BACKGROUND

Abrasive particles and abrasive articles made from the abrasive particles are useful for abrading, finishing, or grinding a wide variety of materials and surfaces in the manufacturing of goods. For example, finishing of welding beads, flash, gates, and risers off castings by off-hand abrading with a handheld right-angle grinder is an important application for coated abrasive discs There continues to be a need for improving the cost, performance and other features of the abrasive articles.

BRIEF DESCRIPTION OF THE FIGURES

The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

FIGs. 1A-1B are schematic diagrams of shaped abrasive particles having a planar trigonal shape, in accordance with various embodiments.

FIGs. 2A-2E are schematic diagrams of shaped abrasive particles having a tetrahedral shape, in accordance with various embodiments.

FIGs. 3A and 3B are sectional views of coated abrasive articles, in accordance with various embodiments.

FIG. 4 is a schematic diagram showing a system for manufacturing abrasive articles in accordance with various embodiments.

FIG. 5 is a section of tooling from the system of FIG. 13 in accordance with various embodiments.

FIG. 6A is a top view of a portion of a coated abrasive disc having a macro pattern in accordance with various embodiments.

FIGs. 6B and 6C are expanded views of the disc of FIG. 6A.

FIG. 7 is a schematic showing an example of a macro pattern in accordance with various embodiments.

FIG. 8 is a schematic showing an example of a macro pattern in accordance with various embodiments.

FIG. 9 is a schematic showing an example of a macro pattern in accordance with various embodiments.

FIG. 10 is a schematic showing an example of a macro pattern in accordance with various embodiments.

FIG. 11 is a schematic showing an example of a macro pattern in accordance with various embodiments. FIG. 12 is a schematic showing an example of a macro pattern in accordance with various embodiments.

DETAILED DESCRIPTION

Reference will now be made in detail to certain embodiments of the disclosed subject matter, examples of which are illustrated in part in the accompanying drawings. While the disclosed subject matter will be described in conjunction with the enumerated claims, it will be understood that the exemplified subject matter is not intended to limit the claims to the disclosed subject matter.

Throughout this document, values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of “about 0.1% to about 5%” or“about 0.1% to 5%” should be interpreted to include not just about 0.1% to about 5%, but also the individual values (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. The statement“about X to Y” has the same meaning as“about X to about Y,” unless indicated otherwise. Likewise, the statement“about X, Y, or about Z” has the same meaning as“about X, about Y, or about Z,” unless indicated otherwise.

In this document, the terms“a,”“an,” or“the” are used to include one or more than one unless the context clearly dictates otherwise. The term“or” is used to refer to a nonexclusive“or” unless otherwise indicated. The statement“at least one of A and B” has the same meaning as“A,

B, or A and B.” In addition, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. Any use of section headings is intended to aid reading of the document and is not to be interpreted as limiting; information that is relevant to a section heading may occur within or outside of that particular section.

In the methods described herein, the acts can be carried out in any order without departing from the principles of the disclosure, except when a temporal or operational sequence is explicitly recited. Furthermore, specified acts can be carried out concurrently unless explicit claim language recites that they be carried out separately. For example, a claimed act of doing X and a claimed act of doing Y can be conducted simultaneously within a single operation, and the resulting process will fall within the literal scope of the claimed process.

The term“about” as used herein can allow for a degree of variability in a value or range, for example, within 10%, within 5%, or within 1% of a stated value or of a stated limit of a range, and includes the exact stated value or range. The term“substantially” as used herein refers to a majority of, or mostly, as in at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%.

As used herein“shaped abrasive particle” means an abrasive particle having a

predetermined or non-random shape. One process to make a shaped abrasive particle such as a shaped ceramic abrasive particle includes shaping the precursor ceramic abrasive particle in a mold having a predetermined shape to make ceramic shaped abrasive particles. Ceramic shaped abrasive particles, formed in a mold, are one species in the genus of shaped ceramic abrasive particles. Other processes to make other species of shaped ceramic abrasive particles include extruding the precursor ceramic abrasive particle through an orifice having a predetermined shape, printing the precursor ceramic abrasive particle though an opening in a printing screen having a predetermined shape, or embossing the precursor ceramic abrasive particle into a predetermined shape or pattern. In other examples, the shaped ceramic abrasive particles can be cut from a sheet into individual particles. Examples of suitable cutting methods include mechanical cutting, laser cutting, or water-jet cutting. Non-limiting examples of shaped ceramic abrasive particles include shaped abrasive particles, such as triangular plates, or elongated ceramic rods/filaments. Shaped ceramic abrasive particles are generally homogenous or substantially uniform and maintain their sintered shape without the use of a binder such as an organic or inorganic binder that bonds smaller abrasive particles into an agglomerated structure and excludes abrasive particles obtained by a crushing or comminution process that produces abrasive particles of random size and shape.

In many embodiments, the shaped ceramic abrasive particles comprise a homogeneous structure of sintered alpha alumina or consist essentially of sintered alpha alumina.

The present application discloses abrasive articles that include shaped abrasive particles, non-shaped abrasive particles or a combination thereof. The abrasive articles can include a plurality of particles that can be arranged in one or more micro patterns and disturbances in the one or more micro patterns can be used to create a macro pattern on the abrasive article. In some examples, the disturbances can include a void on the abrasive article where no particles are attached thereto. A variety of macro patterns can be created using any combination for the size and shape of the voids. The voids can be in a repeating pattern on the abrasive article or the voids can be at random. A void can be created by one particle that is deliberately missing or a void can be created by large groups of particles that are deliberately missing. Such design having one or more micro patterns within a macro pattern can be applicable to abrasive articles in the form of sheets, discs belts, pads, or rolls. As described further below, such design may provide one or more possible advantages.

FIGs. 1A and IB show an example of shaped abrasive particle 100, as an equilateral triangle conforming to a truncated pyramid. As shown in FIGs. 1A and IB shaped abrasive particle 100 includes a truncated regular triangular pyramid bounded by a triangular base 102, a triangular top 104, and plurality of sloping sides 106A, 106B, 106C connecting triangular base 102 (shown as equilateral although scalene, obtuse, isosceles, and right triangles are possible) and triangular top 104. Slope angle 108A is the dihedral angle formed by the intersection of side 106A with triangular base 102. Similarly, slope angles 108B and 108C (both not shown) correspond to the dihedral angles formed by the respective intersections of sides 106B and 106C with triangular base 102. In the case of shaped abrasive particle 100, all of the slope angles have equal value. In some embodiments, side edges 110A, 110B, and 110C have an average radius of curvature in a range of from about 0.5 mm to about 80 mm, about 10 mm to about 60 mm, or less than, equal to, or greater than about 0.5 mm, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or about 80 mm.

In the embodiment shown in FIGs. 1A and IB, sides 106A, 106B, and 106C have equal dimensions and form dihedral angles with the triangular base 102 of about 82 degrees

(corresponding to a slope angle of 82 degrees). However, it will be recognized that other dihedral angles (including 90 degrees) may also be used. For example, the dihedral angle between the base and each of the sides may independently range from 45 to 90 degrees (for example, from 70 to 90 degrees, or from 75 to 85 degrees). Edges connecting sides 106, base 102, and top 104 can have any suitable length. For example, a length of the edges may be in a range of from about 0.5 mm to about 2000 mm, about 150 mm to about 200 mm, or less than, equal to, or greater than about 0.5 mm, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1600, 1650, 1700,

1750, 1800, 1850, 1900, 1950, or about 2000 pm.

As shown in FIG. 1A, shaped abrasive particle 100 can have a length L defined between side edges 110A and HOC of the side 106A, and a height H defined between bottom edge of side 106A and side edge 110B. In an example in which the sides 106 of the particle 100 have differing lengths, the length L can be defined as the longest length among the sides 106. As shown in FIG. IB, a width W of the particle 100 can be defined between base 102 and top 104. (It is recognized that a height of the particle 100 in the coated position on an abrasive article may be different than its original height H as shown in FIG. 1A (before coating and attachment), depending in part on a placement/orientation of the particle 100 to a backing substrate. Given the volume of particles on the article and a size of the particles, occasional particles can be misplaced or misoriented relative to their intended position/orientation.)

FIGs. 2A-2E are perspective views of the shaped abrasive particles 200 shaped as tetrahedral abrasive particles. As shown in FIGs. 2A-2E, shaped abrasive particles 200 are shaped as regular tetrahedrons. As shown in FIG. 2A, shaped abrasive particle 200A has four faces (220A, 222A, 224A, and 226A) joined by six edges (230A, 232A, 234A, 236A, 238 A, and 239 A) terminating at four vertices (240A, 242A, 244A, and 246A). Each of the faces contacts the other three of the faces at the edges. While a regular tetrahedron (e.g., having six equal edges and four faces) is depicted in FIG. 2A, it will be recognized that other shapes are also permissible. For example, tetrahedral abrasive particles 200 can be shaped as irregular tetrahedrons (e.g., having edges of differing lengths). For purposes herein, a length of tetrahedral abrasive particles 200 can be described as the longest length among the differing lengths.

Referring now to FIG. 2B, shaped abrasive particle 200B has four faces (220B, 222B, 224B, and 226B) joined by six edges (230B, 232B, 234B, 236B, 238B, and 239B) terminating at four vertices (240B, 242B, 244B, and 246B). Each of the faces is concave and contacts the other three of the faces at respective common edges. While a particle with tetrahedral symmetry (e.g., four rotational axes of threefold symmetry and six reflective planes of symmetry) is depicted in FIG. 2B, it will be recognized that other shapes are also permissible. For example, shaped abrasive particles 200B can have one, two, or three concave faces with the remainder being planar.

Referring now to FIG. 2C, shaped abrasive particle 200C has four faces (220C, 222C, 224C, and 226C) joined by six edges (230C, 232C, 234C, 236C, 238C, and 239C) terminating at four vertices (240C, 242C, 244C, and 246C). Each of the faces is convex and contacts the other three of the faces at respective common edges. While a particle with tetrahedral symmetry is depicted in FIG. 2C, it will be recognized that other shapes are also permissible. For example, shaped abrasive particles 200C can have one, two, or three convex faces with the remainder being planar or concave.

Referring now to FIG. 2D, shaped abrasive particle 200D has four faces (220D, 222D, 224D, and 226D) joined by six edges (230D, 232D, 234D, 236D, 238D, and 239D) terminating at four vertices (240D, 242D, 244D, and 246D). While a particle with tetrahedral symmetry is depicted in FIG. 2D, it will be recognized that other shapes are also permissible. For example, shaped abrasive particles 200D can have one, two, or three convex faces with the remainder being planar.

