U.S. patent application number 10/304041 was filed with the patent office on 2004-05-27 for nonwoven abrasive articles and methods for making and using the same.
This patent application is currently assigned to 3M Innovative Properties Company. Invention is credited to Hood, Sherri D., Van, Loc X..
Application Number | 20040098923 10/304041 |
Document ID | / |
Family ID | 32325112 |
Filed Date | 2004-05-27 |
United States Patent
Application |
20040098923 |
Kind Code |
A1 |
Hood, Sherri D. ; et
al. |
May 27, 2004 |
Nonwoven abrasive articles and methods for making and using the
same
Abstract
Nonwoven abrasive articles comprise a porous reinforcing
material, a fiber web affixed to the porous reinforcing material,
abrasive particles, and a non-elastomeric binder. Methods of making
and using nonwoven abrasive articles are also disclosed.
Inventors: |
Hood, Sherri D.; (Woodbury,
MN) ; Van, Loc X.; (Woodbury, MN) |
Correspondence
Address: |
3M INNOVATIVE PROPERTIES COMPANY
PO BOX 33427
ST. PAUL
MN
55133-3427
US
|
Assignee: |
3M Innovative Properties
Company
|
Family ID: |
32325112 |
Appl. No.: |
10/304041 |
Filed: |
November 25, 2002 |
Current U.S.
Class: |
51/296 ; 51/293;
51/297; 51/298; 51/307; 51/308; 51/309 |
Current CPC
Class: |
B24D 3/348 20130101;
B24D 18/0027 20130101; B24D 11/005 20130101 |
Class at
Publication: |
051/296 ;
051/297; 051/298; 051/307; 051/308; 051/309; 051/293 |
International
Class: |
B24D 003/00; B24D
011/00; B24D 018/00 |
Claims
What is claimed is:
1. A nonwoven abrasive article comprising: a porous reinforcing
material having first and second opposed major surfaces; a fiber
web, wherein the fiber web is affixed to the first major surface of
the porous reinforcing material; and an abrasive composition
comprising abrasive particles and a non-elastomeric binder, wherein
the abrasive composition contacts at least a portion of the fiber
web and the first major surface of the porous reinforcing material,
wherein the abrasive composition extends through at least a portion
of the porous reinforcing material and contacts at least a portion
of the second major surface of the porous reinforcing material, and
wherein, on a weight basis, there is a first average ratio of
abrasive particles to the non-elastomeric binder at the first major
surface, and a second average ratio of abrasive particles to the
non-elastomeric binder at the second major surface, and wherein the
first average ratio is greater than the second average ratio.
2. A nonwoven abrasive article according to claim 1, wherein the
fiber web is needletacked to the first major surface of the porous
reinforcing material.
3. A nonwoven abrasive article according to claim 1, wherein the
article is a disc.
4. A nonwoven abrasive article according to claim 1, wherein the
article is an endless belt.
5. A nonwoven abrasive article according to claim 1, wherein the
binder comprises at least partially cured phenolic resin.
6. A nonwoven abrasive article according to claim 1, wherein the
abrasive composition comprises a slurry coat.
7. A nonwoven abrasive article according to claim 6, further
comprising a size coat contacting at least a portion of the
abrasive composition.
8. A nonwoven abrasive article according to claim 6, wherein the
size coat comprises an elastomer.
9. A nonwoven abrasive article according to claim 6, wherein the
size coat comprises at least one of a lubricant or a grinding
aid.
10. A nonwoven abrasive article according to claim 7, wherein the
article comprises a disc or an endless belt.
11. A nonwoven abrasive article according to claim 1, wherein the
abrasive composition comprises a make coat and a size coat.
12. A nonwoven abrasive article according to claim 11, wherein the
size coat comprises an elastomer.
13. A nonwoven abrasive article according to claim 11, wherein the
size coat comprises at least one of a lubricant or a grinding
aid.
14. A nonwoven abrasive article according to claim 11, wherein the
article is a disc or an endless belt.
15. A nonwoven abrasive article according to claim 11, wherein the
first binder comprises at least partially cured phenolic resin.
16. A method for making a nonwoven abrasive article comprising:
providing a fiber web; providing a porous reinforcing material
having first and second opposed major surfaces; affixing the fiber
web to the first major surface of the reinforcing material;
applying a first binder precursor and abrasive particles onto the
fiber web, wherein at least a portion of the first binder precursor
penetrates through the porous reinforcing material and contacts at
least a portion of the first and second major surfaces; and at
least partially curing the first binder precursor to form a
non-elastomeric first binder, wherein on a weight basis, there is a
first average ratio of abrasive particles to the non-elastomeric
binder at the first major surface, and a second average ratio of
abrasive particles to the non-elastomeric binder at the second
major surface, and wherein the first average ratio is greater than
the second average ratio.
17. A method according to claim 16, wherein affixing comprises
needletacking.
18. A method according to claim 16, wherein applying comprises
spraying.
19. A method according to claim 16, further comprising forming the
nonwoven abrasive article into at least one of a disc or an endless
belt.
20. A method according to claim 16, wherein the first binder
precursor comprises phenolic resin.
21. A method according to claim 16, wherein the first binder
precursor and abrasive particles comprise a slurry coat
precursor.
22. A method according to claim 16, wherein the first binder
precursor comprises a make coat precursor.
23. A method according to claim 16, further comprising: applying a
second binder precursor to at least a portion of the
non-elastomeric first binder, wherein the second binder precursor;
and at least partially curing the second binder precursor.
24. A method according to claim 23, further comprising forming the
nonwoven abrasive article into at least one of a disc or an endless
belt.
25. A method according to claim 23, wherein the second binder
precursor is at least partially curable to form an elastomer.
26. A method of abrading a surface, the method comprising:
providing a nonwoven abrasive article, wherein the nonwoven
abrasive article comprises: a porous reinforcing material having
first and second opposed major surfaces; a fiber web affixed to the
first major surface of the porous reinforcing material; an abrasive
composition comprising abrasive particles and binder, wherein the
abrasive composition contacts at least a portion of the fiber web
and the first major surface of the reinforcing material, wherein
the abrasive composition extends through at least a portion of the
reinforcing material and contacts at least a portion of the second
major surface of the reinforcing material, wherein on a weight
basis, there is a first average ratio of abrasive particles to the
non-elastomeric binder at the first major surface, and a second
average ratio of abrasive particles to the non-elastomeric binder
at the second major surface, and wherein the first average ratio is
greater than the second average ratio; contacting at least one of
the abrasive particles with the surface of the workpiece; and
moving at least one of the abrasive particles or the contacted
surface relative to the other to abrade at least a portion of the
contacted surface.
27. A method of abrading a workpiece according to claim 26, wherein
the nonwoven abrasive article further comprises a size coat
contacting at least a portion of the slurry coat.
28. A method of abrading a workpiece according to claim 26, wherein
the first binder comprises at least partially cured phenolic resin.
Description
TECHNICAL FIELD
[0001] The present invention relates to nonwoven abrasive
articles.
