EP1386696A1 - Abrasive product and the production process thereof - Google Patents
Abrasive product and the production process thereof Download PDFInfo
- Publication number
- EP1386696A1 EP1386696A1 EP02291955A EP02291955A EP1386696A1 EP 1386696 A1 EP1386696 A1 EP 1386696A1 EP 02291955 A EP02291955 A EP 02291955A EP 02291955 A EP02291955 A EP 02291955A EP 1386696 A1 EP1386696 A1 EP 1386696A1
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- Prior art keywords
- resin
- abrasive
- abrasive product
- web
- coating
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
- B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
- B24D3/001—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as supporting member
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
- B24D11/00—Constructional features of flexible abrasive materials; Special features in the manufacture of such materials
- B24D11/001—Manufacture of flexible abrasive materials
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
- B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
- B24D3/02—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent
- B24D3/20—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent and being essentially organic
- B24D3/28—Resins or natural or synthetic macromolecular compounds
- B24D3/32—Resins or natural or synthetic macromolecular compounds for porous or cellular structure
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
- B24D7/00—Bonded abrasive wheels, or wheels with inserted abrasive blocks, designed for acting otherwise than only by their periphery, e.g. by the front face; Bushings or mountings therefor
- B24D7/02—Wheels in one piece
Definitions
- abrasive products typically incorporate very hard minerals such as aluminum oxide, silicium carbide, and the like that have very high hardness and toughness properties. They are able to abrade any of a variety of workpieces including those made of steel, stone, wood, plastic, and the like. This is an advantage in many applications, for example grinding, finishing and polishing. When used for removing coating layers from a sensitive base substrate, however, such hard abrasive minerals will also attack the substrate and are, accordingly, less satisfactory.
- WO-A-00/41850 discloses a durable, non-woven abrasive product having a significantly longer useful product life compared to conventional, but similar, abrasive products.
- the abrasive product has a porous, lofty web of multiple layers of coiled, autogenously bonded thermoplastic filaments, binder resin, abrasive granules and size resin.
- methyl chloride has been used for many years for removing coatings from base substrates. This chemical has a selective action. Only the top layers react with the methyl chloride and soften, leaving the base material untouched. Methyl chloride is now classified as a low category carcinogen if present in concentrations of more than 1% and, consequently, its use is being phased out.
- Aerospace maintenance companies have found chemical removal of coatings useful because aerospace substrates typically comprise materials, for example aluminum alloy, that are easily damaged by conventional abrasives. Chemical removal of coatings as a technique is also rapidly applicable to large surface areas. The main application is paint removal on the body of an aircraft (one Airbus TM aircraft Model A 340, for example, represents 2000 m 2 of painted surface) but another important application is sealant removal from fuel tanks and various other areas. However, chemical strippers and softeners are not allowed on composite materials and cannot, therefore, be used for coatings removal on all parts of an aircraft.
- the abrasive product may also contain mixtures of several granule sizes, different abrasive materials uniformly incorporated therein or different abrasive sizes, hardnesess or materials.
- Suitable lubricants are alkali metal salts of stearic acid.
- a preferred lubricant is an aqueous dispersion of calcium stearate commercially available under the trade designation SOLUFAX® from HQ France.
- the amount of lubricants included in the present abrasive products is preferably an amount by weight less than 15% of the total dry binder (resin, acrylonitrile butadiene polymer and optional components), preferably less than 10%, more preferably less than 6%, most preferably about 4%.
- polyamide filament-forming material is inserted into an extruder equipped with a spinneret head which has a multitude of openings equally spaced in at least one row, preferably in a plurality of spaced rows of equally spaced openings.
- the row or rows of molten filaments are then extruded downwardly, permitted to freely fall a short distance through an air space and then into a quench bath.
- the filaments enter the quench bath, they begin to coil and undulate, thereby setting up a degree of resistance to the flow of the molten filaments, causing the molten filaments to oscillate just above the bath surface.
- This process produces a web wherein each filament is coiled and undulated throughout its length.
- the undulations of each filament are typically irregular although it is possible to adjust the process to produce regular helically coiled filaments.
- Irregular filament undulation is characterized by random looping, kinking or bending of the filaments through the web in a pattern defined generally by the pattern of openings of the spinneret.
- the abrasive products of the present invention may be in any of a variety of shapes as typically encountered for nonwoven abrasive products.
- suitable shapes are both rectangular pads and disc-shaped pads which may have a central opening for attachment of an arbor or rod for rotation.
- they may be cut into shapes such as rectangular shapes and mounted about the periphery of a rotatable hub to provide a flap wheel.
- Other shapes are also contemplated such as endless belts and abrasive wheels or sheets.
- the wheels typically have a central opening for support by an appropriate arbor to enable the wheel to be rotated in use.
- Fig. 1 is a schematic illustration of the process used to make an abrasive product of the present invention.
- Typical shapes of the abrasive product of the invention include those depicted by Figs. 2 and 3.
- Fig. 2 shows a rectangular shape abrasive product 30 while Fig. 3 shows an annulus shape abrasive product 50.
