Technical Field
[0001] The present disclosure relates to an abrasive article with a cork backing layer.
In addition, the present disclosure relates to a method for producing abrasive articles
comprising a cork backing layer.
Background of the disclosure
[0002] Abrasive articles, especially coated abrasive articles, generally contain an abrasive
material usually in the form of abrasive grains, bonded to a backing by means of at
least one adhesive layer. These abrasive articles usually take the form of sheets,
discs, belts, bands and the like which can be adapted to be grasped by the hand, fastened
to a sanding block or a reusable backup pad mounted to a disc sander, random orbital
sander, or other power tool and mounted on pulleys, wheels or drums. Abrasive articles
can be used for sanding, grinding, or polishing various surfaces of, for example,
steel and other metals, composites, plastics, wood, wood-like laminates, plastic fibreglass,
leather, ceramics, stone, paints, coatings and other materials.
[0003] The backing layers used in abrasive articles are typically made of paper, polymeric
materials, cloth, non-woven materials or combinations of these materials. Many of
these materials show deficiencies because they are not of sufficient strength, flexibility,
or impact resistance for certain applications or they may age rapidly. This may hinder
the cutting capability of the abrasive material. Also, this may cause the abrasive
article to have a shortened life so the finish of a surface to be abraded may be not
be optimal. For example, paper has a relatively low tensile strength at break which
may cause a coated abrasive product with a paper backing to fail prematurely before
its abrasive surface is fully utilized. This is particularly true when the abrasive
granules are of a coarser nature which transmits greater stress to the backing as
the abrasive product is being employed, particularly as an abrasive disc or abrasive
belt.
[0004] Abrasive articles containing cork abrasive particles are known, for example in
JP2004338064 and
CN2016259U.
[0005] There remains a need for an improved abrasive article which is flexible, resistant
to wear and yet provides high level of cut aggression and a finer finish to the abraded
surface.
Summary
[0006] The present disclosure provides an abrasive article comprising a cork backing layer
and an abrasive layer.
[0007] Furthermore, the present disclosure provides a method of making an abrasive article
wherein the method comprises introducing an abrasive slurry comprising abrasive particles
onto a first surface of a cork backing and at least partially curing the abrasive
slurry.
Detailed Description disclosure
[0008] As used herein, the terms "preferred" and "preferably" refer to embodiments described
herein that may afford certain benefits, under certain circumstances. However, other
embodiments may also be preferred, under the same or other circumstances. Furthermore,
the recitation of one or more preferred embodiments does not imply that other embodiments
are not useful, and is not intended to exclude other embodiments from the scope of
the invention.
[0009] As used herein and in the appended claims, the singular forms "a," "an," and "the"
include plural referents unless the context clearly dictates otherwise. Thus, for
example, reference to "a" or "the" component may include one or more of the components
and equivalents thereof known to those skilled in the art. Further, the term "and/or"
means one or all of the listed elements or a combination of any two or more of the
listed elements.
[0010] It is noted that the term "comprises" and variations thereof do not have a limiting
meaning where these terms appear in the accompanying description. Moreover, "a," "an,"
"the," "at least one," and "one or more" are used interchangeably herein.
[0011] Relative terms such as left, right, forward, rearward, top, bottom, side, upper,
lower, horizontal, vertical, and the like may be used herein and, if so, are from
the perspective observed in the particular figure. These terms are used only to simplify
the description, however, and not to limit the scope of the invention in any way.
Unless otherwise specified, testing was performed at standard room temperature of
approximately 21 °C.
[0012] Unless explicitly stated otherwise, all embodiments and optional features of the
present disclosure can be combined freely.
[0013] The present disclosure provides an abrasive article comprising a cork backing layer
and an abrasive layer. The cork backing layer has a first and second surface, wherein
the abrasive layer is coated onto the first surface. The cork backing layer provides
the advantageous combination of a flexible yet sturdy layer, therefore the abrasive
layer is fully utilised without the backing layer failing. Consequently, the abrasive
article can be used for longer, does not have to be replaced as often and accordingly
provides both time and cost efficiencies to users of the abrasive article. Furthermore,
the cork backing layer is firm enough to ensure the abrasive article does not wear
as extensively as conventional products. The described properties of the cork backing
layer also deliver a surprising uplift in cutting aggression of the abrasive layer
compared to conventional products.
