Coated abrasive article and method for making the same

Abstract

The present invention discloses a method for preparing a coated abrasive product, the method comprising: depositing a precisely shaped abrasive flake into a precisely shaped cavity in a production tool; depositing diluted abrasive particles onto the production tool; contacting the precisely shaped abrasive flake and the diluted abrasive particles with a curable make coat precursor disposed on a major surface of a backing; separating the tool from the precisely shaped abrasive flake and the diluted abrasive particles; and at least partially curing the curable make coat precursor to provide an at least partially cured make coat precursor. A coated abrasive product that can be prepared by the method is also disclosed.

Description

Technical Field

[0001] The present disclosure relates broadly to coated abrasive articles and methods of making and using the same. Background Art

[0002] The coated abrasive article comprises abrasive grains adhered to a backing by a material comprising a first cross-linked polymer resin (commonly referred to as a make coat or make coat). In most cases, a second cross-linked polymer resin (commonly referred to as a size coat or make coat) is disposed on the make coat and the abrasive grains. Optionally, a third layer (referred to as a top coat or top size) is disposed on the top coat. If present, the top size typically comprises a grinding aid and / or an anti-filling component.

[0003] In recent years, there has been a trend to use shaped abrasive particles (e.g., triangular flakes), and attempts have been made to position the particles in various desired orientations relative to the backing. However, in many cases, the shaped abrasive particles are substantially tilted from their initial orientation before the make coat precursor resin that forms the make coat is cured. Summary of the invention

[0004] It would be desirable to have methods of making coated abrasive articles in which the abrasive grains substantially retain their initial orientation, and coated abrasive articles that can be made by these methods. Advantageously, the present disclosure provides practical solutions to both of these problems.

[0005] In one aspect, the present disclosure provides a method of preparing a coated abrasive article, the method comprising the sequential steps of:

[0006] a) providing a production tool comprising a carrier member having a dispensing surface, the production tool having a precisely shaped cavity extending from a cavity opening at the dispensing surface into the carrier member;

[0007] b) depositing precisely shaped abrasive flakes into at least some of the precisely shaped cavities;

[0008] c) depositing diluted abrasive particles on the dispensing surface;

[0009] d) contacting the precisely shaped abrasive flakes and the diluted abrasive particles with a curable make layer precursor disposed on a major surface of a backing;

[0010] e) optionally separating the tool from the precisely shaped abrasive flakes and the diluted abrasive grains; and

[0011] f) at least partially curing the curable make layer precursor to provide an at least partially cured make layer precursor.

[0012] In some preferred embodiments, the sequential steps further include:

[0013] g) disposing a curable size layer precursor onto the at least partially cured make layer precursor, the precisely shaped abrasive flakes and the diluted abrasive grains; and

[0014] h) at least partially curing the curable size layer precursor.

[0015] In another aspect, the present disclosure provides a coated abrasive article prepared according to the foregoing method.

[0016] In another aspect, the present disclosure provides a coated abrasive article comprising:

[0017] a backing having a first major surface;

[0018] a primer layer, the primer layer being disposed on the backing and fixed to the backing;

[0019] an abrasive layer contacting and secured to the make coat, wherein the abrasive layer comprises precision-shaped abrasive flakes and diluted abrasive grains, wherein the precision-shaped abrasive flakes include a second major surface disposed at a dihedral angle of less than or equal to 60 degrees relative to the first major surface of the backing, and wherein at least a majority of the precision-shaped abrasive flakes each overhang a corresponding plurality of the diluted abrasive grains; and

[0020] A double-glue layer is disposed on the base glue layer and the abrasive layer.

[0021] In yet another aspect, the present disclosure provides a coated abrasive article comprising:

[0022] a backing having a major surface;

[0023] a primer layer, the primer layer being disposed on the backing and fixed to the backing;

[0024] an abrasive layer contacting and secured to the make coat, wherein the abrasive layer comprises islands, each island containing at least one precisely shaped abrasive flake and diluted abrasive particles, and wherein the islands are separated from one another; and

[0025] A double-glue layer is disposed on the base glue layer and the abrasive layer.

[0026] As used in this article:

[0027] The term "generally aligned with the longitudinal axis" when used with respect to a precisely shaped abrasive sheet means that the longitudinal axis of each precisely shaped abrasive particle is similarly or identically aligned with respect to the longitudinal axis of the coated abrasive article (eg, coated abrasive belt).

[0028] The term "generally aligned with the axis of rotation" when used with respect to a precisely shaped abrasive sheet means that the longitudinal axis of each precisely shaped abrasive particle is similarly or identically aligned with respect to the axis of rotation of the coated abrasive article (eg, coated abrasive disc).

[0029] The term "closed abrasive coating" means that the abrasive layer is tightly packed with substantially no space between adjacent abrasive particles of sufficient size to allow for the deposition of another abrasive particle of comparable size.

[0030] The term "open abrasive coating" refers to a coating that is not a closed abrasive coating. An open coating may be characterized by having areas with few, if any, abrasive particles.

[0031] The term "precision-shaped abrasive grain" refers to an abrasive grain that is substantially in the shape of a cavity portion of a mold or production tool in which the particle precursor is dried prior to optional calcining and then sintering.

[0032] As used herein with respect to precisely shaped abrasive particles and cavities, the term "length" refers to the largest dimension of an abrasive particle or cavity. "Width" refers to the largest dimension of an abrasive particle perpendicular to the length. The term "thickness" or "height" refers to the dimension of a precisely shaped abrasive particle or cavity perpendicular to the length and width.

[0033]

[0026] A further understanding of the features and advantages of the present disclosure will be achieved upon consideration of the detailed description and the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic process flow diagram of an exemplary process 100 according to the present disclosure.

[0035] Figure 2 is a schematic process flow diagram of an exemplary process 200 according to the present disclosure.

[0036] Figure 3 is a schematic process flow diagram of an exemplary process 300 according to the present disclosure.

[0037] Figure 4 is a schematic process flow diagram of an exemplary process 400 according to the present disclosure.

[0038] Figure 5 is a schematic process flow diagram of an exemplary process 500 according to the present disclosure.

[0039] Figure 6 is a schematic side view of an exemplary coated abrasive article 600 according to the present disclosure.

[0040] Fig. 7Ais a schematic side view of an exemplary coated abrasive article 700 according to the present disclosure.

[0041] Figure 7B is a schematic top view of an exemplary coated abrasive article 700 according to the present disclosure.

[0042] Figure 8 is a schematic top view of an exemplary coated abrasive disc 800 according to the present disclosure.

[0043] Fig.9A and Fig. 9B is an optical micrograph of the coated abrasive article prepared in Example 1.

[0044] Fig. 10A and Fig. 10B is an optical micrograph of the coated abrasive article prepared in Comparative Example A.

[0045] Fig.11A and Fig. 11B is an optical micrograph of the coated abrasive article prepared in Example 2.

[0046] Fig. 12A and Fig. 12B is an optical micrograph of the coated abrasive article prepared in Comparative Example B.

[0047] Reference symbols used repeatedly in the specification and drawings are intended to represent the same or similar features or elements of the present disclosure. It should be understood that those skilled in the art can design many other modifications and embodiments that fall within the scope and essence of the principles of the present disclosure. The drawings may not be drawn to scale. DETAILED DESCRIPTION

[0048] See now Figure 1 , an exemplary method 100 of making a coated abrasive article according to the present disclosure provides a production tool 110 including a carrier member 115 and a dispensing surface 112. A precisely formed cavity 120 extends from a cavity opening 114 at the dispensing surface 112 and into the carrier member 115. Such tools are well known and used in the production of coated abrasive articles and typically have the form of a metal roll, a polymer sheet, a polymer roll cover, or a polymer belt.