- the web has a basis weight of between 0.8 and 1.0 Kg/m 2 and a thickness of 1.5 cm, and is formed from nylon 6 fibers having a diameter of between about 13 and 17 mils (0.33 and 0.44 mm).
- the total coating weight of the wet binder resin plus abrasive granules applied to the web is in the range of from 4500 - 7000 g/m 2 (more preferably in the range of from 5000 - 6000 g/m 2 ), of which the abrasive granules preferably comprise between 30 and 60% by weight (more preferably between 35 and 45%).
- Example 1 Abrasive product preparation using a phenolformaldehyde resin in the binder resin material
- Example 2 Abrasive product preparation using an epoxy resin in the binder resin material
- Example 1 The method of Example 1 was followed, except as noted below.
- the compounds poured successively into the agitator were as follows: Aqueous dispersion of a polymer of acrylonitrile and 1,3-budadinene (PERBUNAN® N latex X 2342 of Bayer S.A.) 600g Antifoam (BYK 22 of Byk-chemie) 12.4g Epoxy resin (EPIREZ CMD 3522 W60 from Shell) 410g Catalytic agent (2MI of Merck Clevenot) 12.3g
- Aqueous dispersion of a copolymer of acrylic acid ester and acrylic acid (LATEKOL D® of BASF) 98.3g
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Polishing Bodies And Polishing Tools (AREA)
Abstract
The invention provides an abrasive product comprised of a web of undulated polymer filaments coated with a cured binder resin that includes abrasive particles having a hardness which renders them capable of removing soft coatings from a hard substrate surface but incapable of altering the hard substrate surface. The invention concerns also the use and the process of production of this abrasive product. <IMAGE>
Description
This invention provides a non-woven abrasive product capable of removing coatings from
hard substrate surfaces without altering the substrate surface.
Non-woven, low-density abrasive products made of a uniform lofty web of continuous three-dimensionally
bonded polyamide filaments, such as those abrasive products described in US
Patent No. 4 227 350 (Fitzer), have found successful application for treating or conditioning
various types of surfaces. These applications include, in part, removing mill scale from steel
coil stock, blending of weld lines, preparing surfaces for painting or other coating operations,
and removing various surface coatings in repair and maintenance operations.
Conventional abrasive products typically incorporate very hard minerals such as aluminum
oxide, silicium carbide, and the like that have very high hardness and toughness properties.
They are able to abrade any of a variety of workpieces including those made of steel, stone,
wood, plastic, and the like. This is an advantage in many applications, for example grinding,
finishing and polishing. When used for removing coating layers from a sensitive base
substrate, however, such hard abrasive minerals will also attack the substrate and are,
accordingly, less satisfactory.
It is already known, in the domestic environment, to use non-woven abrasive products for
cleaning sensitive surfaces such as coated cooking utensils, ceramic surfaces and the like.
US-A-4 991 362, for example, describes a hand scouring pad formed from an open lofty array
of filaments. Hand pads for use in the domestic environment are intended for use on small
areas and are not generally suitable for use in an industrial context because they will not
provide the high levels of efficiency that are required and will wear out rapidly.
WO-A-00/41850 discloses a durable, non-woven abrasive product having a significantly
longer useful product life compared to conventional, but similar, abrasive products. The
abrasive product has a porous, lofty web of multiple layers of coiled, autogenously bonded
thermoplastic filaments, binder resin, abrasive granules and size resin.
Other abrasive products that have been proposed for removing coatings from sensitive
substrates include coated abrasives as described, for example, in US-A-3 382 058 and molded
abrasive brushes as described, for example, in US-A-6 126 533.
A number of alternative approaches, not using abrasive products, have been taken in different
industries to specifically remove coating layers from sensitive base substrates.
For example, in some industries, methyl chloride has been used for many years for removing
coatings from base substrates. This chemical has a selective action. Only the top layers react
with the methyl chloride and soften, leaving the base material untouched. Methyl chloride is
now classified as a low category carcinogen if present in concentrations of more than 1% and,
consequently, its use is being phased out.
Aerospace maintenance companies have found chemical removal of coatings useful because
aerospace substrates typically comprise materials, for example aluminum alloy, that are easily
damaged by conventional abrasives. Chemical removal of coatings as a technique is also
rapidly applicable to large surface areas. The main application is paint removal on the body
of an aircraft (one AirbusTM aircraft Model A 340, for example, represents 2000 m2 of painted
surface) but another important application is sealant removal from fuel tanks and various other
areas. However, chemical strippers and softeners are not allowed on composite materials and
cannot, therefore, be used for coatings removal on all parts of an aircraft.
Increasing use is being made of composite and aluminum alloy panels in the automotive
manufacturing industry, and similar problems in selective removal of coatings from such
substrates are also experienced in the automotive repair trade.
Other techniques for removing coatings from substrates include the following: blasting using
plastic and natural media; cryogenic removal; water-jet removal; and laser removal.
