Patent ID: 12208491

DETAILED DESCRIPTION

Magnetizable abrasive particles are described herein by way of example and can have various configurations. For example, the magnetizable abrasive particles can be constructed of various materials including but not limited to ceramics, metal alloys, composites or the like. Similarly, the magnetizable abrasive particles can be substantially entirely constructed of magnetizable material, can have magnetizable portions disposed therein (e.g., ferrous traces), or can have magnetizable portions disposed as layers on one or more surfaces thereof (e.g., one or more surfaces can be coated with a magnetizable material) according to some examples. The magnetizable abrasive particles can be shaped according to some examples. According to other examples the magnetizable abrasive particles can comprise crushed grains, agglomerates, or the like. Magnetizable abrasive particles can be used in loose form (e.g., free-flowing or in a slurry) or they can be incorporated into various abrasive articles (e.g., coated abrasive articles, bonded abrasive articles, nonwoven abrasive articles, and/or abrasive brushes).

Referring now toFIGS.1and1A, an exemplary magnetizable abrasive particle100is disclosed. The magnetizable abrasive particle100can have a shaped ceramic body110and magnetizable layers120A and120B. The magnetizable layers120A and120B are comprised of magnetizable particles125retained in a binder matrix130(also referred to simply as “binder”) as further shown inFIG.1A. The ceramic body110can have two opposed major surfaces160,162connected to each other by three side surfaces140a,140b,140c. The magnetizable layer120A is disposed on side surface140aof ceramic body110and the magnetizable layer120B is disposed on the side surface140c.

The magnetizable layer120A or120B can optionally extend somewhat onto other surfaces of the shaped ceramic body110. In some embodiments, the magnetizable layer can extend to cover a majority of any surface of the shaped ceramic body110as desired. As shown, magnetizable layer120A and120B can be coextensive with side surface140aand140c, respectively. Magnetizable abrasive particles of the type shown can be aligned with the magnetizable layer-coated surface parallel to magnetic field lines of force as will be discussed subsequently.

In general, since orientation of the magnetic field lines tends to be different at the center and edge of a magnet it is also possible to create various desired orientations of the magnetizable abrasive particles during their inclusion into an abrasive article.

The magnetizable layer can be a unitary magnetizable material, or it can comprise magnetizable particles in a binder matrix. Suitable binders can be vitreous or organic, for example, as described for the binder matrix130hereinbelow. The binder matrix can be, for example selected from those vitreous and organic binders. The ceramic body can comprise any ceramic material (a ceramic abrasive material), for example, selected from among the ceramic (i.e., not including diamond) abrasive materials listed hereinbelow. The magnetizable layer can be disposed on the ceramic body by any suitable method such as, for example, dip coating, spraying, painting, physical vapor deposition, and powder coating. Individual magnetizable abrasive particles can have magnetizable layers with different degrees of coverage and/or locations of coverage. The magnetizable layer can be essentially free of (i.e., containing less than 5 weight percent of, in yet other cases containing less than 1 weight percent of) ceramic abrasive materials used in the ceramic body.

The magnetizable layer can consist essentially of magnetizable materials (e.g., >99 to 100 percent by weight of vapor coated metals and alloys thereof), or it can contain magnetic particles retained in a binder matrix. The binder matrix of the magnetizable layer, if present, can be inorganic (e.g., vitreous) or organic resin-based, and is typically formed from a respective binder precursor.

Magnetizable abrasive particles according to the present disclosure can be prepared, for example, by applying a magnetizable layer or precursor thereof to the ceramic body. Magnetizable layers can be provided by physical vapor deposition as discussed hereinbelow. Magnetizable layer precursors can be provided as a dispersion or slurry in a liquid vehicle. The dispersion or slurry vehicle can be made by simple mixing of its components (e.g., magnetizable particles, optional binder precursor, and liquid vehicle), for example. Exemplary liquid vehicles include water, alcohols (e.g., methanol, ethanol, propanol, butanol, ethylene glycol monomethyl ether), ethers (e.g., glyme, diglyme), and combinations thereof. The dispersion or slurry can contain additional components such as, for example, dispersant, surfactant, mold release agent, colorant, defoamer, and rheology modifier. Typically, after coating onto the ceramic bodies the magnetizable layer precursor is dried to remove most or all of the liquid vehicle, although this is not a requirement. If a curable binder precursor is used, then a curing step (e.g., heating and/or exposure to actinic radiation) generally follows to provide the magnetizable layer.

Vitreous binder can be produced from a precursor composition comprising a mixture or combination of one or more raw materials that when heated to a high temperature melt and/or fuse to form a vitreous binder matrix. Further disclosure of appropriate vitreous binders that can be used with the abrasive article can be found in U.S. Provisional Pat. Appl. Ser. Nos. 62/412,402, 62/412,405, 62/412,411, 62/412,416, 62/412,427, 62/412,440, 62/412,459, and 62/412,470, which are each incorporated herein by reference in their entirety.

