U.S. patent application number 11/233250 was filed with the patent office on 2007-03-22 for flexible abrasive article and methods of making and using the same.
This patent application is currently assigned to 3M Innovative Properties Company. Invention is credited to Michael J. Annen, Albert I. Everaerts, Gregory A. Koehnle, Ian R. Owen, James W. Schutz.
Application Number | 20070066186 11/233250 |
Document ID | / |
Family ID | 37607324 |
Filed Date | 2007-03-22 |
United States Patent
Application |
20070066186 |
Kind Code |
A1 |
Annen; Michael J. ; et
al. |
March 22, 2007 |
Flexible abrasive article and methods of making and using the
same
Abstract
Flexible abrasive article comprising a compressible backing
having first and second opposed major surfaces; an elastic
polyurethane film affixed to at least a portion of the first major
surface of the compressible backing; an optional extensible tie
layer affixed to at least a portion of the elastic polyurethane
film; and an abrasive layer affixed to at least a portion of the
optional extensible tie layer or elastic polyurethane film, the
abrasive layer comprising abrasive particles and a binder. Methods
of making and using the flexible abrasive article are also
disclosed.
Inventors: |
Annen; Michael J.; (Hudson,
WI) ; Koehnle; Gregory A.; (Oakdale, MN) ;
Schutz; James W.; (Woodbury, MN) ; Owen; Ian R.;
(Baldwin, WI) ; Everaerts; Albert I.; (Oakdale,
MN) |
Correspondence
Address: |
3M INNOVATIVE PROPERTIES COMPANY
PO BOX 33427
ST. PAUL
MN
55133-3427
US
|
Assignee: |
3M Innovative Properties
Company
|
Family ID: |
37607324 |
Appl. No.: |
11/233250 |
Filed: |
September 22, 2005 |
Current U.S.
Class: |
451/41 ; 451/533;
451/534; 451/56 |
Current CPC
Class: |
B24D 11/001 20130101;
B24D 3/32 20130101 |
Class at
Publication: |
451/041 ;
451/056; 451/533; 451/534 |
International
Class: |
B24B 7/30 20060101
B24B007/30; B24B 1/00 20060101 B24B001/00; B24D 11/00 20060101
B24D011/00 |
Claims
1. A flexible abrasive article comprising: a compressible backing
having first and second opposed major surfaces; an elastic
polyurethane film affixed to at least a portion of the first major
surface of the compressible backing; and an abrasive layer affixed
to at least a portion of the polyurethane film, the abrasive layer
comprising abrasive particles and a binder.
2. A flexible abrasive article according to claim 1, wherein the
polyurethane film has a treated surface, and wherein the abrasive
layer is affixed to at least a portion of the treated surface.
3. A flexible abrasive article according to claim 1, further
comprising an extensible tie layer affixed to at least a portion of
the polyurethane film, wherein the abrasive layer is affixed to at
least a portion of the extensible tie layer.
4. A flexible abrasive article according to claim 3, wherein at
least one of the polyurethane film, extensible tie layer, and
abrasive layer is foraminous.
5. A flexible abrasive article according to claim 3, wherein at
least one of the polyurethane film, extensible tie layer, and
abrasive layer is needletacked.
6. A flexible abrasive article according to claim 3, wherein each
of the polyurethane film, extensible tie layer, and coated abrasive
layer are foraminous, and wherein there exist a plurality of pores
that extend from the second major surface of the backing through
the abrasive layer.
7. A flexible abrasive article according to claim 1, wherein the
abrasive layer comprises a plurality of shaped abrasive
composites.
8. A flexible abrasive article according to claim 1, wherein the
compressible backing comprises an open cell foam.
9. A flexible abrasive article according to claim 1, wherein the
polyurethane film is affixed to the compressible backing by a layer
of adhesive disposed therebetween.
10. A flexible abrasive article according to claim 1, wherein the
polyurethane film contacts the compressible backing.
11. A flexible abrasive article according to claim 1, wherein the
compressible backing has a bulk density of at least 0.03 grams per
cubic centimeter.
12. A flexible abrasive article according to claim 1, wherein the
compressible backing has a thickness of at least 2 millimeters.
13. A flexible abrasive article according to claim 1, wherein the
polyurethane film has a thickness in a range of from 0.02 to 0.1
millimeter.
14. A flexible abrasive article according to claim 1, further
comprising an attachment system affixed to the second major surface
of the compressible backing.
15. A flexible abrasive article according to claim 14, wherein the
attachment system comprises hooks or loops.
16. A flexible abrasive article according to claim 1, wherein the
abrasive article is selected from the group consisting of an
abrasive disc and an abrasive pad.
17. A flexible abrasive article according to claim 1, wherein the
compressible backing comprises a multiplicity of separated
resilient bodies connected to each other in a generally planar
array, which provides open spaces between adjacent connected
bodies, each body having a first and second opposed surfaces.
18. A flexible abrasive article according to claim 17, further
comprising an extensible tie layer affixed to at least a portion of
the polyurethane film, wherein the abrasive layer is affixed to at
least a portion of the extensible tie layer, wherein each the
elastic polyurethane film, extensible tie layer, and abrasive layer
has a plurality of openings therethrough, some of the openings
substantially corresponding in position to openings in the
compressible backing.
19. A flexible abrasive article according to claim 17, wherein the
binder comprises a reaction product of a polymerizable binder
precursor comprising at least one of acrylic acid or methacrylic
acid.
20. A method of abrading a workpiece, the method comprising:
providing a flexible abrasive article according to claim 1;
frictionally contacting at least a portion of the abrasive layer of
the flexible abrasive article with a surface of a workpiece; and
moving at least one of the abrasive layer and the surface of the
workpiece relative to the other to abrade at least a portion of the
surface of the workpiece.
21. A method according to claim 20, wherein the abrasive layer
comprises shaped abrasive composites.
22. A method according to claim 20, wherein the surface of the
workpiece comprises a painted surface.
23. A method according to claim 20, further comprising: providing a
lubricant to the surface of the workpiece.
24. A method of making a flexible abrasive article, the method
comprising: affixing an elastic polyurethane film to a first major
surface of a compressible backing which also has an opposite second
major surface; applying a curable composition comprising a
polymerizable binder precursor and abrasive particles to the
elastic polyurethane film; and at least partially curing the
curable composition to provide an abrasive layer.
25. A method of making a flexible abrasive article according to
claim 24, further comprising; imparting a textured surface to the
curable composition with a production tool; and separating the
production tool from the at least partially cured curable
composition to produce a plurality of shaped abrasive
composites.
26. A method of making a flexible abrasive article according to
claim 24, further comprising affixing an attachment system to the
second major surface of the compressible backing.
27. A method of making a flexible abrasive article according to
claim 24, wherein the elastic polyurethane film is affixed to the
compressible backing by a layer of adhesive disposed
therebetween.
28. A method of making a flexible abrasive article according to
claim 24, wherein the elastic polyurethane film contacts the
compressible backing.
29. A method of making a flexible abrasive article according to
claim 24, further comprises forming a plurality of openings through
at least the elastic polyurethane film and abrasive layer, the
openings substantially corresponding in position to openings in the
compressible backing.
30. A method of making a flexible abrasive article according to
claim 29, wherein forming the plurality of openings comprises
needletacking.
31. A method of making a flexible abrasive article according to
claim 24, wherein the compressible backing comprises open cell
foam.
32. A method of making a flexible abrasive article according to
claim 24, further comprising affixing an attachment system to the
second major surface of the compressible backing.
33. A method of making a flexible abrasive article according to
claim 24, wherein the compressible backing comprises a multiplicity
of separated resilient bodies connected to each other in a
generally planar array, which provides open spaces between adjacent
connected bodies, each body having a first and second opposed
surfaces.
34. A method of making a flexible abrasive article according to
claim 24, further comprises forming a plurality of openings through
at least the elastic polyurethane film and abrasive layer, some of
the openings substantially corresponding in position to openings in
the compressible backing.
35. A method of making a flexible abrasive article according to
claim 24, wherein the polymerizable binder precursor comprises at
least one of acrylic acid or methacrylic acid.
36. A method of making a flexible abrasive article, the method
comprising: affixing an elastic polyurethane film to a first major
surface of a compressible backing, which also has an opposite
second major surface; affixing an extensible tie layer to the
polyurethane film; applying a curable composition comprising a
polymerizable binder precursor and abrasive particles to the
extensible tie layer; and at least partially curing the curable
composition to provide an abrasive layer.
