U.S. patent application number 09/954751 was filed with the patent office on 2002-05-30 for unitary brush having abrasive coated bristles and method of making the same.
This patent application is currently assigned to 3M Innovative Properties Company. Invention is credited to Barber, Loren L. JR., Chou, Yeun-Jong.
Application Number | 20020065031 09/954751 |
Document ID | / |
Family ID | 24772922 |
Filed Date | 2002-05-30 |
United States Patent
Application |
20020065031 |
Kind Code |
A1 |
Chou, Yeun-Jong ; et
al. |
May 30, 2002 |
Unitary brush having abrasive coated bristles and method of making
the same
Abstract
The present invention relates to a unitary brush (such as a cup
brush, for example) which has abrasive particles secured to at
least some of its bristles via a first coating. The unitary brush
is made by providing a unitary brush, coating at least a portion of
the surfaces of the bristles with a first coating, adhering
abrasive particles to at least some of the coated bristles and
curing the first coating.
Inventors: |
Chou, Yeun-Jong; (Woodbury,
MN) ; Barber, Loren L. JR.; (Lake Elmo, MN) |
Correspondence
Address: |
Attention: Richard Francis
Office of Intellectual Property Counsel
3m Innovative Properties Company
P.O. Box 33427
St. Paul
MN
55133-3427
US
|
Assignee: |
3M Innovative Properties
Company
|
Family ID: |
24772922 |
Appl. No.: |
09/954751 |
Filed: |
September 18, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09954751 |
Sep 18, 2001 |
|
|
|
09690550 |
Oct 17, 2000 |
|
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Current U.S.
Class: |
451/466 |
Current CPC
Class: |
A46D 1/0261 20130101;
A46D 1/00 20130101; A46B 13/001 20130101; A46B 2200/3093
20130101 |
Class at
Publication: |
451/466 |
International
Class: |
B24D 013/02 |
Claims
What is claimed:
1. An article comprising: (a) a unitary brush, the brush having a
plurality of bristles, each bristle having a surface; (b) a first
coating over at least a portion of at least some of the bristle
surfaces; and (c) a plurality of abrasive particles secured to at
least a portion of at least some of the bristle surfaces via the
first coating.
2. The article of claim 1 wherein the first coating is an
adhesive.
3. The article of claim 1 which further comprises a second coating
coated over the abrasive particles and the first coating.
4. The article of claim 3 wherein the second coating is an
adhesive.
5. The article of claim 1 wherein the abrasive particles are
partially embedded in the first coating.
6. The article of claim 1 wherein the abrasive particles are
selected from the group consisting of silicon carbide, talc,
garnet, glass bubbles, glass beads, cubic boron nitride, diamond,
and aluminum oxide.
7. The article of claim 1 wherein the first coating comprises a
material selected from the group consisting of polyurethanes, epoxy
resins, and acrylate resins.
8. The article of claim 3 wherein the second coating comprises a
material selected from the group consisting of polyurethanes, epoxy
resins, and acrylate resins.
9. The article of claim 1 wherein the brush is selected from the
group consisting of radial brushes and cup brushes.
10. The article of claim 1 wherein the bristles comprise a material
selected from the group consisting of polyamide, polyester, and
polyolefin.
11. The article of claim 1 wherein the bristles further comprise
abrasive particles which are embedded within the bristles.
12. The article of claim 1 wherein said unitary brush is an
injection molded brush
13. An article comprising: (a) an injection molded brush, the brush
having a plurality of bristles, each bristle having a surface; (b)
a first coating over at least a portion of at least some of the
bristle surfaces; and (c) a plurality of abrasive particles secured
to at least a portion of at least some of the bristle surfaces via
the first coating.
14. A method of making an abrasive brush, said method comprising:
(a) providing a unitary brush comprised of a base portion formed of
a material and a plurality of bristles comprised of the same
material extending therefrom and wherein each bristle has a
surface; (b) coating at least a portion of the surfaces of at least
a portion of the bristles with a first coating; (c) adhering a
plurality of abrasive particles to at least some of the bristle
surfaces via the first coating; and (d) curing the first coating to
adhere the abrasive particles to the bristle surfaces.
15. The method of claim 14 further comprising: (a) coating the
abrasive coated bristles with a second coating; and (b) curing the
second coating
16. The method of claim 14 wherein said unitary brush is an
injection molded brush.