BACKGROUND
[0002] Nonwoven abrasive articles typically comprise an open porous
fiber web having abrasive particles bonded thereto by a binder. For
applications requiring added dimensional stability and/or high
strength, a reinforcing scrim or fabric is typically affixed to the
fiber web. Such reinforced articles are known, for example, in
forms such as discs and belts.
[0003] The reinforcing scrim or fabric is typically affixed to the
fiber web by an adhesive resin and/or by mechanical means such as
needletacking. To aid in maintaining the integrity and/or structure
of the reinforced fiber web during the nonwoven abrasive
manufacturing process, an elastomeric binder precursor (i.e.,
prebond precursor) is commonly applied to the fiber web, and cured
to form a prebonded reinforced fiber web.
[0004] Conventional abrasive nonwoven discs and belts are typically
made from prebonded reinforced fiber web by one of two methods. In
one method, prebonded reinforced fiber web is typically coated with
a slurry of abrasive particles in a curable binder precursor (i.e.,
slurry coat precursor), and then the binder precursor is cured to
form a slurry coat on the reinforced non-woven web. In a second
method, a curable binder precursor (i.e., make coat precursor) is
typically coated onto prebonded reinforced fiber web, abrasive
particles are applied to the make coat precursor, and then the make
coat precursor is at least partially cured to form a make coat.
Another curable binder precursor (i.e., size coat precursor) is
then typically applied onto the make coat, and then cured to form
an abrasive composition (i.e., the make coat, abrasive particles,
and size coat taken collectively) on the reinforced non-woven
web.
[0005] While abrading a workpiece with nonwoven abrasive articles,
portions of the abrasive article may detach in phenomena commonly
referred to as "shelling" (i.e., loss of abrasive particles) or
"chunking" (i.e., loss of chunks of binder, fiber web, and abrasive
particles). Chunking may be especially troublesome in the case of
nonwoven abrasive endless belts. Shelling and chunking are
typically undesirable, as they generally degrade the performance of
the nonwoven abrasive article. There is a continuing need for
nonwoven abrasive articles that have an acceptable level of
chunking and/or shelling during use.
SUMMARY OF THE INVENTION
[0006] In one aspect, the present invention provides a nonwoven
abrasive article comprising:
[0007] a porous reinforcing material having first and second
opposed major surfaces;
[0008] a fiber web, wherein the fiber web is affixed to the first
major surface of the porous reinforcing material; and
[0009] an abrasive composition comprising abrasive particles and a
non-elastomeric binder, wherein the abrasive composition contacts
at least a portion of the fiber web and the first major surface of
the porous reinforcing material, wherein the abrasive composition
extends through at least a portion of the porous reinforcing
material and contacts at least a portion of the second major
surface of the porous reinforcing material, and wherein, on a
weight basis, there is a first average ratio of abrasive particles
to the non-elastomeric binder at the first major surface, and a
second average ratio of abrasive particles to the non-elastomeric
binder at the second major surface, and wherein the first average
ratio is greater than the second average ratio.
[0010] In another aspect, the present invention provides a method
for making a nonwoven abrasive article comprising:
[0011] providing a fiber web;
[0012] providing a porous reinforcing material having first and
second opposed major surfaces;
[0013] affixing the fiber web to the first major surface of the
reinforcing material;
[0014] applying a first binder precursor and abrasive particles
onto the fiber web, wherein at least a portion of the first binder
precursor penetrates through the porous reinforcing material and
contacts at least a portion of the first and second major surfaces;
and
[0015] at least partially curing the first binder precursor to form
a non-elastomeric first binder, wherein on a weight basis, there is
a first average ratio of abrasive particles to the non-elastomeric
binder at the first major surface, and a second average ratio of
abrasive particles to the non-elastomeric binder at the second
major surface, and wherein the first average ratio is greater than
the second average ratio.
[0016] In another aspect, the present invention provides a method
of abrading a surface, the method comprising:
[0017] providing a nonwoven abrasive article according to the
present invention;
[0018] contacting at least one of the abrasive particles of the
abrasive article with the surface of the workpiece; and
[0019] moving at least one of the abrasive particles or the
contacted surface relative to the other to abrade at least a
portion of the contacted surface.
[0020] Nonwoven abrasive articles, according to the present
invention, typically have an acceptable level of shelling and/or
chunking during use, for example, if used as an endless belt
mounted onto equipment (e.g., belt sander) having small diameter
pulleys and/or rollers.
BRIEF DESCRIPTION OF THE DRAWING
[0021] FIG. 1 is a cross-sectional view of an exemplary nonwoven
abrasive article according to the present invention;
[0022] FIG. 2 is a cross-sectional view of another exemplary
nonwoven abrasive article according to the present invention;
[0023] FIG. 3 is a perspective view of an exemplary nonwoven
abrasive disc according to one embodiment of the present invention;
and
[0024] FIG. 4 is a perspective view of an exemplary endless
nonwoven abrasive belt according to one embodiment of the present
invention.
DETAILED DESCRIPTION
[0025] Referring now to FIG. 1, exemplary nonwoven abrasive article
according to the present invention 100 comprises fiber web 110
affixed to porous reinforcing material 120 of thickness 185 and
having first and second opposed major surfaces 122 and 124,
respectively. Slurry coat 130, comprising abrasive particles 135
and non-elastomeric binder 138, contacts at least a portion of
fiber web 110 and first major surface 122 of porous reinforcing
material 120. Optional size coat 170 contacts slurry coat 130,
porous reinforcing material 120, fiber web 110, and fibers 192.
Non-elastomeric binder 138 extends through at least a portion of
porous reinforcing material 120, and contacts at least portion of
second major surface 124 of porous reinforcing material 120. The
average ratio on a weight basis of abrasive particles 135 to
non-elastomeric binder 138 is higher at first major surface 122
than at second major surface 124.
[0026] For purposes of determining the average ratio on a weight
basis of abrasive particles 135 to non-elastomeric binder 138 at a
surface of the backing, the phrase "at the first surface" is to be
construed as referring to zone 180a, which is the combination of
zones 187a and 189a. Zone 187a is the outer 20 percent of thickness
185 that contacts first major surface 122. Zone 189a, which has the
same thickness as zone 187a, contacts zone 187a, and extends beyond
first major surface 122. Similarly, the phrase "at the second
surface" is to be construed as referring to zone 180b, which is the
combination of zones 187b and 189b. Zone 187a is the outer 20
percent of thickness 185 that contacts first major surface 124.
Zone 189b, which has the same thickness as zone 187b, contacts zone
187b, and extends beyond first major surface 124.
[0027] Optionally (e.g., as in the case wherein fiber web 110 is
needletacked to the porous reinforcing material 120), a portion of
fibers comprising fiber web 110 may extend outwardly from second
major surface 124 as exposed fibers 192. In some embodiments,
exposed fibers 192 remain substantially free of non-elastomeric
binder 138 and abrasive particles 135, as the presence of such
materials may tend to hinder proper functioning of the nonwoven
abrasive in some embodiments (e.g., endless belts).