37. A method of making a flexible abrasive article according to
claim 36, further comprising; imparting a textured surface to the
curable composition with a production tool; and separating the
production tool from the at least partially cured curable
composition to produce a plurality of shaped abrasive
composites.
38. A method of making a flexible abrasive article according to
claim 36, further comprising affixing an attachment system to the
second major surface of the compressible backing.
39. A method of making a flexible abrasive article according to
claim 36, wherein the elastic polyurethane film is affixed to the
compressible backing by a layer of adhesive disposed
therebetween.
40. A method of making a flexible abrasive article according to
claim 36, wherein the elastic polyurethane film contacts the
compressible backing.
41. A method of making a flexible abrasive article according to
claim 36, further comprising forming a plurality of openings
through at least the elastic polyurethane film, extensible tie
layer, and abrasive layer, at least some of the openings
substantially corresponding in position to openings in the
compressible backing.
42. A method of making a flexible abrasive article according to
claim 41, wherein forming the plurality of openings comprises
needletacking.
43. A method of making a flexible abrasive article according to
claim 36, wherein the compressible backing comprises open cell
foam.
44. A method of making a flexible abrasive article according to
claim 36, further comprising affixing an attachment system to the
second major surface of the compressible backing.
45. A method of making a flexible abrasive article according to
claim 36, wherein the compressible backing comprises a multiplicity
of separated resilient bodies connected to each other in a
generally planar array in a pattern, which provides open spaces
between adjacent connected bodies, each body having a first and
second opposed surfaces.
46. A method of making a flexible abrasive article according to
claim 36, further comprises forming a plurality of openings through
at least the elastic polyurethane film, extensible tie layer and
abrasive layer, the openings substantially corresponding in
position to openings in the compressible backing.
47. A method of making a flexible abrasive article according to
claim 36, wherein the polymerizable binder precursor comprises at
least one of acrylic acid or methacrylic acid.
Description
BACKGROUND
[0001] Flexible abrasive articles that have an abrasive layer
affixed to a foam backing are used for many abrading applications,
including for example, scuffing painted surfaces such as, for
example, damaged automotive finishes prior to repairing them.
During use, the flexible abrasive articles may be subjected to
harsh forces that result in failure of the flexible abrasive
article at a time when the abrasive layer is otherwise usable. Such
premature failure may occur, for example, by separation of the
abrasive layer from the foam backing and/or by damage caused to the
foam backing.
SUMMARY
[0002] In one aspect, the present invention provides a flexible
abrasive article comprising:
[0003] a compressible backing having first and second opposed major
surfaces;
[0004] an elastic polyurethane film affixed to at least a portion
of the first major surface of the compressible backing; and
[0005] an abrasive layer affixed to at least a portion of the
polyurethane film, the abrasive layer comprising abrasive particles
and a binder.
[0006] In some embodiments, the polyurethane film has a treated
surface, and the abrasive layer is affixed to at least a portion of
the treated surface.
[0007] In some embodiments, the flexible abrasive article further
comprises an extensible tie layer affixed to at least a portion of
the polyurethane film, wherein the abrasive layer is affixed to at
least a portion of the extensible tie layer.
[0008] In some embodiments, the abrasive layer comprises a
plurality of shaped abrasive composites.
[0009] In some embodiments, each of the elastic polyurethane film,
optional extensible tie layer, and abrasive layer in flexible
abrasive articles according to the present invention are
foraminous, and there exist a plurality of continuous pores that
extend from the second major surface of the backing through the
abrasive layer.
[0010] In some embodiments, flexible abrasive articles according to
the present invention further comprise an attachment system affixed
to the second major surface of the compressible backing.
[0011] In another aspect, the present invention provides a method
of making a flexible abrasive article, the method comprising:
[0012] affixing an elastic polyurethane film to a first major
surface of a compressible backing which also has an opposite second
major surface;
[0013] applying a curable composition comprising a polymerizable
binder precursor and abrasive particles to the elastic polyurethane
film; and
[0014] at least partially curing the curable composition to provide
an abrasive layer.
[0015] In another aspect, the present invention provides a method
of making a flexible abrasive article, the method comprising:
[0016] affixing an elastic polyurethane film to a first major
surface of a compressible backing which also has an opposite second
major surface;
[0017] affixing an extensible tie layer to the polyurethane
film;
[0018] applying a curable composition comprising a polymerizable
binder precursor and abrasive particles to the extensible tie
layer; and
[0019] at least partially curing the curable composition to provide
an abrasive layer.
[0020] In some embodiments, the method further comprises:
[0021] imparting a textured surface to the curable composition with
a production tool that has a textured surface; and
[0022] separating the production tool from the at least partially
cured curable composition.
[0023] By including an elastic polyurethane film between the
abrasive layer and compressible backing, the durability (e.g.,
useful life) of flexible abrasive articles is typically improved
without compromising the flexibility, feel, cut, finish and
handling.
[0024] As used herein:
[0025] "elastic polyurethane film" refers to an elastic film having
a polyurethane content greater than about 50 weight percent;
[0026] "elastomer" refers to an elastic polymer;
[0027] "elastic polyurethane film" refers to a film comprising at
least one elastic polyurethane; and
[0028] the term "film" refers to a thin layer of material.
BRIEF DESCRIPTION OF THE DRAWING
[0029] FIG. 1 is a cross-sectional schematic view of an exemplary
flexible abrasive article according to the present invention;
[0030] FIGS. 2A-2C are enlarged schematic cross-sectional views of
various embodiments of abrasive layer 140;
[0031] FIG. 3 is a perspective schematic view of an exemplary
circular flexible abrasive pad according to one embodiment of the
present invention;
[0032] FIG. 4 is a perspective schematic view of an exemplary
flexible abrasive pad according to one embodiment of the present
invention;
[0033] FIG. 5 is a perspective schematic view of an exemplary
flexible abrasive belt according to one embodiment of the present
invention;
[0034] FIG. 6A is a cross-sectional view of an exemplary flexible
abrasive article according to one embodiment of the present
invention;
[0035] FIG. 6B is a perspective view of compressible backing 610
shown in FIG. 6A;
[0036] FIG. 7A is an enlarged view of a representative segment of a
master tooling surface used to make the production tool used in the
Examples;
[0037] FIG. 7B is an enlarged cross-sectional side view along line
7B of the master tooling surface shown in FIG. 7A; and
[0038] FIG. 7C is an enlarged cross-sectional side view along line
7C of the master tooling surface shown in FIG. 7A.
DETAILED DESCRIPTION
[0039] An exemplary flexible abrasive article according to the
present invention is shown in FIG. 1. Referring now to FIG. 1, not
drawn to scale, flexible abrasive article 100 comprises
compressible backing 110 having first and second opposed major
surfaces 115, 116, respectively. Elastic polyurethane film 120 is
affixed to at least a portion of first major surface 115 of
compressible backing 110. Optional extensible tie layer 130 is
affixed to at least a portion of elastic polyurethane film 120.
Abrasive layer 140 is affixed to at least a portion of extensible
tie layer 130, if present, or at least a portion of elastic
polyurethane film 120 if extensible tie layer 130 is not present.
Optional attachment system 150 is affixed to at least a portion of
second major surface 116 of compressible backing 110.
Compressible Backing
[0040] The compressible backing may comprise any compressible
resilient material(s). For example, in some embodiments, the
compressible backing may comprise a resilient nonwoven web,
optionally in combination with one or more thin synthetic polymeric
films affixed thereto. More typically, the compressible backing
comprises at least one foam layer, optionally in combination with
one or more flexible members (e.g., polymeric films) affixed
thereto.
[0041] Useful nonwoven webs include, for example, open fiber webs
(e.g., lofty open fiber webs) wherein the fibers are bonded
together in their mutual contact points by a binder (e.g., formed
by drying and/or curing a binder precursor material). The nonwoven
web may be made, for example, from an air-supported construction
(e.g., as described in U.S. Pat. No. 2,958,593 (Hoover et al.), the
disclosure of which is incorporated herein by reference), from a
carded and cross-lapped construction, or a meltblown construction.
Useful fibers include natural and synthetic fibers, and blends
thereof. Useful synthetic fibers include, for example, those fibers
made of polyester (for example, polyethylene-terephthalate), high
or low resilience nylon (for example, hexamethylene-adipamide,
polycaprolactam), polypropylene, acrylic (formed from acrylonitrile
polymer), rayon, cellulose acetate, chloride copolymers of
vinyl-acrylonitrile, and others. The appropriate natural fibers
include those coming from cotton, wool, jute, and hemp.