Deviations from the depictions in FIGs. 2A-2D can be present. An example of such a shaped abrasive particle 200 is depicted in FIG. 2E, showing shaped abrasive particle 200E, which has four faces (220E, 222E, 224E, and 226E) joined by six edges (230E, 232E, 234E, 236E, 238E, and 239E) terminating at four vertices (240E, 242E, 244E, and 246E). Each of the faces contacts the other three of the faces at respective common edges. Each of the faces, edges, and vertices has an irregular shape.

In any of shaped abrasive particles 200A-200E, the edges can have the same length or different lengths. The length of any of the edges can be any suitable length. As an example, the length of the edges can be in a range of from about 0.5 mm to about 2000 mm, about 150 mm to about 200 mm, or less than, equal to, or greater than about 0.5 mm, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1600, 1650, 1700, 1750, 1800, 1850, 1900, 1950, or about 2000 mm. shaped abrasive particles 200A-200E can be the same size or different sizes. Any of shaped abrasive particles 100 or 200 can include any number of shape features.

The shape features can help to improve the cutting performance of any of shaped abrasive particles 100 or 200. Examples of suitable shape features include an opening, a concave surface, a convex surface, a groove, a ridge, a fractured surface, a low roundness factor, or a perimeter comprising one or more comer points having a sharp tip. Individual shaped abrasive particles can include any one or more of these features.

In addition to the materials already described, at least one magnetic material may be included within or coated to shaped abrasive particle 100 or 200. Examples of magnetic materials include iron; cobalt; nickel; various alloys of nickel and iron marketed as Permalloy in various grades; various alloys of iron, nickel and cobalt marketed as Femico, 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 (about 85:9:6 by weight) marketed as Sendust alloy; Heusler alloys (e.g., Cu ₂ MnSn); 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., Nd2Fe 14B). and alloys of samarium and cobalt (e.g., SmCo5): MnSb; MnOFe ₂ O3; 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 is an alloy containing 8 to 12 weight percent aluminum, 15 to 26 wt% nickel, 5 to 24 wt% cobalt, up to 6 wt% copper, up to 1 % titanium, wherein the balance of material to add up to 100 wt% is iron. In some other embodiments, a magnetizable coating can be deposited on an abrasive particle 100 using a vapor deposition technique such as, for example, physical vapor deposition (PVD) including magnetron sputtering.

Including these magnetizable materials can allow shaped abrasive particle 100 or 200 to be responsive a magnetic field. Any of shaped abrasive particles 100 or 200 can include the same material or include different materials.

Shaped abrasive particle 100 or 200 can be formed in many suitable manners for example, the shaped abrasive particle 100 or 200 can be made according to a multi -operation process. The process can be carried out using any material or precursor dispersion material. Briefly, for embodiments where shaped abrasive particles 100 or 200 are monolithic ceramic particles, the process can include the operations of making either a seeded or non-seeded precursor dispersion that can be converted into a corresponding (e.g., a boehmite sol-gel that can be converted to alpha alumina); fdling one or more mold cavities having the desired outer shape of shaped abrasive particle 100 with a precursor dispersion; drying the precursor dispersion to form precursor shaped abrasive particle; removing the precursor shaped abrasive particle 100 from the mold cavities; calcining the precursor shaped abrasive particle 100 to form calcined, precursor shaped abrasive particle 100 or 200; and then sintering the calcined, precursor shaped abrasive particle 100 or 200 to form shaped abrasive particle 100 or 200. The process will now be described in greater detail in the context of alpha-alumina-containing shaped abrasive particle 100 or 200. In other

embodiments, the mold cavities may be fdled with a melamine to form melamine shaped abrasive particles.

The process can include the operation of providing either a seeded or non-seeded dispersion of a precursor that can be converted into ceramic. In examples where the precursor is seeded, the precursor can be seeded with an oxide of an iron (e.g., FeO). The precursor dispersion can include a liquid that is a volatile component. In one example, the volatile component is water. The dispersion can include a sufficient amount of liquid for the viscosity of the dispersion to be sufficiently low to allow filling mold cavities and replicating the mold surfaces, but not so much liquid as to cause subsequent removal of the liquid from the mold cavity to be prohibitively expensive. In one example, the precursor dispersion includes from 2 percent to 90 percent by weight of the particles that can be converted into ceramic, such as particles of aluminum oxide monohydrate (boehmite), and at least 10 percent by weight, or from 50 percent to 70 percent, or 50 percent to 60 percent, by weight, of the volatile component such as water. Conversely, the precursor dispersion in some embodiments contains from 30 percent to 50 percent, or 40 percent to 50 percent solids by weight.

Examples of suitable precursor dispersions include zirconium oxide sols, vanadium oxide sols, cerium oxide sols, aluminum oxide sols, and combinations thereof. Suitable aluminum oxide dispersions include, for example, boehmite dispersions and other aluminum oxide hydrates dispersions. Boehmite can be prepared by known techniques or can be obtained commercially. Examples of commercially available boehmite include products having the trade designations “DISPERAL” and“DISPAL”, both available from Sasol North America, Inc., or“HIQ-40” available from BASF Corporation. These aluminum oxide monohydrates are relatively pure; that is, they include relatively little, if any, hydrate phases other than monohydrates, and have a high surface area.

The physical properties of the resulting shaped abrasive particle 100 or 200 can generally depend upon the type of material used in the precursor dispersion. As used herein, a“gel” is a three-dimensional network of solids dispersed in a liquid.

The precursor dispersion can contain a modifying additive or precursor of a modifying additive. The modifying additive can function to enhance some desirable property of the abrasive particles or increase the effectiveness of the subsequent sintering step. Modifying additives or precursors of modifying additives can be in the form of soluble salts, such as water-soluble salts. They can include a metal-containing compound and can be a precursor of an oxide of magnesium, zinc, iron, silicon, cobalt, nickel, zirconium, hafnium, chromium, yttrium, praseodymium, samarium, ytterbium, neodymium, lanthanum, gadolinium, cerium, dysprosium, erbium, titanium, and mixtures thereof. The particular concentrations of these additives that can be present in the precursor dispersion can be varied.

The introduction of a modifying additive or precursor of a modifying additive can cause the precursor dispersion to gel. The precursor dispersion can also be induced to gel by application of heat over a period of time to reduce the liquid content in the dispersion through evaporation.

The precursor dispersion can also contain a nucleating agent. Nucleating agents suitable for this disclosure can include fine particles of alpha alumina, alpha ferric oxide or its precursor, titanium oxides and titanates, chrome oxides, or any other material that will nucleate the transformation.

The amount of nucleating agent, if used, should be sufficient to effect the transformation of alpha alumina.

A peptizing agent can be added to the precursor dispersion to produce a more stable hydrosol or colloidal precursor dispersion. Suitable peptizing agents are monoprotic acids or acid compounds such as acetic acid, hydrochloric acid, formic acid, and nitric acid. Multiprotic acids can also be used, but they can rapidly gel the precursor dispersion, making it difficult to handle or to introduce additional components. Some commercial sources of boehmite contain an acid titer (such as absorbed formic or nitric acid) that will assist in forming a stable precursor dispersion.

The precursor dispersion can be formed by any suitable means; for example, in the case of a sol-gel alumina precursor, it can be formed by simply mixing aluminum oxide monohydrate with water containing a peptizing agent or by forming an aluminum oxide monohydrate slurry to which the peptizing agent is added.

Defoamers or other suitable chemicals can be added to reduce the tendency to form bubbles or entrain air while mixing. Additional chemicals such as wetting agents, alcohols, or coupling agents can be added if desired.

A further operation can include providing a mold having at least one mold cavity, or a plurality of cavities formed in at least one major surface of the mold. In some examples, the mold is formed as a production tool, which can be, for example, a belt, a sheet, a continuous web, a coating roll such as a rotogravure roll, a sleeve mounted on a coating roll, or a die. In one example, the production tool can include polymeric material. Examples of suitable polymeric materials include thermoplastics such as polyesters, polycarbonates, poly(ether sulfone), poly(methyl methacrylate), polyurethanes, polyvinylchloride, polyolefin, polystyrene, polypropylene, polyethylene or combinations thereof, or thermosetting materials. In one example, the entire tooling is made from a polymeric or thermoplastic material. In another example, the surfaces of the tooling in contact with the precursor dispersion while the precursor dispersion is drying, such as the surfaces of the plurality of cavities, include polymeric or thermoplastic materials, and other portions of the tooling can be made from other materials. A suitable polymeric coating can be applied to a metal tooling to change its surface tension properties, by way of example. A polymeric or thermoplastic production tool can be replicated off a metal master tool.

The master tool can have the inverse pattern of that desired for the production tool. The master tool can be made in the same manner as the production tool. In one example, the master tool is made out of metal (e.g., nickel) and is diamond-turned. In one example, the master tool is at least partially formed using stereolithography. The polymeric sheet material can be heated along with the master tool such that the polymeric material is embossed with the master tool pattern by pressing the two together. A polymeric or thermoplastic material can also be extruded or cast onto the master tool and then pressed. The thermoplastic material is cooled to solidify and produce the production tool. If a thermoplastic production tool is utilized, then care should be taken not to generate excessive heat that can distort the thermoplastic production tool, limiting its life.

Access to cavities can be from an opening in the top surface or bottom surface of the mold. In some examples, the cavities can extend for the entire thickness of the mold. Alternatively, the cavities can extend only for a portion of the thickness of the mold. In one example, the top surface is substantially parallel to the bottom surface of the mold with the cavities having a substantially uniform depth. At least one side of the mold, the side in which the cavities are formed, can remain exposed to the surrounding atmosphere during the step in which the volatile component is removed.

The cavities have a specified three-dimensional shape to make shaped abrasive particle 100. The depth dimension is equal to the perpendicular distance from the top surface to the lowermost point on the bottom surface. The depth of a given cavity can be uniform or can vary along its length and/or width. The cavities of a given mold can be of the same shape or of different shapes.

A further operation involves filling the cavities in the mold with the precursor dispersion (e.g., by a conventional technique). In some examples, a knife roll coater or vacuum slot die coater can be used. A mold release agent can be used to aid in removing the particles from the mold if desired. Examples of mold release agents include oils such as peanut oil or mineral oil, fish oil, silicones, polytetrafluoroethylene, zinc stearate, and graphite. In general, a mold release agent such as peanut oil, in a liquid, such as water or alcohol, is applied to the surfaces of the production tooling in contact with the precursor dispersion such that from about 0.1 mg/in ² (0.6 mg/cm ² ) to about 3.0 mg/in ² (20 mg/cm ² ), or from about 0.1 mg/in ² (0.6 mg/cm ² ) to about 5.0 mg/in ² (30 mg/cm ² ), of the mold release agent is present per unit area of the mold when a mold release is desired. In some embodiments, the top surface of the mold is coated with the precursor dispersion. The precursor dispersion can be pumped onto the top surface.