[0049] Next, the precisely shaped abrasive flakes 130 are placed within the precisely shaped cavities 120 so that they are oriented. The diluted abrasive particles 140 are then placed on the dispensing surface 112 of the production tool 110.

[0050] The abrasive grain-laden dispensing surface 112 of the production tool 110 is then contacted with the make layer precursor 150 disposed on the backing 160. The make layer precursor 150 is sufficiently adhered so that separation of the backing and make layer precursor combination from the dispensing surface 112 transfers the precisely shaped abrasive flakes 130 and diluted abrasive grains 140 from the production tool 110 to the make layer precursor 150. The make layer precursor is subsequently cured (not shown), and a size layer precursor is applied and cured to produce a coated abrasive article (not shown).

[0051] In a variation of method 100, an exemplary method 200 of making a coated abrasive article according to the present disclosure (see Figure 2 ) A production tool 210 is provided that includes a carrier member 205 and a dispensing surface 212. A precisely formed cavity 220 extends from a cavity opening 214 at the dispensing surface 212 and extends into the carrier member 205 in an inclined manner.

[0052] Next, the precisely shaped abrasive flakes 230 are placed in the precisely shaped cavities 220 so that they are oriented, in some preferred embodiments, in an inclined manner. Then, the diluted abrasive particles 240 are placed on the dispensing surface 212 of the production tool 210 so that some of the diluted abrasive particles are stuck in the precisely shaped cavities and accumulate on the top of the dispensing surface.

[0053] The abrasive grain-laden dispensing surface 212 of the production tool 210 is then contacted with the make layer precursor 250 disposed on the backing 260. The make layer precursor 250 is sufficiently adhered so that optional separation of the backing and make layer precursor combination from the dispensing surface 212 transfers the precisely shaped abrasive flakes 230 and diluted abrasive grains 240 from the production tool 210 to the make layer precursor 250. The make layer precursor is subsequently cured (not shown), and a size layer precursor is applied and cured to produce a coated abrasive article (not shown).

[0054] Variations in cavity and particle size and shape can result in a number of related processes.

[0055] For example, see now Figure 3 , similar to processes 100 and 200, an exemplary method 300 for preparing a coated abrasive article according to the present disclosure provides a production tool 310. A precisely shaped cavity 320 has a cavity opening 314. A precisely shaped abrasive flake 330 is disposed within the precisely shaped cavity 320. Diluted abrasive particles 340 are then disposed side by side with the precisely shaped abrasive flake 330 in the cavity. After being transferred to a make coat precursor 350, the precisely shaped abrasive flake 330 and the diluted abrasive particles 340 are disposed adjacent to each other. The make coat precursor is subsequently cured (not shown), and a size coat precursor is applied and cured to obtain a coated abrasive article (not shown).

[0056] See now Figure 4 , similar to processes 100 and 200, an exemplary method 400 for preparing a coated abrasive article according to the present disclosure provides a production tool 410. A precisely shaped cavity 420 has a cavity opening 414. A precisely shaped abrasive flake 430 is disposed within the precisely shaped cavity 420 to help them be oriented vertically. Diluted abrasive particles 440 are then disposed side by side with the precisely shaped abrasive flake 430 in the cavity. After being transferred to a make coat precursor 450, the precisely shaped abrasive flake 430 and the diluted abrasive particles 440 are disposed adjacent to each other. The make coat precursor is subsequently cured (not shown), and a size coat precursor is applied and cured to obtain a coated abrasive article (not shown).

[0057] See now Figure 5 , similar to processes 100 and 200, an exemplary method 500 for preparing a coated abrasive article according to the present disclosure provides a production tool 510. A precisely shaped cavity 520 has a cavity opening 514. A precisely shaped abrasive flake 530 is disposed within the precisely shaped cavity 520 to help them be oriented vertically. Diluted abrasive particles 540 are then disposed side by side with the precisely shaped abrasive flake 530 in the cavity. After being transferred to a make coat precursor 550, the precisely shaped abrasive flake 530 and the diluted abrasive particles 540 are disposed adjacent to each other. The make coat precursor is subsequently cured (not shown), and a size coat precursor is applied and cured to obtain a coated abrasive article (not shown).

[0058] Useful production tools and methods for making them are well known and practiced in the art. Typically, the openings of the precisely shaped cavities are arranged in a rectangular or rotationally symmetrical array, but this is not required. For example, the cavities can be shaped as regular square pyramids, regular truncated pyramids, cones, or truncated cone cavities.

[0059] Typically, the opening of the cavity at the dispensing surface is rectangular; however, this is not required. The length, width and depth of the cavity in the carrier member will generally be determined at least in part by the shape and size of the abrasive particles used therewith. For example, if the precision-shaped abrasive flakes are formed into equilateral triangular flakes, the length of each cavity is preferably 1.1 to 1.2 times the maximum length of the side of the precision-shaped abrasive flakes, the width of each cavity is preferably 1.1 to 2.5 times the thickness of the precision-shaped abrasive flakes, and if the precision-shaped abrasive flakes are completely contained in the cavity, the corresponding depth of the cavity should preferably be 1.0 to 1.2 times the width of the precision-shaped abrasive flakes, and if not completely contained in the cavity, the corresponding depth of the cavity should be less. Similarly, if it is desired to fill the cavity with precision-shaped abrasive flakes and diluted abrasive particles, larger sizes may be useful and will be apparent to those skilled in the art.

[0060] Alternatively, for example, if the precisely shaped abrasive flakes are shaped as triangular or rectangular flakes, the length of each cavity may preferably be less than the length of the edge of the precisely shaped abrasive flakes, and / or if the precisely shaped abrasive flakes will protrude from the cavities, the corresponding depth of the cavities should be less than the width of the abrasive particles. Similarly, the width of the cavities should be selected so that a single abrasive particle fits within each cavity. Similarly, the width of the cavities should be selected so that at least a single precisely shaped abrasive particle fits within each cavity. The cavity openings may be angled and offset from adjacent openings.

[0061] The carrier member may be in the form of an endless belt, sheet, continuous sheet or web, coating roller, sleeve mounted on a coating roller, or die. If the production tool is in the form of a belt, sheet, web, or sleeve, it will have a contact surface and a non-contact surface. If the production tool is in the form of a roller, it will have only a contact surface.

[0062] The carrier member can be prepared, for example, according to the following process. First, a master tool is provided. The master tool is usually made of a metal such as nickel or is plated with a metal such as nickel. The master tool can be made by any conventional technology, such as, for example, engraving, hobbing, embossing, electroforming, diamond turning or laser machining. If it is desired to have a pattern on the surface of the production tool, the master tool should have a pattern opposite to the pattern on the surface of the production tool. The thermoplastic material can be embossed with the master tool to form a pattern. The embossing can be performed when the thermoplastic material is in a flowable state. After embossing, the thermoplastic material can be cooled to cause solidification.

[0063] The carrier member can also be formed by embossing a pattern into a heat-softened formed polymer film. In this case, the film thickness can be less than the cavity depth. This is advantageous for improving the flexibility of the carrier with a deep cavity.

[0064] Preferably, the carrier member comprises metal and / or organic polymer. Such organic polymer is preferably moldable, has low cost, and is quite durable when used for the abrasive particle deposition process of the present disclosure. Examples of organic polymers suitable for making the carrier member can be thermosetting plastics and / or thermoplastics, including: polypropylene, polyethylene, vulcanized rubber, polycarbonate, polyamide, acrylonitrile-butadiene-styrene plastics (ABS), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyimide, polyetheretherketone (PEEK), polyetherketone (PEK), and polyoxymethylene plastics (POM, acetal), poly(ethersulfone), poly(methyl methacrylate), polyurethane, polyvinyl chloride and their combinations.