[0042] Fibers diameters may be, for example, less than or equal to
1, 2, 4, 6, 10, 13, 17, 70, 110, 120 or 200 denier, although this
is not a requirement. Fiber webs basis weights will depend upon the
web thickness and the degree of openness.
[0043] Examples of suitable binder precursor materials include
latexes (e.g., acrylic latexes or polyurethane latexes), phenolic
resins, aminoplast resins, polymer plastisols, and combinations
thereof.
[0044] The non-woven web is typically formed and then coated with a
binder precursor then submitted to a coating procedure in which a
curable binder precursor is applied to the web, e.g., by roll
coating, dip coating, or spraying.
[0045] In general, in those embodiments wherein the compressible
backing comprises a foam layer, any foam layer with at least one
coatable surface may be used. The foam layer may comprise any
compressible foam material. In some embodiments, the compressible
foam material is elastic. Useful foams include elastic foams such
as, for example, chloroprene rubber foams, ethylene/propylene
rubber foams, butyl rubber foams, polybutadiene foams, polyisoprene
foams, EPDM polymer foams, polyurethane foams, ethylene-vinyl
acetate foams, neoprene foams, and styrene/butadiene copolymer
foams. Useful foams also include thermoplastic foams such as, for
example, polyethylene foams, polypropylene foams, polybutylene
foams, polystyrene foams, polyamide foams, polyester foams,
plasticized polyvinyl chloride (i.e., pvc) foams. The foam layer
may be of an open cell (e.g., foraminous) or closed cell variety,
although typically, if the abrasive article is intended for use
with liquids, an open cell foam having sufficient porosity to
permit the entry of liquid is desirable. Particular examples of
useful open cell foams are polyester polyurethane foams,
commercially available from Illbruck, Inc., Minneapolis, Minn.
under the trade designations "R 200U", "R 400U", "R 600U" and
"EF3-700C".
[0046] The degree of flexibility of the compressible backing will
typically vary with the intended use.
[0047] In those embodiments wherein the compressible backing
comprises a foam layer, the thickness of the compressible foam
layer is typically in a range of from 1 to 50 millimeters, however,
other thickness may also be used. Typically, the bulk density of
the compressible foam layer as determined by ASTM D-3574 is greater
than about 0.03 gram per cm.sup.3 (2 lbs per ft.sup.3), however
lower density foam layers may also be used. In some embodiments,
the foam layer has a bulk density of about 0.03 to about 0.10 grams
per cm.sup.3 (1.8-6 lbs per ft.sup.3). While thinner or thicker
and/or lighter or heavier foams may be useful, they may require
special handling because they are somewhat more difficult to
process on conventional coating equipment.
[0048] The compressible backing is typically in sheet form with
substantially parallel major surfaces, but other
surface-configurations with one or both major surfaces being planar
or other than planar are also useful. For example, in those
embodiments wherein the compressible backing comprises a foam
layer, the second major surface may be planar to facilitate
attachment, while the first major surface may be other than planar,
for example, an undulated or convoluted surface. Convoluted foams
are disclosed in U.S. Pat. Nos. 5,007,128 and 5,396,737 (both to
Englund et al.), the disclosures of which are incorporated herein
by reference.
[0049] In those embodiments wherein the compressible backing
comprises a foam layer, the foam layer may have an elongation in a
range of from about 85 to about 150% (i.e., the stretched length of
the foam minus the unstretched length of the foam all divided by
the unstretched length of the foam and then multiplied by 100
equals 85 to 150%.).
Elastic Polyurethane Film
[0050] The elastic polyurethane film may be a uniform film, or it
may be a composite film (e.g., having multiple layers produced by
coextrusion, heat lamination, or adhesive bonding). In some
embodiments, the elastic polyurethane film typically comprises
elastic polyurethane (e.g., elastomeric polyurethane). Examples of
elastomeric polyurethanes that may be used include, those available
under the trade designation "ESTANE" from B.F. Goodrich & Co.,
Cleveland, Ohio, and those described in U.S. Pat. No. 2,871,218
(Schollenberger); U.S. Pat. No. 3,645,835 (Hodgson); U.S. Pat. No.
4,595,001 (Potter et al.); U.S. Pat. No. 5,088,483 (Heinecke); U.S.
Pat. No. 6,838,589 (Liedtke et al.); and RE 33,353 (Heinecke).
Useful pressure sensitive adhesive coated polyurethane elastomer
films are commercially available from 3M Company under the trade
designation "TEGADERM".
[0051] The elastic polyurethane film is generally from about 0.02
to about 6 millimeters in thickness, for example, from 0.02
millimeter to 0.1 millimeter in thickness; however, this is not a
requirement.
[0052] Typically, the elastic modulus (measured at 1 Hz and
25.degree. C.) of the elastic polyurethane film is between about
2.4.times.10.sup.5 and about 7.times.10.sup.5 Pascals, for example,
between about 3.times.10.sup.5 and about 6.times.10.sup.5 Pascals,
or even between about 4.times.10.sup.5 and about 5.times.10.sup.5
Pascals, although this is not a requirement.
[0053] The elastic polyurethane film is affixed to the compressible
backing by a layer of adhesive disposed therebetween.
[0054] The elastic polyurethane film may contain fillers,
additives, antioxidants, stabilizers, other polymers, and the
like.
[0055] In some embodiments, the elastic polyurethane film may be
made foraminous by perforating the film with an array of needles
deployed in a standard needle board installed in a needletacking
machine (i.e., needletacking).
[0056] In some embodiments, the elastic polyurethane film is
affixed to the compressible backing by a layer of an adhesive
material such as, for example, glue, hot melt adhesive, or a
pressure sensitive adhesive film optionally provided as a transfer
tape. In some embodiments, the elastic polyurethane film is in
direct contact with the compressible backing.
Adhesion of the Abrasive Layer to the Elastic Polyurethane Film
[0057] In some embodiments, an optional tie layer provides good
adhesion of the abrasive layer to the elastic polyurethane
film.
[0058] In some embodiments, the optional tie layer is extensible.
Without wishing to be bound by theory, it is believed that the
extensible tie layer functions at least in part by relieving
stresses that would occur upon stretching between the typically
rigid abrasive layer and the elastic polyurethane film.
[0059] Examples of suitable extensible tie layers include pressure
sensitive adhesives, and elastomeric acrylics (e.g.,
styrene/acrylic elastomers) whether supplied in bulk or latex
form.
[0060] Examples of pressure sensitive adhesives that may be used in
the tie layer include pressure sensitive adhesives derived from
acrylate polymers (for example, polybutyl acrylate), acrylate
copolymers (for example, isooctyl acrylate/acrylic acid), vinyl
ethers (for example, polyvinyl n-butyl ether), alkyd adhesives,
rubber adhesives (for example, natural rubbers, synthetic rubbers
and chlorinated rubbers), and mixtures thereof. The adhesive may be
provided and applied to the elastic polyurethane film in, for
example, bulk, solvent borne, or water-based latex form.
[0061] In some embodiments, the optional extensible tie layer is
elastic, while in others it is not.
[0062] The optional extensible tie layer is generally from about
0.02 millimeter to about 4 millimeters in thickness, for example,
from 0.06 millimeter to 2 millimeters in thickness, however this is
not a requirement.
[0063] Alternatively, or in addition to the optional tie layer the
elastic polyurethane film may be surface treated by corona, flame
or acid or base priming.
[0064] Further, adhesion may be improved in some cases by
incorporating at least one of acrylic acid or methacrylic acid into
a polymerizable binder precursor used to form the abrasive
layer.
Abrasive Layer
[0065] In some embodiments, the abrasive layer comprises make and
size layers and abrasive particles as shown for example, in FIG.
2A. Referring now to FIG. 2A, abrasive layer 140a comprises make
layer 206, abrasive particles 210, size layer 212, and optional
supersize 214. Useful make, size, optional supersize layers,
flexible coated abrasive articles, and methods of making the same
according to these embodiments include, for example, those
described in U.S. Pat. No. 4,588,419 (Caul et al.); U.S. Pat. No.
4,734,104 (Broberg); U.S. Pat. No. 4,737,163 (Larkey); U.S. Pat.
No. 4,751,138 (Tumey et al.); U.S. Pat. No. 5,078,753 (Broberg et
al.); U.S. Pat. No. 5,203,884 (Buchanan et al.); U.S. Pat. No.
5,152,917 (Pieper et al.); U.S. Pat. No. 5,378,251 (Culler et al.);
U.S. Pat. No. 5,366,523 (Rowenhorst et al.); U.S. Pat. No.