[0028] In another exemplary embodiment of the present invention,
shown in FIG. 2, nonwoven abrasive article 200 comprises fiber web
110 affixed to porous reinforcing material 120 of thickness 185 and
having first and second opposed major surfaces 122 and 124,
respectively. Make coat 230, comprising non-elastomeric binder 138,
has abrasive particles 135 bonded thereto, and contacts at least a
portion of fiber web 110 and first major surface 122 of porous
reinforcing material 120. Optional size coat 170 contacts make coat
230, abrasive particles 135, porous reinforcing material 120, fiber
web 110, and fibers 192. Non-elastomeric binder 138 extends through
a portion of porous reinforcing material 120 and contacts a portion
of second major surface 124 of porous reinforcing material 120. The
average ratio on a weight basis of abrasive particles 135 to
non-elastomeric binder 138 is higher at first major surface 122
than at second major surface 124.
[0029] Typically, the fiber web comprises an entangled web of
fibers (i.e., a fibrous nonwoven). Many suitable fiber webs are
known and used in the arts of nonwovens and abrasives. The fiber
web may be made, for example, by conventional air laid, carded,
stitch bonded, spun bonded, wet laid, and/or melt blown procedures.
Air laid fiber webs may be prepared using equipment such as, for
example, that available under the trade designation "RANDO WEBBER"
commercially available from Rando Machine Company of Macedon, N.Y.
Prior to affixing the fiber web to the porous reinforcing material,
the fiber web is typically open (e.g., lofty and open). After
affixing the fiber web to the porous reinforcing material,
depending on the method used (e.g., needletacking), the fiber web
may be denser and thinner.
[0030] The fiber web is selected to be suitably compatible with
adhering binders and abrasive particles while also being
processable in combination with other components of the article
(e.g., binder precursors, hardened binders, abrasive materials),
and typically can withstand temperatures at which such binder
precursors and other materials are applied and processed. In
addition, the fiber may be chosen to affect properties of the
abrasive article such as flexibility, elasticity, durability or
longevity, abrasiveness, and finishing properties. Examples of
fibers that may be suitable include natural fibers, synthetic
fibers, and mixtures of natural and/or synthetic fibers. Examples
of synthetic fibers include those made of polyester (e.g.,
polyethylene terephthalate), nylon (e.g., hexamethylene adipamide,
polycaprolactam), polypropylene, acrylic (formed from a polymer of
acrylonitrile), rayon, cellulose acetate, polyvinylidene
chloride-vinyl chloride copolymers, vinyl chloride-acrylonitrile
copolymers, and so forth. Suitable natural fibers include cotton,
wool, jute, and hemp. The fiber may be of virgin materials or of
recycled or waste materials reclaimed from garment cuttings, carpet
manufacturing, fiber manufacturing, or textile processing, for
example. The fiber may be homogenous or a composite such as a
bicomponent fiber (e.g., a co-spun sheath-core fiber). The fibers
may be tensilized and crimped, but may also be continuous filaments
such as those formed by an extrusion process. It is also within the
scope of the invention to provide an article comprising different
fibers in different portions of the nonwoven (e.g., at a first
major surface, a second major surface, and within the middle
portion therebetween).
[0031] The fiber web may comprise staple fibers having a length of
at least about 20 millimeters (mm), at least about 30 mm, or at
least about 40 mm, and less than about 110 mm, less than about 85
mm, or less than about 65 mm, although shorter and longer fibers
(e.g., continuous filaments) may also be useful. The fibers may
have a fineness or linear density of at least about 1.7 decitex
(dtex), at least about 6 dtex, or at least about 17 dtex, and less
than about 560 dtex, less than about 280 dtex, or less than about
120 dtex, although fibers having lesser and/or greater linear
densities may also be useful. Mixtures of fibers with differing
linear densities may be useful, for example, to provide an abrasive
article that upon use will result in a specifically preferred
surface finish. If a spunbond nonwoven is used, the filaments may
be of substantially larger diameter, for example, up to 2 mm or
more in diameter. The fiber web may optionally be reinforced and/or
consolidated by any of various methods known and understood in the
art of nonwoven materials, including thermal or chemical bonding,
hydroentanglement, and the like.
[0032] The fiber web typically has a weight per unit area (i.e.,
basis weight) of at least about 50 grams per square meter
(g/m.sup.2), at least about 100 g/m.sup.2, or at least about 200
g/m.sup.2; and/or less than about 400 g/m.sup.2, less than about
350 g/m.sup.2, or less than about 300 g/m.sup.2, as measured prior
to any coating (e.g., prior to application of any binder
precursors), although greater and lesser basis weights may also be
used. In addition, the fiber web (prior to any optional
reinforcement and/or consolidation as discussed below) typically
has a thickness of at least about 5 mm, at least about 6 mm, or at
least about 10 mm; and/or less than about 200 mm, less than about
75 mm, or less than about 30 mm, although greater and lesser
thicknesses may also be useful.
[0033] Further details concerning suitable fiber webs and methods
for their manufacture may be found, for example, in U.S. Pat. No.
6,207,246 (Moren et al.); No. 5,591,239 (Larson et al.); No.
4,227,350 (Fitzer); and No. 2,958,593 (Hoover et al.), the
disclosures of which are incorporated herein by reference.
[0034] The reinforcing material may be affixed to the nonwoven by
methods that are useful or known in the art of nonwoven materials,
using conventional materials such as adhesives and needletacking
techniques. For example, in some embodiments of the invention,
(e.g., where the web is to be incorporated into a machine driven
abrasive article such as a belt or abrasive disc), a porous
reinforcing material may be contacted with a surface of the
nonwoven material before needletacking. In such embodiments, the
nonwoven is typically needletacked while contacting the porous
reinforcing material, such that fibers of the nonwoven are pushed
or pulled from the first major surface of the porous reinforcing
material, through the porous reinforcing material, and extend
outwardly out from the second major surface. Although other methods
for affixing the fiber web to the porous reinforcing material may
be used (e.g., adhesive bonding), needletacking is generally
preferred. Needletacking processes are well known in the art of
nonwoven materials, and are readily accomplished by use of
conventional needle loom equipment commercially available, for
example, from Dilo, Charlotte, N.C. or DOA, Linz, Austria.
[0035] The properties of the reinforcing material may also
influence physical properties of an abrasive article prepared
therefrom, including stiffness, flexibility, durability, etc. The
porous reinforcing material may comprise a porous dimensionally
stable, woven, fibrous material (e.g., scrim). The porous
reinforcing material should typically be capable of withstanding
processing into an abrasive article as described herein, and is
preferably stable at temperatures at which binder precursors are
applied and/or processed.
[0036] The term "porous" as applied herein to the reinforcing
material means that the reinforcing material is sufficiently porous
that a binder precursor (e.g., slurry coat precursor, make coat
precursor) may penetrate through the thickness of the reinforcing
material. The reinforcing material may be a woven stretch-resistant
fabric, and may have tensile strain in at least one direction of
less than about 5 percent stretch or less than about 2.5 percent
stretch, at tensile loads up to 100 pounds/inch (174 N/cm).
Suitable reinforcing materials include, for example, thermo-bonded
fabrics, knitted fabrics, stitch-bonded fabrics. The reinforcing
material may include fibers of nylon and/or polyester.