Description
RELATED APPLICATION
[0001] This Application is a continuation-in-part of application
Ser. No. 09/690,550, filed Oct. 17, 2000.
FIELD OF THE INVENTION
[0002] The present invention relates to a unitary brush (such as a
cup brush, for example) that has abrasive particles secured to at
least some of its bristles and to a method of making the brush.
BACKGROUND OF THE INVENTION
[0003] Rotary brushes are known in the abrasive art. Such brushes
are used to clean, abrade, and polish surfaces; to remove coatings;
and to prepare surfaces for subsequent processing. Rotary brushes
are especially useful to clean abutted joints in sheet metal
structures, such as, for example, automotive body panel assemblies,
where the flexible bristles are able to operate in recessed seam
areas (where the sheet metal is out-of-plane) without significantly
rounding or otherwise deforming adjacent (in-plane) sheet metal.
Such articles are exemplified by brush assemblies that include
metallic wire or abrasive-filled polymeric bristles. Composite or
sheath-core bristle brush structures are also known. U.S. Pat. No.
5,737,794 (Barber et al.) describes composite abrasive bristles.
U.S. Pat. No. 5,443,906 (Pihl et al.) describes abrasive filaments
comprising thermoplastic elastomers. The bristles of such brushes
may be oriented to extend radially or perpendicularly from a driven
base structure. Brushes that have bristles that extend radially are
frequently referred to as radial brushes. Brushes that have
bristles that extend perpendicularly from a base are frequently
referred to as right angle brushes.
[0004] Unitary brushes are characterized by having a hub or body
portion comprised of the same composition as the bristles in a
one-piece structure. That is, the hub or body and the bristles
attached to the body are formed from the same mass of material at
the same time without adhesive bonding or mechanical fastening of
bristles to the hub or body portion. Such brushes are valued
because they have excellent bristle anchoring with no concern of
bristle loss caused by adhesive or mechanical fastener failure.
[0005] One type of unitary brush is an injection molded brush.
Injection molded bristle brushes are described in U.S. Pat. Nos.
5,915,436 and 5,903,951 (Johnson et al.). These articles have the
advantages of providing design flexibility and control of bristle
orientation during use. Other types of unitary brushes are made by
cutting, e.g., from a sheet, a shaped hub bearing a radial array of
bristle projections and either using a single shape as a brush or
stacking a multiplicity of such shapes until a unitary stack is
obtained and attaching the shapes together mechanically or with
adhesive.
SUMMARY OF THE INVENTION
[0006] There remains a need to provide a brush having the design
flexibility of a unitary brush but with increased performance as an
abrasive article. The invention provides:
[0007] (a) a unitary brush, the brush having a plurality of
bristles, each bristle having a surface;
[0008] (b) a first coating over at least a portion of at least some
of the bristle surfaces; and
[0009] (c) a plurality of abrasive particles secured to at least a
portion of at least some of the bristle surfaces via the first
coating.
[0010] In a further embodiment, a second coating is included over
the abrasive particles and first coating.
[0011] The invention further provides a method of making an
abrasive brush, said method comprising:
[0012] (a) providing a unitary brush comprised of a base portion
formed of a material and a plurality of bristles comprised of the
same material extending therefrom and wherein each bristle has a
surface;
[0013] (b) coating at least a portion of the surfaces of at least a
portion of the bristles with a first coating;
[0014] (c) adhering a plurality of abrasive particles to at least
some of the bristle surfaces via the first coating; and
[0015] (d) curing the first coating to adhere the abrasive
particles to the bristle surfaces.
[0016] In a further embodiment, a second coating is applied over
the abrasive particles and first coating and the second coating is
cured.
[0017] The term "unitary brush" shall mean any brush that is
comprised of a hub or body and bristles which are attached to the
body or hub and are formed of the same mass of material as the hub
or body without adhesive bonding or mechanical fastening of
bristles to the hub or body portion. Exemplary unitary brushes are
injection molded or formed of an individual cut segment or a stack
of cut segments of sheet material that are die cut, water jet cut,
or laser cut to form single segments of hub portions bearing a
plurality of bristles.
[0018] The unitary brushes are preferably injection molded rotary
brushes and are preferably rotatable about an axis. Preferably,
they are designed to be attached to a rotary tool such as an
electrical or pneumatic tool.
[0019] The novel abrasive article of the invention comprising a
unitary brush has a number of advantages including a broader range
of abrasive performance, design flexibility and brush-making
efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1a illustrates a front plan view of an embodiment of an
article of the invention.
