. No. 5,437,754
(Calhoun). Another useful method of making useful abrasive articles
having shaped abrasive composites where the composites comprise
abrasive agglomerates fixed in a make coat, with optional size
coatings, is described in U.S. Pat. No. 6,217,413
(Christianson).
[0078] The structured abrasive article may be shape converted using
a process such, for example, as rule die cutting, laser cutting, or
water jet cutting.
SELECT EMBODIMENTS OF THE PRESENT DISCLOSURE
[0079] In a first embodiment, the present disclosure provides a
method of finishing a stone surface, the method comprising:
[0080] providing a structured abrasive article comprising a
structured abrasive layer adhered to a major surface of a backing,
the structured abrasive layer comprising shaped abrasive composites
adhered to the major surface, the shaped abrasive composites
comprising milled polycrystalline ceramic abrasive particles
retained in a polymeric binder, wherein the milled polycrystalline
ceramic abrasive particles have a median particle size D.sub.50 of
from 3 to 30 microns;
[0081] frictionally contacting the structured abrasive layer with
the stone surface; and
[0082] moving the structured abrasive layer relative to the stone
surface under conditions sufficient to finish the stone
surface.
[0083] In a second embodiment, the present disclosure provides a
method according to the first embodiment, wherein the structured
abrasive layer has a bearing area ratio of from 40 percent to 70
percent.
[0084] In a third embodiment, the present disclosure provides a
method according to the first or second embodiment, wherein the
milled polycrystalline ceramic abrasive particles comprise milled
polycrystalline alumina particles.
[0085] In a fourth embodiment, the present disclosure provides a
method according to any one of the first to third embodiments,
wherein the shaped abrasive composites comprise hexagonal
posts.
[0086] In a fifth embodiment, the present disclosure provides a
method according to any one of the first to fourth embodiments,
wherein the milled polycrystalline ceramic abrasive particles have
an average Vickers hardness of at least 21 gigapascals.
[0087] In a sixth embodiment, the present disclosure provides a
method according to any one of the first to fifth embodiments,
wherein the milled polycrystalline ceramic abrasive particles have
an average fracture toughness of at least 3 megapascals per
meter.sup.0.5.
[0088] In a seventh embodiment, the present disclosure provides a
method according to any one of the first to sixth embodiments,
wherein the stone surface comprises at least a portion of a
floor.
[0089] In an eighth embodiment, the present disclosure provides a
method according to any one of the first to seventh embodiments,
wherein the stone surface comprises at least a portion of a
counter.
[0090] In a ninth embodiment, the present disclosure provides a
method according to any one of the first to eighth embodiments,
wherein the stone surface comprises at least one of a granite
surface, a marble surface, a cement surface, a terrazzo surface, a
ceramic tile surface, or a concrete surface.
[0091] In a tenth embodiment, the present disclosure provides a
method according to any one of the first to ninth embodiments,
wherein the backing is secured to a lofty open nonwoven backup pad
mounted on a rotary floor machine, wherein the rotary floor machine
operates at a rotational speed of less than 250 rotations per
minute.
[0092] In an eleventh embodiment, the present disclosure provides a
structured abrasive article comprising a structured abrasive layer
adhered to a major surface of a backing, wherein the structured
abrasive layer comprises shaped abrasive composites adhered to the
major surface, wherein the shaped abrasive composites comprise
milled polycrystalline ceramic abrasive particles retained in a
polymeric binder, wherein the milled polycrystalline ceramic
abrasive particles have a mean particle size D.sub.50 of from 3 to
30 microns.
[0093] In a twelfth embodiment, the present disclosure provides a
structured abrasive article according to the eleventh embodiment,
wherein the structured abrasive layer has a bearing area ratio of
from 40 percent to 70 percent.
[0094] In a thirteenth embodiment, the present disclosure provides
a structured abrasive article according to the eleventh or twelfth
embodiment, wherein the milled polycrystalline ceramic abrasive
particles comprise milled polycrystalline alumina particles.
[0095] In a fourteenth embodiment, the present disclosure provides
a structured abrasive article according to any one of the eleventh
to thirteenth embodiments, wherein the abrasive composites comprise
hexagonal prisms.