[0014] Preferably, a tie coat layer is disposed onto the cork backing layer before the abrasive
layer. That is, the tie coat layer, if present, is located between the cork backing
layer and the abrasive layer. A tie coat layer provides greater adhesion of the abrasive
layer to the cork backing layer, and allows for faster processing times in a continuous
manufacturing process.
[0015] It is preferred that the abrasive layer comprises abrasive particles and at least
one first binder. The at least one first binder serves to adhere the abrasive particles
to each other and the backing layer and optionally other additives of the abrasive
layer, for example, grinding aids. The terms 'adhere' as used herein means that the
abrasive particles or other components are completely within the at least one first
binder or at least partially within the binder or attached to the at least one first
binder. The at least one first binder in the abrasive slurry is generally also responsible
for adhering the abrasive layer to the first surface of the cork backing layer.
[0016] The at least one first binder can be a thermoplastic binder. Thermosetting binders
are preferred as they have superior heat and chemical resistance. Examples of suitable
binders that are useful in the abrasive layer include phenolics, aminoplasts, urethanes,
epoxies, acrylics, cyanates, isocyanurates, glue, and combinations thereof. Typically,
the binder is prepared by at least partially curing (polymerising) a corresponding
binder precursor, usually in the presence of an appropriate curative (for example,
photoinitiator, thermal curative, and/or catalyst).
[0017] The binder is preferably formed from a binder precursor. When the binder precursor
is a thermosetting binder precursor, the thermosetting binder precursor is exposed
to an energy source which aids in the initiation of the polymerisation or curing process.
Examples of energy sources include thermal energy and radiation energy which includes
electron beam, ultraviolet light, and visible light. After this polymerisation process,
the binder precursor is converted into a solidified binder.
[0018] Alternatively, for a thermoplastic binder precursor, during the manufacture of the
abrasive article the thermoplastic binder precursor is cooled to a degree that results
in solidification of the binder precursor.
[0019] Examples of mixing techniques to mix the binder precursor, abrasive articles and
optionally other additives include low shear and high shear mixing, with high shear
mixing being preferred. Ultrasonic energy may also be utilized in combination with
the mixing step to lower the abrasive slurry viscosity. Typically, the abrasive particles
are gradually added into the binder precursor. It is preferred that the abrasive slurry
is a homogeneous mixture of binder precursor, abrasive particles and optional additives.
If necessary, water and/or solvent may be added to lower the viscosity. The amount
of air bubbles in the abrasive slurry may be minimized by lowering the pressure of
the surrounding atmosphere, commonly known as "pulling a vacuum" either during or
after the mixing step. In some instances, it is preferred to heat, generally in the
range from about 30 °C to about 100 °C, the abrasive slurry to lower the viscosity.
It is important the viscosity of the abrasive slurry is monitored before coating to
ensure a rheology that coats well and in which the abrasive particles and other fillers
do not settle before coating.
[0020] The abrasive slurry can include optional additives such as fillers, fibres, lubricants,
wetting agents, thixotropic agents, surfactants, pigments, dyes, antistatic agents,
coupling agents, plasticizers, and suspending agents. The amounts of these materials
are selected to provide the properties desired.
[0021] Preferably, the abrasive particles comprise materials selected from aluminium oxide,
silicon carbide, boron carbide, iron oxide, steel, boron nitride, ceramic, cork and
any combinations and mixtures thereof. These materials are commonly used in coated
abrasive articles as they provide significant cut aggression to the surface to be
abraded.
[0022] Abrasive particles useful in this invention may include single abrasive grains or
single abrasive grains bonded together to form an abrasive agglomerate. The abrasive
particles may include a surface coating that can have different functions. The surface
coatings may increase adhesion to the first binder, or alter the abrading characteristics
of the abrasive particle. Examples of surface coatings include coupling agents, halide
salts, metal oxides including silica, refractory metal nitrides, refractory metal
carbides and the like.
[0023] Preferably, the abrasive layer comprises a microreplicated abrasive layer. In the
context of this disclosure, "microreplicated" means the production of a microstructured
surface through a process wherein the structured surface features retain an individual
feature fidelity from a mould during manufacture. A microreplicated abrasive layer
is known to reduce stiction, i.e. the tendency for the abrasive surface to stick to
a workpiece when used in the damp abrading processes typical of industry. Additionally,
the microreplicated abrasive layer ensures consistent cut to the surface to be abraded.