[0021] FIG. 1b illustrates a central cross-section taken through
one of the bristles of the article of FIG. 1a.
[0022] FIG. 2 illustrates an isometric view of another embodiment
of an article of the invention.
[0023] FIG. 3a illustrates a side view of another embodiment of an
article of the invention
[0024] FIG. 3b illustrates a central cross-section taken through
one of the bristles of the article of FIG. 3a.
DETAILED DESCRIPTION OF THE INVENTION
[0025] Abrasive Particles
[0026] Abrasive particles used in the article of the invention may
be organic, inorganic, or a composite of one or both of the
aforementioned. Abrasive particle composition, concentration, and
size are chosen according to the nature of the intended workpiece
surface and the desired effect of the abrasive coated unitary brush
on the workpiece surface. Suitable inorganic particles include, but
are not limited to, those selected from the group consisting of
silicon carbide, talc, garnet, glass bubbles, glass beads, cubic
boron nitride, diamond, and aluminum oxide, including ceramic
aluminum oxide such as that available under the trade designation
CUBITRON abrasive from Minnesota Mining and Manufacturing Company,
St. Paul, Minn. Suitable organic abrasive particles include, but
are not limited to, those of comminuted thermoplastic and/or
thermosetting polymeric materials. Composite abrasive particles
include, but are not limited to, agglomerates comprising inorganic
particles adhered in an organic polymeric or ceramic binder.
Precisely shaped abrasive particles may also be employed. Sizes of
useful abrasive particles typically vary from mean particle
diameters of about 0.1 to about 1000 micrometers, more typically
about 100 to about 500 micrometers. The mean particle diameter is
typically about {fraction (1/10)} to about 1 times the mean bristle
diameter, more typically about 1/5 to about 1/2 times the mean
bristle diameter.
[0027] First Coating
[0028] The first coating which is used to secure the abrasive
particles to the bristles preferably provides good attachment
adhesion or bond to both the bristles and the abrasive particles
and demonstrates wear and flexibility properties similar to that of
the bristles. Coatings may be borne in organic or aqueous solutions
or dispersions or may be 100% solid materials such as thermoplastic
polymeric materials. The first coating is preferably an adhesive.
The first coating preferably comprises a curable organic material
(i.e., a monomer, oligomer, or material capable of polymerizing
and/or crosslinking upon exposure to heat and/or other sources of
energy, such as ultraviolet light, visible light, etc., or with
time upon the addition of a chemical catalyst, moisture, or other
agent which causes the material to cure or polymerize).
Representative coating examples include crosslinkable materials
such as phenolic resins, bismaleimide resins, vinyl ether resins,
aminoplast resins having pendant alpha, beta unsaturated carbonyl
groups, urethane resins, epoxy resins, polyurethane resins,
acrylate resins, acrylated isocyanurate resins, urea-formaldchyde
resins, isocyanurate resins, and mixtures thereof. Other
representative materials the first coating may comprise those
selected from the group consisting of amino polymers or aminoplast
polymers such as alkylated urea-formaldehyde polymers,
melamineformaldehyde polymers, and alkylated
benzoguanamine-formaldehyde polymers; acrylate polymers including
acrylates and methacrylates, alkyl acrylates, acrylated polyesters,
acrylated polyethers, vinyl ethers, acrylated oils, and acrylated
silicones; alkyd polymers such as urethane alkyd polymers;
polyester polymers; reactive urethane polymers; phenolic polymers
such as resole and novolac polymers; phenolic/latex polymers; epoxy
polymers such as bisphenol epoxy polymers; isocyanates;
isocyanurates; polysiloxane polymers including alkylalkoxysilane
polymers; and reactive vinyl polymers. The resulting first coating
may be in the form of monomers, oligomers, polymers, or
combinations thereof.
[0029] In addition to thermosetting polymers, thermoplastic
polymers may also be used. Examples of suitable thermoplastic
polymers include, but are not limited to, polyamides,
polyethylenes, polypropylenes, polyesters, polyurethanes,
polyetherimides, polysulfones, polystyrenes,
acrylonitrile-butadiene-styrene block copolymers,
styrene-butadiene-styre- ne block copolymers,
styrene-isoprene-styrene block copolymers, acetal polymers,
polyvinyl chlorides, and combinations thereof.