In some embodiments, the magnetizable layer can be deposited using a vapor deposition technique such as, for example, physical vapor deposition (PVD) including magnetron sputtering. PVD metallization of various metals, metal oxides and metallic alloys is disclosed in, for example, U.S. Pat. No. 4,612,242 (Vesley) and U.S. Pat. No. 7,727,931 (Brey et al.). Magnetizable layers can typically be prepared in this general manner, but care should be generally taken to prevent the vapor coating from covering the entire surface of the shaped ceramic body. This can be accomplished by masking a portion of the ceramic body to prevent vapor deposition.

Examples of metallic materials that can be vapor coated include stainless steels, nickel, cobalt. Exemplary useful magnetizable particles/materials can comprise: iron; cobalt; nickel; various alloys of nickel and iron marketed as Permalloy in various grades; various alloys of iron, nickel and cobalt marketed as Fernico, Kovar, FerNiCo I, or FerNiCo II; various alloys of iron, aluminum, nickel, cobalt, and sometimes also copper and/or titanium marketed as Alnico in various grades; alloys of iron, silicon, and aluminum (typically about 85:9:6 by weight) marketed as Sendust alloy; Heusler alloys (e.g., Cu2MnSn); manganese bismuthide (also known as Bismanol); rare earth magnetizable materials such as gadolinium, dysprosium, holmium, europium oxide, and alloys of samarium and cobalt (e.g., SmCo5); MnSb; ferrites such as ferrite, magnetite; zinc ferrite; nickel ferrite; cobalt ferrite, magnesium ferrite, barium ferrite, and strontium ferrite; and combinations of the foregoing. In some embodiments, the magnetizable material comprises at least one metal selected from iron, nickel, and cobalt, an alloy of two or more such metals, or an alloy of at one such metal with at least one element selected from phosphorus and manganese. In some embodiments, the magnetizable material is an alloy containing 8 to 12 weight percent (wt. %) aluminum, 15 to 26 wt. % nickel, 5 to 24 wt. % cobalt, up to 6 wt. % copper, up to 1 wt. % titanium, wherein the balance of material to add up to 100 wt. % is iron. Alloys of this type are available under the trade designation “ALNICO”.

Useful abrasive materials that can be used as ceramic bodies include, for example, fused aluminum oxide, heat treated aluminum oxide, white fused aluminum oxide, ceramic aluminum oxide materials such as those commercially available as 3M CERAMIC ABRASIVE GRAIN from 3M Company of St. Paul, Minnesota, black silicon carbide, green silicon carbide, titanium diboride, boron carbide, tungsten carbide, titanium carbide, cubic boron nitride, garnet, fused alumina zirconia, sol-gel derived ceramics (e.g., alumina ceramics doped with chromia, ceria, zirconia, titania, silica, and/or tin oxide), silica (e.g., quartz, glass beads, glass bubbles and glass fibers), feldspar, or flint. Examples of sol-gel derived crushed ceramic particles can be found in U.S. Pat. No. 4,314,827 (Leitheiser et al.), U.S. Pat. No. 4,623,364 (Cottringer et al.); U.S. Pat. No. 4,744,802 (Schwabel), U.S. Pat. No. 4,770,671 (Monroe et al.); and U.S. Pat. No. 4,881,951 (Monroe et al.).

As discussed previously, the body of the abrasive particle can be shaped (e.g., precisely-shaped) or random (e.g., crushed). Shaped abrasive particles and precisely-shaped ceramic bodies can be prepared by a molding process using sol-gel technology as described in U.S. Pat. No. 5,201,916 (Berg); U.S. Pat. No. 5,366,523 (Rowenhorst (Re 35,570)); and U.S. Pat. No. 5,984,988 (Berg). U.S. Pat. No. 8,034,137 (Erickson et al.) describes alumina particles that have been formed in a specific shape, then crushed to form shards that retain a portion of their original shape features. In some embodiments, the ceramic bodies are precisely-shaped (i.e., the ceramic bodies have shapes that are at least partially determined by the shapes of cavities in a production tool used to make them).

Exemplary shapes of ceramic bodies include crushed, pyramids (e.g., 3-, 4-, 5-, or 6-sided pyramids), truncated pyramids (e.g., 3-, 4-, 5-, or 6-sided truncated pyramids), cones, truncated cones, rods (e.g., cylindrical, vermiform), and prisms (e.g., 3-, 4-, 5-, or 6-sided prisms).