Plastic/natural media blasting and laser removal are not suitable for large surface areas, while
cryogenic and water-jet removal are not suitable for use on composites. Moreover, each of
those techniques requires the use of comparatively expensive equipment. There is therefore
an urgent, increasing and important need for a selective coating removal technique featuring
many of the following properties:
- effectiveness on both metallic and composite substrates
- high efficiency, enabling coating removal over an area of at least 4m2/h, preferably 6m2/h (working time only; preparation, for instance masking, protecting, cleaning, not included)
- uniform finish
- selectivity, i.e. no damage to the substrate or its surface preparation (e.g. chromic anodisation in the case of aluminum; primer in the case of composite) coupled with effective removal of the coating(s)
- controlled average roughness of the substrate, to allow repainting
Useful exploitation is made of the surprising discovery that using abrasive granules bonded to
a particular type of porous, lofty web by a particular type of binder resin results in a selective
abrasive product.
The present invention provides an abrasive product comprising:
The present invention further provides a process for making an abrasive product, said process
comprising:
The present invention therefore provides a selective non-woven abrasive product comprising a
porous, lofty web preferably of multiple layers of coiled, autogenously bonded thermoplastic
filaments, a conformable binder resin, abrasive granules and optionally a size resin. The
conformable binder resin is advantageously provided by including a latex in the binder resin
formulation. The abrasive granules are preferably soft, preferably with a Moh's hardness of 4
or less.
More preferably, the present invention provides an abrasive product comprising
- a porous, lofty web of multiple layers of coiled, autogenously bonded polyamide filaments, the web having a basis weight of between 0.8 and 1.80 kg/m2,
- a binder resin wherein the binder resin is selected in the group consisting of
- a) a mix of a phenolformaldehyde resin and an aqueous dispersion of acrylonitrile butadiene polymer with a dry materials weight ratio of resin/polymer in the range of from 15/85 to 35/65, preferably from 20/80 to 40/60,
- b) a mix of a water-dispersible epoxy resin and an aqueous dispersion of acrylonitrile butadiene polymer with a dry materials weight ratio of resin/polymer in the range of from 40/60 to 60/40,
- abrasive granules, and optionally
- a size resin.
The abrasive granules may vary in Moh's hardness depending on the coating to be removed
and the substrate to be preserved. The abrasive granules have preferably a Moh's hardness of
4 or less (typically between 2 and 4).
Suitable abrasive granules may be any known abrasive particles or materials commonly
known as plastic blasting media.
Examples of plastic blasting media include ground thermoplastic or thermosetting polymer
particles, melamine formaldehyde media (plastic media type III) and other particles such as
plastic particles from type I to VI.
The abrasive granule size may vary from 10 grit to 600 grit (average diameter 2 to 0.01 mm).
Agglomerated granules of abrasive particles and a binder may also be useful.
The abrasive product may also contain mixtures of several granule sizes, different abrasive
materials uniformly incorporated therein or different abrasive sizes, hardnesess or materials.
Abrasive granules should preferably be applied in an amount by weight of between 30 and
60% of the wet binder resin mix, more preferably in an amount of between 35 and 45%.
The preferred binder resin employed in the production of the present abrasive products has a
liquid state to provide a coatable and impregnating composition. Yet it can be cured to form a
tough, adherent material capable of adherently bonding the optional abrasive granules to the
web even under aggressive use conditions (though the abrasion nevertheless remains
selective).
When the binder resin material comprises a mix of a phenolformaldehyde resin and an
aqueous dispersion of acrylonitrile butadiene polymer, an anti-foaming agent is preferably
used to prevent latex foaming; a lubricant is preferably used to provide smearing resistance
and a thickener is preferably added to achieve a workable viscosity of coating. The
resin/polymer weight ratio (dry materials) is preferably 25/75.
When the resin binder material comprises a mix of a water-dispersible epoxy resin and an
aqueous dispersion of acrylonitrile butadiene polymer, a curing agent is preferable used for
the epoxy; an anti-foaming agent is preferably used to prevent latex foaming, and a lubricant
is preferably used to provide smearing resistance. The resin/polymer weight ratio (dry
materials) is preferably 50/50.
In an abrasive product in accordance with the invention, the resin component of the binder
resin ensures the cohesion of the porous, lofty web and the adhesion of the abrasive granules,
and provides the product with thermal resistance.
When the resin component of the binder resin is a phenolfonnaldehyde resin, it preferably has
a very high water tolerance to allow admixture with a high percentage of a latex dispersion
without the formation of gels denoting incompatibility. Such a resin would not have
advanced much in the condensation reaction between formaldehyde and phenol and would
have a low molecular weight. Most preferably, the resin has a water tolerance of at least
300% by weight (meaning that it can be mixed with 3 times its own weight of water without
precipitation).
Suitable phenolformaldehyde resins are commercially available, for example, under the trade
designations Lacfen® 420 from Satef Hüttenes Albertus Spa or SW378® from Bakelite
Corporation.
A suitable water-dispersible epoxy resin is commercially available, for example, under the
trade designation EPI-REZ CMD 3522W60, from Shell Chemical Co., and a suitable epoxy
curing agent for the epoxy resin is 2MI commercialized by Merck Clevenot. Further
information on the use of water-dispersible epoxy resins in abrasive products can be obtained
from US-A-5 549 719.