[0030] In the case of a first coating containing ethylenically
unsaturated monomers and oligomers, polymerization initiators may
be included Representative examples include organic peroxides, azo
compounds, quinones, nitroso compounds, acyl halides, hydrazones,
mercapto compounds, pyrylium compounds, imidazoles,
chlorotriazines, benzoin, benzoin alkyl ethers, diketones,
phenones, mixtures thereof, and the like.
[0031] A suitable initiator system may also include a
photosensitizer. Representative photosensitizers may have carbonyl
groups, tertiary amino groups, or combinations thereof. Preferred
photosensitizers having carbonyl groups are benzophenone,
acetophenone, benzil, benzaldehyde, o-chlorobenzaldehyde, xanthone,
thioxanthone, 9,10-anthraquinone, and other aromatic ketones.
Preferred photosensitizers having tertiary amino groups are
methyldiethanolamine, ethyldiethanolamine, triethanolamine,
phenylmethyl-ethanolamine, and dimethylaminoethylbenzoate.
[0032] In general, the amount of photoinitiator may vary from about
0.01 to about 10 percent by weight, more preferably from about 0.25
to 4 percent by weight of the first coating. Additionally, it is
preferred to disperse (preferably uniformly) the initiator in the
first coating before addition of any particulate material, such as
filler particles.
[0033] Cationic initiators may be used to initiate polymerization
when the first coating is based upon an epoxy resin or vinyl ether
functional resin. Examples of cationic initiators include salts of
onium cations, such as arylsulfonium salts, as well as
organometallic salts such as ion arene systems. Other examples are
reported in U.S. Pat. Nos. 4,751,138 (Tumey et al.); 5,256,170
(Harmer et al.); 4,985,340 (Palazotto); and 4,950,696 (Palazotto et
al.) all incorporated herein by reference.
[0034] The first coating may further comprise an additive including
but not limited to those selected from the group consisting of
fillers, pigments, lubricants, and grinding aids.
[0035] A preferred coating composition in accordance with the
present invention comprises 70.37 parts by weight polyurethane
(e.g., that available under the trade designation ADIPRENE BL-16
polyurethane from Uniroyal Chemical Ltd., Elmira, Ontario, Canada),
19.54 parts by weight curative (e.g., 4,4'-diaminobenzanilide,
commercially available from Biddle Sawyer Corporation, New York,
N.Y.); 4.04 parts by weight lubricant (e.g., that available under
the trade designation "PM" lithium stearate, commercially available
from Witco Corporation, Greenwich, Conn.); 5.65 parts by weight
solvent (e.g., that available under the trade designation ARCOSOLV
PM Acetate propylene acetate monomethyl ether acetate, commercially
available from Arco Chemical Company, Houston, Tex.) and 0.5 part
by weight silica fume (e.g., that available under the trade
designation CAB-O-SIL from Cabot Corporation, Tuscola, Ill.).
[0036] The thickness of the first coating can vary. The thickness
of the first coating is dependent upon a number of factors such as
the size and amount of the abrasive particles used. The dry weight
of the first coating on a brush depends on the brush size, and
typically ranges from about 0.01 to about 100 grams per brush. For
example, the first coating on a 3" (7.6 cm) bristle brush
sufficient to adhere ANSI grade 36 silicon carbide particles will
typically have a dry weight of between about 0.1 and about 10
grams. Typically the first coating is thick enough to adhere the
abrasive particles to the bristles but not so thick as to engulf
the abrasive particles. The first coating thickness is typically
proportional to the abrasive particle diameter (i.e. largest
dimension). Typically the first coating thickness is about 25 to
about 70 percent of the abrasive particle diameter, more typically
about 40 to about 60 percent.
[0037] Second Coating
[0038] The article of the invention in one embodiment further
comprises a second coating which is coated over the abrasive
particles and the first coating to the extent which it may be
exposed. The second coating preferably demonstrates good adhesion
to the abrasive particles and to the first coating and wears away
as the abrasive particles wear away. Preferably, the second coating
has a minimal propensity to transfer from the abrasive article to
the workpiece under use conditions.
[0039] The second coating may comprise the same materials as the
first coating described above. The second coating is preferably an
adhesive. The second coating may be the same composition or a
different composition as the first coating. For some embodiments it
may be preferred to provide a second coating composition similar or
identical to the first coating composition in order to provide good
adhesion between the coatings and to provide flexibilities
compatible with the unitary bristles. For other embodiments,
however, it may be preferred to provide a second coating
composition which is harder and more abrasion resistant than the
first coating composition.