[0065] The carrier member can also be prepared from a cured thermosetting resin. Production tools made of thermosetting materials can be prepared according to the following process. Uncured thermosetting resin is applied to a master tool of the above type. When the uncured resin is on the surface of the master tool, the uncured resin can be cured or polymerized by heating so that it solidifies into a shape opposite to the pattern on the surface of the master tool. Then, the cured thermosetting resin is removed from the surface of the master tool. Production tools can be prepared from cured radiation-curable resins, such as, for example, acrylated urethane oligomers. Radiation-cured production tools are prepared in the same manner as production tools prepared from thermosetting resins, except that they are cured by exposure to radiation (e.g., ultraviolet radiation).

[0066] The carrier member can have any thickness as long as it has sufficient depth to accommodate the abrasive particles and has sufficient flexibility and durability for the manufacturing process. If the carrier member comprises an endless belt, a carrier member having a thickness of about 0.5 to about 10 mm can generally be used; however, this is not required.

[0067] The elastic compressible layer can be fixed to the non-distributed surface of the carrier member, regardless of whether the cavity extends through the back surface. This can contribute to web processing and / or remove abrasive particles from the cavity. For example, in the embodiment where the elastic compressible layer includes a molded recessed portion aligned with each of the corresponding second openings in at least a portion of the cavity, the abrasive particles extending into the cavity in the molded recessed portion can be mechanically pushed out of the cavity by the pressure applied by the elastic compressible layer. For example, this can occur by compression at the nip roller, wherein the abrasive particle positioning system contacts the primer coating precursor on the backing during the manufacture of the coated abrasive article. If present, the elastic compressible layer can have any thickness, wherein the specific selection of abrasive particles and equipment conditions determines the selection of thickness, composition and / or hardness. If the elastic compressible layer includes an endless belt, the elastic compressible layer with a thickness of about 1 mm to about 25 mm can be generally adopted, but this is not necessary.

[0068] Exemplary materials suitable for the resiliently compressible layer include resilient foams (eg, polyurethane foams), rubbers, silicones, and combinations thereof.

[0069] The pattern of the contact surface of the production tool is generally characterized by a plurality of cavities or recesses. The openings of these cavities may have any regular or irregular shape, such as, for example, rectangular, semicircular, circular, triangular, square, hexagonal or octagonal.

[0070] The wall of the cavity can be vertical or tapered. The pattern formed by the cavity can be arranged according to a predetermined plan or can be randomly arranged. In some embodiments, the cavities can be adjacent to each other. In other embodiments, the cavities can be separated by a certain distance (e.g., at least 0.1mm, at least 0.2mm, at least 0.3mm, at least 0.4mm, at least 0.5mm, at least 1mm, at least 2mm, at least 3mm, at least 4mm or even at least 5mm).

[0071] Preferably, the orientation and any tilt of the cavities will be selected so that the finished coated abrasive will have the precisely shaped abrasive flakes aligned so that the grinding performance will be substantially optimized for its intended use.

[0072] Further details on the manufacture of useful production tools can be found in, for example, U.S. Patent No. 9,776,302 B2 (Keipert), U.S. Patent Application Publication No. 2016 / 0311084 A1 (Culler et al.), and PCT Patent Publication Nos. WO 2019 / 102331 (Hanschen et al.), WO 2019 / 102332 Al (Hanschen et al.), WO 2019 / 102330 A1 (Hanschen et al.), WO 2019 / 102329 Al (Hanschen et al.), and WO 2019 / 102325 A1 (Hanschen et al.).

[0073] The abrasive particles (eg, precisely shaped abrasive flakes and diluted abrasive particles) have sufficient hardness and surface roughness to act as abrasive particles in the grinding process.

[0074] Abrasive particles may include organic and / or inorganic particles.

[0075] Examples of suitable inorganic abrasive particles include: fused alumina; heat-treated alumina; white fused alumina; ceramic alumina materials, such as those commercially available from 3M Company, St. Paul, MN, under the trade name 3M CERAMIC ABRASIVE GRAIN; brown alumina; blue alumina; silicon carbide (including green silicon carbide); titanium diboride; boron carbide; tungsten carbide; garnet; titanium carbide; diamond; cubic boron nitride; garnet; fused alumina-zirconia; iron oxide; chromium oxide; zirconium oxide; titanium dioxide; tin oxide; quartz; feldspar; flint; corundum; sol-gel derived abrasive particles (e.g., including both precision-shaped and crushed forms); and combinations thereof.

[0076] Preferably, the abrasive particles, particularly the precisely shaped abrasive flakes, comprise sol-gel derived alpha-alumina particles.

[0077] Abrasive particles composed of crystallites of alpha alumina, magnesium aluminum spinel, and rare earth hexagonal aluminates can be prepared using sol-gel precursor alpha alumina particles according to the methods described in, for example, U.S. Pat. No. 5,213,591 (Celikkaya et al.) and U.S. Published Patent Application Nos. 2009 / 0165394A1 (Culler et al.) and 2009 / 0169816A1 (Erickson et al.).

[0078] Precision-shaped abrasive particles based on alpha-alumina can be prepared according to a well-known multi-step process. Briefly, the process includes the following steps: preparing a seeded or unseeded sol-gel alpha-alumina precursor dispersion that can be converted to alpha-alumina; filling one or more mold cavities having the desired shape of the precision-shaped abrasive particles with the sol-gel, drying the sol-gel to form precision-shaped ceramic abrasive particle precursors; removing the precision-shaped ceramic abrasive particle precursors from the mold cavities; calcining the precision-shaped ceramic abrasive particle precursors to form calcined precision-shaped ceramic abrasive particle precursors, and then sintering the calcined precision-shaped ceramic abrasive particle precursors to form precision-shaped ceramic abrasive particles. Additional details regarding methods of preparing sol-gel derived abrasive particles can be found, for example, in U.S. Pat. Nos. 4,314,827 (Leitheiser), 5,152,917 (Pieper et al.), 5,435,816 (Spurgeon et al.), 5,672,097 (Hoopman et al.), 5,946,991 (Hoopman et al.), 5,975,987 (Hoopman et al.), and 6,129,540 (Hoopman et al.) and U.S. Published Patent Application No. 2009 / 0165394 Al (Culler et al.). Additional examples of sol-gel derived precision-shaped alpha-alumina (i.e., ceramic) abrasive particles can be found in U.S. Pat. Nos. 5,201,916 (Berg), 5,366,523 (Rowenhorst (Re 35,570)), 5,984,988 (Berg), 8,142,531 (Adefris et al.), 8,142,891 (Culler et al.), and 8,142,532 (Erickson et al.), and in U.S. Patent Application Publication Nos. 2012 / 0227333 (Adefris et al.), 2013 / 0040537 (Schwabel et al.), and 2013 / 0125477 (Adefris).

[0079] In some embodiments, the bottom and top of the precisely formed abrasive particles are substantially parallel, thereby producing a prismatic or truncated pyramidal shape, but this is not necessary. In some embodiments, the side of the truncated triangular pyramid has equal size and forms a dihedral angle of about 82 degrees with the base. However, it should be understood that other dihedral angles (including 90 degrees) can also be used. For example, the dihedral angle between each side in the base and the side can be independently 45 degrees to 90 degrees, usually 70 degrees to 90 degrees, more usually in the range of 75 to 85 degrees.

[0080] Suitable organic abrasive particles (particularly as dilute abrasive products) can be formed by thermoplastic polymers and / or thermosetting polymers. Organic abrasive particles can be formed by thermoplastic materials, such as polycarbonate, polyetherimide, polyester, polyvinyl chloride (PVC), polymethacrylate, polymethyl methacrylate, polyethylene, polysulfone, polystyrene, acrylonitrile-butadiene-styrene block copolymer, polypropylene, acetal polycondensate, polyurethane, polyamide and their combination. Organic abrasive particles can be a mixture of thermoplastic polymers and thermosetting polymers. Other suitable organic abrasive particles include natural products such as nut shells.