The acrylonitrile butadiene polymer is preferably carboxylated (hereinafter referred to as an
"NBR" latex) and functions to provide the abrasive product with thermal resistance, thereby
protecting the filaments of the porous, lofty web from softening at high temperatures. An
NBR latex does not exhibit residual thermoplasticity as a result of heating, and provides the
abrasive product with flexibility and smear resistance.
Suitable acrylonitrile butadiene polymerlatex compositions are commercially available, for
example, under the trade designations, HYCAR® latex 1561 from B.F. Goodrich Co.;
LN240S® from BASF and, preferably, PERBUNAN® N latex X 2342 commercialized by
Bayer S.A.
Suitable anti foaming agents are commercially available, for example, under the trade
designations "1520" from Dow Coming Corp., of Midland, MI, USA; "1512M" from
Hercules and, preferably, BYK 22 from BYK Chemie. The amount of anti foam agents
included in the present abrasive products can preferably be an amount by weight of less than
5% of the water dispersion of acrylonitrile butadiene polymer, preferably less than 5%, more
preferably less than 4%, most preferably less than 3%.
Suitable lubricants are alkali metal salts of stearic acid. A preferred lubricant is an aqueous
dispersion of calcium stearate commercially available under the trade designation
SOLUFAX® from HQ France. The amount of lubricants included in the present abrasive
products is preferably an amount by weight less than 15% of the total dry binder (resin,
acrylonitrile butadiene polymer and optional components), preferably less than 10%, more
preferably less than 6%, most preferably about 4%.
Suitable thickeners used for adjusting the viscosity of the binder system include for example
salts of polyacrylic acid carboxymethyl cellulose, guar gum, gum tragacanth, homo- and
copolymers of poly (vinyl alcohol), methyl cellulose, modified starch and amorphous silica.
A preferred thickener is commercially available under the trade designation LATEKOL D®
from BASF. The amount of thickener included in the present abrasive products can
preferably be an amount by weight of less than 5% of the water dispersion of acrylonitrile
butadiene polymer, more preferably less than 4%, most preferably less than 3%.
The binder resin of an abrasive product in accordance with the invention may include other
optional additives such as colorants, fillers and grinding aids. Examples of colorants known
for use in abrasive products include inorganic pigments and organic dyes. Fillers known for
use in abrasive products take the form of short organic or inorganic fibres, spheres and
particles, and comprise materials that are primarily inert having regard to the intended use of
the abrasive product. Filler materials that are known for use in abrasive products include
calcium carbonate and fumed silica. Known grinding aids for use in abrasive products include
poly(vinyl chloride) and potassium fluoroborate.
In order to further anchor the optional abrasive granules to the web, a second, or "size"
coating of resin may be applied to the abrasive product. Size resins suitable for these size
coatings are constitutionally the same as those used for the initial coating, and are applied and
hardened in the same manner.
Processes used to prepare the web of the low-density abrasive products used in the present
invention are set out in US Patent No. 4 227 350 or in WO-A-00/41850. The major
differences are the nature of the binder (or binders) and of the abrasive granules used.
The abrasive product can be formed in a continuous process, if desired, virtually directly from
the basic ingredients, i.e., from polyamide filament-forming material, liquid curable binder
resin and abrasive granules. That is, the polyamide filament-forming material can be extruded
directly into a lofty, open, porous, filament web. Abrasive granules, binder and optional size
resins are then applied to the web to provide the finished abrasive product. In the web-making
process employed in the present invention, polyamide filament-forming material is inserted
into an extruder equipped with a spinneret head which has a multitude of openings equally
spaced in at least one row, preferably in a plurality of spaced rows of equally spaced openings.
The row or rows of molten filaments are then extruded downwardly, permitted to freely fall a
short distance through an air space and then into a quench bath. As the filaments enter the
quench bath, they begin to coil and undulate, thereby setting up a degree of resistance to the
flow of the molten filaments, causing the molten filaments to oscillate just above the bath
surface. The spacing of the extrusion openings from which the filaments are formed is such
that, as the molten filaments coil and undulate at the bath surface, adjacent filaments touch
one another. The coiling and undulating filaments are still sufficiently tacky as this occurs,
and where the filaments touch, most adhere to one another to cause autogenous bonding to
produce a lofty, open, porous filament web.
The web is then directed into a quench bath between opposed rollers positioned a distance
below the surface of the quench bath where the filaments of the integrated mat will still be
sufficiently plastic to be permanently deformed as they pass therebetween.
These rolls are operated at the same speed but in opposite directions to draw the formed
filament web away from the area where the filaments initially coil and bond together. The
rolls are spaced to contact the surfaces of the web with slight pressure sufficient to smooth
any uneven surface lops or undulations to provide a web with generally flat surfaces. The
roller contact will not provide a higher density of filaments at either surface of the web.
Instead, the web will have a defined thickness after being passed between the rollers. For this
purpose, the surfaces of the rolls are preferably smooth to produce the generally flat surface.
Since useful abrasive products may also have other than flat surfaces, the roll surfaces may
have other configurations to provide an abrasive product with a modified surface. For
example, a pleated surface roller will produce webs with a pleated surface. Alternatively, the
roller surface may have spikes uniformly disposed on its surface to provide for more secure
web handling. The rolls are operated at a surface speed substantially slower than the
extrusion speed to permit sufficient time for the filaments to coil and undulate and form a
lofty web with a high degree of undulation in each filament.