[0096] In a fifteenth embodiment, the present disclosure provides a
structured abrasive article according to any one of the eleventh to
fourteenth embodiments, wherein the milled polycrystalline ceramic
abrasive particles have an average Vickers hardness of at least 21
gigapascals.
[0097] In a sixteenth embodiment, the present disclosure provides a
structured abrasive article according to any one of the eleventh to
fifteenth embodiments, wherein the milled polycrystalline ceramic
abrasive particles have an average fracture toughness of at least 3
megapascals per meter.sup.0.5.
[0098] Objects and advantages of this disclosure are further
illustrated by the following non-limiting examples, but the
particular materials and amounts thereof recited in these examples,
as well as other conditions and details, should not be construed to
unduly limit this disclosure.
EXAMPLES
[0099] Unless otherwise noted, all parts, percentages, ratios, etc.
in the Examples and the rest of the specification are by weight.
The abbreviations listed in Table 1 (below) are used throughout the
examples.
TABLE-US-00001 TABLE 1 ABBREVIATION DESCRIPTION TMPTA
trimethylolpropane triacrylate; commercially available as SR 351
from Sartomer Co., Exton, Pennsylvania PH2
2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone
photoinitiator, available as IRGACURE 369 from Ciba Specialty
Chemicals, Tarrytown, New York THI
2,2'-azobis(2,4-dimethylpentanenitrile) thermal initiator,
available as VAZO 52 from E.I. du Pont de Nemours and Co.,
Wilmington, Delaware CAS surface-modified calcium metasilicate
filler, available as WOLLASTOCOAT M400 from NYCO, Willsboro, New
York SCA silane coupling agent,
3-methacryloxypropyltrimethoxysilane, available as SILQUEST A-174NT
from Momentive Specialty Chemicals, Columbus, Ohio ASF amorphous
silica filler, available as AEROSIL OX-50 FUMED SILICA from Evonik
Industries AG, Essen, Germany BYK wetting agent, available as BYK
985 from BYK USA Inc., Wallingford, Connecticut PR phenolic resin,
water-based, available as Liquid Phenolic Resin 80 5077A from
Arclin, Mississauga, Ontario, Canada TAL talc filler, available as
MISTRON 353 from Imerys Talc America, Inc., Three Forks, Montana
DYN surfactant, available as DYNOL 604 from Air Products and
Chemicals, Allentown, Pennsylvania H2O tap water 3u CAO milled
ceramic aluminum oxide, 3 microns average particle size, prepared
according to the disclosure of U.S. Pat. No. 5,312,789 (Wood), and
obtained from Fujimi Corp., Tulatin, Oregon 4u CAO milled ceramic
aluminum oxide, 4 microns average particle size, prepared according
to the disclosure of U.S. Pat. No. 5,312,789 (Wood), and obtained
from Fujimi Corp. 6u CAO milled ceramic aluminum oxide, 6 microns
average particle size, prepared according to the disclosure of U.S.
Pat. No. 5,312,789 (Wood), and obtained from Fujimi Corp. 800 CAO
milled ceramic aluminum oxide, available as CUBITRON 321 grade JIS
800, approx. 16 microns average particle size 180 CAO milled
ceramic aluminum oxide, available as CUBITRON 321 grade grade ANSI
180, approx. 78 microns average particle size 2500 WAO white fused
aluminum oxide, grade JIS 2500, available from Treibacher
Schleifmittel, Villach, Austria PDP lofty, non-woven diamond
(approx. 4 microns average particle size) abrasive pad, available
as 3M SCOTCHBRITE PURPLE DIAMOND FLOOR PAD PLUS, from 3M Company,
St. Paul, Minnesota A10 diamond structured abrasive disc (approx.