[0040] The thickness of the second coating may vary. The thickness
of the second coating is dependent upon a number of factors such as
the size and amount of the abrasive particles used. Typically the
second coating is thick enough to reinforce the attachment adhesion
or bond of the abrasive particles to the first coating but not so
thick as to obscure the abrasive texture of the coated bristle. The
second coating thickness is typically proportional to the abrasive
particle diameter (i.e. largest dimension). Typically the second
coating thickness is about 10 to 40 percent of the abrasive
particle mean diameter, more typically about 20 to about 40
percent.
[0041] Brush Type and Usage
[0042] The unitary brushes which are coated to provide the abrasive
article of the invention, as previously mentioned, can be any brush
which has a hub or base portion and bristles or filaments extending
from the hub or base portion made of the same material which forms
the hub or base portion in one piece. That is, the bristles are not
adhesively or mechanically fastened to the hub or base portion, but
instead they are either injection molded, molded by some other
process (cast, compression molded, etc.), or they are formed by
cutting segments from a sheet of material such as a plastic film
forming a base portion segment which bears bristles having the
desired deployment. Such segments may be laser cut, water jet cut,
die cut or mechanically cut. Such segments may then be used singly
or stacked and mechanically fastened or adhesively bonded together
so that the individual segments form a stacked structure with the
bristles deployed outward from the hub as desired. Mechanical
fastening may be accomplished by utilizing suitable clamps that are
readily commercially available or by utilizing a suitable adhesive
bonding material which is, likewise, commercially available. The
stacked segments may be stacked directly on one another or they may
be separated by a spacer hub portion which bears no bristles to
provide space between bristles deployed along the hub. A common
characteristic of the bristles in a unitary brush is the fact that
they are composed of the same material as the hub and are formed at
essentially the same time the hub is formed.
[0043] The abrasive-coated unitary brushes of the invention can be
any one of many types and for a myriad of uses, such as, for
example, cleaning, coating removal, deburring, radiusing, and
imparting decorative finishes onto any of a variety of substrates
such as metal, plastic, glass, wood, and the like. Preferably, the
brush of the invention readily conforms to the contours of a
workpiece. Preferably, the brush of the invention readily sheds
detritus (i.e., does not "load") and has a high cutting rate.
[0044] Typically, the unitary brush comprises a generally planar
base having a first side and a second side, the base having a
plurality of bristles extending from the sides. The bristles are
integrally formed with the base.
[0045] One type of unitary brush has bristles that extend from the
first side of the base. This type of brush is commonly known as a
cup brush, end brush, or right-angle brush, and is typically driven
by a right-angle tool. Such unitary brushes are conveniently made
by one of the molding techniques cited above.
[0046] Another type of unitary brush has bristles that extend from
the outer peripheral edge between the first side and the second
side of the base. Such brushes are commonly known as radial
brushes, wheel brushes, or cylinder brushes. This type of unitary
brush may be made by the previously described molding or cutting
techniques.
[0047] The material which the brush, including the bristles,
comprises may vary and its selection depends on any of a number of
different factors such as, for example, its ability to adhere to a
coating, its ability to sustain the desired rotational speed, and
its ability to sustain wear similar to that of the coating(s). The
brush, including the bristles, can comprise any of a number of
different materials, including, but not limited to, moldable
polymers including polyamides, polyolefins, polyesters,
thermoplastic elastomers, poly(ether imides), polysulfones,
polyaramids, and the like. Typically the brush, including the
bristles, comprises a material selected from the group consisting
of polyesters, polyolefins, polyamides, and thermoplastic
elastomers.
[0048] The design of the unitary brush may contribute to the
successful use of the article of the invention. Design features
such as bristle length, bristle cross section, and bristle
curvature may affect the function and performance of the brush. The
bristle length is preferably sufficiently long to allow for good
life, but not so long as to contribute to bristle fracture when
operated at high speeds. Typically the ratio of average bristle
length to average bristle diameter for a radial brush ranges from
about 3:1 to about 100.1, more typically about 5:1 to about 30:1.
Typically the ratio of average bristle length to average bristle
diameter for a cup brush ranges from about 3:1 to about 50:1, more
typically about 5:1 to about 20:1.