This process produces a web wherein each filament is coiled and undulated throughout its
length.
The undulations of each filament are typically irregular although it is possible to adjust the
process to produce regular helically coiled filaments. Irregular filament undulation is
characterized by random looping, kinking or bending of the filaments through the web in a
pattern defined generally by the pattern of openings of the spinneret.
It should be noted that, where more than one row of filaments is extruded, a web is produced
having layers of coiled and undulated filaments, each layer representing a row of extruded
filaments. Each layer is discernible, sometimes with great difficulty, in the web.
The adjacent filaments between layers will also be autogenously bonded together for the most
part where they touch one another.
A binder resin containing abrasive granules is prepared by mixing the resin, the polymer, the
abrasive granules and the optional components. The binder resin containing abrasive granules
is then applied to the web in an appropriate amount using any suitable known manufacturing
techniques, including roll-coating, dip-coating and spray-coating. After application of the
binder resin containing abrasive granules, the web is exposed to conditions for hardening the
binder. Alternatively, the binder resin may be applied to the web at the desired coating weight
without the abrasive granules, the latter then being drop-coated onto the web before the binder
hardens. As a further alternative, suitable especially for small-scale production of abrasive
discs in accordance with the invention, discs can be prepared from the uncoated web by die-cutting
and then immersed in a mixture of the binder resin and the abrasive granules. The
impregnated discs are then rotated at an appropriate speed to remove a controlled amount of
the mixture until only the desired amount (corresponding to the desired coating weight)
remains. The discs are then exposed to conditions suitable for hardening the binder.
Preferred conditions for hardening the binder include conditions that cause rapid hardening
such as exposure to elevated temperature or exposure to radiation.
The abrasive products produced by the process described above are particularly suited for
selective abrasion.
The present abrasive products are extremely open, porous, and lofty which permits prolonged
usage of the abrasive product for conditioning (for example, surfaces where large amounts of
attrited matter are produced), without filling the web and thus interfering with the abrasive
product's properties. The degree of openness and loftiness is evidenced by the web void
volume which is typically at least about 80% (preferably about 85% to about 97%) in the
uncoated state. Upon coating with the binder resin, the web also has a considerable degree of
structural integrity that permits prolonged usage of the abrasive article.
The flattening effect of the rollers used in the production of the web provides a unique
abrasive structure that is highly open at the surface yet has a flat face capable of use on flat
surfaces without requiring bending or modification of the web. Additionally, the web, even
with the binder resin coating and abrasive granules, is flexible and conformable and will
typically conform to most surfaces upon which it is used.
The web may be made in a wide variety of thicknesses, limited principally by the design of
the spinneret through which it is extruded and the gap between the rollers that direct the web
into the quench bath. Typical web thicknesses useful for abrasive products will vary between
0.5 to 8 cm. The filament diameter of the filaments in the web produced by the process
described above may be varied by modification of the web-making process.
Typically, the filament diameter for a suitable web will be in the range of from 5 to 125 mils
(0.13 to 3.18 mm). Spinneret extrusion openings of 5 to 125 mils (0.13 to 3.18 mm) will
produce such webs. Preferably, the filament diameter is in the range of from 13 to 17 mils
(0.33 to 0.44 mm). The openings in the spinneret will be in rows, as previously stated, and
separated by at least about 0.1 inch (2.54 mm) to produce satisfactory results. The openings
of adjacent rows may be offset from one another although the spinneret performs suitably
when the openings in the rows are aligned.
In order to realize long-life characteristics, the resultant web should weigh between 0.8 and
1.80 kg/m2 and preferably should weigh between 0.8 and 1.0 kg/m2. Lesser weights do not
provide the increased useable life of the resulting abrasive product. Heavier web weights
results in a product that is insufficiently compliant to smoothly run against a typical
workpiece.
The abrasive products of the present invention may be in any of a variety of shapes as
typically encountered for nonwoven abrasive products. For example, suitable shapes are both
rectangular pads and disc-shaped pads which may have a central opening for attachment of an
arbor or rod for rotation. Alternatively, they may be cut into shapes such as rectangular
shapes and mounted about the periphery of a rotatable hub to provide a flap wheel. Other
shapes are also contemplated such as endless belts and abrasive wheels or sheets. The wheels
typically have a central opening for support by an appropriate arbor to enable the wheel to be
rotated in use.
The abrasive product of this invention may be laminated to other layers to provide a modified
abrasive article. For example, the abrasive product may be laminated to a foam or sponge
layer to provide dual functions or to provide a cushioning layer. Alternatively the abrasive
product may be laminated to a web that provides one component of a hook-and loop
attachment system to enable the abrasive product to be secured to the back-up pad of an
abrading machine. Any of a variety of mounting devices or handles may also be applied to
the abrasive product to provide an implement that may have a removable or permanently
attached handle.