10 microns average particle size) available as 3M TRIZACT
INDUSTRIAL DIAMOND QRS CLOTH 673FA, A10 YF-WEIGHT from 3M Company
A45 diamond structured abrasive disc (approx. 45 microns average
particle size) available as 3M TRIZACT INDUSTRIAL DIAMOND QRS CLOTH
673FA, A45 YF-WEIGHT from 3M Company A300 diamond structured
abrasive disc (approx. 170 micron average particle size) available
as 3M TRIZACT INDUSTRIAL DIAMOND QRS CLOTH 673FA, A300 YF-WEIGHT
from 3M Company CT unglazed ceramic quarry tile, available as
VERSATILE from Metropolitan Ceramics, Canton, Ohio PCT precast
cementitious terrazzo tile, 12-inch (30 cm) square, item WT2774,
available from Wausau Tile, Wausau, Wisconsin GMG Grey Maua Granite
tile, 8-inch 20 cm) square, available from Braminas Brasilerira de
Granitos e Marmores Ltd, Sao Paulo, Brazil
Procedure for Making Structured Abrasive Articles (Method 1)
[0100] Structured abrasive articles were prepared according to the
procedure of Example 2 as described in col. 19, line 1 to col. 20,
line 4 of U.S. Pat. No. 8,323,072 (Billig et al.). The abrasive
slurries used to create the shaped abrasive composites were
formulated according to the compositions reported in Table 2
(below).
TABLE-US-00002 TABLE 2 COMPOSITION, grams 800 180 2500 EXAMPLE
TMPTA PH2 THI CAS SCA ASF BYK CAO CAO WAO 1 9552 96 96 8661 372 87
0 11136 0 0 2 9552 96 96 8661 372 87 0 11136 0 0 3 9552 96 96 8661
372 87 0 11136 0 0 4 9552 96 96 8661 372 87 0 11136 0 0 5 9552 96
96 8661 372 87 0 11136 0 0 6 9552 96 96 8661 372 87 0 11136 0 0 7
9552 96 96 8661 372 87 0 11136 0 0 Comparative 6210 62.5 0 6090 305
142.5 0 0 12190 0 Example A Comparative 8230 82.5 0 4962.5 0 150
37.5 0 0 11537.5 Example B
[0101] Structured abrasive discs were assembled by laminating the
backings of the structured abrasive articles prepared above to
KANEBO 2K3 nylon loop fastening material from Kanebo Bell Ltd. New
York, N.Y. using 3M ADHESIVE TRANSFER TAPE 9485PC from 3M Company,
and compressing the assembly through a pneumatic roll laminator set
at 100 psi (0.7 MPa) roll pressure. Five inch (13 cm) diameter
abrasive discs were die-cut from the laminated assembly using a
circular rule die.
Procedure for Making Non-Structured Lofty Non-Woven Abrasive
Articles (Method 2)
[0102] Water-based phenolic abrasive slurries for making lofty,
non-woven abrasive articles were formulated according to the
compositions reported in Table 3 (below).
TABLE-US-00003 TABLE 3 COMPOSITION, grams 3u 4u 6u EXAMPLE PR TAL
CAS DYN H2O CAO CAO CAO Comparative 227.5 31.9 4.5 10 100.0 0 0
91.0 Example C drops Comparative 227.5 32.1 4.3 10 100.1 91.0 0 0
Example D drops Comparative 227.4 32.1 4.3 10 100.1 0 91.2 0
Example E drops
[0103] Eight-inch (20-cm) discs were die-cut from 5/8 inch (1.6 cm)
thick 200 denier nylon non-woven material. The lofty nonwoven nylon
prebond had a basis weight of 500 g/m.sup.2. The nylon prebond
discs were saturated with abrasive slurry and the excess slurry
squeezed out between rubber nip rollers under 80 psi (0.6 MPa) roll
pressure. Wet slurry add-on weight was 165-169 percent by weight.
The wet prebond discs were cured for 30 minutes in a
circulating-air oven set at 300.degree. F. (149.degree. C.).
Surface Roughness Measurement
[0104] The surface roughness is defined by R.sub.a and R.sub.z. The
R.sub.a of a surface is the measurement of the arithmetic average
of the scratch depth. It is the average of 5 individual roughness
depths of five successive measuring lengths, where an individual
roughness depth is the vertical distance between the highest point
and a center line. R.sub.z is the average of 5 individual roughness
depths of a measuring length, where an individual roughness depth
is the vertical distance between the highest point and the lowest
point. R.sub.a and R.sub.z were measured at the end of each
3-minute process step using a Mahr Perthometer M2 contact
profilometer from Mahr Corporation, Cincinnati, Ohio. Reported
values were the average of six measurements on each test tile
specimen.