[0024] Preferably, the cork in the cork backing layer backing is selected from natural cork
and cork particles with at least one second binder. The cork backing layer provides
the advantageous combination of a flexible yet sturdy layer, therefore the abrasive
layer is fully utilised without the backing layer failing. Consequently, the abrasive
article can be used for longer, does not have to be replaced as often and accordingly
provides both time and cost efficiencies to users of the abrasive article. Furthermore,
the cork backing layer is firm enough to ensure the abrasive article does not wear
as extensively as conventional products. The described properties of the cork backing
layer also deliver a surprising uplift in cutting aggression of the abrasive layer
compared to conventional products.
[0025] Preferably, the second binder is selected from rubber, asphalt, gypsum, adhesives
and polymers or a mixture thereof. The second binder binding the cork particles provides
additional properties to the cork including water retention, strength and flexibility.
[0026] More preferably the cork in the cork backing layer is rubber-bonded cork. Rubber-bonded
cork is robust and durable, therefore the abrasive layer is fully utilised without
the backing layer failing. Consequently, the abrasive article can be used for longer.
This has the advantage of providing cost savings and time efficiencies to the user.
[0027] Preferably, the rubber-bonded cork comprises neoprene, nitrile or a mixture thereof.
Rubber-bonded cork comprising neoprene, nitrile or a mixture thereof retains water
advantageously. This property allows the cork backing layer to be flexible and therefore
the abrasive article is flexible. Flexible abrasive articles are longer-wearing and
are adaptable to a wider range of surfaces to be abraded.
[0028] It is preferred that the cork backing layer has a thickness of at least 0.1 mm, preferably
at least 0.5 mm. Preferably, the cork backing layer has a thickness of no more than
approximately 5 cm, more preferably no more than approximately 1cm.
[0029] The thickness of the cork backing layer depends on the application in which the abrasive
article is being used. Cork backing layers which are approximately less than 5 mm
are more flexible and therefore maybe used on surfaces which are not uniform in shape.
These thinner cork backing layers may be advantageously used in belt applications.
They may be used in applications involving metals, plastics and composites. Thicker
cork backing layers which are approximately more than 5 mm are less flexible than
thinner cork backing layers but are more sturdy. They are suitable for abrading uniform
surfaces, where more pressure can be applied to the abrasive article also increasing
cut aggression. Thicker cork backings may provide better a finish to the abraded surface
as the cork backing layer acts as a cushion.
[0030] Abrasive articles according to the present disclosure may be provided in any form.
[0031] In another embodiment, the abrasive article is an abrasive belt having a continuous
backing layer. The belt width may range from about 0.5 cm to 250 cm, typically anywhere
from about one cm to 150 cm. The belt length may range from about 5 cm to 2000 cm,
typically 10 cm to 500 cm. The belt may have straight or scalloped edges. Belts may
contain a splice or a joint such that the belts are endless.
[0032] Preferably the abrasive article is an abrasive disc. The abrasive disc can be used
with or without an abrading tool. Abrasive discs may contain a centre hole or have
no centre hole. Discs may have the following shapes: round, oval, octagon, pentagon,
hexagon or other known shapes. The discs may also contain dust holes, typically for
use with a tool containing a vacuum source. The diameter of the disc may range from
about 0.1 cm to 1500 cm, preferably one cm to 100 cm.
[0033] Preferably the abrasive article is an abrasive sheet. Sheets may be square, triangular,
or rectangular Sheet widths may range from about 0.01 cm to 100 cm, preferably 0.1
cm to 50 cm. Sheet lengths may range from about one cm to 1000 cm, typically 10 cm
to 100 cm.
[0034] Preferably, the abrasive article according to the present invention may be secured
to a support structure, for example, a backup pad secured to a tool, for example,
a random orbital sander. An optional attachment interface layer may be an adhesive
(for example, a pressure sensitive adhesive) layer or a double-sided adhesive tape.
The optional attachment interface layer may be adapted to work with one or more complementary
elements affixed to the support pad or backup pad in order to function properly.
[0035] Preferably, the optional attachment interface layer may comprise a loop fabric for
a hook and loop attachment (for example, for use with a backup or support pad having
a hooked structure affixed thereto), a hooked structure for a hook and loop attachment
(for example, for use with a backup or support pad having a looped fabric affixed
thereto), or an intermeshing attachment interface layer, for example, mushroom type
interlocking fasteners designed to mesh with a like mushroom type interlocking fastener
on a backup or support pad.