The abrasive products of the present invention are selective treating or conditioning
implements that have been found to perform in a superior manner to conventional abrasive
products in the situations such as efficiently removing paint from metallic (such as aluminum)
or composite substrates, allowing complete selective removal of the paint without destroying
the primer covering the metallic or composite substrate. There is no damage to the surface
preparation such as chromic anodisation (CAO) in case of aluminum, primer in case of
composite though a rapid abrasion of the desired layer is obtained.
The present invention is therefore further directed to a process for cleaning a base substrate
covered with a layer to be removed comprising abrading the said layer with an abrasive
product described above. The base substrate is preferably selected in the group consisting of
aluminum or aluminum alloy, steel, plastic materials and composites and more particularly is
made of aluminum, aluminum alloy or composite. The base substrate could, alternatively, be
wood.
The preferred features of the above abrasive products also apply to the above process for
cleaning a base substrate.
The present process provides a cheap and effective alternative to conventional selective paint-removal
processes.
The present invention is illustrated and described in Figures 1-3.
Fig. 1 is a schematic illustration of the process used to make an abrasive product of the
present invention.
Figs. 2-3 are perspective views that illustrate two embodiments of an abrasive product of the
present invention.
The present invention is further illustrated by the following examples.
As illustrated in Fig. 1, polyamide filament-forming material is heated to a molten state and
extruded from an extrusion spinneret 10 which contains at least one row of openings to
provide a bundle of free-falling filaments 11. Filaments 11 are permitted to freely fall through
an air space into a quench bath 12 where they coil and undulate at or near the surface of bath
12 to form an autogenously bonded web 13. While it is still sufficiently plastic to be
permanently deformed, web 13 is then passed between opposed smooth-surfaced rollers 14
and 15 which may have a pattern of uniformly spaced spikes projecting from the roller surface
which are positioned to provide a substantially flat-surfaced web. Web 13 is then drawn
around one of the rollers, e.g. roller 15, for removal from quench bath 12. Web 13 is then
passed over idler roll 16 between guide roll set 17 and dried in forced air oven 18 to remove
residual quench liquid. The web is wound onto a roll and stored for about 4 weeks to allow
morphological equilibration.
The web is then passed through roll coating station 19 where liquid curable binder resin 20 is
applied to web 13. Other conventional web coating techniques may be employed to coat the
web so long as such techniques provide a substantially uniform binder resin coating. For
example, dip coating and spray-coating techniques may also be used. The binder resin
coating should be sufficient to permit uniform coating of the web with abrasive granules.
Thereafter, the wet coated web is passed beneath a first abrasive granule dropping station 21
to coat one side of the web with abrasive granules and deployed in an S-shaped arrangement
around suitable idler rollers 21a, 21b, 21c, 21d and 21e to reverse the web surfaces (that is,
face the bottom side up). The other surface of the web is then passed under a second abrasive
granule depositing station 22 to provide a web, which has been coated on both web surfaces
with abrasive granules. Other abrasive granule applications or coating devices may also be
used; e.g. the abrasive granules may be applied by spray methods such as employed in
sandblasting except with milder conditions, by electrostatic coating method, and the like. The
abrasive granule-coated web is then passed through forced air oven 23, to cure the first binder
resin coating. If required, a second coating of a size resin may be applied with a suitable
device such as spray station 24 which simultaneously sprays top and bottom surfaces of the
web with a quantity of size resin material which will bond the abrasive granules to the surface
of the web. The quantity of the size resin coating should be limited so it will not cover or
mask the abrasive granules. Once coated, the web is then passed through forced air oven 25,
and finally into converting station 26 where it is cut into desired shapes 27.
Typical shapes of the abrasive product of the invention include those depicted by Figs. 2 and
3. Fig. 2 shows a rectangular shape abrasive product 30 while Fig. 3 shows an annulus shape
abrasive product 50.
The filament-forming material which is extruded to provide the lofty web contained in the
low-density abrasive product of the invention is formed of a thermoplastic polyamide material
which can be extruded through extrusion orifices to form filaments. Particularly useful
polyamide materials for forming the polycaprolactam and poly(hexamethylene adipamide)
(e.g., commonly referred to as nylon 6 and nylon 6,6). Other useful filament forming
materials may include polyolefins (e.g., polypropylene and polyethylene), polyester (e.g.,
polyethylene terephthalate), polycarbonates and the like.
In a preferred form the web has a basis weight of between 0.8 and 1.0 Kg/m2 and a thickness
of 1.5 cm, and is formed from nylon 6 fibers having a diameter of between about 13 and 17
mils (0.33 and 0.44 mm). The total coating weight of the wet binder resin plus abrasive
granules applied to the web is in the range of from 4500 - 7000 g/m2 (more preferably in the
range of from 5000 - 6000 g/m2), of which the abrasive granules preferably comprise between
30 and 60% by weight (more preferably between 35 and 45%).
The following compounds were successively poured into an agitator:
and agitated for 20 minutes at about 600 rpm.