Exemplary magnetizable materials that can be suitable for use in magnetizable particles can comprise: iron; cobalt; nickel; various alloys of nickel and iron marketed as Permalloy in various grades; various alloys of iron, nickel and cobalt marketed as Fernico, Kovar, FerNiCo I, or FerNiCo II; various alloys of iron, aluminum, nickel, cobalt, and sometimes also copper and/or titanium marketed as Alnico in various grades; alloys of iron, silicon, and aluminum (typically about 85:9:6 by weight) marketed as Sendust alloy; Heusler alloys (e.g., Cu2MnSn); manganese bismuthide (also known as Bismanol); rare earth magnetizable materials such as gadolinium, dysprosium, holmium, europium oxide, alloys of neodymium, iron and boron (e.g., Nd2Fe14B), and alloys of samarium and cobalt (e.g., SmCo5); MnSb; MnOFe2O3; Y3Fe5O12; CrO2; MnAs; ferrites such as ferrite, magnetite; zinc ferrite; nickel ferrite; cobalt ferrite, magnesium ferrite, barium ferrite, and strontium ferrite; yttrium iron garnet; and combinations of the foregoing. In some embodiments, the magnetizable material comprises at least one metal selected from iron, nickel, and cobalt, an alloy of two or more such metals, or an alloy of at one such metal with at least one element selected from phosphorus and manganese. In some embodiments, the magnetizable material is an alloy (e.g., Alnico alloy) containing 8 to 12 weight percent (wt. %) aluminum, 15 to 26 wt. % nickel, 5 to 24 wt. % cobalt, up to 6 wt. % copper, up to 1 wt. % titanium, wherein the balance of material to add up to 100 wt. % is iron.

The magnetizable particles can have any size, but can be much smaller than the ceramic bodies as judged by average particle diameter, in yet other cases 4 to 2000 times smaller, in yet other cases 100 to 2000 times smaller, and in yet other cases 500 to 2000 times smaller, although other sizes can also be used. In this embodiment, the magnetizable particles can have a Mohs hardness of 6 or less (e.g., 5 or less, or 4 or less), although this is not a requirement.

FIG.2shows an apparatus200for making coated abrasive articles according to one embodiment of the present disclosure. The apparatus200includes magnetizable abrasive particles202such as those previously illustrated and described. These magnetizable abrasive particles202can be removeably disposed within cavities of a distribution tool204as will be discussed subsequently. The apparatus200can have a first web path206guiding the distribution tool204through a coated abrasive article maker such that it passes adjacent to a portion of an outer circumference of an abrasive particle transfer roller222. The apparatus200can also include, for example, an unwind210, a make coat delivery system212, and a make coat applicator214. These components unwind a backing216, deliver a make coat resin218via a make coat delivery system212to the make coat applicator214and apply the make coat resin to a first major surface220of the backing. Thereafter, the resin coated backing216is positioned by an idler roller224for application of the abrasive particles202to the first major surface220coated with the make coat resin218. A second web path226for the resin coated backing216guides the resin coated backing through the coated abrasive article maker apparatus such that it passes adjacent to a portion of the outer circumference of the abrasive particle transfer roller222with the resin layer positioned facing the dispensing surface of the distribution tool204, which can be positioned between the resin coated backing216and the outer circumference of the abrasive particle transfer roller222. Suitable unwinds, make coat delivery systems, make coat resins, coat applicators and backings are known to those of skill in the art. The make coat delivery system212can be a simple pan or reservoir containing the make coat resin or a pumping system with a storage tank and delivery plumbing to translate the make coat resin to the needed location. The backing216can be a cloth, paper, film, nonwoven, scrim, or other web substrate. The make coat applicator can be, for example, a die coater, a roller coater, a spray system, or a rod coater. Alternatively, a pre-coated coated backing can be used for application of the abrasive particles to the first major surface.

As shown in the enlargement ofFIG.2A, the distribution tool204can include a plurality of cavities230having a complimentary shape to the intended magnetizable abrasive particle202to be contained therein.

As shown inFIG.2, an abrasive particle feeder232can supply at least some abrasive particles to the distribution tool204. The abrasive particle feeder232can supply an excess of magnetizable abrasive particles202such that there are more abrasive particles present per unit length of the distribution tool204in the machine direction than cavities230(FIG.2A) present. Supplying an excess of abrasive particles helps to ensure a majority to all of the cavities230within the distribution tool204are eventually filled with the magnetizable abrasive particles202. The abrasive particle feeder232can be the same width as the distribution tool204and supplies the magnetizable abrasive particles202across the entire width of the distribution tool204. The abrasive particle feeder232can be, for example, a vibratory feeder, a hopper, a chute, a silo, a drop coater, or a screw feeder.