In a further operation, a scraper or leveler bar can be used to force the precursor dispersion fully into the cavity of the mold. The remaining portion of the precursor dispersion that does not enter the cavity can be removed from the top surface of the mold and recycled. In some examples, a small portion of the precursor dispersion can remain on the top surface, and in other examples the top surface is substantially free of the dispersion. The pressure applied by the scraper or leveler bar can be less than 100 psi (0.6 MPa), or less than 50 psi (0.3 MPa), or even less than 10 psi (60 kPa). In some examples, no exposed surface of the precursor dispersion extends substantially beyond the top surface.

In those examples where it is desired to have the exposed surfaces of the cavities result in planar faces of the shaped abrasive particles, it can be desirable to overfill the cavities (e.g., using a micronozzle array) and slowly dry the precursor dispersion.

A further operation involves removing the volatile component to dry the dispersion. The volatile component can be removed by fast evaporation rates. In some examples, removal of the volatile component by evaporation occurs at temperatures above the boiling point of the volatile component. An upper limit to the drying temperature often depends on the material the mold is made from. For polypropylene tooling, the temperature should be less than the melting point of the plastic. In one example, for a water dispersion of from about 40 to 50 percent solids and a polypropylene mold, the drying temperatures can be from about 90° C to about 165° C, or from about 105° C to about 150° C, or from about 105° C to about 120° C. Higher temperatures can lead to improved production speeds but can also lead to degradation of the polypropylene tooling, limiting its useful life as a mold.

During drying, the precursor dispersion shrinks, often causing retraction from the cavity walls. For example, if the cavities have planar walls, then the resulting shaped abrasive particle 100 can tend to have at least three concave major sides. It is presently discovered that by making the cavity walls concave (whereby the cavity volume is increased) it is possible to obtain shaped abrasive particle 100 that have at least three substantially planar major sides. The degree of concavity generally depends on the solids content of the precursor dispersion.

A further operation involves removing resultant precursor shaped abrasive particle 100 from the mold cavities. The precursor shaped abrasive particle 100 or 200 can be removed from the cavities by using the following processes alone or in combination on the mold: gravity, vibration, ultrasonic vibration, vacuum, or pressurized air to remove the particles from the mold cavities.

The precursor shaped abrasive particle 100 or 200 can be further dried outside of the mold. If the precursor dispersion is dried to the desired level in the mold, this additional drying step is not necessary. However, in some instances it can be economical to employ this additional drying step to minimize the time that the precursor dispersion resides in the mold. The precursor shaped abrasive particle 100 or 200 will be dried from 10 to 480 minutes, or from 120 to 400 minutes, at a temperature from 50° C to 160° C, or 120° C to 150° C.

A further operation involves calcining the precursor shaped abrasive particle 100 or 200. During calcining, essentially all the volatile material is removed, and the various components that were present in the precursor dispersion are transformed into metal oxides. The precursor shaped abrasive particle 100 or 200 is generally heated to a temperature from 400° C to 800° C and maintained within this temperature range until the free water and over 90 percent by weight of any bound volatile material are removed. In an optional step, it can be desirable to introduce the modifying additive by an impregnation process. A water-soluble salt can be introduced by impregnation into the pores of the calcined, precursor shaped abrasive particle 100. Then the precursor shaped abrasive particle 100 are pre-fired again.

A further operation can involve sintering the calcined, precursor shaped abrasive particle 100 or 200 to form particles 100 or 200. In some examples where the precursor includes rare earth metals, however, sintering may not be necessary. Prior to sintering, the calcined, precursor shaped abrasive particle 100 or 200 are not completely densified and thus lack the desired hardness to be used as shaped abrasive particle 100 or 200. Sintering takes place by heating the calcined, precursor shaped abrasive particle 100 or 200 to a temperature of from 1000° C to 1650° C. The length of time for which the calcined, precursor shaped abrasive particle 100 or 200 can be exposed to the sintering temperature to achieve this level of conversion depends upon various factors, but from five seconds to 48 hours is possible.

In another embodiment, the duration of the sintering step ranges from one minute to 90 minutes. After sintering, the shaped abrasive particle 14 can have a Vickers hardness of 10 GPa (gigaPascals), 16 GPa, 18 GPa, 20 GPa, or greater.

Additional operations can be used to modify the described process, such as, for example, rapidly heating the material from the calcining temperature to the sintering temperature, and centrifuging the precursor dispersion to remove sludge and/or waste. Moreover, the process can be modified by combining two or more of the process steps if desired.

FIG. 3 A is a sectional view of coated abrasive article 300. Coated abrasive article 300 includes backing 302 defining a surface along an x-y direction. Backing 302 has a first layer of binder, hereinafter referred to as make coat 304, applied over a first surface of backing 302.

Attached or partially embedded in make coat 304 are a plurality of shaped abrasive particles 200A. Although shaped abrasive particles 200A are shown any other shaped abrasive particle described herein can be included in coated abrasive article 300. An optional second layer of binder, hereinafter referred to as size coat 306, is dispersed over shaped abrasive particles 200A. As shown, a major portion of shaped abrasive particles 200A have at least one of three vertices (240, 242, and 244) oriented in substantially the same direction. Thus, shaped abrasive particles 200A are oriented according to a non-random distribution, although in other embodiments any of shaped abrasive particles 200A can be randomly oriented on backing 302. In some embodiments, control of a particle’s orientation can increase the cut of the abrasive article.

Backing 302 can be flexible or rigid. Examples of suitable materials for forming a flexible backing include a polymeric film, a metal foil, a woven fabric, a knitted fabric, paper, vulcanized fiber, a staple fiber, a continuous fiber, a nonwoven, a foam, a screen, a laminate, and combinations thereof. Backing 302 can be shaped to allow coated abrasive article 300 to be in the form of sheets, discs, belts, pads, or rolls. In some embodiments, backing 302 can be sufficiently flexible to allow coated abrasive article 300 to be formed into a loop to make an abrasive belt that can be run on suitable grinding equipment.

Make coat 304 secures shaped abrasive particles 200A to backing 302, and size coat 306 can help to reinforce shaped abrasive particles 200A. Make coat 304 and/or size coat 306 can include a resinous adhesive. The resinous adhesive can include one or more resins chosen from a phenolic resin, an epoxy resin, a urea-formaldehyde resin, an acrylate resin, an aminoplast resin, a melamine resin, an acrylated epoxy resin, a urethane resin, a polyester resin, a dying oil, and mixtures thereof.

FIG. 3B shows an example of coated abrasive article 300B, which includes shaped abrasive particles 100 instead of shaped abrasive particles 200. As shown, shaped abrasive particles 100 are attached to backing 302 by make coat 304 with size coat 306 applied to further attach or adhere shaped abrasive particles 100 to the backing 302. As shown in FIG. 3B, the majority of the shaped abrasive particles 100 are tipped or leaning to one side. This results in the majority of shaped abrasive particles 100 having an orientation angle b less than 90 degrees relative to backing 302.

Abrasive article 300 can also include conventional (e.g., crushed) abrasive particles. Examples of useful abrasive particles include fused aluminum oxide-based materials such as aluminum oxide, ceramic aluminum oxide (which can include one or more metal oxide modifiers and/or seeding or nucleating agents), and heat-treated aluminum oxide, silicon carbide, co-fused alumina-zirconia, diamond, ceria, titanium diboride, cubic boron nitride, boron carbide, garnet, flint, emery, sol-gel derived abrasive particles, and mixtures thereof.

The conventional abrasive particles can, for example, have an average diameter ranging from about 10 mm to about 2000 mm, about 20 mm to about 1300 mm, about 50 mm to about 1000 mm, less than, equal to, or greater than about 10 mm, 20, 30, 40, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1650, 1700, 1750, 1800, 1850, 1900, 1950, or 2000 mm. For example, the conventional abrasive particles can have an abrasives industry-specified nominal grade. Such abrasives industry-accepted grading standards include those known as the American National Standards Institute, Inc. (ANSI) standards, Federation of European Producers of Abrasive Products (FEPA) standards, and Japanese Industrial Standard (HS) standards. Exemplary ANSI grade designations (e.g., specified nominal grades) include: ANSI 12 (1842 mm), ANSI 16 (1320 mm), ANSI 20 (905 mm), ANSI 24 (728 mm), ANSI 36 (530 mm), ANSI 40 (420 mm), ANSI 50 (351 mm), ANSI 60 (264 mm), ANSI 80 (195 mm), ANSI 100 (141 mm), ANSI 120 (116 mm), ANSI 150 (93 mm), ANSI 180 (78 mm), ANSI 220 (66 mm), ANSI 240 (53 mm), ANSI 280 (44 mm), ANSI 320 (46 mm), ANSI 360 (30 mm), ANSI 400 (24 mm), and ANSI 600 (16 mm). Exemplary FEPA grade designations include P12 (1746 mm), P16 (1320 mm), P20 (984 mm), P24 (728 mm), P30 (630 mm), P36 (530 mm), P40 (420 mm), P50 (326 mm), P60 (264 mm), P80 (195 mm), P100 (156 mm), P120 (127 mm), P120 (127 mm), P150 (97 mm), P180 (78 mm), P220 (66 mm), P240 (60 mm), P280 (53 mm), P320 (46 mm), P360 (41 mm), P400 (36 mm), P500 (30 mm), P600 (26 mm), and P800 (22 mm). An approximate average particles size of reach grade is listed in parenthesis following each grade designation.

Shaped abrasive particles 100 or 200 or crushed abrasive particles can include any suitable material or mixture of materials. For example, shaped abrasive particles 100 can include a material chosen from an alpha-alumina, a fused aluminum oxide, a heat-treated aluminum oxide, a ceramic aluminum oxide, a sintered aluminum oxide, a silicon carbide, a titanium diboride, a boron carbide, a tungsten carbide, a titanium carbide, a diamond, a cubic boron nitride, a garnet, a fused alumina-zirconia, a sol-gel derived abrasive particle, a cerium oxide, a zirconium oxide, a titanium oxide, and combinations thereof. In some embodiments, shaped abrasive particles 100 or 200 and crushed abrasive particles can include the same materials. In further embodiments, shaped abrasive particles 100 or 200 and crushed abrasive particles can include different materials.