Phenolformaldehyde resin (LACFEN® 420 of Satef Hüttenes Albertus SpA) | 165 g |
Aqueous dispersion of a polymer of acrylonitrile and 1,3-budadinene (PERBUNAN® N latex X 2342 of Bayer S.A.) | 845 g |
Antifoam ( | 17 g |
Aqueous dispersion of calcium stearate (SOLUFAX® of HQ France) | 92 g |
Aqueous dispersion of a copolymer of acrylic acid ester and acrylic acid (LATEKOL D® of BASF) | 17 g |
760 g of plastic material granules having a hardness of 3.5 Moh (Melamine Formaldehyde
30/40 of Maxi Blast, IN, USA) were added in small parts under agitation. Agitation was
continued for 20 minutes after the last addition of plastic material granules. A suspension of
plastic material granules in the binder resin was thus obtained.
A continuous filament non-woven web having a thickness of 1.5 cm was prepared as
disclosed in WO 00/41850 from nylon 6 fibers. The web had a basis weight of about 0.9
Kg/m2 and was formed from fibres having a diameter of about 15 mils (0.39 mm). Discs
having a diameter of 15 cm were prepared from the web by die cutting.
The discs were mounted on the spin rod of the agitator and immersed in the above mixture of
binder resin and plastic material granules for a few minutes. The impregnated discs were then
removed from the mixture and rotated and their weight was checked at intervals until a target
weight was obtained that corresponded to a wet coating weight of the mixture in the range
5600 - 5770g/m2.
The discs were put in an oven at 120°C for 45 minutes, and were then allowed to cool.
The method of Example 1 was followed, except as noted below.
The compounds poured successively into the agitator were as follows:
The compounds poured successively into the agitator were as follows:
Aqueous dispersion of a polymer of acrylonitrile and 1,3-budadinene (PERBUNAN® N latex X 2342 of Bayer S.A.) | 600g |
Antifoam ( | 12.4g |
Epoxy resin (EPIREZ CMD 3522 W60 from Shell) | 410g |
Catalytic agent (2MI of Merck Clevenot) | 12.3g |
Aqueous dispersion of a copolymer of acrylic acid ester and acrylic acid (LATEKOL D® of BASF) | 98.3g |
The same plastic material granules were used but in an amount of 810g. The impregnated
discs were rotated until a target weight was obtained that corresponded to a wet coating
weight of the binder resin/plastic granules mixture in the range 5100 - 5550g/m2. The discs
were then put in an oven at 120°C for 100 minutes, following which they were allowed to
cool.
Abrasive discs prepared according to the Examples 1 and 2 were evaluated for performance
by using a selectivity test.
The selectivity test comprised rotating the abrasive discs against a sample of aerospace panel
for a period of about 10 seconds.
The aerospace panel consisted of an anodised aluminum alloy substrate covered with a base
primer and then a paint system comprising a primer layer, intermediate layers and a top coat.
The panel was artificially aged in an oven.
Each abrasive disc was rotated on a rotating shaft at 3400 rpm with a hand-held force on the
panel. As the disc was rotated, it was oscillated in a linear direction on the panel's surface for
a distance of 3 to 4 cm, producing an abraded area with a width corresponding to the diameter
of the disc.
It was found that the layers of the paint system were removed exposing the base primer but
without exposing the aluminum alloy substrate.
Abrasive discs prepared according to the Examples 1 and 2 were evaluated for performance
by performing a surface finish test.
A procedure similar to the selectivity test procedure was used but, as the disc was rotated, it
was oscillated in a linear direction on the panel's surface in order to remove the layers of the
paint system and expose the base primer over an area of about 20 cm2.
The surface finish in the treated area was good. The panel had the uniform color of the base
primer and the surface was smooth enough to allow direct re-painting.
Abrasive discs prepared according to the Examples 1 and 2 were evaluated by using a
smearing test. Each disc was rotated, in a rotating shaft at 3400 rpm with a hand-held force,
against a stainless steel panel. As the disc was rotated, it was oscillated in a linear direction
on the panel.
The smearing resistance was good since there was no deposit left by any of the discs on the
panel.
Claims (27)
- An abrasive product comprising:a. a three-dimensional web comprised of a plurality of undulated polymeric filaments, with adjacent filaments contacting and being bonded to one another;b. a cured binder resin comprised of the cured product of a mixture of an aqueous dispersion of carboxylated butadiene-acrylonitrile copolymer and a second binder selected from the group consisting of phenolic resin and aqueous-dispersible epoxy resin; andc. a plurality of abrasive particles having a hardness which renders them capable of removing soft coatings from a hard substrate surface but incapable of altering the hard substrate surface.
- The surface conditioning product of claim 1, wherein said abrasive particles have a Moh's hardness value not greater than 4.
- The abrasive product of claim 1 wherein said three-dimensional web comprises a web of multiple layers of coiled, autogenously bonded polyamide filaments having a basis weight of between 0.8 and 1.80 kg/m2.
- The abrasive product of claim 3, wherein said three-dimensional web has a basis weight of between 0.8 and 1.0 Kg/m2.
- The abrasive product of claim 1 wherein said phenolic resin is a phenolformaldehyde resin.
- The abrasive product of claim 1 wherein said phenolformaldehyde resin and said carboxylated butadiene-acrylonitrile polymer are contained in said mixture on a dry weight basis in a ratio of phenolformaldehyde resin to carboxylated butadiene-acrylonitrile copolymer in the range of 15/85 to 35/65.