Optionally, a filling assist member234can be provided after the abrasive particle feeder232to move the magnetizable abrasive particles202around on the surface of the distribution tool204and to help orientate or slide the abrasive particles into the cavities230(FIG.2A). The filling assist member234can be, for example, a doctor blade, a felt wiper, a brush having a plurality of bristles, a vibration system, a blower or air knife, a vacuum box236, one or more magnets or combinations thereof. The filling assist member234moves, translates, sucks, or agitates the magnetizable abrasive particles on the dispensing surface238(outside or outer facing surface of the distribution tool204inFIG.2A) to place more magnetizable abrasive particles into the cavities.

The vacuum box236, if in conjunction with the distribution tool204, can communicate with cavities230as will be further illustrated and described in reference toFIG.3. This can be accomplished by passages extending through the distribution tool204.

Further details regarding various additional elements and sub-assemblies that can be used with the apparatus200and the distribution tool204described herein can be found in PCT International Publ. Nos. WO2015/100020, WO2015/100220 and WO2015100018, which are each incorporated herein by reference in their entirety.

FIG.2Ashows the distribution tool204having a carrier member203designed to carry the magnetizable abrasive particles202. The distribution tool204with the magnetizable abrasive particles202can pass closely adjacent the backing216. The apparatus200as shown inFIG.2Aincludes a magnet (a permanent or electromagnet)250disposed adjacent to the abrasive particle transfer roller222. The magnet250exerts a first magnetic force (illustrated as F1) on the magnetizable abrasive particles202during at least a portion of the magnetizable abrasive particles202travel around the roller222when the particles become partially or totally inverted relative to the force of gravity and/or the backing216.

For the purposes of this disclosure, the first magnetic force F1can optionally be used to retain or move the magnetizable abrasive particles within the cavities230of the distribution tool204prior to transfer to the backing216. The first magnetic force F1can be substantially uniform over the magnetizable abrasive particles in the distribution tool204, or it can be uneven, or even effectively separated into discrete sections. The orientation of the first magnetic force F1is configured to retain the magnetizable abrasive particles within respective cavities230.

Examples of magnetic field configurations and apparatuses for generating them are described in U.S. Patent Application. Publication. Nos. 2008/0289262 A1 (Gao) and U.S. Pat. No. 2,370,636 (Carlton), U.S. Pat. No. 2,857,879 (Johnson), U.S. Pat. No. 3,625,666 (James), U.S. Pat. No. 4,008,055 (Phaal), U.S. Pat. No. 5,181,939 (Neff), and British Pat. No. (G. B.) 1 477 767 (Edenville Engineering Works Limited), which are each incorporated herein by reference in their entirety.

In some embodiments, a second magnet252(a permanent or electromagnet) having a second magnetic field (indicated as F2) can be used to urge the magnetizable abrasive particles202out of the cavities230and onto a first major surface220of the backing216. According to further embodiments, rather than having a second magnet, the first magnet250can have a portion with a second polarity designed to urge the magnetizable abrasive articles from the cavities230.

The urging illustrated can be done in tandem with gravity as inFIG.2A. The backing216can have a make layer precursor (i.e., the binder precursor for the make layer) coated therein. As desired the magnetic abrasive particle202can maintain a vertical or somewhat inclined orientation relative to the horizontal backing216. For example, a majority of the magnetizable abrasive particles202can have a major planar surface (previously discussed and illustrated with regard toFIG.1) disposed at an angle of at least 70 degrees relative to the first major surface220of the backing216upon transfer to the backing216. After at least partially curing the make layer precursor, the magnetizable abrasive particles202are fixed in their placement and orientation. In some embodiments, a size layer precursor can be disposed on at least a portion of the at least partially cured make layer precursor. The size layer precursor can be at least partially cured. An analogous process can be used for manufacture of slurry coated abrasive articles, except that the magnetic field acts on the magnetizable particles within the slurry. The above processes can also be carried out on nonwoven backings to make nonwoven abrasive articles.

FIG.3shows another embodiment comprising an abrasive article positioning system300. The system300can include aspects of the apparatus200previously described and can include magnetizable abrasive particles302, a distribution tool304, a backing316and a magnet350.

FIG.3shows the distribution tool304in a cross-web direction in complete inversion relative to the backing316and gravitational force G. The gravitational force G can aid in removal of the magnetizable abrasive particles302from the distribution tool304and facilitate transfer to the backing316according to the embodiment ofFIG.3. The distribution tool304can comprise a carrier member328having shaped cavities330that open to a dispensing surface332of the carrier member328. The cavities330can be shaped to match a shape of the magnetizable abrasive particles302. According to some examples, the carrier member328comprises a polymer and is flexible.

In the embodiment ofFIG.3, the distribution tool304can include passages334that communicate with each of the cavities330. The passages334allow for the application of a vacuum force VF. The vacuum force VF can aid in the retention of the magnetizable abrasive particles302within the cavities330. The vacuum force VF can be applied from a source such as the vacuum box previously illustrated.