Test Method 1
[0105] A 4-foot (1.2-m).times.5-foot (1.5-m) area of 12-inch
(30-cm) square red marble flooring tiles was wet-abraded and
finished according to the following steps.
[0106] Interface attachment discs having hooks on both surfaces
were used to attach abrasive test discs to a floor machine driver
pad. Interface attachment discs were formed by laminating sheets of
adhesive-backed reclosable fastener similar to those available
under the trade designation 3M DUAL LOCK LOW PROFILE RECLOSABLE
FASTENER SJ4570 from 3M Company, and then die-cutting 5 inch
(13-cm) diameter interface attachment discs.
[0107] Four 5-inch (13-cm) structured abrasive test discs were
attached at the 12:00, 3:00, 6:00 and 9:00 positions on the outer
perimeter of a lofty. 17-inch (43-cm) nonwoven machine driver pad
obtained as 3M WHITE SUPERPOLISH PAD 4100 from 3M Company. The
abrasive discs and driver pad were attached to a 17-inch (43-cm)
SEARAY 175 swing-type floor machine from Pacific Floorcare,
Muskegon, Mich. The machine was operated at 175 rpm. The test floor
surface was wetted with water, and each set of abrasive discs was
tested by making six successive passes over the red marble test
area.
Test Method 2
[0108] Square test tile specimens were placed on a layer of 1/8
inch (32 mm) thick high-density foam attached to a benchtop surface
to hold tile specimens in place for abrasive preparation and
finishing. A continuous water stream was directed onto the test
tile surface at an approximately 30 ml/minute flow rate for
wet-abrasive preparation steps. Finishing steps were conducted with
no water flow, and only after a previously-prepared wetted surface
had dried completely.
[0109] Structured abrasive articles were mounted to a 5-inch (13
cm) hook-type back-up pad (item 915 from 3M Company) and rotated at
1000 rpm using a variable-speed rotary polishing tool (model 28391)
from 3M Company. Non-structured, lofty non-woven abrasive articles
were mounted to a 6-inch (15 cm) hook-type back-up pad (item 916
from 3M Company) and rotated at 1400 rpm using the rotary polishing
tool.
[0110] All preparation and finishing process steps were carried out
for three successive one-minute intervals, rotating the tile
90.degree. counterclockwise between each finishing step. The
polishing tool was operated under light downward hand pressure and
was circulated across the entire test tile holding the abrasive
article flat to the tile surface to produce a uniformly-finished
surface.
[0111] Aesthetic measurements for Examples 9-12 and Comparative
Examples H-K were made using a RHOPOINT IQ 20 60. DOI gloss haze
meter. Aesthetic measurements for Examples 13-17 and Comparative
Examples L-Q were made using a RHOPOINT NOVO-GLOSS IQ
goniophotometer. Both Rhopoint instruments were obtained from
Imbotec Industrial Solutions. Ontario, Canada. Reported values were
the average of six measurements on each test tile specimen.
Example 8 and Comparative Examples F and G
[0112] Structured abrasive discs incorporating milled
polycrystalline ceramic abrasive particles and micron-grade white
fused alumina were tested on an array of 12 inches.times.12 inches
(30 cm by 30 cm) red marble tiles. Four 5-inch (13-cm) diameter
structured abrasive discs made according to Method 1 were used on
the 17-inch (43-cm) SEARAY 175 swing-type floor machine. Mechanical
surface scratch profiles were measured before and after each
abrading step to gauge the surface refinement capability of
non-diamond abrasives on marble.
[0113] Surface roughness data reported in TABLE 4 (below) are the
average of six measurements taken on at least six tile locations,
using a Mahr Perthometer M2 profilometer from Mahr Corporation,
Cincinnati, Ohio.
TABLE-US-00004 TABLE 4 R.sub.a, R.sub.z, microinches microinches
EXAMPLE STEP PROCEDURE/COMMENTS (microns) (microns) 0 Starting
condition finished 4.8 (0.12) 49 (1.2) using a PDP pad dry.