5,417,726 (Stout et al.); U.S. Pat. No. 5,436,063 (Follett et al.);
U.S. Pat. No. 5,490,878 (Peterson et al.); U.S. Pat. No. 5,496,386
(Broberg et al.); U.S. Pat. No. 5,609,706 (Benedict et al.); U.S.
Pat. No. 5,520,711 (Helmin); U.S. Pat. No. 5,954,844 (Law et al.);
U.S. Pat. No. 5,961,674 (Gagliardi et al.); U.S. Pat. No. 4,751,138
(Tumey et al.); U.S. Pat. No. 5,766,277 (DeVoe et al.); U.S. Pat.
No. 6,059,850 (Lise et al.); U.S. Pat. No. 6,077,601 (DeVoe et
al.); U.S. Pat. No. 6,228,133 (Thurber et al.); and U.S. Pat. No.
5,975,988 (Christianson); the disclosures of which are incorporated
herein by reference
[0066] In other embodiments, the abrasive layer comprises abrasive
particles in a binder, typically substantially uniformly
distributed throughout the binder, as shown for example, in FIG.
2B. Referring now to FIG. 2B, abrasive layer 140b comprises binder
236 and abrasive particles 210. Details concerning materials and
methods for making such abrasive layers may be found, for example,
in U.S. Pat. No. 4,927,431 (Buchanan et al.); U.S. Pat. No.
5,014,468 (Ravipati et al.); U.S. Pat. No. 5,378,251 (Culler et
al.); U.S. Pat. No. 5,942,015 (Culler et al.); U.S. Pat. No.
6,261,682 (Law); and U.S. Pat. No. 6,277,160 (Stubbs et al.); and
U.S. Pat. Appln. Publ. Nos. 2003/0207659 A1 (Annen et al.) and
2005/0020190 A1 (Schutz et al.); the disclosures of which are
incorporated herein by reference. In these embodiments, the
abrasive layer is typically applied to the elastic member as the
slurry of abrasive particles in a binder precursor, and then at
least partially cured.
[0067] In some embodiments, the abrasive layer comprises a
structured abrasive layer, for example, as described in FIG. 2C.
Referring now to FIG. 2C, abrasive layer 140c comprises precisely
shaped abrasive composites 265. Precisely shaped abrasive
composites 265 comprise abrasive particles 210 dispersed throughout
binder 236.
[0068] Structured abrasive layers, useful in practice of the
present invention, comprise a plurality of non-randomly shaped
abrasive composites and affixed to the elastic polyurethane film.
As used herein, the term "abrasive composite" refers to a body that
includes abrasive particles and a binder. In some embodiments,
shaped abrasive composites may be arranged according to a
predetermined pattern (e.g., as an array).
[0069] In some embodiments, at least a portion of the shaped
abrasive composites may comprise "precisely shaped" abrasive
composites. This means that the shape of the abrasive composites is
defined by relatively smooth surfaced sides that are bounded and
joined by well-defined edges having distinct edge lengths with
distinct endpoints defined by the intersections of the various
sides. The terms "bounded" and "boundary" refer to the exposed
surfaces and edges of each composite that delimit and define the
actual three-dimensional shape of each abrasive composite. These
boundaries are readily visible and discernible when a cross-section
of an abrasive article is viewed under a scanning electron
microscope. These boundaries separate and distinguish one precisely
shaped abrasive composite from another even if the composites abut
each other along a common border at their bases. By comparison, in
an abrasive composite that does not have a precise shape, the
boundaries and edges are not well defined (e.g., where the abrasive
composite sags before completion of its curing). Typically,
precisely shaped abrasive composites are arranged on the backing
according to a predetermined pattern or array, although this is not
a requirement.
[0070] Shaped abrasive composites may be arranged such that some of
their work surfaces are recessed from the polishing surface of the
abrasive layer.
[0071] Precisely shaped abrasive composites may be of any
three-dimensional shape that results in at least one of a raised
feature or recess on the exposed surface of the abrasive layer.
Useful shapes include, for example, cubic, prismatic, pyramidal
(e.g., square pyramidal or hexagonal pyramidal), truncated
pyramidal, conical, frusto-conical, pup tent shaped, and ridged.
Combinations of differently shaped and/or sized abrasive composites
may also be used. The abrasive layer of the structured abrasive may
be continuous or discontinuous.
[0072] For fine finishing applications, the density of shaped
abrasive composites in the abrasive layer is typically in a range
of from at least 1,000, 10,000, or even at least 20,000 abrasive
composites per square inch (e.g., at least 150, 1,500, or even
7,800 abrasive composites per square centimeter) up to and
including 50,000, 70,000, or even as many as 100,000 abrasive
composites per square inch (up to and including 7,800, 11,000, or
even as many as 15,000 abrasive composites per square centimeter),
although greater or lesser densities of abrasive composites may
also be used.
[0073] Further details concerning structured abrasive layers having
precisely shaped abrasive composites, and methods for their
manufacture may be found, for example, in U.S. Pat. No. 5,152,917
(Pieper et al.); U.S. Pat. No. 5,304,223 (Pieper et al.); U.S. Pat.
No. 5,435,816 (Spurgeon et al.); U.S. Pat. No. 5,672,097 (Hoopman);
U.S. Pat. No. 5,681,217 (Hoopman et al.); U.S. Pat. No. 5,454,844
(Hibbard et al.); U.S. Pat. No. 5,549,962 (Holmes et al.); U.S.
Pat. No. 5,700,302 (Stoetzel et al.); U.S. Pat. No. 5,851,247
(Stoetzel et al.); U.S. Pat. No. 5,910,471 (Christianson et al.);
U.S. Pat. No. 5,913,716 (Mucci et al.); U.S. Pat. No. 5,958,794
(Bruxvoort et al.); U.S. Pat. No. 6,139,594 (Kincaid et al.); U.S.
Pat. No. 6,923,840 (Schutz et al.); and U.S. Pat. Appln. Nos.
2003/0022604 (Annen et al.); the disclosures of which are
incorporated herein by reference.
[0074] Structured abrasive layers may be prepared by coating a
slurry comprising a polymerizable binder precursor, abrasive
particles, and an optional silane coupling agent through a screen
that is in contact with the elastic polyurethane film, or
extensible tie layer). In this embodiment, the slurry is typically
then further polymerized (e.g., by exposure to an energy source
such as heat or electromagnetic radiation) while it is present in
the openings of the screen thereby forming a plurality of shaped
abrasive composites generally corresponding in shape to the screen
openings. Further details concerning this type of screen coated
structured abrasive may be found, for example, in U.S. Pat. No.
4,927,431 (Buchanan et al.); U.S. Pat. No. 5,378,251 (Culler et
al.); U.S. Pat. No. 5,942,015 (Culler et al.); U.S. Pat. No.
6,261,682 (Law); and U.S. Pat. No. 6,277,160 (Stubbs et al.); the
disclosures of which are incorporated herein by reference.
[0075] In some embodiments, a slurry comprising a polymerizable
binder precursor, abrasive particles, and an optional silane
coupling agent may be deposited on the elastic polyurethane film,
or extensible tie layer in a patterned manner (e.g., by screen or
gravure printing), partially polymerized to render at least the
surface of the coated slurry plastic but non-flowing, a pattern
embossed upon the partially polymerized slurry formulation, and
subsequently further polymerized (e.g., by exposure to an energy
source) to form a plurality of shaped abrasive composites affixed
to the elastic polyurethane film, or extensible tie layer. Further
details concerning this and related methods are described, for
example, in U.S. Pat. Appl. Pub. No. 2001/0041511 (Lack et al.),
the disclosure of which is incorporated herein by reference.
[0076] Useful polymerizable binder precursors that may be cured to
form the above-mentioned binders are well-known and include, for
example, thermally curable resins and radiation curable resins,
which may be cured, for example, thermally and/or by exposure to
radiation energy. Exemplary polymerizable binder precursors include
phenolic resins, aminoplast resins, urea-formaldehyde resins,
melamine-formaldehyde resins, urethane resins, polyacrylates (e.
g., an aminoplast resin having pendant free-radically polymerizable
unsaturated groups, urethane acrylates, acrylate isocyanurate,
(poly)acrylate monomers, and acrylic resins), alkyd resins, epoxy
resins (including bis-maleimide and fluorene-modified epoxy
resins), isocyanurate resins, allyl resins, furan resins, cyanate
esters, polyimides, and mixtures thereof. Polymerizable binder
precursors may contain one or more reactive diluents (e.g., low
viscosity monoacrylates) and/or adhesion promoting monomers (e.g.,
acrylic acid or methacrylic acid).