[0036] Likewise, a second surface of the cork backing layer may have a plurality of integrally
formed hooks protruding therefrom. These hooks will then provide the engagement between
the structured abrasive article and a backup pad that has a loop fabric affixed thereto.
[0037] The present disclosure further provides a method of making an abrasive article, the
method comprising, introducing an abrasive slurry comprising abrasive particles onto
a first surface of a cork backing and at least partially curing the abrasive slurry.
[0038] Preferably, a tie coat layer is disposed onto the first surface of the cork backing
layer before the abrasive slurry is introduced onto the cork backing layer. A tie
coat layer provides greater adhesion of the abrasive layer to the cork backing layer,
and allows for faster processing times in a continuous manufacturing process.
[0039] The tie coat layer is preferably formed from a tie coat precursor. The tie coat precursor
comprises a resinous adhesive in an uncured and flowable state that is capable of
solidifying. The solidification can be achieved by curing (i.e., polymerising and/or
crosslinking) or by drying (e.g., driving off a liquid) and curing. The tie coat precursor
can be organic solvent-borne, water-borne, or 100 % solids (i.e., a substantially
solvent-free) compositions. That is, tie coat may be formed from a 100 % solids formulation
or it may be coated out of a solvent (e.g., a ketone, tetrahydrofuran, or water) with
subsequent drying and curing. If a solvent is used, it is one that does not react
with the other components of the precursors, but can be driven off by heat, for example,
although complete elimination is not necessarily required.
[0040] Preferably the abrasive slurry is introduced onto a production tool or the production
tool is introduced onto the abrasive slurry. The term 'production tool' as used herein
means an article containing cavities or openings therein. For example, a production
tool may be a cylinder, a flexible web, an endless belt, a sheet or web, a sleeve
mounted on a coating roll or die.
[0041] The outer surface of the production tool can be smooth or have a surface topography
or pattern. The pattern will generally consist of a plurality of cavities or features.
The resulting abrasive layer will have the inverse of the pattern from the production
tool. These cavities can be any geometric shape such as rectangle, semicircle, circle,
triangle, square.
[0042] The production tool can be made of metal or can be made from a thermoplastic material.
The metal tool can be fabricated by any conventional technique such as engraving,
hobbing, electroforming, diamond turning and the like. The thermoplastic production
tool is generally made using the following method. A master tool is first provided.
If a pattern is desired in the production tool, then the master tool should also have
the inverse or the pattern for the production tool. The master tool is preferably
made from metal, for example, nickel. The metal master tool can be fabricated by any
conventional techniques such as engraving, hobbing, electroforming, diamond turning
and the like. The thermoplastic material is then heated optionally along with the
master tool so that the thermoplastic material is embossed with the master tool pattern.
After the embossing, the thermoplastic material is cooled to solidify.
[0043] Preferably, the abrasive article and the production tool are separated. The production
tool may also contain a release coating to permit easier release of the abrasive article
from the production tool. Examples of such release coatings for metals include hard
carbide, nitrides or borides coatings. Examples of release coatings for thermoplastics
include silicones and fluorochemicals.
[0044] Preferably, the production tool has microreplicated features. The production tool
imparts a microreplicated structure onto the abrasive layer. A microreplicated abrasive
layer is known to reduce stiction, the tendency for the abrasive surface to stick
to a workpiece when used in the damp abrading processes typical of industry. Additionally,
the microreplicated abrasive layer ensures consistent cut to the surface to be abraded.
[0045] Preferably the abrasive slurry is at least partially cured by a method of curing
selected from radiation curing, UV curing, heat curing and moisture curing.
[0046] The present disclosure also provides a method of abrading a work surface, the method
comprising, providing an abrasive article, contacting an abrasive layer of the abrasive
article with the work surface optionally introducing water to the work surface or
the abrasive article or both and moving the abrasive article or the work surface relative
to the other to abrade at least a portion of the work surface.
[0047] The present disclosure provides a use of an abrasive article comprising a cork backing
layer and an abrasive layer for abrading materials preferably selected from metal,
metal alloys, exotic metal alloys, ceramics, painted surfaces, plastics, polymeric
coatings, stone, polycrystalline silicon, wood, marble, and combinations thereof.