[0049] In one embodiment, the brush, including the bristles, may
further comprise abrasive particles which are contained within the
brush and/or bristles. In another embodiment, the unitary brush
including the bristles, may further comprise one or more additives
such as those selected from the group consisting of lubricants,
colorants, coupling agents, compatibilizers, mold release agents,
nucleating agents, and the like.
[0050] Method of Making the Article
[0051] The amount of surface area of the bristles which has
abrasive particles secured thereto may vary depending upon a number
of factors such as, for example, the nature of the surface to be
abraded, the expected life of the abrasive article, and the design
of the brush. The abrasive particles are typically applied over
substantially the entire surface of the bristles although in some
circumstances it may be desirable to have the abrasive particles
attached to only a portion of the bristles. The concentration of
the abrasive particles on the bristles of the brush may also vary.
For some applications it may be desirable to have a high
concentration of abrasive particles on the bristles. For other
applications it may be desirable to have a lower concentration of
abrasive particles on the bristles. Typically, the amount of the
bristle surface covered with abrasive particles ranges from about
10 to about 100 percent, more typically about 50 to about 100
percent, and most typically about 90 to about 100 percent.
[0052] The article of the invention may be made as follows, for
example. First, a unitary brush is provided. Next, a first coating
is applied to at least a portion of at least some of the bristles,
preferably all of the bristles. Preferably the first coating is
applied to the entire surface of at least some of the bristles,
more preferably all of the bristles. The first coating may be
applied by any of several different methods including, but not
limited to, roll coating, spray coating, "dip and spin" methods,
etc. The phrase "dip and spin" refers to dipping the bristles in
the coating and spinning the brush to remove excess coating from
the bristles. Next, abrasive particles are applied to the first
coating. This can be done by any of a number of different methods
including, but not limited to, spray coating, drop coating,
fluidized bed coating, and/or electrostatic coating. This is
followed by a step of curing or hardening the first coating,
thereby securing the abrasive particles to the coated unitary
brush. This step can be achieved by heating to dry and/or
polymerize the coating, by the application of radiation energy
(such as ultraviolet radiation, for example), by allowing
atmospheric moisture to crosslink the coating, or by cooling a
thermoplastic coating. This is followed, for some embodiments, by
an additional step of applying a second coating over the abrasive
particles and first coat followed by curing or hardening the second
coating, thereby further securing the abrasive particles to the
bristles. Curing or hardening of the second coating may be achieved
by heating to dry and/or polymerize the coating, by the application
of radiation energy or atmospheric moisture to crosslink the
coating, or by cooling a thermoplastic coating.
[0053] This invention will be better understood by referring to the
following figures.
[0054] FIG. 1a illustrates a front plan view of an embodiment of an
article of the invention. Article 2 is a radial brush which
comprises a central hub 3 having bristles 4 extending radially
therefrom. Central hub 3 has a hole 7 in the center thereof
Bristles 4 have abrasive particles 6 adhered thereto via first
coating 8 (shown in FIG. 1b). Second coating 10 is applied over the
abrasive particles 6 and first coating 8. FIG. 1b is a central
cross-section taken through one of the bristles of FIG. 1a.
[0055] FIG. 2 is an isometric view of an article 20 of the
invention comprising three articles 2 of FIG. 1 secured together
via a metal adapter 22 in order to form a larger brush 20.
[0056] FIG. 3a is a side view of another embodiment of an article
of the invention. The article 24 is a right angle, or cup, brush
having a base 26 and bristles 28 attached to the base 26 at a right
angle to the base 26. Abrasive particles 30 are adhered to the
bristles 28 via first coating 32. The base 26 has a hole 34 in the
center thereof The hole 34 perimeter is threaded to allow for easy
attachment to a rotary hand tool, for example. FIG. 3b is a central
cross-section taken through one of the bristles of FIG. 3a.
[0057] The invention is further illustrated by the following
examples wherein all parts and percentages are by weight unless
otherwise indicated.
EXAMPLES
[0058] Procedure for Injection Molding of Brush
[0059] An injection molded radial bristle brush having forty 2.2 cm
long integral bristles, a 1.5 inch (3.8 cm) hub, a 3.0 inch (7.6 cm
diameter), and a weight of 1.65 grams was molded from polyamide 11
(BESNO P40TL, available commercially from Elf Atochem, Arlington
Heights, Ill.). A single-cavity mold was employed. The injection
molding machine used was a 220-ton (200,000 kg) clamping force
machine from Cincinnati Milacron (Batavia, Ohio), which employed a
single shot extruder with a general purpose screw.