[0077] If either ultraviolet radiation or visible radiation is to
be used, the polymerizable binder precursor typically further
comprises a photoinitiator.
[0078] Examples of photoinitiators that generate a free radical
source include, but are not limited to, organic peroxides, azo
compounds, quinones, benzophenones, nitroso compounds, acyl
halides, hydrazones, mercapto compounds, pyrylium compounds,
triacrylimidazoles, bisimidazoles, phosphene oxides,
chloroalkyltriazines, benzoin ethers, benzil ketals, thioxanthones,
acetophenone derivatives, and combinations thereof.
[0079] Cationic photoinitiators generate an acid source to initiate
the polymerization of an epoxy resin. Cationic photoinitiators can
include a salt having an onium cation and a halogen containing a
complex anion of a metal or metalloid. Other cationic
photoinitiators include a salt having an organometallic complex
cation and a halogen containing complex anion of a metal or
metalloid. These are further described in U.S. Pat. No. 4,751,138,
incorporated herein by reference. Another example of a cationic
photoinitiator is an organometallic salt and an onium salt
described in U.S. Pat. No. 4,985,340 and European Pat. Appl. Publ.
Nos. 306,161 and 306,162; all of which are incorporated herein by
reference. Still other cationic photoinitiators include an ionic
salt of an organometallic complex in which the metal is selected
from the elements of Periodic Group IVB, VB, VIB, VIIB and
VIIIB.
[0080] The polymerizable binder precursor may also comprise resins
that are curable by sources of energy other than radiation energy,
such as condensation curable resins. Examples of such condensation
curable resins include phenolic resins, melamine-formaldehyde
resins, and urea-formaldehyde resins.
[0081] The binder precursor and binder may include one or more
optional additives selected from the group consisting of grinding
aids, fillers, wetting agents, chemical blowing agents,
surfactants, pigments, coupling agents, dyes, initiators, energy
receptors, and mixtures thereof. The optional additives may also be
selected from the group consisting of potassium fluoroborate,
lithium stearate, glass bubbles, inflatable bubbles, glass beads,
cryolite, polyurethane particles, polysiloxane gum, polymeric
particles, solid waxes, liquid waxes and mixtures thereof.
[0082] Abrasive particles useful in the present invention can
generally be divided into two classes: natural abrasives and
manufactured abrasives. Examples of useful natural abrasives
include: diamond, corundum, emery, garnet (off-red color),
buhrstone, chert, quartz, garnet, emery, sandstone, chalcedony,
flint, quartzite, silica, feldspar, natural crushed aluminum oxide,
pumice and talc. Examples of manufactured abrasives include: boron
carbide, cubic boron nitride, fused alumina, ceramic aluminum
oxide, heat treated aluminum oxide (both brown and dark grey),
fused alumina zirconia, glass, glass ceramics, silicon carbide,
iron oxides, tantalum carbide, chromia, cerium oxide, tin oxide,
titanium carbide, titanium diboride, synthetic diamond, manganese
dioxide, zirconium oxide, sol gel alumina-based ceramics, silicon
nitride, and agglomerates thereof. Examples of sol gel abrasive
particles can be found in U.S. Pat. No. 4,314,827 (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.) and
U.S. Pat. No. 4,881,951 (Wood et al.), all incorporated herein by
reference.
[0083] The size of an abrasive particle is typically specified to
be the longest dimension of the abrasive particle. In most cases
there will be a range distribution of particle sizes. The particle
size distribution may be tightly controlled such that the resulting
abrasive article provides a consistent surface finish on the
workpiece being abraded, however, broad and/or polymodal particle
size distributions may also be used.
[0084] The abrasive particle may also have a shape associated with
it. Examples of such shapes include rods, triangles, pyramids,
cones, solid spheres, hollow spheres and the like. Alternatively,
the abrasive particle may be randomly shaped.
[0085] Abrasive particles can be coated with materials to provide
the particles with desired characteristics. For example, materials
applied to the surface of an abrasive particle have been shown to
improve the adhesion between the abrasive particle and the polymer.
Additionally, a material applied to the surface of an abrasive
particle may improve the adhesion of the abrasive particles in the
softened particulate curable binder material. Alternatively,
surface coatings can alter and improve the cutting characteristics
of the resulting abrasive particle. Such surface coatings are
described, for example, in U.S. Pat. No. 5,011,508 (Wald et al.);
U.S. Pat. No. 3,041,156 (Rowse et al.); U.S. Pat. No. 5,009,675
(Kunz et al.); U.S. Pat. No. 4,997,461 (Markhoff-Matheny et al.);
U.S. Pat. No. 5,213,591 (Celikkaya et al.); U.S. Pat. No. 5,085,671
(Martin et al.) and U.S. Pat. No. 5,042,991 (Kunz et al.), the
disclosures of which are incorporated herein by reference.
[0086] In some embodiments, for example, those including shaped
abrasive composites, the abrasive particles have a particle size
ranging from about 0.1 micrometer to about 1500 micrometers, more
typically ranging from about 0.1 micrometer to about 1300
micrometers. In some embodiments, the abrasive particles have a
size within a range of from JIS grade 600 (18 micrometers at 50%
midpoint) to JIS grade 4000 (3 micrometers at 50% midpoint) or even
JIS grade 8000 (1.5 micrometers at 50% midpoint), inclusive.
[0087] Typically, the abrasive particles used in the present
invention have a Moh's hardness of at least 8, more typically above
9; however, abrasive particles having a Moh's hardness of less than
8 may be used.
[0088] In some embodiments, at least one of the compressible
backing, elastic polyurethane film, extensible tie layer, and
abrasive layer is foraminous. This may be accomplished by a
suitable means, including, for example, die cutting or perforating,
needlepunching, or any or all of the aforementioned components of
the flexible abrasive article; or, for example, as in the case of
the abrasive layer by providing the abrasive layer with openings by
a suitable coating method, such as described in U.S. Pat. No.
6,923,840 (Schutz et al.), the disclosure of which is herein
incorporated by reference.
[0089] In some embodiments, it may be desirable to thermally emboss
flexible abrasive articles according to the present invention. For
example, channels may be embossed into at least the abrasive layer
to facilitate fluid transport and/or swarf removal. U.S. Publ. Pat.
Appl. No. 2003/0150169 A1 (Annen), the disclosure of which is
incorporated herein by reference, describes such embossing
techniques.
[0090] For example, the compressible backing, elastic polyurethane
film, extensible tie layer, and abrasive layer may be foraminous
and interrelated such that there exist a plurality of continuous
pores that extend from the second major surface of the compressible
backing through the abrasive layer.
[0091] In some embodiments, flexible abrasive articles according to
the present invention may be embossed, for example, to create a
pattern of higher and lower areas that would facilitate swarf
removal during use.
Attachment System
[0092] Flexible abrasive articles according to the present
invention may be secured to a support structure, commonly referred
to as a backup pad. The flexible abrasive article may be secured by
means of, for example, a pressure sensitive adhesive, hook and loop
attachment, or some other mechanical means.
[0093] Accordingly, flexible abrasive articles according to the
present invention may further comprise an attachment system affixed
to the second major surface of the compressible backing. The
attachment system is typically designed to secure the flexible
abrasive article to a tool (optionally having a back up pad mounted
thereto) such as, for example, a rotary sander.
[0094] In some embodiments, the attachment system comprises a layer
of pressure sensitive adhesive, typically made by applying a layer
of pressure sensitive adhesive to the second major surface of the
compressible backing. Useful pressure sensitive adhesives for this
layer include, for example, acrylic polymers and copolymers (e.g.,
polybutyl acrylate), vinyl ethers, e.g., polyvinyl n-butyl ether,
vinyl acetate adhesives, alkyd adhesives, rubber adhesives, e.g.,
natural rubber, synthetic rubber, chlorinated rubber, and mixtures
thereof. One preferred pressure sensitive adhesive is an isooctyl
acrylate:acrylic acid copolymer. The pressure sensitive adhesive
may be coated out of organic solvent, water or be coated as a hot
melt adhesive.
[0095] In some embodiments, the attachment system comprises a quick
connect mechanical fastener such as, for example, those described
in U.S. Pat. No. 3,562,968 (Johnson et al.); U.S. Pat. No.