Filler particles can also be included in abrasive articles 200 or 300. Examples of useful fdlers include metal carbonates (such as calcium carbonate, calcium magnesium carbonate, sodium carbonate, magnesium carbonate), silica (such as quartz, glass beads, glass bubbles and glass fibers), silicates (such as talc, clays, montmorillonite, feldspar, mica, calcium silicate, calcium metasilicate, sodium aluminosilicate, sodium silicate), metal sulfates (such as calcium sulfate, barium sulfate, sodium sulfate, aluminum sodium sulfate, aluminum sulfate), gypsum, vermiculite, sugar, wood flour, a hydrated aluminum compound, carbon black, metal oxides (such as calcium oxide, aluminum oxide, tin oxide, titanium dioxide), metal sulfites (such as calcium sulfite), thermoplastic particles (such as polycarbonate, polyetherimide, polyester, polyethylene, poly(vinylchloride), polysulfone, polystyrene, acrylonitrile-butadiene-styrene block copolymer, polypropylene, acetal polymers, polyurethanes, nylon particles) and thermosetting particles (such as phenolic bubbles, phenolic beads, polyurethane foam particles and the like). The filler may also be a salt such as a halide salt. Examples of halide salts include sodium chloride, potassium cryolite, sodium cryolite, ammonium cryolite, potassium tetrafluoroborate, sodium

tetrafluoroborate, silicon fluorides, potassium chloride, magnesium chloride. Examples of metal fillers include, tin, lead, bismuth, cobalt, antimony, cadmium, iron and titanium. Other miscellaneous fillers include sulfur, organic sulfur compounds, graphite, lithium stearate and metallic sulfides. In some embodiments, individual shaped abrasive particles 100 or individual crushed abrasive particles can be at least partially coated with an amorphous, ceramic, or organic coating. Examples of suitable components of the coatings include, a silane, glass, iron oxide, aluminum oxide, or combinations thereof. Coatings such as these can aid in processability and bonding of the particles to a resin of a binder. Some shaped abrasive particles 100 or 200 can include a polymeric material and can be characterized as soft abrasive particles. The soft shaped abrasive particles described herein can independently include any suitable material or combination of materials. For example, the soft shaped abrasive particles can include a reaction product of a polymerizable mixture including one or more polymerizable resins. The one or more polymerizable resins such as a hydrocarbyl polymerizable resin. Examples of such resins include those chosen from a phenolic resin, a urea formaldehyde resin, a urethane resin, a melamine resin, an epoxy resin, a bismaleimide resin, a vinyl ether resin, an aminoplast resin (which may include pendant alpha, beta unsaturated carbonyl groups), an acrylate resin, an acrylated isocyanurate resin, an isocyanurate resin, an acrylated urethane resin, an acrylated epoxy resin, an alkyl resin, a polyester resin, a drying oil, or mixtures thereof. The polymerizable mixture can include additional components such as a plasticizer, an acid catalyst, a cross-linker, a surfactant, a mild-abrasive, a pigment, a catalyst and an antibacterial agent.

Where multiple components are present in the polymerizable mixture, those components can account for any suitable weight percentage of the mixture. For example, the polymerizable resin or resins, may be in a range of from about 35 wt% to about 99.9 wt% of the polymerizable mixture, about 40 wt% to about 95 wt%, or less than, equal to, or greater than about 35 wt%, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92,

93, 94, 95, 96, 97, 98, or about 99.9 wt%.

If present, the cross-linker may be in a range of from about 2 wt% to about 60 wt% of the polymerizable mixture, from about 5 wt% to about 10 wt%, or less than, equal to, or greater than about 2 wt%, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or about 15 wt%. Examples of suitable cross linkers include a cross-linker available under the trade designation CYMEL 303 LF, of Allnex USA Inc., Alpharetta, Georgia, USA; or a cross-linker available under the trade designation CYMEL 385, of Allnex USA Inc., Alpharetta, Georgia, USA.

If present, the mild-abrasive may be in a range of from about 5 wt% to about 65 wt% of the polymerizable mixture, about 10 wt% to about 20 wt%, or less than, equal to, or greater than about 5 wt%, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29

30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55,

56, 57, 58, 59, 60, 61, 62, 63, 64, or about 65 wt%. Examples of suitable mild-abrasive s include a mild-abrasive available under the trade designation MINSTRON 353 TALC, of Imerys Talc America, Inc., Three Forks, Montana, USA; a mild-abrasive available under the trade designation USG TERRA ALBA NO.l CALCIUM SULFATE, of USG Corporation, Chicago, Illinois, USA; Recycled Glass (40-70 Grit) available from ESCA Industries, Ltd., Hatfield, Pennsylvania, USA, silica, calcite, nephebne, syenite, calcium carbonate, or mixtures thereof. If present, the plasticizer may be in a range of from about 5 wt% to about 40 wt% of the polymerizable mixture, about 10 wt% to about 15 wt%, or less than, equal to, or greater than about 5 wt%, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,

31, 32, 33, 34, 35, 36, 37, 38, 39, or about 40 wt%. Examples of suitable plasticizers include acrylic resins or styrene butadiene resins. Examples of acrylic resins include an acrylic resin available under the trade designation RHOPLEX GL-618, of DOW Chemical Company, Midland, Michigan, USA; an acrylic resin available under the trade designation HYCAR 2679, of the Lubrizol Corporation, Wickliffe, Ohio, USA; an acrylic resin available under the trade designation HYCAR 26796, of the Lubrizol Corporation, Wickliffe, Ohio, USA; a polyether polyol available under the trade designation ARCOL LG-650, of DOW Chemical Company, Midland, Michigan, USA; or an acrylic resin available under the trade designation HY CAR 26315, of the Lubrizol Corporation, Wickliffe, Ohio, USA. An example of a styrene butadiene resin includes a resin available under the trade designation ROVENE 5900, of Mallard Creek Polymers, Inc., Charlotte, North Carolina, USA.

If present, the acid catalyst may be in a range of from 0.5 wt% to about 20 wt% of the polymerizable mixture, about 5 wt% to about 10 wt%, or less than, equal to, or greater than about 1 wt%, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or about 20 wt%. Examples of suitable acid catalysts include a solution of aluminum chloride or a solution of ammonium chloride.

If present, the surfactant can be in a range of from about 0.001 wt% to about 15 wt% of the polymerizable mixture about 5 wt% to about 10 wt%, less than, equal to, or greater than about 0.001 wt%, 0.01, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or about 15 wt%. Examples of suitable surfactants include a surfactant available under the trade designation GEMTEX SC-85-P, of Innospec Performance Chemicals, Salisbury, North Carolina, USA; a surfactant available under the trade designation DYNOL 604, of Air Products and Chemicals, Inc., Allentown, Pennsylvania, USA; a surfactant available under the trade designation ACRYSOL RM-8W, of DOW Chemical Company, Midland, Michigan, USA; or a surfactant available under the trade designation

XIAMETER AFE 1520, of DOW Chemical Company, Midland, Michigan, USA.

If present, the antimicrobial agent may be in a range of from 0.5 wt% to about 20 wt% of the polymerizable mixture, about 10 wt% to about 15 wt%, or less than, equal to, or greater than about 0.5 wt%, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or about 20 wt%. An example of a suitable antimicrobial agent includes zinc pyrithione.

If present, the pigment may be in a range of from about 0.1 wt% to about 10 wt% of the polymerizable mixture, about 3 wt% to about 5 wt%, less than, equal to, or greater than about 0.1 wt%, 0.2, 0.4, 0.6, 0.8, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, or about 10 wt%. Examples of suitable pigments include a pigment dispersion available under the trade designation SUNSPERSE BLUE 15, of Sun Chemical Corporation, Parsippany, New Jersey, USA; a pigment dispersion available under the trade designation SUNSPERSE VIOLET 23, of Sun Chemical Corporation, Parsippany, New Jersey, USA; a pigment dispersion available under the trade designation SUN BLACK, of Sun Chemical Corporation, Parsippany, New Jersey, USA; or a pigment dispersion available under the trade designation BLUE PIGMENT B2G, of Clariant Ltd., Charlotte, North Carolina, USA. The mixture of components can be polymerized by curing.

As shown in FIGs. 3A and 3B each of the plurality of shaped abrasive particles 100 or 200 can have a specified z-direction rotational orientation about a z-axis passing through shaped abrasive particles 100 or 200 and through backing 302 at a 90 degree angle to backing 302. Shaped abrasive particles 100 or 200 are orientated with a surface feature, such as a substantially planar surface particle 100 or 200, rotated into a specified angular position about the z-axis. The specified z-direction rotational orientation abrasive article 300A or 300B occurs more frequently than would occur by a random z-directional rotational orientation of the surface feature due to electrostatic coating or drop coating of the shaped abrasive particles 100 or 200 when forming the abrasive article 300A or 300B. As such, by controlling the z-direction rotational orientation of a significantly large number of shaped abrasive particles 100 or 200, the cut rate, finish, or both of coated abrasive article 300A or 300B can be varied from those manufactured using an electrostatic coating method. In various embodiments, at least 50, 51, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 99 percent of shaped abrasive particles 100 or 200 can have a specified z-direction rotational orientation which does not occur randomly and which can be substantially the same for all of the aligned particles. In other embodiments, about 50 percent of shaped abrasive particles 100 or 200 can be aligned in a first direction and about 50 percent of shaped abrasive particles 100 or 200 can be aligned in a second direction. In one embodiment, the first direction is substantially orthogonal to the second direction.

The specific z-direction rotational orientation of formed abrasive particles can be achieved through use of a precision apertured screen that positions shaped abrasive particles 100 or 200 into a specific z-direction rotational orientation such that shaped abrasive particle 100 or 200 can only fit into the precision apertured screen in a few specific orientations such as less than or equal to 4, 3, 2, or 1 orientations. For example, a rectangular opening just slightly bigger than the cross section of shaped abrasive particle 100 or 200 comprising a rectangular plate will orient shaped abrasive particle 100 or 200 in one of two possible 180 degree opposed z-direction rotational orientations. The precision apertured screen can be designed such that shaped abrasive particles 100 or 200, while positioned in the screen's apertures, can rotate about their z-axis (normal to the screen's surface when the formed abrasive particles are positioned in the aperture) less than or equal to about 30, 20, 10, 5, 2, or 1 angular degrees.