- The abrasive product of claim 1 wherein said aqueous-dispersible epoxy resin and said carboxylated butadiene-acrylonitrile polymer, on a dry weight basis, are contained in said mixture in a weight ratio of resin to polymer of from 40/60 to 60/40.
- The abrasive product of claim 1 further including a size coating over the abrasive particles and cured binder resin coating.
- The abrasive product of claim 8 wherein said size coating is comprised of the same components as the cured binder resin coating.
- The abrasive product of claim 1 wherein said abrasive particles are comprised of plastic blasting media.
- The abrasive product of any of claims 1 to 10, wherein the binder resin is a mix of a phenolformaldehyde resin and an aqueous dispersion of carboxylated butadiene-acrylonitrile copolymer with a dry materials weight ratio of resin/polymer of 25/75.
- The abrasive product of any of claims 1 to 11, wherein the binder resin further comprises a lubricant.
- The abrasive product of any of claims 1 to 12, wherein the binder resin further comprises an anti-foaming agent.
- The abrasive product of any of claims 1 to 13, wherein the binder resin further comprises a thickener.
- The abrasive product of any of claims 1 to 14, wherein the binder resin is a mix of an aqueous-dispersible epoxy resin and an aqueous dispersion of acrylonitrile butadiene polymer with a dry materials weight ratio of resin/polymer of 50/50.
- The abrasive product of any of claims 1 to 15 wherein the binder resin further comprises a curing agent for the epoxy resin.
- The abrasive product of any of claims 1 to 16, wherein the polymer filament is comprised of nylon 6 or nylon 6,6.
- The abrasive product of any of claims 1 to 17, wherein the filaments have a diameter of 13 to 17 mils (0.33 to 0.44 mm).
- The abrasive product of any of claims 1 to 18, wherein the filaments are extruded thermoplastic polyamide material.
- A process for cleaning a base substrate covered with a layer to be removed comprising abrading the said layer with an abrasive product of any of claims 1 to 19.
- The process of claim 20, wherein the base substrate is selected in the group consisting of aluminum or aluminum alloy, steel, plastic materials and composites.
- The process of claim 20 or claim 21, wherein the base substrate is made of aluminum, aluminum alloy or composite.
- A process for making an abrasive product, said process comprising:a. providing a three-dimensional web comprised of a plurality of undulated polymeric filaments, with adjacent filaments contacting and being bonded to one another;b. coating the polymeric filaments of the web with a resin binder comprised of a mixture of an aqueous dispersion of carboxylated butadiene-acrylonitrile copolymer with a second binder selected from the group consisting of phenolic resin and aqueous-dispersible epoxy resin;c. depositing on the coating before curing a plurality of abrasive particles having a hardness which renders them capable of removing soft coatings from a hard substrate but incapable of altering the hard substrate surface; andd. curing the coating to provide the abrasive product.
- The method of claim 23, wherein said abrasive particles have a Moh's hardness value not greater than 4.
- The method of claim 23, wherein said three-dimensional web comprises a web of multiple layers of coiled, autogenously bonded polyamide filaments having a basis weight of between 0.8 and 1.80 kg/m2.
- The method of claim 23 further including applying a size coating over the resin binder coating and curing the size coating.
- The method of claim 23 wherein steps b and c are carried out simultaneously by mixing the abrasive particles with the resin binder mixture and coating the resin binder mixture containing abrasive particles onto the web.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP02291955A EP1386696A1 (en) | 2002-08-02 | 2002-08-02 | Abrasive product and the production process thereof |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP02291955A EP1386696A1 (en) | 2002-08-02 | 2002-08-02 | Abrasive product and the production process thereof |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1386696A1 true EP1386696A1 (en) | 2004-02-04 |
Family
ID=30011279
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP02291955A Withdrawn EP1386696A1 (en) | 2002-08-02 | 2002-08-02 | Abrasive product and the production process thereof |
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Country | Link |
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EP (1) | EP1386696A1 (en) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1996009141A1 (en) * | 1994-09-19 | 1996-03-28 | Minnesota Mining And Manufacturing Company | Abrasive articles and methods of making same |
US5919549A (en) * | 1996-11-27 | 1999-07-06 | Minnesota Mining And Manufacturing Company | Abrasive articles and method for the manufacture of same |
US5954844A (en) * | 1996-05-08 | 1999-09-21 | Minnesota Mining & Manufacturing Company | Abrasive article comprising an antiloading component |
-
2002
- 2002-08-02 EP EP02291955A patent/EP1386696A1/en not_active Withdrawn
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1996009141A1 (en) * | 1994-09-19 | 1996-03-28 | Minnesota Mining And Manufacturing Company | Abrasive articles and methods of making same |
US5954844A (en) * | 1996-05-08 | 1999-09-21 | Minnesota Mining & Manufacturing Company | Abrasive article comprising an antiloading component |
US5919549A (en) * | 1996-11-27 | 1999-07-06 | Minnesota Mining And Manufacturing Company | Abrasive articles and method for the manufacture of same |
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