3,667,170 (Mackay, Jr.); U.S. Pat. Nos. 3,270,467; and 3,562,968
(Block et al.); and in commonly assigned U.S. Ser. No. 10/828,119
(Fritz et al.), filed Apr. 20, 2004; the disclosures of which are
incorporated herein by reference.
[0096] In some embodiments, the attachment system comprises a loop
substrate. The purpose of the loop substrate is to provide a means
that the flexible abrasive article can be securely engaged with
hooks from a support pad. The loop substrate may be laminated to
the coated abrasive backing by any conventional means. The loop
substrate may be a chenille stitched loop, a stitchbonded loop
substrate or a brushed loop substrate (e.g., brushed nylon).
Examples of typical loop backings are further described in U.S.
Pat. Nos. 4,609,581 and 5,254,194 (both to Ott), the disclosures of
which are incorporated herein by reference. The loop substrate may
also contain a sealing coat to seal the loop substrate and prevent
subsequent coatings from penetrating into the loop substrate.
[0097] In some embodiments, the attachment system comprises an
intermeshing attachment system. An example of such an attachment
system may be found in U.S. Publ. Pat. Appln. No. 2003/0143938
(Braunschweig et al.), the disclosure of which is incorporated
herein by reference.
[0098] Likewise, the back side of the abrasive article may contain
a plurality of hooks; these hooks are typically in the form of
sheet like substrate having a plurality of hooks protruding
therefrom, for example, as described in U.S. Pat. No. 5,672,186
(Chesley et al.), the disclosure of which is incorporated herein by
reference. These hooks will then provide the engagement between the
coated abrasive article and a support pad that contains a loop
fabric. This hook substrate may be laminated to the coated abrasive
backing by any conventional means.
Method of Making
[0099] Flexible abrasive articles according to the present
invention may generally be made by: providing a compressible
backing with first and second opposed major surfaces; affixing an
elastic polyurethane film to at least a portion of the first major
surface of the compressible backing; and affixing an abrasive layer
to the elastic polyurethane film, wherein the abrasive layer
comprises abrasive particles in a binder. The surface of the
elastic polyurethane film may be surface treated to enhance
adhesion as discussed hereinabove.
[0100] In those embodiments including an extensible tie layer,
flexible abrasive articles according to the present invention may
generally be made by affixing the extensible tie layer to the
elastic polyurethane film, and then affixing the abrasive layer to
the extensible tie layer.
[0101] Affixing the various components may be accomplished by any
suitable means such as, for example, an adhesive (e.g., hot melt or
pressure sensitive), glue, mechanical fasteners, coextrusion, by
heat and/or pressure laminating, or any other suitable method.
[0102] Useful adhesives include, for example, acrylic pressure
sensitive adhesive, rubber-based PSA, waterborne lattices,
solvent-based adhesives, and two-part resins (e.g., epoxies,
polyesters, or polyurethanes). Examples of suitable pressure
sensitive adhesives include acrylate polymers (for example,
polybutyl acrylate), acrylate copolymers (for example, isooctyl
acrylate/acrylic acid), vinyl ethers (for example, polyvinyl
n-butyl ether), alkyd adhesives, rubber adhesives (for example,
natural rubbers, synthetic rubbers and chlorinated rubbers), and
mixtures thereof. An example of a pressure sensitive adhesive
coating is described in U.S. Pat. No. 5,520,957 (Bange et al.), the
disclosure of which is incorporated herein by reference.
[0103] Adhesives may be applied by any suitable means including,
for example, roll coating, brushing, extrusion, spraying, bar
coating, and knife coating.
[0104] The abrasive layer may be affixed to the optional extensible
tie layer or elastic polyurethane film by coating and curing an
abrasive layer precursor thereon. Details concerning such
procedures are discussed hereinabove.
[0105] In one embodiment, a structured abrasive layer is affixed to
either of the optional extensible tie layer or elastic polyurethane
film according to the procedures of U.S. Pat. No. 6,929,539 (Schutz
et al.), the disclosure of which is incorporated herein by
reference.
[0106] Briefly, the procedure involves applying a curable
composition comprising abrasive particles and a polymerizable
binder precursor. The curable composition is capable of being cured
by radiation energy (e.g., ultraviolet or visible light, or e-beam
radiation). The polymerizable binder precursor can polymerize, for
example, via a free radical mechanism or a cationic mechanism.
[0107] During the manufacture of the shaped, handleable structure,
radiation energy is transmitted through the production tool and
into the mixture to at least partially cure the curable
composition. The phrase "partial cure" means that the binder
precursor is polymerized to such a state that the resulting mixture
releases from the production tool. The binder precursor can be
further cured once it is removed from the production tool by any
energy source, such as, for example, thermal energy or radiation
energy. The binder precursor can also be further cured before the
shaped, handleable structure is removed from the production
tool.
[0108] Useful sources of radiation energy for this invention
include, for example, electron beam, ultraviolet light, and visible
light. Other sources of radiation energy include infrared and
microwave. Thermal energy can also be used. Electron beam
radiation, which is also known as ionizing radiation, can be used
at a dosage of about 0.1 to about 10 Mrad, preferably at a dosage
of about 1 to about 10 Mrad. Ultraviolet radiation refers to
non-particulate radiation having a wavelength, within the range of
about 200 to 400 nanometers, preferably within the range of about
250 to 400 nanometers. It is preferred that ultraviolet radiation
be provided by ultraviolet lamps operating in a range of 100 to 300
Watts/cm. Visible radiation refers to non-particulate radiation
having a wavelength within the range of about 400 to about 800
nanometers, for example, within the range of about 400 to about 550
nanometers.
[0109] Typically, radiation energy is transmitted through the
production tool and directly into the mixture. It is desirable that
the material from which the production tool is made not absorb an
appreciable amount of radiation energy or be degraded by radiation
energy. If ultraviolet radiation or visible radiation is used, the
production tool material should transmit sufficient ultraviolet or
visible radiation, respectively, to bring about the desired level
of cure.
[0110] The production tool should be operated at a velocity that is
sufficient to avoid degradation by the source of radiation.
Production tools that have relatively high resistance to
degradation by the source of radiation can be operated at
relatively lower velocities; production tools that have relatively
low resistance to degradation by the source of radiation can be
operated at relatively higher velocities. In short, the appropriate
velocity for the production tool depends on the material from which
the production tool is made.
[0111] The production tool can be in the form of a belt, e.g., an
endless belt, a sheet, a continuous sheet or web, a coating roll, a
sleeve mounted on a coating roll, or die. The surface of the
production tool that will come into contact with the mixture has a
topography or pattern. This surface is referred to herein as the
"contacting surface." If the production tool is in the form of a
belt, sheet, web, or sleeve, it will have a contacting surface and
a non-contacting surface. If the production tool is in the form of
a coating roll, it will have a contacting surface only. The
topography of the abrasive article formed by the method of this
invention will have the inverse of the pattern of the contacting
surface of the production tool. The pattern of the contacting
surface of the production tool will generally be characterized by a
plurality of cavities or recesses. The opening of these cavities
can have any shape, regular or irregular, such as a rectangle,
semicircle, circle, triangle, square, hexagon, octagon, etc. The
walls of the cavities can be vertical or tapered. The pattern
formed by the cavities can be arranged according to a specified
plan or can be random. The cavities can butt up against one
another.
[0112] Thermoplastic materials that can be used to construct the
production tool include polyesters, polycarbonates, poly(ether
sulfone), poly(methyl methacrylate), polyurethanes,
polyvinylchloride, polyolefins, polystyrene, or combinations
thereof. Thermoplastic materials can include additives such as
plasticizers, free radical scavengers or stabilizers, thermal
stabilizers, antioxidants, and ultraviolet radiation absorbers.
These materials are substantially transparent to ultraviolet and
visible radiation. One type of production tool is described in U.S.
Pat. No. 5,435,816 (Spurgeon et al.). Examples of materials forming
the production tool include polycarbonate and polyester. The
material forming the production tool should exhibit low surface
energy. The material of low surface energy improves ease of release
of the abrasive article from the production tool. Examples of
materials suitable include polypropylene and polyethylene. In some
production tools made of thermoplastic material, the operating
conditions for making the abrasive article should be set such that
excessive heat is not generated. If excessive heat is generated,
this may distort or melt the thermoplastic tooling. In some
instances, ultraviolet light generates heat. It should also be
noted that a tool consisting of a single layer is also acceptable,
and is the tool of choice in many instances. A thermoplastic
production tool can be made according to the procedure described in
U.S. Pat. No. 5,435,816 (Spurgeon et al.), the disclosure of which
is incorporated herein by reference.