The precision apertured screen having a plurality of apertures selected to z-directionally orient shaped abrasive particles 100 and 200 into a pattern, can have a retaining member such as adhesive tape on a second precision apertured screen with a matching aperture pattern, an electrostatic field used to hold the particles in the first precision screen or a mechanical lock such as two precision apertured screens with matching aperture patterns twisted in opposite directions to pinch particles 100 and 200 within the apertures. The first precision aperture screen is filled with shaped abrasive particles 100 and 200, and the retaining member is used to hold shaped abrasive particles 100 in place in the apertures. In one embodiment, adhesive tape on the surface of a second precision aperture screen aligned in a stack with the first precision aperture screen causes shaped abrasive particles 100 to stay in the apertures of the first precision screen stuck to the surface of the tape exposed in the second precision aperture screen's apertures.

Following positioning in apertures, coated backing 302 having make layer 304 is positioned parallel to the first precision aperture screen surface containing the shaped abrasive particles 100 or 200 with make layer 304 facing shaped abrasive priticles 100 or 200 in the apertures. Thereafter, coated backing 302 and the first precision aperture screen are brought into contact to adhere shaped abrasive particles 100 or 200 to the make layer. The retaining member is released such as removing the second precision aperture screen with taped surface, untwisting the two predsion aperture screens, or eliminating the electrostatic field. Then the first precision aperture screen is then removed leaving the shaped abrasive particles 100 or 200 having a specified z-directional rotational orientation on the coated abrasive article 300 for further conventional processing such as applying a size coat and curing the make and size coats.

In the case of a coated abrasive article, the curable binder precursor comprises a make layer precursor, and the magnetizable particles comprise magnetizable abrasive particles. A size layer precursor may be applied over the at least partially cured make layer precursor and the magnetizable abrasive particles, although this is not a requirement. If present, the size layer precursor is then at least partially cured at a second curing station, optionally with further curing of the at least partially cured make layer precursor. In some embodiments, a supersize layer is disposed on the at least partially cured size layer precursor.

Another tool and method to form abrasive article 300 in which shaped abrasive particles 100 or 200 have a specified z-direction rotational angle is to use the system shown in FIGs. 4 and 5. In FIGs. 4 and 5, coated abrasive article system 1300 according to the present disclosure includes shaped abrasive particles 1302 removably disposed within cavities 1402 of production tool 1350 having first web path 1304 guiding production tool 1350 through system 1300 such that it wraps a portion of an outer circumference of shaped abrasive particle transfer roll 1308. System 1300 can include, for example, idler rollers 1310 and make coat delivery system 1312. These components unwind backing 1314, deliver make coat resin 1316 via make coat delivery system 1312 to a make coat applicator and apply make coat resin to first major surface 1318 of backing 1314. Thereafter resin coated backing 1314 is positioned by an idler roll 1310 for application of shaped abrasive particles 1302 to the first major surface 1318 coated with make coat resin 1316. Second web path 1306 for resin coated backing 1314 passes through the system 1300 such that the resin layer is positioned feeing a dispensing surface 1404 (FIG. 5) of production tool 1350 that is positioned between resin coated backing 1314 and an outer circumference of the shaped abrasive particle transfer roll 1308. Suitable unwinds, make coat delivery systems, make coat resins, coaters and backings are known to those of skill in the art. Make coat delivery system 1312 can be a simple pan or reservoir containing the make coat resin or a pumping system with a storage tank and delivery plumbing to translate make coat resin 1316 to a needed location. Backing 1314 can be a cloth, paper, film, nonwoven, scrim, or other web substrate. Make coat applicator 1312 can be, for example, a coater, a roll coaler, a spray system, a die coater, or a rod coater. Alternatively, a pre-coated coated backing can be positioned by an idler roll 1310 for application of shaped abrasive particles 1302 to the first major surface.

As shown in FIG. 5, production tool 1350 comprises a plurality of cavities 1402 having a complimentary shape to intended shaped abrasive particle 1302 to be contained therein. Shaped abrasive particle feeder 1320 supplies at least some shaped abrasive particles 1302 to production tool 1350. Shaped abrasive particle feeder 1320 can supply an excess of shaped abrasive particles 1302 such that there are more shaped abrasive particles 1302 present per unit length of production tool in the machine direction than cavities 1402 present Supplying an excess of shaped abrasive partides 1302 helps to ensure that a desired number of cavities 1402 within fee production tool 1350 are eventually filled with shaped abrasive particle 1302. Since fee bearing area and spacing of shaped abrasive particles 1302 is often designed into production tooling 1350 for the specific grinding application it is desirable to not have too many unfilled cavities 1402. Shaped abrasive particle feeder 1320 can be the same width as the production tool 1350 and can supply shaped abrasive particles 1302 across the entire width of production tool 1350. Shaped abrasive particle feeder 1320 can be, for example, a vibratory feeder, a hopper, a chute, a silo, a drop coater, or a screw feeder.

Optionally, filling assist system 1330 is provided after shaped abrasive partide feeder 1320 to move shaped abrasive particles 1302 around on the surface of production tool 1350 and to help orientate or slide shaped abrasive partides 1302 into the cavities 1402. Filling assist system 1330 can be, for example, a doctor blade, a felt wiper, a brash having a plurality of bristles, a vibration system, a blower or air knife, a vacuum box, or combinations thereof. Filling assist system 1330 moves, translates, sucks, or agitates shaped abrasive partides 1302 on dispensing surface 1404 (top or upper surface of production tool 1350 in FIG. 4) to place more shaped abrasive partides 1302 into cavities 1402. Without filling assist system 1330, generally at least some of shaped abrasive particles 1302 dropped onto dispensing

surface 1404 will fall directly into cavities 1402 and no further movement is required but others may need some additional movement to be directed into cavities 1402. Optionally, filling assist system 1330 can be oscillated laterally in the cross direction or otherwise have a relative motion such as circular or oval to the surface of production tool 1350 using a suitable drive to assist in completely filling each cavity 1402 in production tool 1350 with a shaped abrasive particle 1302.

If a brush is included as a component of the filling assist system 1330, the bristles may cover a section of dispensing surface 1404 from 2-60 inches (5.0-153 cm) in length in the machine direction across all or most all of the width of dispensing surface 1404, and lightly rest on or just above dispensing surface 1404, and be of a moderate flexibility. Vacuum box 1332, if included in the filling assist system 1330, can be in conjunction with production tool 1350 having cavities 1402 extending completely through production tool 1350. Vacuum box may be located near shaped abrasive particle feeder 1320 and may be located before or after shaped abrasive particle feeder 1320, or encompass any portion of a web span between a pair of idler rolls 1310 in the shaped abrasive particle filling and excess removal section of the apparatus. Alternatively, production tool 1350 can be supported or pushed on by a shoe or a plate to assist in keeping it planar in this section of the apparatus instead or in addition to vacuum box 1332. As shown in FIG. 4, it is possible to include one or more components in system 1330 to remove excess shaped abrasive particles 1302, in some embodiments it may be possible to include only one component in system 1330.

After leaving the shaped abrasive particle filling and excess removal section of system 1300, shaped abrasive particles 1302 in production tool 1350 travel towards resin coated backing 1314. Shaped abrasive particle transfer roll 1308 is provided and production

tooling 1350 can wrap at least a portion of the roll's circumference. In some embodiments, production tool 1350 wraps between 30 to 180 degrees, or between 90 to 180 degrees of the outer circumference of shaped abrasive particle transfer roll 1308. In some embodiments, the speed of the dispensing surface 1404 and the speed of the resin layer of resin coated backing 1314 are speed matched to each other within ±10 percent, ±5 percent, or ±1 percent, for example.

Various methods can be employed to transfer shaped abrasive particles 1302 from cavities 1402 of production tool 1350 to resin coated backing 1314. One method includes a pressure assist method where each cavity 1402 in production tooling 1350 has two open ends or the back surface or the entire production tooling 1350 is suitably porous and shaped abrasive particle transfer roll 1308 has a plurality of apertures and an internal pressurized source of air. With pressure assist, production tooling 1350 does not need to be inverted but it still may be inverted. Shaped abrasive particle transfer roll 1308 can also have movable internal dividers such that the pressurized air can be supplied to a specific arc segment or circumference of the roll to blow shaped abrasive particles 1302 out of the cavities and onto resin coated backing 1314 at a specific location. In some embodiments, shaped abrasive particle transfer roll 1308 may also be provided with an internal source of vacuum without a corresponding pressurized region or in combination with the pressurized region typically prior to the pressurized region as shaped abrasive particle transfer roll 1308 rotates. The vacuum source or region can have movable dividers to direct it to a specific region or arc segment of shaped abrasive particle transfer roll 1308. The vacuum can suck shaped abrasive particles 1302 firmly into cavities 1402 as the production tooling 1350 wraps shaped abrasive particle transfer roll 1308 before subjecting shaped abrasive particles 1302 to the pressurized region of shaped abrasive particle transfer roll 1308. This vacuum region be used, for example, with shaped abrasive particle removal member to remove excess shaped abrasive particles 1302 from dispensing surface 1404 or may be used to simply ensure shaped abrasive particles 1302 do not leave cavities 1402 before reaching a specific position along the outer circumference of the shaped abrasive particle transfer roll 1308.

After separating from shaped abrasive particle transfer roll 1308, production tooling 1350 travels along first web path 1304 back towards the shaped abrasive particle filling and excess removal section of the apparatus with the assistance of idler rolls 1310 as necessary. An optional production tool cleaner can be provided to remove stuck shaped abrasive particles still residing in cavities 1402 and/or to remove make coat resin transferred to dispensing surface 1404. Choice of the production tool cleaner can depend on the configuration of the production tooling and could be either alone or in combination, an additional air blast, solvent or water spray, solvent or water bath, an ultrasonic horn, or an idler roll the production tooling wraps to use push assist to force shaped abrasive particles 1302 out of the cavities 1402. Thereafter production tooling 1350 or belt advances to a shaped abrasive particle filling and excess removal section to be filled with new shaped abrasive particles 1302.

Various idler rolls 1310 can be used to guide the shaped abrasive particle coated backing 1314 having a predetermined, reproducible, non-random pattern of shaped abrasive particles 1302 on the first major surface that were applied by shaped abrasive particle transfer roll 1308 and held onto the first major surface by the make coat resin along second web path 1306 into an oven for curing the make coat resin. Optionally, a second shaped abrasive particle coater can be provided to place additional abrasive particles, such as another type of abrasive particle or diluents, onto the make coat resin prior to entry in an oven. The second abrasive particle coater can be a drop coater, spray coater, or an electrostatic coater as known to those of skill in the art Thereafter a cured backing with shaped abrasive particles 1302 can enter into an optional festoon along second web path 1306 prior to further processing such as the addition of a size coat, curing of the size coat, and other processing steps known to those of skill in the art of making coated abrasive articles.