[0048] The disclosure will now be described, by way of example only, with reference to the
following drawings, in which:
Figure 1 is an enlarged cross-section of a coated abrasive article
Figure 2 is a perspective of a coated abrasive belt
Figure 3 is an enlarged perspective view of the backside of the spliced section of
the coated abrasive belt
Figure 4 is an enlarged cross-section of a coated abrasive disc
[0049] Figure 1 illustrates a cross-section of a coated abrasive article 101. The abrasive
article 101 comprises an abrasive layer 103. The abrasive layer 103 is an abrasive
slurry comprising a plurality of precisely shaped abrasive composites 109, each composite
having a predetermined shape and being disposed on a tie-coat layer 105 in a predetermined
array. Abrasive composites 109 have a discernible precise shape (e.g., pyramidal)
and comprise a plurality of abrasive particles dispersed in a binder. In this embodiment,
the binder bonds abrasive composites 109 to a tie coat layer 105 which in turn ensures
enhanced adhesion of the abrasive composites 109 to a cork backing layer 107.
[0050] The coated abrasive article 101 is produced by at least partially curing or solidifying
the abrasive slurry while the slurry is being held within precisely shaped microreplicated
recesses of a production tool. The precisely shaped recesses of the production tool
function to mould the abrasive slurry to the desired precise shape. The binder precursor
of the abrasive slurry must be at least partially cured or solidified while being
held in the precisely shaped recesses so that that the abrasive slurry is "set" and
does not lose its precise shape upon removal from the production tool.
[0051] Referring now to Figure 2, a perspective view of an endless coated abrasive belt
201 is shown. The belt 201 comprises a continuous cork backing layer 203, an abrasive
layer 207 and a tie coat layer (not seen). The belt also comprises a splice 205 comprising
two ends 211, 213 of a coated abrasive sheet which are joined together to form a joint
209.
[0052] Figure 3 is an enlarged perspective view of the back side of the spliced section
of the coated abrasive belt 301. The 'back side' of the coated abrasive article refers
to the side of the article not bearing the abrasive layer.
[0053] A splice 319 comprises two ends 315, 317 of a coated abrasive sheet according to
the present invention, which are joined together to form a joint 309.
[0054] The coated abrasive sheet 321 comprising the cork backing layer 305 is first cut
to a desired length, preferably ranging from 15 cm to about 500 cm. The end 315 is
cut such that it is interlocking with end 317 when cut. The ends 315, 317 comprise
shaped protrusions such as triangular, rectangular and recesses of corresponding shape
to engage with these shaped protrusions. The two ends 315, 317 are preferably cut
so that there is minimal gap between the two ends and it is preferred that the ends
315, 317 do not overlap at all.
[0055] A splice adhesive may be added to the surface of the joint 309. This will increase
strength of the joint 309.
[0056] A spliced medium 311 is placed over the joint 309. Polymeric films are preferred
for splice media. Representative examples of polymeric films suitable for splice media
include polyester film, polyamide film, polypropylene film, polyethylene film, polyimide
film and polyurethane film. Preferably, the polymeric film is a hot-melt polyurethane
film. An example of a suitable polyurethane film is "PU CLEAR HIGH MELT JOIN FILM"
available from Habasit UK Ltd, Elland, West Yorkshire, UK. The two ends 315,317 are
placed in a laminator such as "MAESTRO 300" available from Ammeraal Beltech, Alkmaar,
The Netherlands, and the heated press holds the two ends in place. The heat causes
the hot-melt polyurethane film to melt and secure the splice 309 whilst the pressure
from the laminator ensures the ends 315, 317 stay interlocked at joint 309.
[0057] Figure 4 shows an enlarged cross-section of an abrasive disc. The abrasive article
401 comprises an abrasive layer 403. The abrasive layer 403 is an abrasive slurry
comprising a plurality of precisely shaped abrasive composites 409, each composite
having a predetermined shape and being disposed on a tie-coat layer 405 in a predetermined
array. Abrasive composites 409 have a discernible precise shape (i.e., pyramidal)
and comprise a plurality of abrasive particles dispersed in a binder. In this embodiment,
the binder bonds abrasive composites 409 to a tie coat layer 405 which in turn ensures
enhanced adhesion of the abrasive composites 409 to a first surface 415 of a cork
backing layer 407.