[0060] Typical molding parameters included: nozzle temperature
232.degree. C. (450.degree. F.), temperature at the front of the
barrel (proximate the nozzle) 216.degree. C. (420.degree. F.),
temperature at the rear of the barrel (proximate the hopper)
232.degree. C. (450.degree. F.), screw rotation 75% of maximum,
2760-3450 kPa (400-500 psi) injection pressure, and a 2 29 cm (0.90
inch) shot distance or length. A complete cycle time on average was
about 20 seconds per injection molded brush.
Example 1
[0061] Abrasive coated injection molded radial brushes of the
invention were prepared as follows. The adhesive composition used
for coating each injection molded brush is reported in Table I.
Twelve injection molded polyamide ("BESNO P40TL", available
commercially from Elf Atochem) brushes, each prepared according to
"Procedure for Injection Molding of Brush," were mounted on an
electrically-driven mandrel with 1.5 inch (3.8 cm) wide and 0.5
inch (1.3 cm) thick TEFLON polytetrafluroethylene spacers between
each brush, rotated at about 15 RPM, submerged in the adhesive
composition for about 10 seconds while the rotation continued,
removed from the adhesive composition, and rotated at about 300 RPM
for about 10 seconds to remove excess adhesive. The resultant first
coating was applied to achieve a dry add-on weight of 0.3 gram per
brush.
[0062] The mandrel was transported to a spray booth, where ANSI
grade 36 silicon carbide abrasive particles were applied via a
spray gun to the wet first coating on each brush. The abrasive
particles were applied to both sides of eleven of the brushes until
no additional abrasive particles would adhere to the wet first
coatings, which was about 2.4 grams of abrasive particles per
brush. The abrasive coated brushes were then heated to 130.degree.
C. for 45 minutes to harden the first coating and secure the
abrasive particles to the injection molded brushes. A brush without
abrasive particle was also heated under the same conditions. (This
brush aided in the calculation of the first coating dry weight.)
Following heating, a second coating (having the same composition as
that of the first coating) was applied to all the brushes. This
second coating was used to further secure the abrasive particles to
the brushes. The second coating was applied in an identical manner
to that of the first coating, with the exception that the rotation
period at 300 RPM was extended to about 15 seconds. The resulting
second coating had a dry weight of about 0.4 gram per brush. The
brushes were subsequently heated in an oven set at 130.degree. C.
for 45 minutes to harden the second coating. Following removal from
the processing mandrel, four of the cured abrasive coated brushes
were stacked one upon another and secured with a metal adaptor to
make a larger radial abrasive article for testing.
1TABLE I Parts by Component Source Weight Polyurethane ADIPRENE
BL-16, Uniroyal Chemical Ltd., 70.37 Elmira, Ontario, Canada
Curative 4,4'-diaminobenzanilide, Biddle Sawyer 19.54 Corp., New
York, NY Lubricant "PM" lithium stearate, Witco Corporation, 4.04
Greenwich, CT Solvent ARCOSOLV PM Acetate (propylene acetate 5.65
monomethyl ether acetate, Arco Chemical Co., Houston, TX) Silica
fume CAB-O-SIL, Cabot Corp., Tuscola, IL 0.5
Comparative Examples A-D
[0063] Comparative Examples A-D are indicative of the
state-of-the-art abrasive articles which are used to condition
surfaces. Descriptions of Comparative Examples A-D are provided in
Table II. Due to variation in construction, the manufacturer's
recommended operating speeds varied, and are indicated in Table
II.
2TABLE II Manufacturer`s Recommended Operating Speed, Example
Description RPM Comparative 3" (7.6 cm) CLEAN & STRIP disc,
4,000 Example A Minnesota Mining & Manufacturing Company, St.
Paul, Minnesota (an abrasive coated three dimensional polymeric
web). Comparative 3" (7.6 cm) CLEAN & STRIP XT disc, 4,000
Example B Minnesota Mining & Manufacturing Company, St. Paul,
Minnesota (an abrasive coated three dimensional polymeric web more
dense than that of Comparative Example A). Comparative 3" (7.6 cm)
NYALOX Wheel Brush 2,500 Example C Blue, Dico Products Corporation,
Utica, New York (an abrasive filled plastic radial brush)
Comparative 3" (7.6 cm) Cup Flared Wire Brush 25,000 Example D
(Part No. 23319) Milwaukee Brush, Menomonee Falls, Wisconsin
[0064] Test Methods
[0065] Example 1 and Comparative Examples A-D were evaluated at
removing paint from an automotive panel. The panel was 0.032" (0.8
mm) thick cold-rolled steel, wherein the primer was U28RWO35K
(which is a polyester melamine composition), the base coat was
E86KE524S Black (which is an acrylic melamine composition), and the
clearcoat was E 1 26CEO 1 2 (which is an acrylic melamine
composition), prepared by ACT Laboratory, Inc., Hillsdale, Mich.