[0081] It is also contemplated that the abrasive particles may comprise abrasive agglomerates, such as those described in, for example, U.S. Pat. Nos. 4,652,275 (Bloecher et al.), 4,799,939 (Bloecher et al.), 6,521,004 (Culler et al.), or 6,881,483 (McArdle et al.). It is also contemplated that the abrasive particles may comprise precisely shaped polymer particles comprising an organic binder and optional abrasive particles, such as those described in US 5,714,259 (Holmes et al.). Additional examples include shaped abrasive composites of abrasive particles in a binder matrix, such as those described in U.S. Pat. No. 5,152,917 (Pieper et al.). Many such abrasive particles, agglomerates, and composites are known in the art.

[0082] In some embodiments, the abrasive particles can be surface treated with a coupling agent (e.g., an organosilane coupling agent) or other physical treatments (e.g., iron oxide or titanium oxide) to enhance the adhesion of the abrasive particles to the binder. The abrasive particles can be treated before they are combined with the binder, or they can be surface treated in situ by including a coupling agent into the binder.

[0083] In some embodiments, the abrasive particles have a Mohs hardness of at least 4, at least 5, at least 6, at least 7, or even at least 8.

[0084] In some preferred embodiments, the abrasive particles include shaped ceramic abrasive particles (eg, shaped sol-gel derived polycrystalline alpha-alumina particles) that are generally triangular in shape (eg, triangular prisms or truncated three-sided pyramids).

[0085] The length of the abrasive particles is typically selected to be in the range of 1 micron to 4 millimeters, more typically 10 microns to about 3 millimeters, and still more typically 150 microns to 2600 microns, although other lengths may be used.

[0086] The width of the abrasive particles is typically selected to be in the range of 0.1 microns to 3500 microns, more typically 100 microns to 3000 microns, and more typically 100 microns to 2600 microns, although other lengths may be used.

[0087] The thickness of the abrasive particles is typically selected to be in the range of 0.1 micrometers to 1600 micrometers, more typically 1 micrometer to 1200 micrometers, although other thicknesses may be used.

[0088] In some embodiments, the abrasive particles can have an aspect ratio (ratio of length to thickness) of at least 2, 3, 4, 5, 6, or more.

[0089] The surface coating on the abrasive particles can be used to improve the adhesion between the shaped ceramic abrasive particles and the binder in the coated abrasive article, or can be used to assist in the electrostatic deposition of the shaped ceramic abrasive particles. In one embodiment, the surface coating described in U.S. Pat. No. 5,352,254 (Celikkaya) can be used in an amount of 0.1% to 2% of the surface coating relative to the weight of the abrasive particles. Such surface coatings are described in U.S. Pat. Nos. 5,213,591 (Celikkaya et al.), 5,011,508 (Wald et al.), 1,910,444 (Nicholson), 3,041,156 (Rowse et al.), 5,009,675 (Kunz et al.), 5,085,671 (Martin et al.), 4,997,461 (Markhoff-Matheny et al.), and 5,042,991 (Kunz et al.). In addition, the surface coating can prevent the shaped abrasive particles from blocking. The term "blocking" is used to describe the phenomenon whereby metal particles from the workpiece being abraded become welded to the tops of the shaped ceramic abrasive particles. Surface coatings that perform the above functions are known to those skilled in the art.

[0090] Abrasive particles can be independently sized according to a specified nominal grade recognized by the abrasive industry. Exemplary abrasive industry recognized grading standards include those issued by ANSI (American National Standards Institute), FEPA (European Abrasive Manufacturers Federation) and JIS (Japanese Industrial Standards). ANSI grade designations (i.e., specified nominal grades) include, for example: ANSI 4, ANSI 6, ANSI 8, ANSI 16, ANSI 24, ANSI 36, ANSI 46, ANSI 54, ANSI 60, ANSI 70, ANSI 80, ANSI 90, ANSI 100, ANSI 120, ANSI 150, ANSI 180, ANSI 220, ANSI 240, ANSI 280, ANSI 320, ANSI 360, ANSI 400 and ANSI 600. FEPA grade numbers include F4, F5, F6, F7, F8, F10, F12, F14, F16, F16, F20, F22, F24, F30, F36, F40, F46, F54, F60, F70, F80, F90, F100, F120, F150, F180, F220, F230, F240, F280, F320, F360, F400, F500, F600, F800, F1000, F1200, F1500 and F2000. JIS grade numbers include: JIS8, JIS12, JIS16, JIS24, JIS36, JIS46, JIS54, JIS60, JIS80, JIS100, JIS150, JIS180, JIS220, JIS240, JIS280, JIS320, JIS360, JIS400, JIS600, JIS800, JIS1000, JIS1500, JIS2500, JIS4000, JIS6000, JIS8000 and JIS10,000.

[0091] According to an embodiment of the present disclosure, the average diameter of the abrasive particles may be in the range of 260 micrometers to 4000 micrometers according to FEPA grades F60 to F24.

[0092] Alternatively, the abrasive particles can be graded to a nominal sieving grade using American Standard Test Sieves that conform to ASTM E11-17 "Standard Specification for Woven Wire Test Sieve Cloth and Test Sieves". ASTM E11-17 specifies the design and construction requirements for test sieves that classify materials according to a specified particle size using the media of a woven wire mesh screen cloth mounted in a frame. A typical designation may be expressed as -18+20, which means that the abrasive particles can pass through a test sieve conforming to the ASTM E11-17 specification of an 18 mesh screen and be retained on a test sieve conforming to the ASTM E11-17 specification of a 20 mesh screen. In one embodiment, the shaped abrasive particles have a particle size such that most of the particles pass through an 18 mesh test sieve and can be retained on a 20 mesh, 25 mesh, 30 mesh, 35 mesh, 40 mesh, 45 mesh, or 50 mesh test sieve. In various embodiments, the abrasive particles can have the following nominal screen grades: -18+20, -20 / +25, -25+30, -30+35, -35+40, 5-40+45, -45+50, -50+60, -60+70, -70 / +80, -80+100, -100+120, -120+140, -140+170, -170+200, -200+230, -230+270, -270+325, -325+400, -400+450, -450+500, or -500+635. Alternatively, a custom mesh size such as -90+100 can be used.

[0093] The precisely shaped abrasive particles can be deposited into the cavity by any suitable method, including, for example, dripping and / or wiping, preferably using the vibration or air assistance of the production tool. Typically, an excess of precisely shaped abrasive particles are deposited onto the distribution surface by an abrasive particle feeder so that more precisely shaped abrasive particles are present in the production tool cavity per unit length. Providing an excess of precisely shaped abrasive particles helps to ensure that substantially all cavities in the production tool are eventually filled with precisely shaped abrasive particles. Since the support area and spacing of precisely shaped abrasive particles are usually designed into the production tool for specific grinding applications, it is desirable not to produce too many unfilled cavities. The abrasive particle feeder is usually the same as the width of the production tool (especially if the production tool includes a roller, a roller sleeve or an endless belt), and supplies precisely shaped abrasive particles over the entire width of the production tool. The abrasive particle feeder can be, for example, a vibrating feeder, a hopper, a chute, a silo, a drip coater or a screw feeder.

[0094] Optionally, a filling auxiliary member is provided after the abrasive grain feeder to move the precisely shaped abrasive grains back and forth on the surface of the production tool and to help orient or slide the precisely shaped abrasive grains into the cavity. The filling auxiliary member can be, for example, a scraper, a felt wiper, a brush with multiple bristles, a vibrating system, a blower or an air knife, a vacuum box, or a combination thereof. The filling auxiliary member moves, translates, sucks, or shakes the precisely shaped abrasive grains on the distribution surface to place more precisely shaped abrasive grains in the cavity. In the absence of a filling auxiliary member, at least some of the precisely shaped abrasive grains that usually fall onto the distribution surface will fall directly into the cavity and do not need to be moved further, but other abrasive grains require some additional movement to enter the cavity.