[0058] The coated abrasive article 401 is produced by at least partially curing or solidifying
of the present invention while the abrasive slurry is being held within precisely
shaped microreplicated recesses of a production tool. The precisely shaped recesses
of the production tool function to mould the abrasive slurry to the desired precise
shape. The binder precursor of the abrasive slurry must be at least partially cured
or solidified while being held in the precisely shaped recesses so that that the abrasive
slurry is "set" and does not lose its precise shape upon removal from the production
tool.
[0059] A second surface 417 of the cork backing layer 407 comprises a double-sided adhesive
tape 421 which is attached to a fabric 419 with integrally formed loops protruding
therefrom. These loops will then provide the engagement between the cork backing layer
407 and a backup pad 411 that has a hook fabric 413 affixed thereto. The backup pad
411 may be attached a tool such as a random orbital sander.
Examples
[0060] The following non-limiting examples will further illustrate the invention, wherein
all parts and percentages are by weight unless otherwise indicated.
Materials
[0061] "SR 351" is a trimethylolproprane diacrylate monomer available from Sartomer Company,
Exton, Pa., USA.
[0062] "SR 368D" is an isocyanurate triacrylate available from Sartomer Company, Exton,
Pa., USA.
[0063] "'SR 339C" is a 2-phenoxyethyl acrylate available from Sartomer Company, Exton, Pa.,
USA.
[0064] "IR-651" is a 2,2-dimethoxy-1,2-diphenyl ethan-1-one photoinitiator available under
the trade designation IRGACURE® 651 from BASF Corp., Charlotte, N.C., USA
[0065] "IR-369" is a 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 UV curing
agent available under the trade designation IRGACURE® 369 from BASF Corp., Charlotte,
N.C., USA.
[0066] "IR-TPO-L" is a 2,4,6-trimethylbenzoylphenyl phosphinate photoinitiator available
under the trade designation IRGACURE® TPO-L from BASF Corp., Charlotte, N.C., USA.
[0067] "A-174™" is a gamma-methacryloxypropyltrimethoxysilane resin modifier available under
the trade designation SILQUEST™ A-174™ silane from Witco Corporation, Greenwhich,
Conn., USA.
[0068] "OX-50" is a fumed silicon dioxide available under the trade designation AEROSIL®
OX 50 from Evonik Industries, Essen, Germany.
[0069] KBF
4 is potassium fluoroborate available from Washington Mills, Manchester, UK.
[0070] "SC24000" is a polymeric dispersant available under the trade designation SOLSPERSE™
24000 GR/SC from Lubrizol Ltd., Derby, UK.
[0071] "P180" is an aluminium oxide mineral available under the trade designation DURALUM
GW 180 Washington Mills, Manchester, UK
[0072] "GC2500" is a green silicon carbide available under the trade designation GC2500
from Fujimi Corp., Elmhurst, III, USA.
[0073] "300LSE" is a double-sided adhesive tape available under the trade designation 3M™
Double Coated Tape 93010LE available from 3M Company, St Paul, MN., USA.
[0074] "Hookit™ II Laminating Backing" is one part of a 2-part fastening system comprising
sheet material bearing on one side a multiplicity of erect stems that have flattened
distal ends that is made according to
U.S. Pat. No. 5,667,540 and manufactured by 3M Company of St. Paul, MN. The flattened stems are engageable
in a fabric material which provides the other part of 2-part fastening system, as
described in
U.S. Pat. No. 5,962,102.
Testing
[0075] The following materials were used in testing Examples 1-6 and Comparative Example
A.
[0076] AOEM clear coated black painted cold roll steel test panels obtained from Advanced
Coating Technologies Laboratories, Inc.,Hillsdale, Michigan having dimensions of 18inches
by 24inches.
[0077] Random orbital sander available under the trade designation "3M™ ELITE NON-VACUUM
RANDOM ORBITAL SANDER, 28500" from 3M Company, St. Paul, MN, USA.
[0078] Profilometer available under the trade designation "SURTRONIC S128" available from
Taylor Hobson, Inc., Leicester, UK.
Water spray bottle
Stopwatch
[0079] The following materials were used in the testing Example 7 and Comparative Example
B.
[0080] Stainless steel test panels obtained from Gtec Engineering Ltd, Atherstone, UK having
dimensions of 50cm by 50 cm with 0.5 cm depth.