The brush of Example 1 was evaluated on an electrically-driven tool
operating at 25,000 RPM. The abrasive articles of Comparative
Examples A-D were evaluated at their respective recommended speeds.
Comparative Examples A and B were driven by a hand-held pneumatic
tool, which was an AP533 straight grinder available from Astro
Pneumanic Tool Co., Japan, while Example I and Comparative Example
D were driven by a hand-held electrical tool, which was a Makita
Die Grinder Model 906H available from Makita Company, Japan.
Comparative Example C. was driven by a Black & Decker 6040 1/4"
(6.1 mm) VSR drill, Type 100, commercially available from Black
& Decker. Each abrasive article was tested for five minutes.
The paint removal rate and brush wear were measured.
[0066] Subjective ratings of abrasive article conformability (the
ability of the article to reach into interior corners) and surface
loading (fouling of the abrasive article surface by workpiece
swarf) were also made.
[0067] For the evaluation of both conformability and surface
loading, the workpiece specimen was a coupon that was prepared by
folding a 0.032" (0.8 mm) thick.times.5 cm wide.times.33 cm long
cold rolled steel sheet so that the width of the folded coupon was
3 cm, and 2 cm of the width was a double thickness. This
configuration presents a step feature (which imitates a "tight"
corner) to facilitate the conformability evaluation.
[0068] For the brush surface loading evaluation, the test articles
were operated for two minutes against the coupon surface coated
with "HEAVY DUTY SEALER 08531" nitrile rubber based sealer
commercially available from Minnesota Mining & Manufacturing
Company, Automotive Aftermarket Division, St. Paul, Minn. The
results are shown in Table III.
[0069] Test Results
[0070] The brushes of Example 1 and Comparative Example D required
no manual pressure to remove the paint from the panel. Comparative
Examples A, B, and C, however, did require additional urging of the
abrasive article against the panel to effect paint removal. The
brush of Example 1 demonstrated a high rate of paint removal,
superior conformability, and no loading of the abrasive surface
compared to the abrasive articles of the Comparative Examples.
Abrasive articles with good conformability are better at removing
paint from inside comers.
3TABLE III Paint Removal Rate, Abrasive Conformability in.sup.2/5
minutes Article 1 = best, Surface Example (cm.sup.2/5 minutes)
Wear, grams 3 = worst Loading 1 144 (929) 3.99 1 No Comp. A 135
(870) 3.43 2 Some Comp. B 90 (580) 0.87 3 Some Comp. C 10 (65) 0.48
2 No Comp. D 90 (580) 0.52 2 No
Example 2
[0071] Example 2 was prepared identically to Example 1, with the
same number of bristles and the same dimensions as Example 1, with
the exception that the unitary brush was cut with scissors from a
0.021 inch (0.53 mm) thick extruded film of PEBAX 6333
thermoplastic elastomer (Elf Atochem, Arlington Heights, Ill.).
Example 3
[0072] Example 3 was prepared identically to Example 1 with the
exception that the unitary brush was prepared by casting a molded
brush having forty 2.2 cm long integral bristles, a 1.5 inch (3.8
cm) hub, a 3.0 inch (7.6 cm diameter) from an elastomeric casting
resin commercially available as SG2181 from MCP Systems, Fairfield,
Conn., followed by curing for 45 minutes at 65.degree. C.
Example 4
[0073] Example 4 was prepared identically to Example 2 with the
exception that the unitary brush was cut via a water jet cutter
from a 0.021 inch (0.53 mm) thick extruded film of PEBAX 6333
thermoplastic elastomer (Elf Atochem).
[0074] The coated brushes of Examples 2-4 were tested by subjective
evaluation to finish the recessed areas of intricately carved wood
(pine). Coated brushes of all three examples provided a refined
finish uniformly along and within the carved recesses.
[0075] 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 illustrative
embodiments set forth herein.
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