Specular glossy appearance. Comparative 1 Abraded using A100 discs
wet. 18.3 (0.465) 165 (4.19) Example F No low-angle reflected
image. Matte appearance 8 2 Finished using Example 1 discs 8.4
(0.21) 82 (2.1) wet. Distinct low-angle reflected image. Glossy
appearance. Comparative 3 Finished using A6 discs wet. 10.2 (0.259)
85 (2.2) Example G Indistinct low-angle reflective image.
Semi-glossy appearance
[0114] In Table 4, each step 1 to 4 was carried out
consecutively.
[0115] Profilometric measurements in Table 4 show the ability of
structured abrasive articles according to the present disclosure to
finish the surface of marble floor material. Unexpectedly, use of
significantly finer-grade conventional fused alumina (Step 4) did
not further refine the surface, and produced a visually degraded
aesthetic appearance.
Examples 9-12 and Comparative Examples H-K
[0116] Lofty, non-woven abrasives were produced with milled
polycrystalline ceramic aluminum oxide abrasive mineral of varying
sizes, as described in Method 2 and Table 3. Cured pad specimens
were tested on 6-inch (15-cm) unglazed ceramic quarry tiles (CT)
according to Test Method 2, which were previously wet-polished
using A45 and A10 abrasives. Results are reported in Table 5
(below).
TABLE-US-00005 TABLE 5 R.sub.a, PROCEDURE/ microinch 20.degree.
60.degree. 20.degree. EXAMPLE TILE COMMENTS (micron) GLOSS GLOSS
DOI Comparative 1 Initial 38.3 (0.97) 1.5 6.2 21.4 Example H
Finished using 26.1 (0.66) 15.8 43.6 21.7 a PDP pad dry 9 1 Initial
32.6 (0.83) 1.5 6.2 21.4 Finished using 20.5 (0.52) 9.6 40.9 6.5 6u
CAO pad dry Comparative 2 Initial 32.2 (0.82) 1.1 4.1 2.6 Example I
Finished using 24.6 (0.62) 10.9 34.5 18.6 a PDP pad dry 10 2
Initial 27.9 (0.71) 1.1 3.7 5.4 Finished using 27.4 (0.70) 1.6 9.9
5.3 3u CAO pad dry Comparative 3 Initial 24.4 (0.62) 1.2 4.8 8.3
Example J Finished using 19.4 (0.49) 10.3 32.2 25.5 a PDP pad dry
11 3 Initial 26.7 (0.68) 1.1 4.6 5.4 Finished using 23.5 (0.60) 4.0
18.2 11.4 4u CAO pad dry Comparative 4 Initial 28.7 (0.73) 1.1 3.9
5.4 Example K Finished using 25.2 (0.64) 13.3 39.3 22.4 a PDP pad
dry 12 4 Initial 27.2 (0.69) 1.1 3.7 3.7 Finished using 24.8 (0.63)
15.4 37.6 64.5 Example 2 disc dry
[0117] The results in Table 5 show that when utilized in lofty,
nonwoven constructions, milled polycrystalline ceramic aluminum
oxide with particle sizes comparable to the diamond abrasive
particles contained in PDP achieve inferior aesthetic quality. When
utilized in a rigid, structured abrasive construction, milled
polycrystalline ceramic aluminum oxide of 16-micron particle size
(4 times larger than the diamond abrasive particles in PDP),
achieved superior surface quality. This is indicated by a
three-fold greater image clarity compared to PDP, with image
brightness comparable to PDP.
Examples 13-14 and Comparative Example L
[0118] Structured abrasive articles were produced as described in
Method 1 and Table 2 above. Structured abrasive articles were
compared against PDP lofty nonwoven abrasives to show the dry
finishing efficacy of a rigid structured abrasive article
construction on unglazed ceramic tile (CT). In these Examples,
unglazed ceramic tiles (CT) were initially prepared with a 120-grit
resin-bond grinding wheel, followed by pre-finishing with A45 and
A10 in succession, according to Method 2. In these Examples, the
important "Haze" aesthetic measurement was included for the
comparison. Results are summarized in Table 6 (below).