[0037] Optionally, the second major surface of the porous
reinforcing material may be coated with a thermoplastic polymer or
thermosetting resin to encapsulate outwardly extending fibers and
provide a smooth surface as described, for example, in U.S. Pat.
No. 5,482,756 (Berger et al.), the disclosure of which is
incorporated herein by reference. If used, such thermoplastic
polymer or thermosetting resin is typically applied after any
coatings (e.g., make, size, slurry, and/or supersize) have been
applied, in order that the backing is at least partially permeable
to such coatings.
[0038] Any binder precursor used in preparation of the abrasive
composition (e.g., slurry coat precursor, make coat precursor) is
typically applied to the fiber web after it is affixed to the
porous reinforcing material. The binder precursor is typically
applied to the fiber web in liquid form (e.g., by conventional
methods), and subsequently hardened (e.g., at least partially
cured) to form a layer coated on at least a portion of the fiber
web and porous reinforcing material.
[0039] In a first exemplary method, a slurry coat precursor
comprising abrasive particles and a first binder precursor is
applied to the fiber web and the first major surface of the porous
reinforcing material, and then at least partially cured. Typically,
prior to curing, the first binder precursor component diffuses
through at least a portion of the porous reinforcing material
(i.e., from the first major surface of porous reinforcing material
to at least a portion of the second major surface of the
reinforcing material). Optionally, a second binder precursor (i.e.,
a size coat precursor), which may be the same as or different from
the slurry coat precursor may be applied to the slurry coat,
typically after at least partially curing the slurry coat
precursor.
[0040] In a second exemplary method, a make coat precursor
comprising a first binder precursor is typically applied to the
fiber web, abrasive particles are deposited on the make coat, and
then the make coat precursor is hardened (e.g., by evaporation,
cooling, and/or at least partially curing). Typically, prior to
curing, the make coat precursor diffuses through at least a portion
of the porous reinforcing material (i.e., from the first major
surface of porous reinforcing material to at least a portion of the
second major surface of the reinforcing material). Subsequently, a
second binder precursor (i.e., a size coat precursor), which may be
the same as or different from the make coat precursor, is typically
applied over the make coat and abrasive particles, and then at
least partially cured.
[0041] Typically, binder precursors employed in slurry coat
precursors, or at least one of make coat precursors and/or size
coat precursors (e.g., as described above), comprise a monomeric or
polymeric material that may be at least partially cured (i.e.,
polymerized and/or crosslinked). Typically, upon at least partial
curing, such binder precursors form a non-elastomeric binder (e.g.,
a hard brittle binder) that may have a Knoop hardness number (KHN,
expressed in kgf/mm.sup.2) of, for example, at least about 20, at
least about 40, at least about 60, or at least about 80 as measured
in accordance with ASTM Test Method D1474-98(2002) "Standard Test
Methods for Indentation Hardness of Organic Coatings") that bonds
abrasive particles to the fiber web.
[0042] Examples of binder precursors that may be at least partially
cured to form a non-elastomeric binder material include
condensation curable materials and/or addition polymerizable
materials. Such binder precursors may be solvent based, water
based, or 100 percent solids. Exemplary binder precursors include
phenolic resins, bismaleimides, vinyl ethers, aminoplasts,
urethanes, epoxy resins, acrylates, acrylated isocyanurates,
urea-formaldehyde resins, isocyanurates, acrylated urethanes,
acrylated epoxies, or mixtures of any of the foregoing. Phenolic
resins and epoxy resins, and combinations thereof, are among
preferred binder precursors due to their high performance, wide
availability, and low cost.
[0043] Exemplary phenolic resins suitable for use in binder
precursors include resole phenolic resins and novolac phenolic
resins. Exemplary commercially available phenolic materials include
those having the trade designations "DUREZ" or "VARCUM" (available
from Occidental Chemical Corporation, Dallas, Tex.); "RESINOX"
(available from Monsanto Company, St. Louis, Mo.); "AROFENE" or
"AROTAP" (available from Ashland Chemical Company, Columbus, Ohio);
and "BAKELITE" from Dow Chemical Company, Midland, Mich. Further
details concerning suitable phenolic resins may be found, for
example, in U.S. Pat. No. 5,591,239 (Larson et al.) and No.
5,178,646 (Barber, Jr. et al.), the disclosures of which are
incorporated herein by reference.
[0044] Exemplary epoxy resins include the diglycidyl ether of
bisphenol A, as well as materials that are commercially available
under the trade designations "EPON" (e.g., "EPON 828", "EPON 1004",
and "EPON 1001F") from Shell Chemical Co., Houston, Tex.; and under
the trade designations "DER" (e.g., "DER-331", "DER-332", and
"DER-334") or "DEN" (e.g., "DEN-431" and "DEN-428") from Dow
Chemical Company, Midland, Mich.
[0045] Exemplary urea-formaldehyde resins and melamine-formaldehyde
resins include those commercially available under the trade
designation "UFORMITE" (e.g., from Reichhold Chemical, Durham,
N.C.); "DURITE" (from Borden Chemical Company, Columbus, Ohio); and
"RESIMENE" (e.g., from Monsanto, St. Louis, Mo.).
[0046] Suitable methods for applying slurry coat precursors, make
coat precursors, size coat precursors, etc. are well known in the
art of nonwoven abrasive articles, and include coating methods such
as curtain coating, roll coating, spray coating, and the like.
Typically, spray coating is an effective and economical method for
applying slurry coat and make coat precursors. Exemplary slurry
coating techniques are described, for example, in U.S. Pat. No.
5,378,251 (Culler et al.) and No. 5,942,015 (Culler et al.), the
disclosures of which are incorporated herein by reference.
[0047] A slurry coat precursor or make coat precursor, depending on
the specific embodiment of the present invention, is applied to the
fiber web and porous reinforcing material. The slurry coat
precursor or make coat precursor typically penetrates into pores of
a first major surface of the porous reinforcing material, and
extends through at least a portion of the porous reinforcing
material (as opposed to mere edge contact), emerging at the second
major surface of the porous reinforcing material. During
penetration, abrasive particles that are present in the slurry coat
precursor, are typically at least partially filtered out such that
the average ratio of abrasive particles to binder precursor is
substantially higher at the first major surface of the porous
reinforcing material than at the second major surface. For example,
the average ratio of abrasive particles to binder precursor at the
first major surface may be at least 2, at least 10, at least 50, or
a least 100 times the average ratio of abrasive particles to binder
precursor at the second major surface.
[0048] The optional size coat may be elastomeric or non-elastomeric
and may contain various additives such as, for example, one or more
of a lubricant and/or a grinding aid. The optional size coat may
comprise an elastomer (e.g., a polyurethane elastomer). Exemplary
useful elastomers include those known for use as a size coat for
nonwoven abrasive articles. For example, elastomers may be derived
from isocyanate-terminated urethane prepolymers such as, for
example, those commercially available under the trade designations
"VIBRATHANE" or "ADIPRENE" from Crompton & Knowles Corporation,
Middlebury, Conn.; and "MONDUR" or "DESMODUR" from Bayer
Corporation, Pittsburgh, Pa.