The magnet350(a permanent or electromagnet) can be part of the distribution tool304and system300but may be spaced from the carrier member328, the cavities330and the dispensing surface332as illustrated inFIG.3. The magnet350can apply a magnetic field (indicated by F) to retain the magnetizable abrasive particles302disposed in the cavities330or remove the magnetizable abrasive particles302from the cavities330as previously illustrated inFIG.2A. According to some embodiments, the magnetic force F that retains the magnetizable abrasive particles302in the cavities330can be selectively removed or changed prior to or simultaneous with transfer of the magnetizable abrasive particles302from the plurality of cavities330. Removal of the magnetic force F can occur but removing power to the magnet350if the magnet350comprises an electromagnet or by positioning the magnet350such that the strength of the magnetic field is substantially reduced to zero as previously illustrated inFIG.2A. In other embodiments, the magnetic force F can be changed (e.g., reversed in polarity, reduced in strength to a point where the gravitational force G exceeds the force applied on the magnetizable abrasive particles302by the magnetic force F) rather than being removed. It should be recognized that in other embodiments, the configuration ofFIG.3can be reversed or otherwise oriented relative to the gravitational force G such that the gravitational force G may not help the magnetizable abrasive particles exit the cavities330in all cases.

FIG.4shows a portion of a distribution tool404in both cross-web and down-web directions with exemplary magnetizable abrasive particles402disposed adjacent thereto. A magnet450(permanent or electromagnet) can be disposed adjacent the distribution tool404to apply a magnetic field to the magnetizable abrasive particles402.

According to the embodiment ofFIG.4, the distribution tool404comprises carrier member428having a dispensing surface432and a back surface434. The carrier member428can define cavities430that are open to the dispensing surface432. More particularly, the cavities430extend into carrier member428from cavity openings436at the dispensing surface432. Optionally, a compressible resilient layer438is secured to back surface434. The cavities430can be disposed in an array or pattern.

Typically, the cavity openings436of the carrier member428can be rectangular; however, this is not a requirement. The length, width, and depth of the cavities420in the carrier member428will generally be determined at least in part by the shape and size of the magnetizable abrasive particles402with which they are to be used. For example, if the magnetizable abrasive particles402are shaped as equilateral triangular platelets, then the lengths of individual cavities should be from 1.1-1.2 times the maximum length of a side of the magnetizable abrasive particles402, the widths of individual cavities430are from 1.1-2.5 times the thickness of the magnetizable abrasive particles402, and the respective depths of the cavities430are 1.0 to 1.2 times the width of the magnetizable abrasive particles402if the magnetizable abrasive particles402are to be contained within the cavities430.

Alternatively, for example, if the magnetizable abrasive particles402are shaped as equilateral triangular plates, then the lengths of individual cavities430could be less than that of an edge of the magnetizable abrasive particles402, and/or the respective depths of the cavities430could be less than that of the width of the magnetizable abrasive particles402if the magnetizable abrasive particles402are to protrude from the cavities430. Similarly, the width of the cavities430could be selected such that a single magnetizable abrasive particle402fits within each one of the cavities430.

Optionally, longitudinally-oriented standoff members460can be disposed along opposite edges (e.g., using adhesive or other means) of the dispensing surface432. The standoffs460can provide a height or distance to keep the backing (not shown) from contacting the distribution surface432.

If present, the longitudinally-oriented standoff members460may have any height, width and/or spacing (they have a height of from about 0.1 mm to about 1 mm, a width of from about 1 mm to about 50 mm, and a spacing of from about 7 to about 24 mm). Individual longitudinally-oriented standoff members may be, for example, continuous (e.g., a rib) or discontinuous (e.g., a segmented rib, or a series of posts). In the case, that the distribution tool404comprises a web or belt, the longitudinally-oriented standoff members are typically parallel to the machine direction.

Suitable carrier members428may be rigid or flexible, but are sufficiently flexible to permit use of normal web handling devices such as rollers. According to some embodiments, the carrier member428comprises metal and/or organic polymer. Such organic polymers are moldable, have low cost, and are reasonably durable when used in the abrasive particle deposition process of the present disclosure.

The distribution tool404can be in the form of, for example, an endless belt (e.g., endless belt as shown inFIG.2), a sheet, a continuous sheet or web, a coating roller, a sleeve mounted on a coating roller, or die. If the distribution tool404is in the form of a belt, sheet, web, or sleeve, it will have a contacting surface and a non-contacting surface. It should be understood with any of the disclosed embodiments that one of the backing and the distribution tool can be moved relative to the other of the backing and distribution tool. For example, the distribution tool404can utilize a belt and the backing can move relative to the belt (i.e. at a higher or lower rate of speed). According to other embodiments, the distribution tool may be stator and the backing can move relative to the distribution tool. In yet further embodiments, the distribution tool can move while the backing can remain stator. The apparatuses and systems described can be part of a method of making an abrasive article, in particular, the method can be that of a continuous process or a batch process.