TABLE-US-00006 TABLE 6 R.sub.a, R.sub.z, PROCEDURE/ microinch
microinch 60.degree. 60.degree. EXAMPLE COMMENTS (micron) (micron)
GLOSS HAZE DOI Comparative Initial 23 (0.58) 231 (5.87) 18.2 3.8
86.0 Example L Finished using 19 (0.48) 220 (5.59) 53.5 10.5 81.1
PDP pad dry 13 Initial 22 (0.56) 248 (6.30) 17.2 3.5 86.5 Finished
using 19 0.48) 220 (5.59) 40.9 6.3 93.1 the Example 3 disc dry 14
Initial 22 (0.56) 226 (5.74) 6.6 1.2 78.7 Finished using 19 (0.48)
209 (5.31) 13.0 4.0 76.1 A10 disc dry Finished using 19 (0.48) 236
(5.99) 44.8 8.7 92.4 the Example 4 disc dry
[0119] As shown in Table 6, the R.sub.a and R.sub.z surface
profilometric measurements indicated little macroscopic surface
roughness refinement whether using diamond abrasive particles or
milled ceramic aluminum oxide abrasive particles in lofty nonwoven
or rigid abrasive constructions, beneath the initial starting
surface
[0120] The aesthetic data in Table 6 show that use of 4-micron
diamond abrasive particles in PDP construction reduced reflected
image clarity compared to the initial starting surface, but
increased the 60.degree. gloss (the image brightness level). Haze
increased .about.2.8.times. after finishing with 4-micron diamonds
abrasives in PDP. The 16-micron milled ceramic aluminum oxide
abrasive particles abrasive used in Example 13 and Example 14
produced significantly increased t DOI image clarity, with a
slightly lesser gloss attainment, and an .about.1.8.times. increase
in haze.
Example 15 and Comparative Example M
[0121] Precast cementitious terrazzo tiles (PCT) were cut into
6-inch (15-cm) square specimens using a water-cooled diamond
tile-cutting saw. The terrazzo specimens were used to illustrate
finishing performance on a soft inorganic composite surface. The
Portland cement-based Wausau tiles have a high sand content and a
relatively weak bond phase. While easily abraded, the soft surface
made it difficult to produce a very high aesthetic quality as
reported in Table 7. In these Examples, the tests were conducted
according to Test Method 2, and the precast cementitious terrazzo
tiles were initially prepared using A45 and A10 in succession,
prior to final finishing. Factory-produced surface characteristics
for the terrazzo tiles are included in Table 7 (below) for
reference.
TABLE-US-00007 TABLE 7 R.sub.a, R.sub.z, PROCEDURE/ microinches
microinches 60.degree. 60.degree. EXAMPLE COMMENTS (microns)
(microns) GLOSS HAZE DOI Factory-finished 69 (1.75) 544 (13.82)
37.0 3.1 87.0 surface Comparative Initial 31 (0.79) 284 (7.21) 4.9
1.0 27.3 Example M Finished using 40 (1.02) 386 (9.80) 40.0 14.9
46.9 PDP pad dry Example 15 Initial 31 (0.79) 284 (7.21) 4.9 1.0
27.3 Finished using 25 (0.64) 272 (6.91) 15.9 4.9 68.6 the Example
5 disc dry
[0122] In the examples reported in Table 7 (above), neither the
4-micron PDP pad of Comparative Example M nor the 16-micron Example
5 structured abrasive disc in Example 15 produced a surface quality
comparable to the factory-finished surface. However, the Example 5
structured abrasive disc increased DOI 2.5.times. over the
intermediate pre-finished surface produced by A10 structured
abrasive disc, whereas the PDP used for Comparative Example M
increased DOI 1.7.times. over the initial pre-finished surface.
Significantly, the lofty non-woven PDP used for Comparative Example
M increased haze 15.times. over the initial pre-finished surface,
whereas in Example 15 the Example 5 structured abrasive disc
increased haze only 5.times. over the initial pre-finished
surface.