[0049] Optionally, the slurry coat, make coat, and/or size coat may
further include one or more catalysts and/or curing agents to
initiate and/or accelerate the curing process (e.g., thermal
catalyst, hardener, crosslinker, photocatalyst, thermal initiator,
photoinitiator) as well as in addition, or alternatively, other
known additives such as fillers, thickeners, tougheners, grinding
aids, pigments, fibers, tackifiers, lubricants, wetting agents,
surfactants, antifoaming agents, dyes, coupling agents,
plasticizers, suspending agents, and the like.
[0050] Exemplary lubricants include metal stearate salts such as
lithium stearate and zinc stearate, or materials such as molybdenum
disulfide, and mixtures thereof.
[0051] As used herein, the term "grinding aid" refers to a
non-abrasive (e.g., having a Mohs hardness of less than 7)
particulate material that has a significant effect on the chemical
and physical processes of abrading. In general, the addition of a
grinding aid increases the useful life of a nonwoven abrasive.
Exemplary grinding aids include inorganic and organic materials,
include waxes, organic halides (e.g., chlorinated waxes, polyvinyl
chloride), halide salts (e.g., sodium chloride, potassium cryolite,
cryolite, ammonium cryolite, potassium tetrafluoroborate, sodium
tetrafluoroborate, silicon fluorides, potassium chloride, magnesium
chloride), metals (e.g., tin, lead, bismuth, cobalt, antimony,
cadmium, iron, and titanium and their alloys), sulfur, organic
sulfur compounds, metallic sulfides, graphite, and mixtures
thereof.
[0052] Binder precursors utilized in practice according to the
present invention may typically be cured by exposure to, for
example, thermal energy (e.g., by direct heating, induction
heating, and/or by exposure to microwave and/or infrared
electromagnetic radiation) and/or actinic radiation (e.g.,
ultraviolet light, visible light, particulate radiation). Exemplary
sources of thermal energy include ovens, heated rolls, and infrared
lamps.
[0053] Abrasive particles suitable for use in abrasive compositions
utilized in practice according to the present invention include any
abrasive particles known in the abrasive art. Exemplary useful
abrasive particles include fused aluminum oxide based materials
such as aluminum oxide, ceramic aluminum oxide (which may include
one or more metal oxide modifiers and/or seeding or nucleating
agents), and heat-treated aluminum oxide, silicon carbide, co-fused
alumina-zirconia, diamond, ceria, titanium diboride, cubic boron
nitride, boron carbide, garnet, flint, emery, sol-gel derived
abrasive particles, and mixtures thereof. Desirably, the abrasive
particles comprise fused aluminum oxide, heat-treated aluminum
oxide, ceramic aluminum oxide, silicon carbide, alumina zirconia,
garnet, diamond, cubic boron nitride, sol-gel derived abrasive
particles, or mixtures thereof. Examples of sol-gel abrasive
particles include those described U.S. Pat. No. 4,314,827
(Leitheiser et al.); No. 4,518,397 (Leitheiser et al.); No.
4,623,364 (Cottringer et al.); No. 4,744,802 (Schwabel); No.
4,770,671 (Monroe et al.); No. 4,881,951 (Wood et al.); No.
5,011,508 (Wald et al.); No. 5,090,968 (Pellow); No. 5,139,978
(Wood); No. 5,201,916 (Berg et al.); No. 5,227,104 (Bauer); No.
5,366,523 (Rowenhorst et al.); No. 5,429,647 (Larmie); No.
5,498,269 (Larmie); and No. 5,551,963 (Larmie), the disclosures of
which are incorporated herein by reference. The abrasive particles
may be in the form of, for example, individual particles,
agglomerates, composite particles, and mixtures thereof. Exemplary
agglomerates and composite particles are described, for example, in
U.S. Pat. No. 4,652,275 (Bloecher et al.); No. 4,799,939 (Bloecher
et al.); No. 5,549,962 (Holmes et al.), the disclosures of each of
which is incorporated herein by reference.
[0054] The abrasive particles may, for example, have an average
diameter of at least about 0.1 micrometer, at least about 1
micrometer, or at least about 10 micrometers, and less than about
2000, less than about 1300 micrometers, or less than about 1000
micrometers, although larger and smaller abrasive particles may
also be used. Coating weights for the abrasive particles may
depend, for example, on the binder precursor used, the process for
applying the abrasive particles, and the size of the abrasive
particles. For example, the coating weight of the abrasive
particles may be at least 200 grams per square meter (g/m.sup.2),
at least 600 g/m.sup.2, or at least 800 g/m.sup.2; and/or less than
2000 g/m.sup.2, less than about 1600 g/m.sup.2, or less than about
1200 g/m.sup.2, although greater or lesser coating weights may be
also be used.
[0055] Abrasive particles may be applied to a fiber web having a
make coat thereon by methods known in the abrasive art for
application of such particles. For example, the abrasive particles
may be applied to the make coat by blowing, dropping,
electrostatically coating the particles onto uncured binder
precursor, or by a combination thereof.
[0056] Various optional conventional treatments and additives may
be used in conjunction with the fiber web and/or reinforcing
material such as, for example, a prebond coating (i.e., a material
applied to the fiber web and hardened or thermoset to provide
chemical bonding between fibers of the fiber web), antistatic
agents, lubricants, or corona treatment. However, if used, such
treatments should typically not prevent penetration of diffusion of
the binder precursor of the abrasive composition precursor through
the porous reinforced backing. If the fiber web is affixed to the
porous reinforcing material by needletacking, the optional prebond
may be applied, for example, after the needletacking step.
[0057] It is also within the scope according to the present
invention to have additional coatings (e.g., a supersize), which
for example, may be present as a continuous or discontinuous layer
in contact with at least a portion of the abrasive composition. For
example, it may be desirable to include a supersize to provide, for
example, a grinding aid, and/or as an anti-loading coating. The
supersize is typically derived from a curable binder precursor.
Optional supersize may be applied by methods well known in the
abrasive arts, for example, by spraying or metered roll coating.
Further details concerning supersizes may be found, for example, in
U.S. Pat. No. 3,256,076 (Duwell et al.); No. 5,520,711 (Helmin);
No. 5,213,589 (Ronning et al.); No. 5,306,319 (Krishnan); No.
5,556,437 (Lee et al.); and No. 6,039,775 (Ho et al.), the
disclosures of which are incorporated herein by reference.
[0058] Nonwoven abrasive articles according to the present
invention (e.g., nonwoven abrasive articles 100 or 200, as shown in
FIG. 1 or FIG. 2, respectively) may be used in sheet form, stacked
together with or without additional adhesive or binder to form a
wheel or brush product, or may be further processed to provide
finished articles (e.g., hand pads, discs, endless belts) suitable
for use in surface finishing applications.
[0059] For example, in one embodiment according to the present
invention (shown in FIG. 3), nonwoven abrasive disc 300 having
optional center arbor hole 310 therein, is formed from nonwoven
abrasive article 100. Nonwoven abrasive discs having a diameter in
a range of from about 2 centimeters (cm) to about 20 cm may
typically be used with a right-angle power tool having a suitable
attachment means (e.g., via a center arbor hole, pressure-sensitive
adhesive, "hook-and-loop" or another type of mechanical
fastener).