Abrasive Articles
[0113] Flexible abrasive articles according to the present
invention may be manufactured to have any form. For example, the
flexible abrasive article may have the form of a circular abrasive
pad (e.g., shown as 300 in FIG. 3). Referring to FIG. 3, pores 302
in foraminous abrasive layer 140d, permit liquid to penetrate
abrasive layer 140, Foraminous elastic polyurethane film 120a is
affixed to porous compressible backing 110a. Optional foraminous
extensible tie layer 130 is affixed to at least a portion of
foraminous elastic polyurethane film 120. Abrasive layer 140d is
affixed to at least a portion of extensible tie layer 130a, if
present, or at least a portion of elastic polyurethane film 120a if
extensible tie layer 130a is not present. Loops 350 affixed to
compressible backing 110a provide an attachment system. Flexible
abrasive articles according to the present invention may also have
forms such as, for example, a rectangular abrasive pad (e.g., as
shown as 400 in FIG. 4), or an abrasive belt (e.g., as shown as 500
in FIG. 5).
[0114] In some embodiments that are useful, for example, as sanding
cloths, the compressible backing comprises a multiplicity of
separated resilient bodies connected to each other in a generally
planar array in a pattern, which provides open spaces between
adjacent connected bodies, each body having a first and second
opposed surfaces.
[0115] FIGS. 6A and 6B, not drawn to scale, illustrate a flexible
abrasive product 600 according to one such embodiment, and which is
suitable for use as a sanding cloth. Referring now to FIG. 6A,
flexible abrasive product 600 includes compressible backing 610
(shown in perspective in FIG. 6B), which comprises resilient bodies
612, each of which includes a first surface 622 which is convex or
domed and a second surface 618. Elastic polyurethane film 620 is
affixed to first surfaces 622. Optional extensible tie layer 630 is
affixed to elastic polyurethane film 620, and abrasive layer 640 is
affixed to optional extensible tie layer 630, if present, or
elastic polyurethane film 620 if extensible tie layer 630 is not
present.
[0116] Such compressible backings 610 may be formed, for example,
by dipping a scrim into a liquid, which is curable to form a foam,
and curing by placing the dipped scrim in an oven, which causes the
composition to expand and solidify.
[0117] The scrim may be made of natural or synthetic fibers, which
may be either knitted or woven in a network having intermittent
openings spaced along the surface of the scrim. The scrim need not
be woven in a uniform pattern but may also include a nonwoven
random pattern. Thus, the openings may either be in a pattern or
randomly spaced. The scrim network openings may be rectangular or
they may have other shapes including a diamond shape, a triangular
shape, an octagonal shape or a combination of these shapes.
[0118] Typically, the scrim comprises a first set of rows of
separated fibers deployed in a first direction and a second set of
fibers deployed in a second direction to provide a grid including
multiple adjacent openings wherein resilient bodies are located in
alternate openings with openings between resilient bodies being
devoid of resilient bodies, although this is not a requirement. The
scrim may also comprise an open mesh selected from the group
consisting of woven or knitted fiber mesh, synthetic fiber mesh,
natural fiber mesh, metal fiber mesh, molded thermoplastic polymer
mesh, molded thermoset polymer mesh, perforated sheet materials,
slit and stretched sheet materials and combinations thereof.
[0119] The composition of the resilient bodies may either be foamed
or non-foamed and may be composed of any of a variety of
elastomeric materials including, but not limited to, polyurethane
resins, polyvinyl chloride resins, ethylene vinyl acetate resins,
synthetic or natural rubber compositions, acrylate resins, and/or
other suitable elastomeric resin compositions.
[0120] In this embodiment, the compressible backing is
characterized by having openness between resilient bodies to
provide a cumulative openness as compared to the total area of the
resilient body on the order of about 20% to about 80%, more
typically, between about 30% to about 60%.
[0121] The compressible backing may have a sufficient thickness to
make it convenient for being hand held. The thickness is measured
between the highest point of the first major surface of the
resilient body to the second surface of the resilient body. The
thickness typically is between about 1 millimeter and about 15
millimeters, more typically about 3 millimeters to about 10
millimeters, although other thicknesses may also be used.
[0122] While a square or rectangular shape of the resilient body is
often desirable, the body may be any convenient geometric shape
including, but not limited to, square, rectangular, triangular,
circular, and in the shape of a polygon. The resilient bodies are
typically uniform in shape, but they need not be. The resilient
bodies may be aligned in rows longitudinally and in a transverse
direction but for some applications it may be preferable that they
not be aligned because in sanding operations where the abrasive
product is moved in only one direction, for example, the
longitudinal direction, longitudinally aligned abrasive covered
resilient bodies could produce an unwanted scratch pattern in the
surface being abraded.
[0123] The dimensions of the resilient bodies may vary from about 2
millimeters to about 25 millimeters, more typically from 5
millimeters to 10 millimeters. When referring to the dimensions of
the resilient body, the dimensions are intended to include the
widths in the longitudinal or transverse direction or the maximum
dimension of the body when measured from one side to the other
notwithstanding any direction.
[0124] In this embodiment, the openings in the compressible backing
are generally individually smaller than the adjacent resilient body
and may have dimensions on the order of about 2 millimeters to
about 25 millimeters, preferably of about 5 millimeters to about 10
millimeters. The openings may be somewhat rectangular, if the
resilient bodies are rectangular or they may take any other
configuration depending on the shape of the adjacent resilient
bodies. The shape of the openings is typically defined by the shape
of the edges of the resilient bodies. The resilient bodies and the
openings are generally uniformly distributed throughout the entire
area of the flexible abrasive product of the invention but this is
not necessary in all cases.
[0125] Exemplary compressible backings according to this embodiment
are well known, for example, as commercially available under the
trade designations "OMNI-GRIP", "MAXI-GRIP", "ULTRA GRIP",
"EIRE-GRIP", and "LOC-GRIP" from Griptex Industries, Inc. of
Calhoun, Ga., or made according to U.S. Pat. No. 5,707,903
(Schottenfeld), the disclosure of which is incorporated herein by
reference.
[0126] In this embodiment, each the elastic polyurethane film,
extensible tie layer, and abrasive layer may form continuous
uninterrupted layers or may having openings therethrough, the
openings in the film generally corresponding in position to
openings in the compressible backing.
[0127] Further details concerning flexible abrasive articles
according to this embodiment such as, for example, the compressible
backing and the abrasive layer, may be found in U.S. Pat. No.
6,613,113 (Minick et al.), the disclosure of which is incorporated
herein by reference.
Method of Using
[0128] Flexible abrasive articles may be used, for example, by hand
or in combination with a power tool such as for example, a rotary
sander or belt sander.
[0129] Flexible abrasive articles according to the present
invention are useful for abrading (including finishing) a workpiece
by a method that includes: providing a flexible abrasive article
according to the present invention; frictionally contacting at
least one abrasive particle with a workpiece; and moving at least
one of the abrasive particle and the workpiece relative to the
other to abrade at least a portion of the surface of the workpiece.
For example, the abrasive article may oscillate at the abrading
interface during use.
[0130] The workpiece can be any of a variety of types of material
such as painted substrates (e.g., having a clear coat, base (color)
coat, primer or e-primer), coated substrates (e.g., with
polyurethane, lacquer, etc.), plastics (thermoplastic,
thermosetting), reinforced plastics, metal, (carbon steel, brass,
copper, mild steel, stainless steel, titanium and the like) metal
alloys, ceramics, glass, wood, wood-like materials, composites,
stones (including gem stones), stone-like materials, and
combinations thereof. The workpiece may be flat or may have a shape
or contour associated with it. Examples of common workpieces that
may be polished by the abrasive article of the invention include
metal or wooden furniture, painted or unpainted motor vehicle
surfaces (car doors, hoods, trunks, etc.), plastic automotive
components (headlamp covers, tail-lamp covers, other lamp covers,
arm rests, instrument panels, bumpers, etc.), flooring (vinyl,
stone, wood and wood-like materials), counter tops, and other
plastic components.
[0131] During abrading processes it may be desirable to provide a
liquid to the surface of the workpiece and/or the abrasive layer.
The liquid may comprise water, an organic compound, additives such
as defoamers, degreasers, liquids, soaps, corrosion inhibitors, and
the like, and combinations thereof.
[0132] Objects and advantages of this invention 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 invention.