Example 16 and Comparative Examples N-O
[0123] Samples of Grey Maua granite (GMG) were used to test
finishing performance on very hard natural stone surfaces. The
8-inch (20-cm) square granite tiles were cut into 4-inch (10-cm)
square specimens using a water-cooled diamond tile-cutting saw. In
accordance with Test Method 2, the rough, wire-sawn back surface of
the granite tiles produced from the stone quarry was ground and
prepared using A300, A45, and A10 discs in succession and final
finishing steps were conducted. Test results are reported in Table
8. Factory-produced surface characteristics for the granite tiles
are included in Table 8 (below) for reference.
TABLE-US-00008 TABLE 8 R.sub.a, R.sub.z, PROCEDURE/ microinches
microinches 60.degree. 60.degree. EXAMPLE COMMENTS (microns)
(microns) GLOSS HAZE DOI Factory-polished 16 (0.41) 176 (4.47) 64.2
5.3 91.6 surface Comparative Initial 10 (0.25) 102 (2.59) 7.2 1.2
74.9 Example N Finished using 9 (0.23) 99 (2.51) 71.4 9.3 75.7 PDP
pad dry Comparative Initial 9 (0.23) 137 (3.48) 7.9 1.4 81.4
Example O Finished using 7 (0.18) 85 (2.16) 47.6 11.3 76.9 6u CAO
pad dry Example 16 Initial 11 (0.28) 124 (3.15) 9.3 1.7 86.3
Finished using 9 (0.23) 104 (2.64) 54.9 4.9 95.7 the Example 6 disc
dry
[0124] Neither Comparative Example N nor Comparative Example O
achieved aesthetic surface quality comparable to the
factory-produced finish. While reflected image brightness was
acceptable in both of Comparative Examples N and O, which were
lofty open nonwoven constructions. Reflected image clarity as
measured by DOI was significantly less than the factory-produced
surface for both lofty non-woven Comparative Examples N and O. Both
Comparative Examples N and O yielded haze levels twice those of the
factory-produced surface. Example 16 achieved comparable brightness
to the factory-produced surface, and further, produced haze and DOI
levels better than the factory-polished surface.
Example 17 and Comparative Examples P-Q
[0125] Six-inch (15 cm) square tile specimens were cut from a
1.5-inch (3.8 cm) thick, cured, unreinforced concrete slab using a
water-cooled diamond tile-cutting saw. The steel-troweled surface
of the concrete specimens was tested. In these Examples, the
steel-troweled test surfaces were first prepared for final
finishing using A300, A45, and A10 discs in succession, all
according to Test Method 2. The results are summarized in Table 9
(below).
TABLE-US-00009 TABLE 9 R.sub.a, R.sub.z, PROCEDURE/ microinches
microinches 60.degree. 60.degree. EXAMPLE COMMENTS (microns)
(microns) GLOSS HAZE DOI Comparative Initial 26 (0.66) 280 (7.11)
6.4 1.4 63.5 Example P Finished using 18 (0.46) 197 (5.00) 66.3
15.9 59.5 PDP pad dry Comparative Initial 28 (0.71) 273 (6.93) 8.4
2.2 56.0 Example Q Finished using 16 (0.41) 212 (5.38) 15.8 5.4
56.9 A10 disc dry Example 17 Initial 28 (0.71) 286 (7.26) 8.4 1.8
70.0 Finished using 16 (0.41) 190 (4.83) 30.4 5.4 84.5 the Example
7 disc dry
[0126] As shown in Table 9 (above). Comparative Example P (PDP
pad), using a 4-micron diamond pad, yielded significantly increased
gloss, but decreased DOI, and resulted in a large increase in haze
over the initial surface condition. Comparative Example Q (A10 disc
dry), using 10-micron diamond abrasives, yielded a modestly
increased gloss, and unchanged DOI. Example 17 (Example 7 disc
dry), using 16-micron milled polycrystalline ceramic aluminum oxide
abrasive, yielded a moderate gloss increase and significantly
increased DOI.
[0127] All cited references, patents, or patent applications in the
above application for letters patent are herein incorporated by
reference in their entirety in a consistent manner. In the event of
inconsistencies or contradictions between portions of the
incorporated references and this application, the information in
the preceding description shall control. The preceding description,
given in order to enable one of ordinary skill in the art to
practice the claimed disclosure, is not to be construed as limiting
the scope of the disclosure, which is defined by the claims and all
equivalents thereto.
* * * * *