[0081] Flat-bed sander available from Surface Technology Products Limited, Birmingham, UK
under the trade designation "SURTECH MODEL L84" modified to accommodate a sanding
pad.
[0082] Profilometer available under the trade designation "SURTRONIC S128" from Taylor Hobson,
Inc., Leicester, UK.
[0083] Table 1 shows the cork backing materials obtained from Advanced Seals & Gaskets Ltd,
Dudley, UK.
TABLE 1
Example |
Description |
Thickness (mm) |
1 |
Neoprene-bonded cork |
1.5 |
2 |
Nitrile-bonded cork |
1.5 |
3 |
Natural cork |
3 |
4 |
Neoprene-bonded cork |
3 |
5 |
Nitrile-bonded cork |
3 |
6 |
Neoprene-bonded cork |
5 |
[0084] Table 2 shows the backings of Comparative Examples A and B.
TABLE 2
Example |
Backing |
Comparative Example A |
Latex-coated foam |
Comparative Example B |
Fabric |
Examples 1-5
[0085] A tie-coat was prepared by mixing one- part IR-651, 39.6 parts SR 368D and 59.4 parts
SR 351.
[0086] An abrasive slurry (AS1) was prepared by mixing 19.47 parts SR351, 12.94 parts SR
339, 3.08 parts SC24000, 1.93 parts A-174™, 1.08 parts TPO-L and 61.50 parts GC2500.
[0087] The tie coat was applied to a cork backing sheet and the abrasive slurry was applied
to a polypropylene tool having a microreplicated surface, the surface being the reverse
pattern of that desired for the shaped abrasive surface. The coated tool was applied
to the tie-coat so that contact was established between the tie-coat and the slurry
side of the tool. The tool side of the resulting lamination was then exposed to ultra-violet
radiation by exposure to a D-bulb at 100 % power while moving the backing at 22 meter/minute.
The tool was then removed from the fully cured shaped abrasive coating on the tie-coated
cork backing.
[0088] This process was repeated for each of Examples 1-5.
[0089] 6" circular discs were cut from the cork backing sheet and Hookit™ II Laminating
Backing ready for testing.
Comparative Example A
[0090] Comparative Example A was a 3M™ TRIZACT™ HOOKIT™ FOAM ABRASIVE DISC 443SA available
from 3M Company, St. Paul, MN, USA laminated to Hookit™ II Laminating Backing.
[0091] The test panels were prepared by first sanding their surfaces with a 3M™ HOOKIT™
FINISHING FILM ABRASIVE DISC 260L, grade P1200 available from 3M Company, St. Paul,
MN, USA. The random orbital sander was operated at 12,000 rpm using moderate but consistent
downward pressure. Sanding was started in the upper left-hand corner of the test panel
and moved back and forth across the panel from top to bottom. Initial finish (Rz)
of the prepared panel was measured using the profilometer. Three to five readings
were taken from the panel and an average of these readings was the initial Rz of the
test panel. The initial panel weight was measured in grams.
[0092] The test pad was then mounted onto the random orbital sander and was used to finish
the prepared panel. Water was sprayed over the panel in a sufficient amount to prevent
sticking of the product to the panel. One test disc was used on each panel. Sanding
once again started from the upper-left hand corner of the test panel and moved back
and forth across the panel from top to bottom. Rz is the average of the highest vertical
point to the lowest vertical point of each scratch indent, where four Rz measurements
were taken for each sample. Rz was measured after 60 seconds and after 120 seconds.
The panel was also weighed after 60 seconds and after 120 seconds to determine the
difference in mass from the initial panel weight. The difference was abrasive cut
in grams.
[0093] Results are shown in Table 3. It can be seen Examples 1-5 are comparable in both
cut and Rz to Comparative Example A. The products were found to be surprisingly easy
to handle, with relatively little stiction, i.e. the tendency for the abrasive coating
to stick to the workpiece with unwanted results. The cork samples felt more sturdy
and secure owing to the strength and rigidity of the cork backing.