[0060] In another exemplary embodiment according to the present
invention (shown in FIG. 4), nonwoven abrasive endless belt 400
comprises a strip of nonwoven abrasive material 100 joined at both
ends by splice 410, such that fiber web 110 is outwardly
disposed.
[0061] In the formation of endless belts, strips are typically cut
having a length and a width suitable for the formation of endless
belts that will fit, for example, on an abrasive belt sander.
Conventional splicing techniques may be used to form the finished
belt. One such technique, known as a butt splice, generally
requires that the ends of the composite strips be angled in a
mating configuration, and the ends may then be spliced using a
conventional urethane splicing adhesive and a heated belt splicing
technique. Of course, other belt forming materials and techniques
may be used such as conventional nonwoven abrasive belt
manufacturing techniques and adhesives.
[0062] In use, endless belts according to the present invention may
be mounted on a conventional belt sander. As used with conventional
belt sanders, endless belts typically travel around wheels that may
be small in diameter, which in turn may cause the belt to chunk.
Nonwoven abrasive articles according to the present invention
typically have acceptable levels of chunking and are well suited
for use as endless belts.
[0063] Nonwoven abrasive articles according to the present
invention are typically useful for abrading a workpiece. One such
method includes frictionally contacting a nonwoven abrasive article
with a surface of the workpiece, and moving at least one of the
nonwoven abrasive article or the workpiece relative to the other to
abrade at least a portion of the surface. Examples of workpiece
materials include metal, metal alloys, exotic metal alloys,
ceramics, glass, wood, wood-like materials, composites, painted
surfaces, plastics, reinforced plastics, stone, and/or combinations
thereof. The workpiece may be flat or have a shape or contour
associated with it. Exemplary workpieces include metal components,
plastic components, particleboard, camshafts, crankshafts,
furniture, and turbine blades.
[0064] Nonwoven abrasive articles according to the present
invention, may be used by hand and/or used in combination with a
machine. Abrading may be conducted under wet or dry conditions.
Exemplary liquids for wet abrading include water, water containing
conventional rust inhibiting compounds, lubricant, oil, soap, and
cutting fluid. The liquid may also contain defoamers, degreasers,
and/or the like.
[0065] The present invention will be more fully understood with
reference to the following non-limiting examples in which all
parts, percentages, ratios, and so forth, are by weight unless
otherwise indicated.
EXAMPLES
[0066] Unless otherwise noted, all reagents used in the examples
were obtained, or are available, from general chemical suppliers
such as, for example, Aldrich Chemical Company, Milwaukee, Wis., or
may be synthesized by known methods.
[0067] The following abbreviations are used throughout the examples
that follow:
1 AO60 ANSI Grade 60 brown aluminum oxide abrasive particles
obtained under the trade designation "DURALUM G52" from Washington
Mills Electro Minerals Company, Niagara Falls, New York AO80 ANSI
Grade 80 brown aluminum oxide abrasive particles obtained under the
trade designation "DURALUM G52" from Washington Mills Electro
Minerals Company AO100-150 Brown aluminum oxide abrasive particles
having the trade designation "DURALUM G52" (ANSI grade 100-150, 2
percent 100 grit particles, 41 percent 120 grit particles, 26
percent 140 grit particles, 17 percent 170 grit particles, and 14
percent particles finer than 170 grit) obtained from Washington
Mills Electro Minerals Company HTAO60 P60 grit heat-treated
aluminum oxide particles obtained under the trade designation
"ALODUR BFRPL" from Treibacher Schleifmittel AG, Villach, Austria
HTAO80 P80 grit heat-treated aluminum oxide particles obtained
under the trade designation "ALODUR BFRPL" from Treibacher
Schleifmittel AG BC Bentonite clay obtained under the trade name
"VOLCAY 325" from American Colloid Company, Arlington Heights,
Illinois BR2 A reaction product of one equivalent of
poly(tetramethylene glycol) polymer with two equivalents of toluene
diisocyanate to produce a difunctional isocyanate prepolymer that
was subsequently blocked with methyl ethyl ketoxime (equivalent
weight of the blocked adduct was 757) obtained under the trade
designation "ADIPRENE BL-16" from Crompton & Knowles
Corporation, Stamford, Connecticut BR4 A reaction product of one
equivalent of poly(tetramethylene glycol) polymer with two
equivalents of toluene diisocyanate to produce a difunctional
isocyanate prepolymer that was subsequently blocked with methyl
ethyl ketoxime (equivalent weight of the blocked adduct was 1000)
obtained under the trade designation "ADIPRENE BL-11" from Crompton
& Knowles Corporation BR5 A 49.5-52.5 percent solids acrylic
copolymer latex obtained under the trade designation "TYCRYL BS
2100" from Dow Reichhold Specialty Latex, Research Triangle Park,
North Carolina BR6 A resole phenolic resin obtained under the trade
designation "BB077" from Neste Resins Canada, Mississauga, Ontario,
Canada CaCO.sub.3 Calcium carbonate obtained under the trade
designation "HUBERCARB Q325" from Huber Engineered Materials,
Atlanta, Georgia CR1 A high molecular weight, crosslinked copolymer
of acrylic acid and a hydrophobic co-monomer obtained under the
trade designation "PEMULEN 1621" from Noveon, Cleveland, Ohio CR2 A
high molecular weight, crosslinked copolymer of acrylic acid and a
hydrophobic comonomer obtained under the trade designation "PEMULEN
1622" from Noveon CUR1 4,4'-methylene-bis-(2,6-diethyl- )aniline
obtained under the trade designation "LONZACURE M-DEA" from Lonza
AG, Switzerland CUR2 An amidoamine curing agent obtained under the
trade designation "EPI-CURE 3015 CURING AGENT" from Resolution
Performance Products, Houston, Texas CUR3 A mixture of 31.7 parts
of the diglycidyl ether of bisphenol A obtained under the trade
designation "EPON RESIN 828" from Shell Chemical Company, Houston,
Texas; 28.3 parts isophorone diamine obtained from Degussa
Corporation, Calvert City, Kentucky; and 40 parts PMA FS Fumed
silica obtained under the trade designation "CAB-O-SIL UNTREATED
FUMED SILICA M5" from Cabot Corporation of Boston, Massachusetts
HEU Hydroxyethyl ethylene urea obtained under the trade designation
"SR511" from Sartomer Company, Exton, Pennsylvania LIST A 44.1
percent by weight solution of lithium stearate in PMA LUB
Hydrocarbon distillate obtained under the trade designation
"ACELUBE 23N" from Gopher Oil Company, Minneapolis, Minnesota MDA A
35 percent by weight solution of 4,4'-methylenedianiline in PMA
NH.sub.4OH Aqueous ammonium hydroxide (26.degree. Baume) obtained
from LaRoche Industries, Atlanta, Georgia PMA Propylene glycol
monomethyl ether acetate obtained from Lyondell Chemical Company,
Houston Texas PME Propylene glycol monomethyl ether obtained under
the trade designation "POLYSOLV MPM" from Arch Chemicals,
Brandenburg, Kentucky SURF Polyethylene glycol sorbitan monooleate
(i.e., polysorbate 80) obtained under the trade designation "TWEEN
80" from Uniqema, New Castle, Delaware
[0068] Belt Chunking Test
[0069] An endless 1/2 inch.times.24 inch (1.2 cm.times.61 cm) belt
was mounted and maintained in tension via an air cylinder under 20
psi (140 kPa) pressure between a 2.5 inch (6.4 cm) diameter driving
wheel and a {fraction (7/16)} inch (1.1 cm) steel contact wheel.