The topography of the abrasive article formed by the method will have the inverse of the pattern of the contacting surface of the production tool. The pattern of the contacting surface of the production tool will generally be characterized by a plurality of cavities or recesses. The opening of these cavities can have any shape, regular or irregular, such as, for example, a rectangle, semicircle, circle, triangle, square, hexagon, or octagon. The walls of the cavities can be vertical or tapered. The pattern formed by the cavities can be arranged according to a specified plan or can be random.

Further distribution tools that can be used with the magnetizable abrasive particles disclosed herein can be found in United States which are each incorporated herein by reference in their entirety.

Abrasive articles according to the present disclosure are useful for abrading a workpiece. Methods of abrading range from snagging (i.e., high pressure high stock removal) to polishing (e.g., polishing medical implants with coated abrasive belts), wherein the latter is typically done with finer grades of abrasive particles. One such method includes the step of frictionally contacting an abrasive article with a surface of the workpiece, and moving at least one of the abrasive article or the workpiece relative to the other to abrade at least a portion of the surface.

Examples of workpiece materials include metal, metal alloys, exotic metal alloys, ceramics, glass, wood, wood-like materials, composites, painted surfaces, plastics, reinforced plastics, stone, and/or combinations thereof. The workpiece may be flat or have a shape or contour associated with it. Exemplary workpieces include metal components, plastic components, particleboard, camshafts, crankshafts, furniture, and turbine blades. The applied force during abrading typically ranges from about 1 kilogram to about 100 kilograms.

Abrasive articles according to the present disclosure may be used by hand and/or used in combination with a machine. At least one of the abrasive article and the workpiece is moved relative to the other when abrading. Abrading may be conducted under wet or dry conditions. Exemplary liquids for wet abrading include water, water containing conventional rust inhibiting compounds, lubricant, oil, soap, and cutting fluid. The liquid may also contain defoamers, degreasers, for example.

The following embodiments are intended to be illustrative of the present disclosure and not limiting.

VARIOUS NOTES & EXAMPLES

Example 1 is a method of making an abrasive layer on a backing. The method can comprise the steps of: providing a distribution tool having a dispensing surface with cavities, providing a backing having a first major surface, supplying magnetizable abrasive particles to the dispensing surface such that at least one of the magnetizable abrasive particles is disposed in a respective one of the cavities, applying a magnetic field to retain the magnetizable abrasive particles disposed in the cavities, aligning the backing with the dispensing surface with the first major surface facing the dispensing surface, transferring the magnetizable abrasive particles from the cavities to the backing, and sequent to or simultaneous with transferring the abrasive particles, removing or changing a magnetic field so the magnetic field no longer retains the magnetizable abrasive particles in the cavities.

In Example 2, the subject matter of Example 1 optionally includes: providing a layer of a first curable binder precursor disposed on at least a portion of the first major surface; attaching the magnetizable abrasive particles to the first curable binder precursor layer; and at least partially curing the layer of the first curable binder material precursor to provide an at least partially cured abrasive layer secured to the backing.

In Example 3, the subject matter of Example 2 optionally includes disposing a second curable binder material precursor onto the at least partially cured abrasive layer, and at least partially curing the second curable binder material precursor.

In Example 4, the subject matter of any one or more of Examples 1-3 optionally includes supplying an excess of magnetizable abrasive particles to the dispensing surface such that more magnetizable abrasive particles are provided than the number of cavities, wherein a majority of the cavities have at least one of the magnetizable abrasive particles disposed therein, and removing at least a portion of the excess magnetizable abrasive particles not disposed within a cavity after filling step from the dispensing surface.

In Example 5, the subject matter of Examples 1-3 can further comprise urging the magnetizable abrasive particles to direct the magnetizable abrasive particles into the cavities using the magnetic field.

In Example 6, the subject matter of any one or more of Examples 1-5 optionally include inverting the distribution tool relative to the backing such that the magnetizable abrasive particles face the first major surface prior to or during transferring the magnetizable abrasive particles from the cavities.

In Example 7, the subject matter of Example 6 optionally includes wherein the dispensing surface is positioned to allow the force of gravity to slide the magnetizable abrasive particles into the cavities and the dispensing surface is inverted during the transferring step to allow the force of gravity to slide the magnetizable abrasive particles out of the cavities.