EXAMPLES
[0133] Unless otherwise noted, all parts, percentages, ratios, etc.
in the examples and the rest of the specification are by weight,
and all reagents used in the examples were obtained, or are
available, from general chemical suppliers such as, for example,
Sigma-Aldrich Company, Saint Louis, Miss., or may be synthesized by
conventional methods.
The following abbreviations are used throughout the Examples:
[0134] AS1: trimethylolpropane triacrylate monomer available under
the trade designation "SR 351" from Sartomer Company, Exton, Pa.
[0135] AS2: 2-phenoxyethyl acrylate aromatic monomer available
under the trade designation "SR 339" from Sartomer Company. [0136]
AS3: polymeric dispersant available under the trade designation
"SOLPLUS D520" from Noveon, Inc., Cleveland, Ohio. [0137] AS4:
gamma-methacryloxypropyltrimethoxysilane resin modifier available
under the trade designation "SILQUEST A174" from Witco Corporation,
Greenwich, Conn. [0138] AS5: ethyl
2,4,6-trimethylbenzoylphenylphosphinate photoinitiator available
under the trade designation "LUCIRIN TPO-L" from BASF Corp.,
Charlotte, N.C. [0139] AS6: silicon dioxide available under the
trade designation "AEROSIL OX-50" from Degussa Corp., Dusseldorf,
Germany. [0140] AS7: acrylic acid. [0141] AS8: green silicon
carbide abrasive particles having a JIS grade size of 800 and an
average particle size of 14 micrometers at 50% point, available
under the trade designation "FUJIMI GC 800" from Fujimi Abrasives
Company, Elmhurst, Ill.
Example 1
[0142] A layer of transfer adhesive, commercially available under
the trade designation "HS300LSE" from 3M Company, St. Paul, Minn.,
was applied to one surface of a 2.3 mm thick open cell polyurethane
foam, commercially available under the trade designation "R600U"
from Illbruck, Inc., Minneapolis, Minn. A polypropylene-laminated
loop material, part of a hook and loop mechanical fastener system
was then laminated to the transfer adhesive with the loops
outwardly disposed. Another layer of the transfer adhesive was
applied to the opposing surface of the foam and a 0.8 mil (203
micrometer) thick polyurethane elastomeric transfer film,
commercially available under the trade designation "TEGADERM", from
3M Company, was laminated to the transfer adhesive. The release
layer was removed from the TEGADERM film, exposing the adhesive
surface.
[0143] An abrasive slurry was made by mixing until homogeneous, at
20.degree. C., 14.0 parts of AS1, 14.0 parts of AS2, 4.0 parts of
AS3, 3.0 parts of AS4, 1.0 parts of AS5, 7.0 parts of AS6, and 57.0
parts of AS8. The slurry was applied via knife coating to a
polypropylene production tool having a uniformly distributed array
of three-sided pyramids with a peak height of 178 micrometers,
shown in FIGS. 7A-7C. The coated production tool was applied to the
exposed adhesive face of the TEGADERM film. The production tool was
then irradiated with an ultraviolet (UV) lamp, type "D" bulb, from
Fusion Systems Inc., Gaithersburg, Md., at 600 Watts per inch (236
Watts per cm) while moving the web at 30 feet per minute (9.14
meters/minute), and a nip pressure of 90 pounds per square inch
(620.5 kilopascals (kPa)) for a 10 inch (25.4 cm) wide web. The
production tool was then separated from substantially cured shaped
abrasive coating, and flexible abrasive discs, 6-inch (15.2-cm)
diameter, were then die cut from the abrasive material.
Example 2
[0144] Example 2 was carried out according to the method described
in Example 1, except that the flexible abrasive material was
subsequently perforated by needle-tacking with a punch density of
53 perforations per square inch (8.2 perforations per cm.sup.2)
using needles designated as "15.times.18.times.25.times.3.5 RB"
available from Foster Needle Co., Inc., Manitowoc, Wis. The
perforations were made from the abrasive side down through the
attachment system.
Example 3
[0145] Flexible abrasive discs were made according to the method
described in Example 1, except the TEGADERM film was replaced with
a 0.8 mil film of ESTANE 58309NAT022 polyurethane resin (B.F.
Goodrich, Cleveland, Ohio), and the abrasive slurry composition
was: 13.7 parts of AS1, 13.7 parts of AS2, 3.9 parts of AS3, 2.9
parts of AS4, 1.0 parts of AS5, 6.8 parts of AS6, 2.4 parts of AS7,
and 55.6 parts of AS8.
Example 4
[0146] Flexible abrasive discs were made according to the method
described in Example 3, except the slurry formulation was: 13.3
parts of AS1, 13.3 parts of AS2, 3.8 parts of AS3, 2.9 parts of
AS4, 1.0 parts of AS5, 6.7 parts of AS6, 4.8 parts of AS7, and 54.2
parts of AS8.
Example 5
[0147] Flexible abrasive discs were made according to the method
described in Example 3, except the slurry formulation was: 13.0
parts of AS1, 13.0 parts of AS2, 3.7 parts of AS3, 2.8 parts of
AS4, 0.9 parts of AS5, 6.5 parts of AS6, 7.0 parts of AS7, and 53.0
parts of AS8.
Comparative Example A
[0148] A 6-inch (15.2 cm) abrasive foam disc, commercially
available under the trade designation "443SA TRIZACT HOOKIT II
BLENDING DISC P1000" from 3M Company. Comparative Example A is
similar to Example 2, except the attachment layer is the hook
component of a hook and loop mechanical fastener system, and it
does not have does it have a polymeric transfer film.
Cut and Finish Testing
[0149] Abrasive performance testing was performed using 18 inches
by 24 inches (45.7 cm by 61 cm) clear coated black painted cold
roll steel test panels, obtained from ACT Laboratories, Inc.,
Hillsdale, Mich., as the sanding substrate. Sanding was performed
using a random orbit sander, model number "59025" obtained from
Dynabrade, Inc., Clarence, N.Y., operating at a line pressure of 40
pounds per square inch (258 kilopascals (kPa)). For testing
purposes, flexible abrasive discs prepared according to Examples 1
through 5 were attached to a 6-inch (15.2 cm) interface pad, which
was then attached to a 6-inch (15.2 cm) backup pad, both
commercially available under the trade designations "HOOKIT
INTERFACE PAD, PART NO. 05251" and "HOOKIT BACKUP PAD, PART NO.
05876", from 3M Company. Comparative Example A was similarly
attached to a 6-inch (15.2 cm) "HOOKIT II" type interface pad and
backup pad, part numbers "05774" and "05274", respectively.
[0150] Each test panel was divided into four 18'' (45.7 cm) long
lanes, each lane being 6 inches (15.2 cm) wide. Each abrasive disc
was tested by damp-sanding (with water) for 30 seconds in a single
lane. The test panel was weighed before and after sanding of each
lane. The difference in mass is the measured cut, reported as grams
per 30 seconds. After sanding, the average surface finish (R.sub.z)
in micrometers (.mu.m) of each lane was measured using a
profilometer available under the trade designation "SURTRONIC 3+
PROFILOMETER" from Taylor Hobson, Inc., Leicester, England. R.sub.z
is the average of 5 individual measurements of the vertical
distance between the highest point and the lowest point over the
sample length of an individual profilometer measurement. Five
finish measurements were made per lane. Four abrasive discs were
tested per Lot and the results are reported as average of all four
abrasive discs, such that the reported cut is the average of four
measurements and the reported finish is the average of 20
measurements.
[0151] The sanding results are reported in Table 1 (below).
TABLE-US-00001 TABLE 1 AVERAGE CUT R.sub.Z, ABRASIVE DISC (grams
per 30 seconds) (micrometers) Example 1 0.29 1.24 Example 2 0.29
1.07 Example 3 0.32 1.55 Example 4 0.32 1.64 Example 5 0.30 1.45
Comparative A 0.34 1.57
Durability Testing
[0152] Test panels were damp sanded by hand, using finger-point
pressure to contact the abrasive disc to the test panel, using
abrasive discs of Examples 1 and 2, and Comparative A. The sanding
action was linear. After 23 seconds of sanding, Comparative A
developed a hole, approximately 0.5 inches (12.7 mm) in diameter,
in the abrasive and foam backing. Upon further sanding, this hole
continued to expand. However, after 60 seconds of sanding, neither
Example 1 nor Example 2 showed any degradation or wear.
[0153] Various modifications and alterations of this invention may
be made by those skilled in the art without departing from the
scope and spirit of this invention, and it should be understood
that this invention is not to be unduly limited to the illustrative
embodiments set forth herein.
* * * * *