The driving wheel was driven by a motor having the trade
designation "GOLDLINE BRUSHLESS P. M. SERVOMOTOR" obtained from
Kollmorgen Corporation, Waltham, Mass., and operating at 7500 rpm.
The belt was weighed before each test, again after 1 minute, and
again either after 3 minutes or at the end of belt life as
determined by excessive belt stretch, whichever occurred first.
[0070] Disc Wear Test
[0071] A carbon steel bar 4 inches.times.18 inches.times.1/2 inch
(10.2 cm.times.46.0 cm.times.1.3 cm) was mounted on a bench with
one 18 inch.times.1/2 inch (46.0 cm.times.1.3 cm) face in full
contact with the bench. A nonwoven abrasive disc to be tested was
mounted on a 7-inch (18 cm) diameter back-up pad obtained from 3M
Company (Saint Paul, Minn.) under the trade designation "3M DISC
PAD HOLDER 917". The resultant disc/back-up pad assembly was then
mounted on an air driven right angle grinder capable of rotating
the disc at 6000 rpm (under zero load). Power was supplied to the
grinder and the disc/backup pad assembly was moved in a
reciprocating motion along the length of the workpiece at a rate of
32-36 cycles per minute, with the abrasive surface of the disc
maintained at an angle of 7.degree. to the steel bar against the
distal surface of the bar. The grinder assembly and the bar were
urged together under the weight of the grinder assembly, which was
7 pounds (3.2 kg). The above test procedure was conducted for one
minute (i.e., one test cycle). The bar was weighed to measure the
cut (i.e., weight loss). The test cycle was repeated until a
portion of the outer 1/2 inch of disc diameter of the working face
of the disc was worn down to the scrim.
Comparative Example 1
[0072] A 24-inch.times.1/2-inch (61 cm.times.1.2 cm) nonwoven
abrasive belt obtained under the trade designation "BRITERITE RAPID
CUT BELT (COARSE GRADE)" from Standard Abrasives, Simi Valley,
Calif.
Comparative Example 2
[0073] A 24-inch.times.1/2-inch (61 cm.times.1.2 cm) nonwoven
abrasive belt obtained under the trade designation "BRITERITE RAPID
CUT BELT (MEDIUM GRADE)" from Standard Abrasives.
Comparative Example 3
[0074] A 7-inch (18 cm) diameter nonwoven abrasive disc obtained
under the trade designation "BRITERITE RAPID CUT DISC (COARSE
GRADE)" from Standard Abrasives.
Comparative Example 4
[0075] A 7-inch (18 cm) diameter nonwoven abrasive disc obtained
under the trade designation BRITERITE RAPID CUT DISC (MEDIUM GRADE)
from Standard Abrasives.
Comparative Example 5
[0076] A surface conditioning VELCRO disc (178 mm), medium grit
(grit 100-120) aluminum oxide commercially available from Bibielle,
Margarita, Italy.
Example 1
[0077] An air-laid fiber web having a thickness of 3/4 inch (1.8
cm), a basis weight of 293 g/m.sup.2, and consisting of a 75/25
blend of 70 and 58 denier (74 and 68 dtex) nylon staple fibers,
respectively, was laid onto the surface of a low-stretch polyester
sateen reinforcing fabric (thread count per inch: warp=11, fill=43;
basis weight=303 g/m.sup.2 at 55 percent relative humidity obtained
from Milliken & Company, Spartanburg, S.C.), and then passed
through a needletacking machine (obtained under the trade
designation "FIBERLOCKER" from James Hunter Machine Company, North
Adams, Mass.) fitted with a needle board with 23 rows of
15.times.18.times.25.times.3.5 RB needles (Foster Needle Company,
Manitowoc, Wis.) spaced 1.1 cm apart with adjacent needles within
each row spaced 1.3 cm apart. The needletacking machine was
operated at 560 punches per minute, a penetration depth of 2.2 cm,
and at a fiber web rate of 3.1 m/minute. Needletacking affixed the
fiber web to the reinforcing fabric. The resultant reinforced fiber
web, with a total thickness of 1/4 inch (0.6 cm), had approximately
60 percent of its thickness above the center plane of the polyester
reinforcing fabric and approximately 40 percent of its thickness
below the center plane. The composite web was then brought into
contact with a roll heated at 177.degree. C. A slurry coat
precursor consisting of the ingredients in Table 1 (below) was
sprayed onto the composite web at a target dry add-on weight of
1340 g/m.sup.2, and then heated for 10 minutes at 150.degree.
C.
2 TABLE 1 COMPONENT PARTS BR6 25.8 PME 21.8 LUB 3.5 BC 0.9 CUR2 5.9
AO80 92.9
[0078] The heated composite web was then saturated with the size
coat precursor composition shown in Table 2 (below). The size coat
precursor saturated web was compressed between a pair of rubber
rolls to remove excess size coating precursor. The size composition
was coated at a dry add-on weight of 627 g/m.sup.2, and the
size-coated web was then cured for 20 minutes at 135.degree. C.
resulting in a nonwoven abrasive article.
3 TABLE 2 COMPONENT PARTS BR6 25.4 Water 9.8 BR5 146.6 CaCO.sub.3
15.8
Example 2
[0079] A nonwoven abrasive article was prepared as in Example 1,
except that the size coat precursor of TABLE 2 was replaced by the
size coat precursor composition of Table 3 (below), which was
applied to heated composite web at a dry add-on of 481
g/m.sup.2.
4 TABLE 3 COMPONENT PARTS BR2 25.3 Water 42.0 CUR1 4.8 CR1 3.0 SURF
0.6 NH.sub.4OH 0.0257
Example 3
[0080] A nonwoven abrasive article was prepared as in Example 1,
except that HTAO80 was substituted for AO80, and the size coat
precursor of Table 2 was replaced with a size coat precursor having
the composition given in Table 4 (below), which was applied to
heated composite web at a dry add-on of 481 .mu.m.sup.2.
5 TABLE 4 COMPONENT PARTS BR4 77.0 CUR3 39.0 LIST 9.5 PME 33.9
Example 4
[0081] A nonwoven abrasive article was prepared as in Example 3,
except that the size coat precursor having the composition given in
Table 4 was replaced by a size coat precursor having the
composition given in Table 3.
Example 5
[0082] A nonwoven abrasive article was prepared as in Example 4,
except that AO100-150 was substituted for HTAO80 in the slurry coat
precursor, the slurry coat dry add-on weight was 1190 g/m.sup.2,
and the air-laid web consisted solely of 58 den (64 dtex)
fibers.