In Example 8, the subject matter of any one or more of Examples 1-7 optionally include wherein removing or changing the magnetic field includes at least one of: reversing a polarity of the magnetic field to push the magnetizable abrasive particles out of the cavities, moving the distribution tool relative to magnetic tool to reduce the magnetic field, eliminating the magnetic field by switching off an electromagnet that produces the magnetic field, or providing a second magnetic field of greater strength than and in substantially opposing direction from the magnetic field to push the magnetizable abrasive particles out of the cavities.

In Example 9, the subject matter of any one or more of Examples 1-8 optionally include wherein the magnetizable abrasive particles comprise triangular platelets.

Example 10 is an abrasive particle positioning system. The system can comprise: a distribution tool comprising: a carrier member having a dispensing surface and a back surface opposite the dispensing surface, wherein the carrier member has cavities formed therein, wherein the cavities extend into the carrier member and are open to the dispensing surface; magnetizable abrasive particles removably disposed within at least some of the cavities; and a magnet applying a magnetic field to retain the magnetizable abrasive particles disposed in the cavities or remove the magnetizable abrasive particles from the cavities.

In Example 11, the subject matter of Example 10 optionally includes wherein the carrier member comprises a polymer and is flexible.

In Example 12, the subject matter of any one or more of Examples 10-11 optionally include wherein the distribution tool comprises an endless belt.

In Example 13, the subject matter of any one or more of Examples 10-12 optionally include each of the magnetizable abrasive particles comprises a shaped ceramic body having at least one surface, and one or more magnetic layers are disposed on at least a portion of the at least one surface of the shaped ceramic body.

In Example 14, the subject matter of any one or more of Examples 10-13 optionally the magnet urges the magnetizable abrasive particles into the cavities of the carrier member.

In Example 15, the subject matter of any one or more of Examples 10-14 optionally include wherein the magnetizable abrasive particles comprise triangular platelets.

Example 16 is a coated abrasive article fabrication apparatus. The apparatus can comprise: a distribution tool having a dispensing surface with a plurality of cavities, a web path for a backing guiding the backing into close proximity with the distribution tool such that a first major surface of the backing is positioned facing the dispensing surface, magnetizable abrasive particles removably received in the plurality of cavities, and a magnet applying a magnetic field to retain the magnetizable abrasive particles disposed in the cavities, magnetizable abrasive particles are transferred from the plurality of cavities to the backing as the backing and the distribution tool come into the close proximity, and the magnetic field that retains the magnetizable abrasive particles in the cavities is selectively removed or changed prior to or simultaneous with transfer of the magnetizable abrasive particles from the plurality of cavities.

In Example 17, the subject matter of Example 16 optionally includes the distribution tool includes a carrier member that is formed of a polymer and is flexible.

In Example 18, the subject matter of any one or more of Examples 16-17 optionally include the distribution tool comprises an endless belt.

In Example 19, the subject matter of any one or more of Examples 16-18 optionally include each of the magnetizable abrasive particles comprises a shaped ceramic body having at least one surface, and one or more magnetic layers are disposed on at least a portion of the at least one surface of the shaped ceramic body.

In Example 20, the subject matter of any one or more of Examples 16-19 optionally include the magnet urges the magnetizable abrasive particles into the cavities of the carrier member.

Example 21 is a method of making an abrasive layer on a backing. The method can comprise the steps of: providing a distribution tool having a dispensing surface with cavities; providing a backing having a first major surface, supplying magnetizable abrasive particles to the dispensing surface such that at least one of the magnetizable abrasive particles is disposed in a respective one of the cavities, applying a vacuum to retain the magnetizable abrasive particles disposed in the cavities, aligning the backing with the dispensing surface with the first major surface facing the dispensing surface, transferring the magnetizable abrasive particles from the cavities to the resin coated backing and attaching the magnetizable abrasive particles to the resin layer, and sequent to or simultaneous with transferring the abrasive particles, applying a magnetic field to the magnetizable abrasive particles to at least partially facilitate transferring the magnetizable abrasive particles from the cavities.

Each of these non-limiting examples can stand on its own, or can be combined in various permutations or combinations with one or more of the other examples.

The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention can be practiced. These embodiments are also referred to herein as “examples.” Such examples can include elements in addition to those shown or described. However, the present inventors also contemplate examples in which only those elements shown or described are provided. Moreover, the present inventors also contemplate examples using any combination or permutation of those elements shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein.

In the event of inconsistent usages between this document and any documents so incorporated by reference, the usage in this document controls.

In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In this document, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, composition, formulation, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.

The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) can be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description. The Abstract is provided to comply with 37 C.F.R. § 1.72(b), to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features can be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter can lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description as examples or embodiments, with each claim standing on its own as a separate embodiment, and it is contemplated that such embodiments can be combined with each other in various combinations or permutations. The scope of the invention can be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

WORKING EXAMPLES

Unless otherwise noted, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight. Unless stated otherwise, all other reagents were obtained, or are available from fine chemical vendors such as Sigma-Aldrich Company, St. Louis, Missouri, or may be synthesized by known methods.