Although system 1300 is shown as including production tool 1350 as a belt, it is possible in some alternative embodiments for system 1300 to include production tool 1350 on vacuum pull roll 1308. For example, vacuum pull roll 1308 may include a plurality of cavities 1402 to which shaped abrasive particles 1302 are directly fed. Shaped abrasive particles 1302 can be selectively held in place with a vacuum, which can be disengaged to release shaped abrasive particles 1302 on backing 1314. Further details on system 1300 and suitable alternative may be found at US 2016/0311081, to 3M Company, St Paul MN, the contents of which are hereby incorporated by reference.

Although shaped abrasive particles are used as an example, the system 1300 described above may also be used to accurately place non-shaped particles. Due to the configuration of the production tool 1350 placement of particles is very specifically controlled, and may be used to form patterns of a first level, second level, and higher despite the particles themselves not having any pre-determined shape. In one example, a blend of shaped and non-shaped particles may also be used. In selected examples, relatively precise placement of non-shaped particles, using methods and equipment described above may be used to form one or more patterns, in a similar manner to patterns formed through placement of shaped particles of the abrasive article, etc. It is recognized that the example abrasive articles described herein can include precisely-shaped particles, non- shaped particles or a combination thereof.

A macro pattern can be created on the abrasive article using the particles themselves to form a micro pattern and creating a macro pattern by inserting disturbances or disruptions in the micro pattern. In some examples, the macro pattern can be created by repeating first and second micro patterns - such as, for example, alternating patterns of longitudinally aligned rows of particles and laterally aligned rows of particles. In other examples, the macro pattern can be created by one micro pattern that can be broken up by multiple disturbances that create voids in the micro pattern and such voids can be present in a repeating pattern or in a random pattern. The variations in the size and shape of the voids on the abrasive article can be nearly limitless and the macro patterns described herein are not limited to any particle type of voids. The voids can be achieved by individual particles that are deliberately missing from the article in a pattern or at random, or the voids can be achieved by large groups of particles that are deliberately missing.

The voids can be defined by enclosed regions (such as the voids 2014 shown in FIG. 11) or the voids can be in the form of a continuous region that can extend across substantially all of the abrasive article, or across long portions of the abrasive article. Such design of abrasive articles having a macro pattern, with one or more micro patterns contained therein, can be applicable to abrasive articles in the form of sheets, discs, belts, pads, or rolls.

In describing a position of the particles relative to other particles, for purposes herein, the term“adjacent particle” refers to particles that are next to each other in different rows, and the term“neighboring” or“neighbor” refers to particles that are next to each other in the same row. Each particle can be described as having a unique lateral, longitudinal position on the abrasive article. The example macro patterns shown in FIGs. 15-21 can be used on a disc or a belt.

FIG. 6A shows a portion of an abrasive article 1500 in the form of a disc. The disc 1500 can comprise a plurality of particles, such as ceramic particles, attached to a backing substrate 1504 through use of an adhesive. The disc 1500 includes a six by six alternating pattern across the portion of the disc 1500 shown in FIG. 6A. The alternating pattern includes a first pattern 1506 and a second pattern 1508. The first pattern 1506 includes six longitudinal rows of particles and the second pattern 1508 includes six lateral rows of particles. For simplicity and given the individual size of the particles relative to the size of the disc 1500, in FIG. 6A, each line 1510 of the first pattern 1506 represents a row of particles and each line 1512 of the second pattern 1508 represents a row of particles. The individual particles are shown in FIGs. 6B and 6C.

The alternating pattern of the first pattern 1506 and second pattern 1508 can create a macro pattern on the disc 1500. The macro pattern may mask (or minimize to the eye of an individual looking at the abrasive article 1500) any unfilled or irregularly filled positions on the disc 1500 where a particle was intended to be placed. The macro pattern may guide or draw the eye away from the smaller scale pattern of the rows in each pattern 1506 and 1508. Given the volume of particles intended for placement on the backing substrate, the small size of the particles, as well as other factors, it is common that positions on the disc 1500 may go unfilled and thereby create gaps that may be noticeable to the user or another individual looking at the disc 1500. Through use of the macro pattern, any such gaps in particle placement on the backing substrate 1504 can be masked or downplayed, or otherwise minimized, when the user looks at the disc 1500 as a whole. The macro pattern of the first pattern 1506 and second pattern 1508 is shown on an example disc; however, such macro pattern can be applicable to any type of abrasive article, including a belt. Similarly, the other example macro patterns shown in the figures and described herein can be applicable to any type of abrasive article, including a disc or belt.

The disc 1500 can include a plurality of disruptions 1514. Each occurrence of the pattern 1506, 1508 can be separated by a disruption or disturbance 1514 (from the plurality of disruptions 1514) that breaks or ends that particular occurrence of the pattern 1506, 1508. Thus each disruption or disturbance 1514 can serve as a separation between adjacent patterns. The disruption or disturbance 1514 can also be referred to herein as a termination of the pattern, although such termination can be considered a temporary termination of the pattern 1506, 1508 on the disc 1500 since each of the patterns 1506, 1508 repeat in an alternating manner on the disc 1500.

FIG. 6B is an expanded view of a portion of the disc 1500 to further illustrate the features on the disc 1500. FIG. 6B specifically shows two occurrences of the first pattern 1506 and two occurrences of the second pattern 1508. In an example, an area occupied by each of the first pattern 1506 and the second pattern 1508 can be generally equal. In other examples, the first pattern 1506 can occupy more or less area on the disc 1500, relative to the second pattern 1508. FIG. 6C shows a further expanded view of a top portion of the first pattern 1506 and second pattern 1508 of FIG. 6B. Individual particles 1516 are visible in FIGs. 6B and 6C.

The six longitudinal rows of particles 1516 in the first pattern 1506 are designated as a first longitudinal row 1518, a second longitudinal row 1520, a third longitudinal row 1522, a fourth longitudinal row 1524, a fifth longitudinal row 1526 and a sixth longitudinal row 1528. Similarly, the six lateral rows of particles 1516 in the second pattern 1508 are designated as a first lateral row 1530, a second lateral row 1532, a third lateral row 1534, a fourth lateral row 1536, a fifth lateral row 1538 and a sixth lateral row 1540.

In FIGs. 6B and 6C, for simplicity, each individual shaped abrasive particle 1506 is represented as a short line segment representative of the position of the base (sloping sidewall) of the particle 1506 attached to the make coat (for attaching the particle 1506 to the substrate 1502).

In an example, the particles 1516 of the first pattern 1506 and second pattern 1508 are aligned both laterally and longitudinal such that the particles 1506 in the longitudinal rows 1518-1528 are also aligned laterally across the pattern 1506. In another example, the particles 1516 in one or both of the first pattern 1506 and second pattern 1508 can include a staggered linear pattern. In the staggered linear pattern, the rows of particles can be aligned longitudinally and staggered laterally such that particles 1516 in adjacent longitudinal rows can be laterally misaligned or staggered relative to one another, or the particles can be aligned laterally and staggered longitudinally such that particles 1616 in adjacent lateral rows can be longitudinally misaligned or staggered relative to one another. Reference is made to co-pending application No. 62/780,987 filed December 18, 2018, titled“STAGGERED LINEAR PATTERN.”

Particle 1516A in the fifth row 1526 of the first pattern 1506 is in alignment with adjacent particle 1516A’ in the sixth row 1528; similarly, particle 1516B in the fifth row 1526 is in alignment with adjacent particle 1516B’ in the sixth row 1528. Neighboring particles 1516A and 1516B are in alignment relative to one another along a first longitudinal position, and neighboring particles 1516A’ and 1516B’ are in alignment relative to one another along a second longitudinal position. A distance 1542 can represent spacing between adjacent particles in different rows in the first pattern 1506. A distance 1544 can represent spacing between neighboring particles 1516 within the same row in the first pattern 1506.

Particle 1516AA in the first row 1530 of the second pattern 1508 is in alignment with adjacent particle 1516AA’ in the second row 1532; similarly, particle 1516BB in the first row 1530 is in alignment with adjacent particle 1516BB’ in the second row 1532. Neighboring particles 1516AA and 1516BB are in alignment relative to one another along a first lateral position, and neighboring particles 1516AA’ and 1516BB’ are in alignment relative to one another along a second lateral position. A distance 1546 can represent spacing between adjacent particles in different rows in the second pattern 1508. A distance 1548 can represent spacing between neighboring particles 1516 within the same row in the second pattern 1508.

It is recognized that there are different ways that the distances or spaces between neighboring particles and adjacent particles can be defined. For example, a spacing between neighboring particles or adjacent particles can be defined as a distance from a center point of the first particle to a center point of the second particle.

A first occurrence 1506A of the first pattern 1506 can be separated from a first occurrence 1508A of the second pattern 1508 by a first disruption 1514A. In an example, the disruption 1514A can constitute a void on the backing substrate 1502 such that the disruption 1514A not only designates a transition from one pattern 1506 to another pattern 1508, the disruption 1514A also represents an area on the substrate 1502 having no particles attached thereto. The void of the disruption 1514A is described further below in reference to FIG. 6C. A second occurrence 1508A of the second pattern 1508 can be separated from the first occurrence 1506A of the first pattern 1506 by a second disruption 1514B. The second occurrence 1508B of the second pattern 1508 can be separated from a second occurrence 1506B of the first pattern 1506 by a third disruption 1514C. The second occurrence 1506B of the first pattern 1506 can be separated from the first occurrence 1508A of the second pattern 1508 by a fourth disruption 1514D.

As shown in FIG. 6C, a distance 1550 can represent a lateral distance of the void created by the first disruption 1514A. In an example, the distance 1550 can be greater than a width of the particles 1516 in the first pattern 1506 or a width of the particles 1516 in the second pattern 1508.

In an example, the distance 1550 can be greater than one or both of the distances 1542 and 1544. In an example, the distance 1550 can be equal to or greater than two times the distance

1542. In an example, the distance 1550 can be equal to or greater than two times the distance

1544. Similarly, the distance 1550 can be greater than one or both of the distances 1546 and 1548. In an example, the distance 1550 can be equal to or greater than two times the distance

1546. In an example, the distance 1550 can be equal to or greater than two times the distance

1548. In an example, the distances 1544 and 1548 can be generally equal. In another example, the distances 1544 and 1548 can be different. In an example, the distances 1542 and 1546 can be generally equal. In another example, the distances 1542 and 1546 can be different. The spacing between neighboring particles or between adjacent particles in the same pattern can depend on the intended density of the particles on the backing substrate 1502. In some examples, the particle density of the first pattern 1506 can be different than the particle density of the second pattern 1508. In other examples, the particle density of the first pattern 1506 can be generally the same as the particle density of the second pattern 1508. It is recognized that FIGs. 6A-6C, as well as FIGs. 7-12, may not necessarily be drawn to scale. The particles 1516 may be more or less compact, relative to one another, than what is shown in FIGs. 6A-6C.