[0095] Optionally, the filling aid member can be swung sideways in a direction crosswise to the longitudinal direction, or otherwise moved relative to the production tool, such as in a circular or elliptical motion relative to the surface of the production tool using a suitable driving force, to help the abrasive particles completely fill each cavity in the production tool. Typically, if a brush is used as a filling aid member, the bristles can cover a portion of the dispensing surface, covering a length of 2 inches to 4 inches (5.0 cm to 10.2 cm) in the longitudinal direction, preferably covering all or nearly all of the width of the dispensing surface, and resting lightly on or just above the dispensing surface, and having moderate flexibility. A vacuum box, if used as a filling aid member, is typically used in conjunction with a production tool having a cavity that extends completely through the production tool; however, even a production tool with a solid back surface can be advantageous because it will flatten the production tool and pull it flatter to improve the filling of the cavity.

[0096] If the production tool is an endless belt, the endless belt has a positive slope to propel it to a greater height as it moves past the abrasive particle feeder. If the production tool is a roller, the abrasive particle feeder can be positioned so that it applies abrasive particles to the roller before top dead center on the periphery of the roller, such as between 270 degrees and 350 degrees on the face of the roller, with top dead center being 0 degrees when traveling clockwise around the roller (the roller rotates clockwise in operation).

[0097] Optionally, an abrasive particle removal member can be provided to help remove excess precisely shaped abrasive particles from the surface of a production tool when most or all of the cavities are filled with abrasive particles. The abrasive particle removal member can be, for example, an air source for blowing off excess precisely shaped abrasive particles from the distribution surface of a production tool, such as an air wand, an air shower, an air knife, a Coanda effect nozzle, or a blower. A contact device can be used as an abrasive particle removal member, such as a brush, a scraper, a wiper, or a powder scraper. A vibrator such as an ultrasonic horn can be used as an abrasive particle removal member.

[0098] Alternatively, for a production tool having a cavity therein extending completely through the production tool, a vacuum source such as a vacuum box or vacuum roller positioned along a portion of the first web path after the abrasive particle feeder can be used to hold the precisely shaped abrasive particles in the cavity. During this span or section of the first web path, the dispensing surface of the production tool can be reversed or have a larger upward or downward slope approaching or exceeding 90 degrees to use gravity to remove excess precisely shaped abrasive particles, causing them to slide or fall from the dispensing surface, while the precisely shaped abrasive particles placed in the cavity are held by the vacuum until the dispensing surface returns to an orientation that holds the precisely shaped abrasive particles in the cavity (due to gravity) or is released from the cavity onto the resin-coated backing.

[0099] In embodiments where the abrasive particles are completely contained within the cavities of the production tool, the abrasive particle removal member can slide excess precision-shaped abrasive particles across the dispensing surface of the production tool and away from the production tool without disturbing the precision-shaped abrasive particles contained within the cavities. The removed excess precision-shaped abrasive particles can be collected and returned to the abrasive particle feeder for reuse. Alternatively, the excess precision-shaped abrasive particles can be moved in a direction opposite to the direction of travel of the production tool through or toward the abrasive particle feeder, whereby they can fill unoccupied cavities.

[0100] Further details regarding depositing precisely shaped abrasive particles into cavities of a production tool can be found, for example, in U.S. Patent Application Publication No. 2016-0311081A1 (Culler et al.).

[0101] The diluted abrasive particles can be applied by any suitable means that does not remove the precisely shaped abrasive particles from the cavity; however, the diluted abrasive particles can also be stuck in the cavity with the precisely shaped abrasive particles. The diluted abrasive particles can be applied using an abrasive feeder. The abrasive particle feeder can be, for example, a vibrating feeder, a hopper, a chute, a silo, a drop coater, or a screw feeder. A preferred deposition method is drop coating. An abrasive particle removal member (e.g., as discussed above) can be used to help remove excess diluted abrasive particles from the surface of the production tool.

[0102] Typically, the smallest average dimension (e.g., average particle size) of the diluted abrasive particles is smaller than the longest dimension of the precisely shaped abrasive flakes. For example, the ratio of the average particle size of the diluted abrasive particles to the average longest dimension of the precisely shaped abrasive flakes may be less than 1 / 2, less than 1 / 3, less than 1 / 4, less than 1 / 5, less than 1 / 6, or even less than 1 / 8, however, this is not required.

[0103] If desired, grinding aid particles can be deposited with the diluted abrasive particles using a simultaneous or sequential procedure. Useful grinding aids include cryolite, fluoroborates (e.g., potassium tetrafluoroborate), fatty acid metal salts (e.g., zinc stearate or calcium stearate), salts of phosphate esters (e.g., potassium behenyl phosphate), phosphate esters, urea-formaldehyde resins, mineral oils, crosslinked silanes, crosslinked silicones, and / or fluorine-containing compounds.

[0104] Once the diluted abrasive grains have been deposited (as an open coat, a closed coat, or a patterned coat) on the dispensing surface of the production tool, they are brought into contact with the make layer precursor disposed on the backing. Once in contact, the abrasive grains adhere to the make layer precursor and remain adhered to the make layer precursor after the backing and make layer precursor are optionally separated from the production tool.

[0105] See now Figure 2 , wherein an inclined orientation of the precisely shaped abrasive flake is shown, wherein after transfer, at least a majority (e.g., at least 50%, at least 60%, at least 70%, at least 80%, or even at least 90%) of the precisely shaped abrasive flake is overhanging above a corresponding plurality of diluted abrasive grains.

[0106] A variety of methods can be used to transfer abrasive particles from the cavities of the production tool to the primer layer precursor. In no particular order, the various methods include, for example: gravity assistance, in which the production tool and the distribution surface are reversed so that the abrasive particles fall from the cavity onto the primer layer precursor under the action of gravity; push assistance, in which each cavity in the production tool has two open ends, so that the abrasive particles can reside in the cavity and a portion of the abrasive particles extends through the back surface of the production tool; vibration assistance, in which the abrasive particle conveying roller or the production tool is vibrated by a suitable source such as an ultrasonic device to shake the abrasive particles out of the cavity and onto the resin-coated backing; and pressure assistance, in which each cavity in the production tool has two open ends or the back surface or the entire production tool has a suitable porous structure, and the abrasive particle conveying roller has multiple holes and an internal pressurized air source. The various embodiments listed above are not limited to use alone, and they can be mixed and matched as needed to more efficiently convey abrasive particles from the cavity to the primer layer precursor.

[0107] The make layer precursor is then at least partially cured (in an amount at least sufficient to secure the abrasive grains for further processing) to form the make layer. Thereafter, the make layer and abrasive grains are coated with a size layer precursor, which is then at least partially cured (in an amount at least sufficient to secure the abrasive grains for the intended grinding process). Optionally, other process steps are known to those skilled in the art of preparing coated abrasive articles.

[0108] It will be apparent to those skilled in the art that the make layer precursor, optional size layer precursor, and optional supersize layer can be coated using conventional techniques such as, for example, gravure coating, curtain coating, knife coating, spray coating, roll coating, reverse roll gravure coating, or rod coating.

[0109] Exemplary backings include those known in the art for preparing coated abrasive articles, including conventional sealed coated abrasive backings and porous non-sealed backings. Typically, the backing has two opposing major surfaces, but not necessarily. The thickness of the backing is typically in the range of about 0.02 mm to about 5 mm, advantageously in the range of about 0.05 mm to about 2.5 mm, and more advantageously in the range of about 0.1 mm to about 0.4 mm, but thicknesses outside these ranges may also be used.