Material abbreviations used in the Examples are described in Table 1, below.

Unit Abbreviations Used in the Examples:

° C.: degrees Centigradecm: centimeterg/m2: grams per square metermm: millimeter

Material abbreviations used in the Examples are described in Table 1, below.

TABLE 1ABBREVIATIONDESCRIPTIONPRResole phenolic resin, a 1.5:1 to 2.1:1(phenol:formaldehyde) condensate catalyzed by 2.5%potassium hydroxide, obtained as GP 8339 R-23155B fromGeorgia Pacific Chemicals, Atlanta, Georgia.PMEPropylene glycol methyl ether, obtained as “DOWANOLPM” from DOW Chemical Company, Midland, Michigan.SAPShaped abrasive particles were prepared according to thedisclosure of U.S. Pat. No. 8,142,531 (Adefris et al). Theshaped abrasive particles were prepared by molding aluminasol gel in equilateral triangle-shaped polypropylene moldcavities. After drying and firing, the resulting shapedabrasive particles were about 1.4 mm (side length) × 0.35 mm(thickness), with a draft angle approximately 98degrees.TOOLA tooling having vertically-oriented triangular cavitiesgenerally described in patent publication WO2015/100220and configured as shown in FIG. 3A-3C inWO2015/100220, wherein length = 1.875 mm, width =0.785 mm, depth = 1.62 mm, bottom width = 0.328 mm)arranged in a rectangular array (length-wise pitch = 1.978 mm,width-wise pitch = 0.886 mm) with all long dimensionsin the same direction.

Preparation of Magnetizable Abrasive Particles

SAP was coated with 304 stainless steel using physical vapor deposition with magnetron sputtering. 304 Stainless steel sputter target, described by Barbee et al. in Thin Solid Films, 1979, vol. 63, pp. 143-150, deposited as the magnetic ferritic body centered cubic form. The apparatus used for the preparation of 304 stainless steel film coated abrasive particles (i.e., magnetizable abrasive particles) was disclosed in U.S. Pat. No. 8,698,394 (McCutcheon et al.). The physical vapor deposition was carried out for 4 hours at 1.0 kilowatt at an argon sputtering gas pressure of 10 millitorr (1.33 pascal) onto 51.94 grams of SAP. The density of the coated SAP was 4.0422 grams per cubic centimeter. The weight percentage of metal coating in the coated SAP was approximately 2% and the coating thickness is 1.5 micrometers.

Example 1

A section of cloth backing obtained as ERATEX QUALITY N859 P39 YB1700 from Gustav Ernstmeier GmbH & Co. KG, Herford, Germany, was coated with 209.2 g/m2of a phenolic make resin consisting of 49.2 parts of PR, 40.6 parts of calcium metasilicate (obtained as WOLLASTOCOAT from NYCO Company, Willsboro, NY), and 10.2 parts of water. A brush was used to apply the resin.

A 2 inches (5.08 cm)×2 inches (5.08 cm) section of TOOL was filled with coated SAP particles by placing 50 grams of coated SAP on top of the TOOL and then shaking and tapping the TOOL to allow the particles to fill the cavities. Excess particles were removed with a gentle stream of air directed across the surface. The tooling was then placed on top of a 4 inches (10.16 cm)×2 inches (5.08 cm)×1 inch (2.54 cm) Neodymium magnet (Grade N42), which was magnetized through the 1-inch thickness. The entire assembly of magnet and TOOL was inverted. All of the particles were retained in the TOOL as shown inFIG.5. While still inverted, the assembly of magnet and TOOL was placed over the coated cloth backing at a gap distance of 0.010 inch (0.254 mm) and the magnet was quickly removed. The particles were released from the TOOL and affixed to the coated cloth backing. The particles retained orientation as shown inFIG.6. The sample was cured in an oven at 90° C. for 90 minutes.

Comparative Example A

The procedure generally described in EXAMPLE 1 was repeated, with the exception that the procedure was carried out without ever being subjected to the magnetic field (i.e. no magnet was used). Approximately 90% of the particles fell out immediately upon inversion as shown inFIG.7. Since the particles were not retained in the TOOL, they were not able to retain orientation on the coated backing, as shown inFIG.8.

All cited references, patents, and patent applications in the above application for letters patent are herein incorporated by reference in their entirety in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description shall control. The preceding description, given in order to enable one of ordinary skill in the art to practice the claimed disclosure, is not to be construed as limiting the scope of the disclosure, which is defined by the claims and all equivalents thereto.