In an example, the alternating pattern and corresponding disruptions 1514 on the disc 1500 can extend across essentially all of the disc 1500. In another example, the alternating pattern and disruptions can extend across a part but not all of the disc 1500.

For purposes herein, the term“adjacent pattern” refers to a pattern that is next to a reference pattern, and the adjacent pattern and reference pattern are separated by a disturbance or disruption. In the example of the disc 1500 in FIG. 6A, one occurrence of the first pattern 1506 can be surrounded by four occurrences of the second pattern 1508. Each of the four occurrences of the second pattern 1508 surrounding the first pattern 1506 can be described for purposes herein as an adjacent pattern or an adjacent different pattern. Similarly, one occurrence of the second pattern 1508 can be surrounded by four occurrences of the first pattern 1506. In other examples, such as those shown in FIGs. 9 and 10 and described below, the micro pattern can include more than one occurrence of the first pattern. In other words, repeating first patterns can be adjacent to one another, with each occurrence separated by a disturbance or disruption having a void that contains no particles. The repeating first pattern can be used with a second pattern in alternative designs to what is shown in FIGs. 6A-6C.

The particles of the micro pattern can be arranged in a variety of configurations to accommodate a desired spacing between neighboring particles (in the same longitudinal or lateral rows), a desired spacing between adjacent particles (in different longitudinal or lateral rows) and a desired spacing between adjacent micro patterns. The desired spacing between adjacent micro patterns can also be described as a distance or area of the void created by a specific disturbance of the micro pattern.

FIG. 7 shows an example macro pattern 1600 having an alternating first pattern 1606 and second pattern 1608. Like the pattern on the disc 1500, the macro pattern 1600 can be a 6 by 6 alternating pattern. Relative to the pattern on the disc 1500, the first pattern 1606 and second pattern 1608 can be spaced closer to one another such that any void created by the disruptions in the pattern 1600 can span less distance relative to the voids 1514 on the disc 1500. In some examples, the spacing between adjacent particles of adjacent different patterns can be about equal to a spacing between neighboring particles with the micro pattern.

FIG. 8 shows an example macro pattern 1700 having an alternating pattern of a first pattern 1706 and a second pattern 1708. Instead of a six by six pattern, the macro pattern 1700 is a three by three pattern - three longitudinal rows of particles in the first pattern 1706 and three lateral rows of particles in the second pattern 1708. The particles within each pattern, 1706 1708 are less densely packed, compared to FIGs. 6 and 7. Moreover, the distance of the void 1714 between each pattern 1706, 1708 can be greater than such corresponding void 1514 on the disc 1500.

FIG. 9 shows an example macro pattern 1800 having two adjacent occurrences of a first pattern 1806 and two adjacent occurrences of a second pattern 1808. In this example, instead of an occurrence of the first pattern 1806 being surrounded by four occurrences of the second pattern 1808, the occurrence of the first pattern 1806 is surrounded by three occurrences of the second pattern 1808 and one occurrence of the second pattern 1808. The macro pattern 1800 is a four by four pattern - four longitudinal rows of particles in the first pattern 1806 and four lateral rows of particles in the second pattern 1808.

FIG. 10 shows an example macro pattern 1900 having alternating rows of repeating occurrences of a first pattern 1906 and repeating occurrences of a second pattern 1908. In an example, each occurrence of the first pattern 1906 is separated from another occurrence of the first pattern 1906 by a disruption or void 1914. Similarly, each occurrence of the second pattern 1908 is separated from another occurrence of the second pattern 1906 by another occurrence of the void 1914. Adjacent rows of the first pattern 1906 and second pattern 1908 are separated from each other by additional occurrences of the void 1914. In an example, the void 1914 spans a lateral distance 1950 that is equal to or greater than a width of at least two of the particles.

It is recognized that the macro pattern can include any combination of the first pattern and second pattern. There can be more of the first pattern than the second pattern or vice versa. The first and second patterns can have the same number of longitudinal and lateral rows, relative to one another, or a different number. The first and second patterns can have the same general particle density or a different particle density, relative to one another. The particles in the first and second patterns are shown in FIGS. 6-10 as being orthogonal to one another. In other examples, the particles in the first and second patterns can be oriented at other angles relative to one another.

As an alternative to a repeating first pattern and a repeating second pattern (which can have generally the same type of disruption or void across the substrate), the macro pattern can be created by one type of micro pattern that repeats across the substrate and the plurality of disruptions or disturbances breaks up the single micro pattern. The disruptions or disturbances can be created by repeating voids that can be random or regular, equally spaced or variably spaced.

An example macro pattern can include a single micro pattern (such as, for example, the first pattern 1506 or the second pattern 1508) which can repeat and be separated by voids similar to the voids 1510 shown in FIGS. 6A-6C. Instead of having a repeating pattern of the first pattern alternating with the second pattern, the second pattern can be replaced with repeat occurrences of the first pattern separated by voids 1514, or vice versa. Other examples of macro patterns having one type of micro pattern are shown in FIGs. 11 and 12 and described below.

FIG. 11 shows an example macro pattern 2000 having a micro pattern of longitudinally aligned rows 2018 and laterally aligned rows 2020 of particles 2016. The macro pattern 2000 includes a plurality of disruptions 2014 in the micro pattern. In the example shown in FIG. 11, each of the disruptions 2014 can span a lateral distance 2022 that generally equates to a distance of two particles 2016 arranged laterally and a longitudinal distance 2024 that generally equates to a distance of two particles 2016 arranged longitudinally. Because there is spacing between adjacent particles, the lateral distance 2022, as shown in FIG. 11, can be greater than two times the width of the particles 2016 and the longitudinal distance 2024, as shown in FIG. 11, can be greater than two times the length of the particles 2016. In other examples, the lateral distance 2022 can generally equate to a distance of one particle 2016 arranged laterally and the longitudinal distance 2024 can generally equate to a distance of one particle 2016 arranged longitudinally. In other examples, the lateral distance 2022 can generally equate to a distance of two or more particles 2016 arranged laterally and the longitudinal distance 2024 can generally equate to a distance of one particle arranged longitudinally. It is recognized that the longitudinal and lateral dimensions of the disruptions 2014 can be of any combination. The longitudinal and lateral distances can be equal to one another or different from one another. The dimensions of the disruptions 2014 can be constant across the abrasive article or vary across the abrasive article.

In the example macro pattern 2000 of FIG. 11, the disruptions 2014 are of generally the same size and orientation. In other examples, the distributes 2014 across the macro pattern 2000 can be different sizes and orientations of the rectangular shape. In an example, the pattern of the disruptions 2014 can be constant across the macro pattern 2000 such that each disruption 2014 is equally spaced from other disruptions 2014. In another example, the pattern of the disruptions 2014 can vary such that the disruptions 2014 are variably spaced from one another.

FIG. 12 shows an example macro pattern 2100 having a micro pattern of longitudinally aligned rows 2118 and laterally aligned rows 2120 of particles 2116. The macro pattern 2100 includes a plurality of disruptions 2114 in the micro pattern. The disruptions 2114 in adjacent lateral rows can be arranged relative to one another to form a stair-step configuration of the disruptions 2114. In an example, the stair-step configuration of the disruptions 2114 can create a x-shaped pattern in those occurrences in which different stair-step occurrences of the disruptions 2114 converge with one another.

Each of the disruptions 2114 as shown in FIG. 12 can span a lateral distance 2122 that generally equates to a distance of two particles 2116 arranged laterally and a longitudinal distance 2124 that generally equates to a distance of one particle 2116 arranged longitudinal. It is recognized that this is just one example of the size and shape of the void (created by the disruptions 2114) that can be used in the macro pattern 2100. In other examples, the distances 2122 and 2124 can be greater or less than what is shown in FIG. 12. In an example, a similar macro pattern having a stair-step configuration can be created by voids that are only equivalent to one particle missing, and such voids can be located in adjacent lateral rows in the stair-step orientation shown in FIG. 12. The distances 2122 and 2124 can be equal or different, relative to each other. In other examples, the disruptions 2114 can be arranged in a different pattern. In other examples, the disruptions 2114 can cover more or less area on the backing substrate that the macro pattern 2100 is used on.

FIGs. 6-12 are provided as examples of the types of macro patterns that can be used to mask or guide the eye away from any defects or inconsistencies in particle placement on the abrasive article. As described above, the macro patterns described herein can include any number of configurations of micro patterns in combination with a plurality of disruptions to create the macro pattern. The disruptions can be continuous across all or a portion of the article. The voids caused by the disruptions can be enclosed by other particles as shown in FIG. 20. The disruptions can be as little as the equivalent of one particle missing in the micro pattern or as big as the equivalent of several particles missing in the micro pattern. The example macro patterns are shown in the figures and described above as having a longitudinal and lateral alignment relative to the abrasive article. It is recognized that the macro patterns do not have to be aligned as such on the abrasive article. The macro patterns, as well as the particles of the micro patterns, can be arranged at various angles and positions on the abrasive article.

In an example, abrasive articles having a macro pattern with a micro pattern contained therein can include precisely-shaped particles, non-shaped particles, or a combination thereof. In an example, the abrasive articles can include coated, shaped abrasive particles and at least a portion of the shaped abrasive articles can have a similar size and geometry. In an example, the shaped abrasive particles can include triangular-shaped particles (described above in detail as an equilateral triangle conforming to a truncated pyramid), tetrahedral-shaped particles or a combination thereof.

It is recognized that the micro patterns described herein can extend across some or all of the abrasive article. In an example, substantially all of the particles on the abrasive article can be arranged in a repeating micro pattern with a plurality of disturbances arranged at various points within the micro pattern to create a macro pattern. Similarly, the resulting macro pattern can extend across some or all of the abrasive article. In an example, some of the particles on the abrasive article can be arranged in a micro pattern and some of the particles can be randomly arranged on the backing substrate.

Examples

Various embodiments of the present disclosure can be better understood by reference to the following Examples which are offered by way of illustration. The present disclosure is not limited to the Examples given herein.

Example 1 provides an abrasive article comprising a backing substrate, a plurality of particles attached to the backing substrate, and an adhesive for attaching the particles to the backing substrate. The plurality of particles can be arranged in a first predetermined order to form a first pattern that repeats on at least a portion of the backing substrate, and neighboring particles within the first pattern are separated from one another by a first distance. The backing substrate can include a plurality of disruptions of the first pattern on the backing substrate to form a macro pattern on at least a portion of the backing substrate, and each disruption of the plurality of disruptions comprises a void on the backing substrate, the voids defined as an area of the backing substrate having no particles attached thereto. Each of the voids can span a lateral distance and a longitudinal distance.