[0110] The backing may be flexible or rigid. Preferably, the backing is flexible. Exemplary backings include polymer films (including primed films) such as polyolefin films (e.g., polypropylene, polyester films, polyamide films, cellulose ester films including biaxially oriented polypropylene), metal foils, meshes, foams (e.g., natural sponge materials or polyurethane foams), cloth (e.g., cloth made of fibers or yarns, including polyester, nylon, silk, cotton and / or rayon), paper, hardened paper, vulcanized fibers, nonwoven materials, combinations thereof, and processed versions thereof. The cloth backing may be, for example, woven, knitted, or stitched. The backing may also be a laminate of two materials (e.g., paper / film, cloth / paper, film / cloth).

[0111] The backing can be treated to include a presize layer (i.e., a barrier coating covering the major surface of the backing on which the abrasive layer is applied), a backsize layer (i.e., a barrier coating covering the major surface of the backing opposite to the major surface on which the abrasive layer is applied), an impregnant (i.e., a barrier coating applied to all exposed surfaces of the backing), or a combination thereof. Useful presize, backsize, and impregnant compositions include glue, phenolic resins, latex, epoxy resins, urea-formaldehyde, polyurethane, melamine-formaldehyde, neoprene, butyl acrylate, styrene, starch, and combinations thereof. Other optional layers known in the art (e.g., bonding layers; see, e.g., U.S. Pat. No. 5,700,302 (Stoetzel et al.)) may also be used.

[0112] The backing treatment may contain additional additives, such as fillers and / or antistatic materials (e.g., carbon black particles, vanadium pentoxide particles). The addition of antistatic materials can reduce the tendency of the coated abrasive article to accumulate static electricity when sanding wood or wood-like materials. Additional details on antistatic backings and backing treatments can be found, for example, in U.S. Pat. Nos. 5,108,463 (Buchanan et al.), 5,137,542 (Buchanan et al.), 5,328,716 (Buchanan), and 5,560,753 (Buchanan et al.).

[0113] Typically, at least one major surface of the backing is smooth (e.g., this surface can serve as the first major surface). The second major surface of the backing can include an anti-slip or friction coating. Examples of such coatings include inorganic particles (e.g., calcium carbonate or quartz) dispersed in a binder.

[0114] The backing may contain various additives. Examples of suitable additives include colorants, processing aids, reinforcing fibers, heat stabilizers, UV stabilizers, and antioxidants. Examples of useful fillers include clay, calcium carbonate, glass beads, talc, clay, mica, wood chips, and carbon black.

[0115] The backing may be a fiber-reinforced thermoplastic, such as, for example, that described in U.S. Pat. No. 5,417,726 (Stout et al.), or may be an endless belt, such as that described in U.S. Pat. No. 5,573,619 (Benedict et al.). Likewise, the backing may be a polymer substrate having hooks protruding therefrom, such as, for example, that described in U.S. Pat. No. 5,505,747 (Chesley et al.). Similarly, the backing may be a loop fabric, such as, for example, that described in U.S. Pat. No. 5,565,011 (Follett et al.).

[0116] The make layer precursor and the size layer precursor comprise respective curable binder precursor compositions, which may be the same or different.

[0117] Examples of curable binder precursor compositions used in primer and / or glue layer precursors include phenolic resins, urea-formaldehyde resins, acrylate resins, polyurethane resins, epoxy resins, amino plastic resins, and combinations thereof. Curable binder precursor compositions may also include various additives, including, for example, plasticizers, fillers, fibers, lubricants, surfactants, wetting agents, dyes, pigments, defoamers, dyes, coupling agents, plasticizers, and suspending agents.

[0118] Depending on any curable binder precursor composition selected, a suitable curing agent may be added to facilitate curing. Such curing agents will be apparent to those skilled in the art, and may be, for example, thermally activated, photochemically activated, or both.

[0119] Optionally, a top size layer may be applied to at least a portion of the resize layer. When present, the top size typically includes a grinding aid and / or an anti-filling material. The optional top size layer may help prevent or reduce the accumulation of abrasive debris (material ground from the workpiece) between the abrasive particles, which can significantly reduce the cutting ability of the coated abrasive belt. Available top size layers typically include grinding aids such as cryolite, tetrafluoroborate (e.g., potassium tetrafluoroborate), fatty acid metal salts (e.g., zinc stearate or calcium stearate), salts of phosphate esters (e.g., potassium behenyl phosphate), phosphate esters, urea-formaldehyde resins, mineral oils, cross-linked silanes, cross-linked organosilicones and / or fluorinated compounds. Available top size materials are additionally described in, for example, U.S. Pat. No. 5,556,437 (Lee et al.). Typically, the amount of grinding aid incorporated into the coated abrasive product is from about 50 to about 400 gsm, more typically from about 80 to about 300 gsm. The supersize may contain a binder, such as, for example, those used to prepare a size coat or make coat, but it need not have any binder.

[0120] Further details regarding coated abrasive belts comprising an abrasive layer secured to a backing, wherein the abrasive layer comprises abrasive grains and a make layer, a size layer, and an optional top size layer are well known and can be found, for example, in U.S. Pat. Nos. 4,734,104 (Broberg); 4,737,163 (Larkey); 5,203,884 (Buchanan et al.); 5,152,917 (Pieper et al.); 5,378,251 (Culler et al.); 5,417,726 (Stout et al.); 5,436,063 (Folle et al.); tt et al.), 5,496,386 (Broberg et al.), 5,609,706 (Benedict et al.), 5,520,711 (Helmin), 5,954,844 (Law et al.), 5,961,674 (Gagliardi et al.), 4,751,138 (Bange et al.), 5,766,277 (DeVoe et al.), 6,077,601 (DeVoe et al.), 6,228,133 (Thurber et al.), and 5,975,988 (Christianson).

[0121] The coated abrasive belt according to the present invention can be used to abrade workpieces. Preferred workpieces include metals (eg, aluminum, nickel alloys, stainless steel, mild steel), composites, plastics, and wood.

[0122] It will be apparent to those skilled in the art that the make layer precursor, optional size layer precursor, and optional supersize layer can be coated using conventional techniques such as, for example, gravure coating, curtain coating, knife coating, spray coating, roll coating, reverse roll gravure coating, or rod coating.

[0123] See now Figure 6 In one exemplary embodiment, a coated abrasive article 600 includes a backing 610 having a major surface 612. A make coat 630 is disposed on and secured to the backing 610. An abrasive layer 620 contacts and secures the make coat 630. The abrasive layer 620 includes precisely shaped abrasive flakes 632 and diluted abrasive particles 624. The precisely shaped abrasive flakes 622 are disposed at a dihedral angle β of less than or equal to 60 degrees relative to the major surface 612 of the backing 610. At least a majority (e.g., at least 50%, at least 60%, at least 70%, at least 80%, or even at least 90%) of the precisely shaped abrasive flakes 632 each overhang a corresponding plurality of diluted abrasive particles 624. A size coat 670 is disposed on the make coat 630 and the abrasive layer 620.

[0124] Referring now to FIG. 7 , in another exemplary embodiment, a coated abrasive article 700 includes a coated abrasive article 700 having a backing 710 with a major surface 712. A make coat 730 is disposed on and secured to the backing 710. An abrasive layer 720 contacts and secures the make coat 730. The abrasive layer 720 includes islands 725. Each island 725 contains at least one precisely shaped abrasive flake 722 and diluted abrasive particles 724. The islands 725 are separated from one another. A size coat 770 is disposed on the make coat 730 and the abrasive layer 720. The precisely shaped abrasive flakes 722 are generally aligned relative to a longitudinal axis 790 of the coated abrasive article 700.

[0125] With respect to a coated abrasive article 800 used with rotational motion (e.g., Figure 8 For the coated abrasive disc shown in FIG. 8 , the precisely shaped abrasive flakes 822 are generally aligned relative to the axis of rotation ( 875 , perpendicular to the page) of the coated abrasive article 800 .