Example 6
[0083] A nonwoven abrasive article was prepared as in Example 1,
except that the slurry coat precursor of Table 1 was replaced by a
slurry coat precursor consisting of the components listed in Table
5 (below) and sprayed at a dry add-on of 1338 g/m.sup.2, and that
the size coat precursor having the composition given in Table 2 was
replaced by a size coat precursor having the composition given in
Table 4, which was applied to the heated web to achieve a dry
add-on weight of 481 g/m.sup.2 and then heated for 10 minutes at
135.degree. C.
6 TABLE 5 COMPONENT PARTS BR6 58.5 PME 6.2 HEU 7.8 Water 24.7
HTAO60 201.3 FS 1.5
[0084] The nonwoven abrasive articles of Examples 1-6 were
converted into endless belts (0.5 inch (1.3 cm).times.24 inches (61
cm)) endless belts as follows:
[0085] The nonwoven abrasive was cut into a 1/2 inch (1.3
cm).times.24 inches (61 cm), 45 parallelogram-shaped strip.
Two-part urethane adhesive was mixed and applied onto the same side
of each end of the strip. The ends were abutted and attached
together by a 1 inch (2.5 cm) splice tape. Pressure (40-60 psi
(0.3-0.4 MPa)) was applied until the adhesive cured. These belts
and the belts of Comparative Examples 1 and 2 were then evaluated
using the Belt Chunking Test. Each belt exhibited chunking under
conditions of the test. Results are presented in Table 6
(below).
7TABLE 6 WEIGHT WEIGHT WEIGHT WEIGHT LOSS AFTER 3 LOSS INITIAL
AFTER 1 AFTER 1 MIN- AFTER 3 WEIGHT, MINUTE, MINUTE, UTES, MINUTES,
BELT g g percent g percent Example 1 15.73 15.32 2.6 15.04 4.4
Example 2 16.21 15.94 1.7 15.93 1.7 Example 3 17.54 17.15 2.2 16.75
4.5 Example 4 19.58 19.32 1.3 19.1 2.5 Example 5 18.02 17.82 1.1
17.73 1.6 Example 6 18.58 18.18 2.2 18.06 2.8 Com- 17.09 12.2 18.6
9.8 42.7 parative Example 1 Com- 18.02 14.41 13.0 6.3 62.0 parative
Example 2
Example 7
[0086] Mixture 7D was prepared as follows:
[0087] BR2 (39.62 parts, at 43.degree. C.) was stirred at
sufficient speed that a vortex formed. CUR1 (7.52 parts, at
107.degree. C.) was added into the vortex, and then SURF (0.47
parts, at 21.degree. C.) was added into the vortex. The mixture was
stirred until it appeared homogenous (Mixture 7A).
[0088] Water (3.40 parts, at 21.degree. C.) was stirred at
sufficient speed that a vortex formed. CR2 (0.14 parts, at
21.degree. C.) was added into the vortex, and the mixture (Mixture
7B) was stirred until it appeared homogenous.
[0089] Water (43.96 parts, at 49.degree. C.) was stirred at
sufficient speed that a vortex formed. Mixture 7B (3.54 parts, at
21.degree. C.) was added into the vortex. The mixture was stirred
until it appeared homogenous, and then NH.sub.4OH (0.11 parts, at
21.degree. C.) was added into the vortex with continued mixing
until homogenous (Mixture 7C).
[0090] Mixture 7C (47.62 parts, at 60.degree. C.) was stirred at
sufficient speed that a vortex formed. Mixture 7A (47.62 parts, at
21.degree. C.) was added into the vortex, and the mixture was
stirred until it appeared homogenous. Water (4.76 parts, at
49.degree. C.) was added into the vortex, and the mixture was
stirred until it appeared homogenous (Mixture 7D).
[0091] A nonwoven abrasive article was prepared as in Example 1,
except that the fabric was a plain weave nylon scrim (16.times.16
nylon scrim; Type 6,6; Style 6703832 obtained from Highland
Industries, Greensboro, N.C.), the slurry coat precursor of Table 1
was replaced by a slurry coat precursor consisting of the
components listed in Table 7 (below) and sprayed at a dry add-on of
1338 g/m.sup.2, and the size coat precursor having the composition
listed in Table 2 was replaced by Mixture 7D applied at a dry
add-on weight of 481 g/m.sup.2.
8 TABLE 7 COMPONENT PARTS BR6 20.0 Water 8.4 HEU 2.7 FS 0.2 AO80
68.7
[0092] The resultant nonwoven abrasive article was die cut into a
7-inch diameter disc.
Example 8
[0093] A nonwoven abrasive article was prepared as in Example 7,
except that AO100-150 was substituted for AO80 in the slurry coat
precursor.
Example 9
[0094] A nonwoven abrasive article was prepared as in Example 7,
except that size coat precursor having the composition of Mixture
7D was replaced by a size coat precursor having the composition
listed in Table 8 (below), which was coated and the resultant
coated article was then heated at 110.degree. C. for 30
minutes.
9 TABLE 8 COMPONENT PARTS BR5 63.3 BR6 11.8 water 24.9
Example 10
[0095] A nonwoven abrasive article was prepared as in Example 9,
except that AO100-150 was substituted for AO80 in the slurry coat
precursor.
Example 11
[0096] A nonwoven abrasive article was prepared as in Example 9,
except that the size coat precursor having the composition listed
in Table 8 was replaced by a size coat precursor having the
composition listed in Table 4.
[0097] Results of the Disc Wear Test are listed in Table 9
(below).
10TABLE 9 NO. OF 1- CUT, g MINUTE EXAMPLE EXAMPLE EXAMPLE EXAMPLE
EXAMPLE COMPARATIVE COMPARATIVE COMPARATIVE CYCLES 7 8 9 10 11
EXAMPLE 3 EXAMPLE 4 EXAMPLE 5 1 11.4 8.1 11.8 8.2 15 12.2 4.1 8.6 2
11.8 7.5 11.3 8.0 14.7 10.2 4.1 7.0 3 12 7.9 12.2 7.0 14.7 -- 5.3
6.2 4 10.4 7.7 10.6 8.0 12.1 -- -- 6.8 5 11.2 8.4 10.9 8.6 14.5 --
-- 4.8 6 11.3 8.2 11.2 7.4 12.5 -- -- -- 7 13.5 7.5 8.4 7.1 11.5 --
-- -- 8 10.6 7.5 10.5 7.0 10.0 -- -- -- 9 11.3 9.2 8.3 5.6 9.2 --
-- -- 10 11.7 7.7 8.5 5.4 9.8 -- -- -- 11 -- -- 8.7 6.2 10.0 -- --
-- 12 -- -- 5.8 7.6 7.8 -- -- -- 13 -- -- -- 7.1 -- -- -- -- 14 --
-- -- 6.4 -- -- -- -- In Table 9, "--" means not determined because
the Wear Test endpoint was reached.
[0098] Various modifications and alterations of this invention will
become apparent to 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 illustrated
embodiments set forth herein.
* * * * *