Example 2 provides the abrasive article of Example 1 optionally configured wherein each disruption of the plurality of disruptions separates an occurrence of the first pattern from an adjacent occurrence of the first pattern. Example 3 provides the abrasive article of any one of Examples 1 or 2 optionally configured wherein the plurality of particles are arranged in a second predetermined order different from the first predetermined order to form a second pattern that repeats on at least a portion of the substrate.

Example 4 provides the abrasive article of Example 3 optionally configured wherein the plurality of disruptions comprises a first disruption and a second disruption, and wherein the first disruption separates a first occurrence of the first pattern from a first occurrence of the second pattern and the second disruption separates the first occurrence of the second pattern from a second occurrence of the first pattern.

Example 5 provides the abrasive article of any one of Examples 3 or 4 optionally configured wherein the first predetermined order comprises two or more rows of particles arranged in longitudinal alignment on the backing substrate.

Example 6 provides the abrasive article of any one of Examples 3-5 optionally configured wherein the second predetermined order comprises two or more rows of particles arranged in lateral alignment on the backing substrate.

Example 7 provides the abrasive article of any one of Examples 1-6 optionally configured wherein the lateral and longitudinal distances of the voids are generally constant across the portion of the backing substrate having the first pattern.

Example 8 provides the abrasive article of any one of Examples 1-6 optionally configured wherein at least one of the lateral distance of the void or the longitudinal distance of the void is different among at least two disruptions of the plurality of disruptions.

Example 9 provides the abrasive article of any one of Examples 1-8 optionally configured wherein the lateral distance is greater than a width of one particle and the longitudinal distance is greater than the length of one particle.

Example 10 provides the abrasive article of any one of Examples 1-9 optionally configured wherein the lateral distance is greater than twice the width of one particle.

Example 11 provides the abrasive article of any one of Examples 1-10 optionally configured wherein the longitudinal distance is greater than twice the length of one particle.

Example 12 provides the abrasive article of any one of Examples 1-11 optionally configured wherein the plurality of particles are arranged in longitudinal and lateral rows such that particles are aligned longitudinally and laterally to form the first pattern, and the plurality of disruptions comprise at least one disruption in each of the lateral rows.

Example 13 provides the abrasive article of Example 12 optionally configured wherein the voids in adjacent lateral rows are arranged in a stair step configuration.

Example 14 provides the abrasive article of Example 1 optionally configured wherein the plurality of particles are arranged in longitudinal and lateral rows such that particles are aligned longitudinally and laterally to form the first pattern, and wherein each void has a rectangular shape and the lateral distance is greater than two times the particle width.

Example 15 provides the abrasive article of any one of Examples 1-14 optionally configured wherein the longitudinal distance of each void is greater than two times the particle length.

Example 16 provides the abrasive article of any one of Examples 1-15 optionally configured wherein each of the particles has a height, and the first distance ranges between about half of the height of the particles and three times the height of the particles.

Example 17 provides the abrasive article of any one of Examples 1-3 optionally configured wherein particles along a perimeter of adjacent micro patterns are separated from another by a second distance that is greater than the first distance.

Example 18 provides the abrasive article of Example 17 optionally configured wherein the second distance is at least about two times the first distance.

Example 19 provides the abrasive article of any one of Examples 1-18 optionally configured wherein the plurality of particles comprises crushed particles without a precise shape, precisely-shaped particles, and a combination thereof.

Example 20 provides the abrasive article of Example 19 optionally configured wherein at least one of the precisely-shaped particles comprises a first side and a second side separated by a thickness t, the first side comprises a first face having a triangular perimeter and the second side comprises a second face having a triangular perimeter, wherein the thickness t is equal to or smaller than the length of the shortest side-related dimension of the particle.

Example 21 provides the abrasive article of Example 20 optionally further comprising at least one sidewall connecting the first side and the second side.

Example 22 provides the abrasive article of Example 21 optionally configured wherein the at least one sidewall is a sloping sidewall.

Example 23 provides the abrasive article of Example 19 optionally configured wherein at least one of the precisely-shaped particles is tetrahedral and comprises four faces joined by six edges terminating at four tips, each one of the four faces contacting three of the four faces.

Example 24 provides the abrasive article of Example 23 optionally configured wherein at least one of the four faces is substantially planar.

Example 25 provides the abrasive article of any one of Examples 23 or 24 optionally configured wherein at least one of the four faces is concave.

Example 26 provides the abrasive article of any one of Examples 23-25 optionally configured wherein at least one of the four faces is convex.

Example 27 provides the abrasive article of any one of Examples 1-26 optionally configured wherein a z-direction rotational angle about a line perpendicular to a major surface of the backing substrate and passing through individual particles of the plurality of particles is substantially the same for a portion of the plurality of particles.

Example 28 provides the abrasive article of any one of Examples 1-27 optionally configured wherein the backing substrate is a disc.

Example 29 provides the abrasive article of any one of Examples 1-27 optionally configured wherein the backing substrate is a belt.

Example 30 provides a coated abrasive article comprising a flexible backing substrate, a plurality of particles attached to the backing substrate, and a curable adhesive to attach the particles to the backing substrate. Multiple particles in the plurality of particles can be arranged relative to one another in a first predetermined order to form a first micro pattern on a portion of the abrasive article, and neighboring particles within the first micro pattern are separated from one another by a first distance. Multiple particles in the plurality of particles can be arranged in a second predetermined order to form a second micro pattern on a portion of the abrasive article, the second predetermined order different from the first predetermined order, and neighboring particles within the second micro pattern are separated from one another by a second distance. The second micro pattern can be located adjacent to the first micro pattern, and a repeating pattern of the first micro pattern and the second micro pattern on at least a portion of the abrasive article creates a macro pattern.

Example 31 provides the abrasive article of Example 30 optionally configured wherein outer particles at a perimeter of the first micro pattern and outer particles at a perimeter of the second micro pattern are separated by a third distance, and the third distance is greater than at least one of the first distance and the second distance.

Example 32 provides the abrasive article of Example 30 optionally configured wherein outer particles at a perimeter of the first micro pattern and outer particles at a perimeter of the second micro pattern are separated by a third distance, and the third distance is equal to at least one of the first distance and the second distance.

Example 33 provides the abrasive article of any one of Examples 30-32 optionally configured wherein the second distance is generally equal to the first distance.

Example 34 provides the abrasive article of any one of Examples 30-33 optionally configured wherein the first micro pattern includes two or more rows of multiple particles arranged laterally on the backing substrate.

Example 35 provides the abrasive article of any one of Examples 30-34 optionally configured wherein the second micro pattern includes two or more rows of multiple particles arranged longitudinally on the backing substrate.

Example 36 provides the abrasive article of any one of Examples 30-35 optionally configured wherein each of the plurality of particles in the first micro pattern has a similar geometry relative to other particles in the first micro pattern, and each of the plurality of particles in the second micro pattern has a similar geometry relative to other particles in the second micro pattern.

Example 37 provides the abrasive article of any one of Examples 30-36 optionally configured wherein the shaped particles comprise at least one of triangular plates having two opposed substantially planar surfaces and tetrahedral plates having two opposed substantially planar surfaces.

Example 38 provides the abrasive article of any one of Examples 30-37 optionally configured wherein the backing substrate is a disc.

Example 39 provides the abrasive article of any one of Examples 30-37 optionally configured wherein the backing substrate is a belt.

Example 40 provides an abrasive article comprising a backing substrate, a plurality of particles attached to the backing substrate, and an adhesive for attaching the particles to the backing substrate. The plurality of particles can comprise particles arranged in a micro pattern of repeating laterally-aligned rows and repeating longitudinally-aligned rows on at least a portion of the substrate, and the backing substrate can include a plurality of voids in the micro pattern to form a macro pattern, each void defined as an area of the backing substrate having no particles attached thereto.

Example 41 provides the abrasive article of Example 40 optionally configured wherein each void spans a lateral distance greater than two times the width of at least one particle of the plurality of particles.

Example 42 provides the abrasive article of Example 40 optionally configured wherein the lateral distance of at least one void of the plurality of voids is greater than three times the width of the at least one particle of the plurality of particles.

Example 43 provides the abrasive article of any one of Examples 40-42 optionally configured wherein each void spans a longitudinal distance greater than two times the length of the at least one particle of the plurality of particles.

Example 44 provides the abrasive article of any one of Examples 40-43 optionally configured wherein a distance between adjacent voids on the backing substrate is generally constant on the abrasive article.

Example 45 provides the abrasive article of any one of Examples 40-43 optionally configured wherein a distance between adjacent voids on the backing substrate is variable on the abrasive article.

Example 46 provides the abrasive article of any one of Examples 40-45 optionally configured wherein each laterally -aligned row includes one or more voids.

Example 47 provides the abrasive article of Example 46 optionally configured wherein the voids in adjacent lateral rows are arranged in a stair step configuration. Example 48 provides a method of forming an abrasive article, the method comprising aligning a plurality of particles in a first predetermined order to form a first repeating pattern, transferring the particles to a backing substrate containing a layer of adhesive, and curing the adhesive. The particles can have a plurality of disruptions in the first repeating pattern such that voids are created by each disruption, the voids defined as an area having no particles. The repeating first pattern and plurality of disruptions form a macro pattern on at least a portion of the backing substrate.

Example 49 provides the method of Example 48 optionally further comprising aligning a plurality of particles in a second first predetermined order to form a second repeating pattern, the macro pattern created by a configuration of repeating first patterns and repeating second patterns.

Example 50 provides the method of any one of Example 48 or 49 optionally configured wherein aligning the plurality of particles in a first predetermined order to form a first repeating pattern includes arranging the particles into at least one of lateral alignment and longitudinal alignment.

Example 51 provides the method of any one of Examples 48-50 optionally configured wherein aligning the plurality of particles in a first predetermined order to form a first repeating pattern includes collecting the plurality of shaped particles into pockets formed in a tooling surface.

Example 52 provides an article or method of any one or any combination of Examples 1- 51, which can be optionally configured such that all steps or elements recited are available to use or select from.

The terms and expressions that have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the embodiments of the present disclosure. Thus, it should be understood that although the present disclosure has been specifically disclosed by specific embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those of ordinary skill in the art, and that such modifications and variations are considered to be within the scope of embodiments of the present disclosure.

Various aspects of the disclosure have been described. These and other aspects are within the scope of the following claims.