[0126] Coated abrasive articles according to the present invention can be used to abrade a workpiece. One such method includes frictionally contacting at least a portion of an abrasive layer of the coated abrasive article with at least a portion of a surface of the workpiece, and moving at least one of the coated abrasive article or the workpiece relative to the other to abrade at least a portion of the surface.

[0127] Examples of workpiece materials include metals, metal alloys, exotic metal alloys, ceramics, glass, wood, wood-like materials, composite materials, painted surfaces, plastics, reinforced plastics, stone, and / or combinations thereof. The workpiece may be flat or have a shape or contour associated therewith. Exemplary workpieces include metal parts, plastic parts, particle board, camshafts, crankshafts, furniture, and turbine blades.

[0128] The coated abrasive article according to the present invention can be used manually and / or in conjunction with a machine. When abrading is performed, at least one of the coated abrasive article and the workpiece is usually moved relative to the other or both are moved relative to each other.

[0129] Grinding can be performed under wet or dry conditions. Exemplary liquids for wet grinding include water, water containing conventional rust-inhibiting compounds, lubricants, oils, soaps, and cutting fluids. The liquid may also contain defoamers, degreasers, and / or the like.

[0130] Selected Embodiments of the Disclosure

[0131] In a first embodiment, the present disclosure provides a method of making a coated abrasive article, the method comprising the following sequential steps:

[0132] a) providing a production tool comprising a carrier member having a dispensing surface, the production tool having a precisely shaped cavity therein;

[0133] b) depositing precisely shaped abrasive flakes into at least some of the precisely shaped cavities;

[0134] c) depositing diluted abrasive particles on the dispensing surface;

[0135] d) contacting the precisely shaped abrasive flakes and the diluted abrasive particles with a curable make layer precursor disposed on a major surface of a backing;

[0136] e) optionally separating the tool from the precisely shaped abrasive flakes and the diluted abrasive grains; and

[0137] f) at least partially curing the curable make layer precursor to provide an at least partially cured make layer precursor.

[0138] In a second embodiment, the present disclosure provides a method according to the first embodiment, wherein the sequential steps further comprise:

[0139] g) disposing a curable size layer precursor onto the at least partially cured make layer precursor, the precisely shaped abrasive flakes and the diluted abrasive grains; and

[0140] h) at least partially curing the curable size layer precursor.

[0141] In a third embodiment, the present disclosure provides a method according to the first embodiment or the second embodiment, wherein steps a) to e) are continuous.

[0142] In a fourth embodiment, the present disclosure provides a method according to any one of the first to third embodiments, wherein after step b) and before step c), at least a majority of the precisely shaped abrasive flakes are oriented at respective dihedral angles less than or equal to 60 degrees relative to the dispensing surface of the tool.

[0143] In a fifth embodiment, the present disclosure provides a method according to any one of the first to fourth embodiments, wherein after step c), at least a majority of the precisely shaped abrasive flakes depend from a corresponding plurality of the diluted abrasive grains.

[0144] In a sixth embodiment, the present disclosure provides a method according to any one of the first to fifth embodiments, wherein the diluted abrasive particles include pulverized abrasive particles.

[0145] In a seventh embodiment, the present disclosure provides a method according to any one of the first to sixth embodiments, wherein after step c), the precisely shaped abrasive flakes and the diluted abrasive grains form a closed abrasive coating.

[0146] In an eighth embodiment, the present disclosure provides a method according to any one of the first to seventh embodiments, wherein after step c), the precisely shaped abrasive flakes and the diluted abrasive grains form an open abrasive coating.

[0147] In a ninth embodiment, the present disclosure provides a coated abrasive article prepared according to the method of any one of the first to eighth embodiments.

[0148] In a tenth embodiment, the present disclosure provides a coated abrasive article comprising:

[0149] a backing having a first major surface;

[0150] a primer layer, the primer layer being disposed on the backing and fixed to the backing;

[0151] an abrasive layer contacting and secured to the make coat, wherein the abrasive layer comprises precision-shaped abrasive flakes and diluted abrasive grains, wherein the precision-shaped abrasive flakes include a second major surface disposed at a dihedral angle of less than or equal to 60 degrees relative to the first major surface of the backing, and wherein at least a majority of the precision-shaped abrasive flakes each overhang a corresponding plurality of the diluted abrasive grains; and

[0152] A double-glue layer is disposed on the base glue layer and the abrasive layer.

[0153] In an eleventh embodiment, the present disclosure provides a coated abrasive article according to the tenth embodiment, wherein the precisely shaped abrasive flakes are generally aligned with respect to a longitudinal axis of the coated abrasive article.

[0154] In a twelfth embodiment, the present disclosure provides a coated abrasive article according to the tenth embodiment, wherein the precisely shaped abrasive flakes are generally aligned with respect to an axis of rotation of the coated abrasive article.

[0155] In a thirteenth embodiment, the present disclosure provides a coated abrasive article according to any one of the tenth to twelfth embodiments, wherein the precisely shaped abrasive flakes comprise triangular flakes.

[0156] In a fourteenth embodiment, the present disclosure provides a coated abrasive article according to any one of the tenth to thirteenth embodiments, wherein after step c), the precisely shaped abrasive flakes comprise rectangular flakes.

[0157] In a fifteenth embodiment, the present disclosure provides a coated abrasive article according to any one of the tenth to fourteenth embodiments, wherein the diluted abrasive particles comprise comminuted abrasive particles.

[0158] In a sixteenth embodiment, the present disclosure provides a coated abrasive article according to any one of the tenth to fifteenth embodiments, wherein the precisely shaped abrasive flakes and the diluted abrasive grains form a closed abrasive coating.

[0159] In a seventeenth embodiment, the present disclosure provides a coated abrasive article according to any one of the tenth to fifteenth embodiments, wherein the precisely shaped abrasive flakes and the diluted abrasive grains form an open abrasive coating.

[0160] In an eighteenth embodiment, the present disclosure provides a coated abrasive article according to any one of the tenth to seventeenth embodiments, wherein the precisely shaped abrasive flakes are positioned substantially according to a predetermined pattern.

[0161] In a nineteenth embodiment, the present disclosure provides a coated abrasive article comprising:

[0162] a backing having a major surface;

[0163] a primer layer, the primer layer being disposed on the backing and fixed to the backing;

[0164] an abrasive layer contacting and secured to the make coat, wherein the abrasive layer comprises islands, each island containing at least one precisely shaped abrasive flake and diluted abrasive particles, and wherein the islands are separated from one another; and

[0165] A double-glue layer is disposed on the base glue layer and the abrasive layer.

[0166] In a twentieth embodiment, the present disclosure provides a coated abrasive article according to the nineteenth embodiment, wherein the dilute abrasive particles are primarily disposed below respective overhangs of at least a majority of the precisely shaped abrasive flakes.

[0167] In a twenty-first embodiment, the present disclosure provides a coated abrasive article according to the nineteenth embodiment or the twentieth embodiment, wherein the islands are separated from one another by a distance that is at least twice the smallest distance between the closest precisely shaped abrasive flakes of adjacent islands.

[0168] In a twenty-second embodiment, the present disclosure provides a coated abrasive article according to any one of the nineteenth to twenty-first embodiments, wherein the precisely shaped abrasive flakes are positioned substantially according to a predetermined pattern.

[0169] In a twenty-third embodiment, the present disclosure provides a coated abrasive article according to any one of the nineteenth to twenty-second embodiments, wherein the precisely shaped abrasive flakes are generally aligned with respect to a longitudinal axis of the coated abrasive article.

[0170] In a twenty-fourth embodiment, the present disclosure provides a coated abrasive article according to any one of the nineteenth to twenty-second embodiments, wherein the precisely shaped abrasive flakes are generally aligned relative to an axis of rotation of the coated abrasive article.