TABLE 3
Example |
Average cut, g after 60 s |
Average cut, g after 120 s |
Rz (micrometer) after 60 s |
Rz (micrometer) after 120 s |
1 |
0.30 |
0.12 |
0.8 |
0.8 |
2 |
0.30 |
0.12 |
0.7 |
0.7 |
3 |
0.34 |
0.16 |
0.8 |
0.8 |
4 |
0.28 |
0.14 |
0.7 |
0.8 |
5 |
0.33 |
0.14 |
1.0 |
0.9 |
Comparative Example A |
0.36 |
0.15 |
0.7 |
0.8 |
Example 7
[0094] A tie-coat was prepared by mixing one-part IR-651, 39.6 parts SR 368D and 59.4 parts
SR 351.
[0095] A first mixture was prepared using mixing 56.49 parts of SR 351 and SR 368D, 1.99
parts OX-50, 1.99 parts A-174 and 38.57 parts KBF
4 in a paddle mixer. 42 parts of the first mixture were then mixed with 58 parts of
P180 with the paddle mixer.
[0096] The tie coat was spread across a cork backing of dimensions with a 20 micrometer
bar. The slurry was then poured directly onto the cork backing sample of dimension
100 cm by 20 cm and the slurry was spread as evenly as possible with a flat metal
spreader bar. A matching length of polypropylene tool was placed on the abrasive slurry
such that the reverse microreplicated pattern of that desired for the shaped abrasive
surface was facing the abrasive slurry. The cork backing and polypropylene tool were
taped together using adhesive masking tape available under the trade designation "3M
501E SPECIALITY HIGH TEMPERATURE MASKING TAPE" from 3M Company, St. Paul, MN, USA
A roller was adopted to push downwards on to the tooling and spread the slurry underneath
by hand. A quartz plate was then placed over the top of the tooling and the whole
sampled exposed twice to ultra-violet radiation by exposure to a D-bulb at 100 % power.
The polypropylene tool was removed to leave a microreplicated abrasive surface on
the cork backing.
[0097] Samples were cut into sheets measuring 16 x 10 cm and the samples adhered to a sanding
pad using "300LSE".
Comparative Example B
[0098] Comparative Example B was a 3M™ TRIZACT™ CLOTH BELT 307EA available from 3M Company,
St. Paul, MN, USA. The belt was cut to a 16 cm length and two 5 cm width belt sheets
were adhered side by side to a sanding pad using "300LSE".
[0099] Three abrading steps were conducted each for 1 minute. Sanding was done in one direction
from top to bottom across the panel. Rz of the panel was measured after step 2 and
step 3 using the profilometer. 3 readings were taken from the panel and an average
of these readings was the Rz of the test panel. The initial panel weight was measured
in grams. The panels were then weighed after each step to determine the difference
in mass from the initial panel weight. The difference was abrasive cut in grams.
[0100] The panels were rotated by 90° after each step such that the sanding lines were adjacent
to the previous step. This was so that ridges, from scratches, from the abrasive at
each step could be countered more effectively at the next step.
Step 1: The test panels were sanded with 3M™ CUBITRON™ II CLOTH BELT 947A available
from 3M Company, St. Paul, MN, USA cut to 16 cm by 10cm and adhered to a sanding pad
with "300LSE.
Step 2: The test panels were sanded with either Example 6 or Comparative Example B.
Step 3: The test panels were sanded with 3M™ TRIZACT™ CLOTH BELT 307EA A45 available
from 3M Company, St. Paul, MN, USA cut to 16 cm by 10 cm and adhered to a sanding
pad with "300LSE.
[0101] Step 1-3 were repeated 3 times for each of Example 6 and Comparative Example B. The
average cut results are depicted in Table 4 and average finish results are depicted
in Table 5. Cut is higher for Example 6 as the cork provides higher cutting aggression
due to its rigidity and relative hardness. Finish is smoother for Example 6 due to
the cushioning effect of the cork backing, whereas the thin cloth of Comparative Example
B causes a deeper scratch.
TABLE 4
Example |
Average cut, g after Step 1 |
Average cut, g after Step 2 |
Average cut, g after Step 3 |
6 |
0.46 |
0.3 |
0.06 |
Comparative Example B |
0.46 |
0.14 |
0.2 |
TABLE 5
Example |
Rz (micrometer) after Step 2 |
Rz (micrometer) after Step 3 |
6 |
3.7 |
6.7 |
Comparative Example B |
11.5 |
3.3 |
[0102] Various modifications and alterations of this invention may be made by those skilled
in the art without departing from the scope and spirit of this invention, and it should
be understood that this invention is not to be unduly limited to the illustrative
embodiments set forth herein.