[0171] In a twenty-fifth embodiment, the present disclosure provides a method of grinding a workpiece, the method comprising:

[0172] Providing a coated abrasive article according to any one of the ninth to twenty-fourth embodiments;

[0173] frictionally contacting at least a portion of the coated abrasive article with at least a portion of a surface of the workpiece; and

[0174] At least one of the coated abrasive article or the workpiece is moved relative to the other to abrade at least a portion of the surface.

[0175] Objects and advantages of this disclosure are further illustrated by the following non-limiting examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure.

[0176] Example

[0177] Unless otherwise indicated, all parts, percentages, ratios, etc. in the examples and the rest of the specification are by weight.

[0178] Unless otherwise noted, all other reagents were obtained or purchased from fine chemical suppliers such as Sigma-Aldrich Company, St. Louis, Missouri, or may be synthesized by known methods.

[0179] Unit abbreviations used in the examples: °C: degrees Celsius; cm = centimeters; g = grams; g / m 2 = grams per square meter; rpm = revolutions per minute; mm = millimeter; wt.% = weight percent.

[0180] The materials used in the examples are described in Table 1 below:

[0181] Table 1

[0182]

[0183] Example 1

[0184] Coated abrasive article having a 90 degree SAP orientation

[0185] A production tool with vertically oriented triangular openings was used to place abrasive particles, these openings were generally configured as described in U.S. Patent Application Publication No. 2016 / 0311081 A1 (Culler et al.) (length = 1.875 mm, width = 0.785 mm, depth = 1.62 mm, bottom width = 0.328 mm), arranged in a rectangular array (longitudinal spacing = 1.978 mm, lateral spacing = 0.886 mm, all long dimensions in the same direction).

[0186] In the first step, fill most of the cavities of the production tool with P36 grade SAP. 2) WoosterSpiffy brush carefully removes excess SAP. Approximately 9.2 g of SAP particles are loaded onto a 37 square inch area of ​​the tool surface.

[0187] In the second step, the gap between the SAP and the cavity wall was filled with P80 grade crushed garnet particles. Excess crushed garnet particles were carefully removed with a 3-inch Wooster Spiffy brush. About 4.4 g of crushed garnet particles were loaded onto a 37 square inch area of ​​the tool surface.

[0188] Primer layer precursor

[0189] The fiber disk backing was coated with Primer Resin 1 by brush to a weight of 3.0 to 3.1 grams.

[0190] Transferring abrasive minerals to make layer precursors

[0191] The fiber disc backing with the make coat precursor is then flipped over and brought into contact with the abrasive grain-laden surface of the production tool. The assembly is clamped together with binder clips and then flipped over to facilitate gravity transfer of the abrasive grains to the make coat precursor. The vibration of the production tool further facilitates the transfer of the abrasive grains. The production tool is separated from the make coat precursor and abrasive grains so that both the SAP and crushed abrasive grains have been transferred to the make coat resin layer. The make coat precursor of the coated disc is pre-cured at 90°C for 1 hour and then at 103°C for 3 hours.

[0192] Adhesive coating

[0193] The precured disc was then coated with curable size resin 1 by brush. Excess size resin was removed with a dry brush until the immersed glossy appearance was reduced to a matte appearance. The size resin disc was weighed to determine the size resin weight. The amount of size resin added was 11.5 g to 13.0 g of size resin coating (i.e., size layer precursor). The disc was cured at 90°C for 90 minutes and then cured at 103°C for 16 hours. The cured disc was orthogonally flexed on a 1.5 inch (3.8 cm) diameter roller. The surface of the resulting coated abrasive article was characterized using an optical microscope. The results are shown in Fig.9A and Fig. 9B middle.

[0194] Comparative Example A

[0195] Coated abrasive article having a 90 degree SAP orientation

[0196] The procedure of Example 1 was repeated, except that the SAP loaded on the production tool was first transferred to the make coat precursor, and then the P80 grade crushed garnet particles were directly applied to the fiber disk substrate by drop coating (the abrasive particles fell onto the make coat precursor by gravity). The results are shown in Fig. 10A and Fig. 10B middle.

[0197] Example 2

[0198] Coated abrasive article having a 60 degree SAP orientation

[0199] The procedure of Example 1 was repeated except that: (1) a production tool having 60° oriented triangular openings (length = 1.875 mm, width = 1.1775 mm, depth = 1.62 mm, base width = 0.328 mm) arranged in a rectangular array (longitudinal spacing = 1.978 mm, transverse spacing = 1.229 mm, all long dimensions in the same direction) was used; and (2) 8.3 g of SAP and then 6.8 g of P80 grade crushed garnet particles were loaded onto the production tool. The results are shown in Fig.11A and Fig. 11B middle.

[0200] Comparative Example B

[0201] Coated abrasive article with 60 degree SAP vertical orientation

[0202] The procedure of Example 2 was repeated, except that the SAP loaded on the production tool was first transferred to the primer layer precursor, and then 8.2 g of P80 grade crushed garnet particles were directly applied to the primer layer precursor by drop coating. The results are shown in Fig. 12A and Fig. 12B as shown in .

[0203] All references, patents, and patent applications cited in this application are incorporated by reference in a consistent manner. In the event of inconsistencies or conflicts between the incorporated references and this application, the information in this application shall prevail. The foregoing description given to enable one of ordinary skill in the art to practice the disclosure protected by the claims should not be construed as limiting the scope of the disclosure, which is defined by the claims and all equivalents thereof.

Claims

1. A method for preparing a coated abrasive article, the method comprising the following steps in sequence: a) providing a production tool comprising a carrier member having a dispensing surface, the production tool having a precisely shaped cavity therein; b) depositing precisely shaped abrasive flakes into at least some of the precisely shaped cavities; c) depositing diluted abrasive particles on the dispensing surface; d) contacting the precisely shaped abrasive flakes and the diluted abrasive grains with a curable make layer precursor disposed on a major surface of a backing to transfer the precisely shaped abrasive flakes and the diluted abrasive grains from the production tool to the make layer precursor; and f) at least partially curing the curable make layer precursor to provide an at least partially cured make layer precursor.

2. The method of claim 1, wherein the sequential steps further comprise: g) disposing a curable size layer precursor onto the at least partially cured make layer precursor, the precisely shaped abrasive flakes, and the diluted abrasive grains; and h) at least partially curing the curable size layer precursor.

3. The method of claim 1 further comprising, between step d) and step f), a step e) of separating the production tool from the precisely shaped abrasive flakes and the diluted abrasive grains. The method according to claim 3 , wherein steps a) to e) are continuous.

5. The method of claim 1 wherein after step b) and before step c), a majority of the precisely shaped abrasive flakes are oriented at respective dihedral angles less than or equal to 60 degrees relative to the dispensing surface of the production tool.

6. The method of claim 1 wherein after step c), at least 50% of the precisely shaped abrasive flakes overhang a corresponding plurality of the diluted abrasive grains.

7. The method of claim 1, wherein the diluted abrasive particles comprise crushed abrasive particles.

8. The method of claim 1, wherein after step c), the precisely shaped abrasive flakes and the diluted abrasive grains form a closed abrasive coating.

9. The method of claim 1, wherein after step c), the precisely shaped abrasive flakes and the diluted abrasive grains form an open abrasive coating.

10. A coated abrasive article prepared by the method of claim 1.

11. A coated abrasive article, comprising: a backing having a first major surface; a primer layer, the primer layer being disposed on the backing and fixed to the backing; an abrasive layer contacting and secured to the make coat, the abrasive layer comprising precisely shaped abrasive flakes and diluted abrasive grains transferred to the make coat by a production tool including a carrier member having a dispensing surface and having precisely shaped cavities therein, wherein the precisely shaped abrasive flakes include a second major surface disposed at a dihedral angle of less than or equal to 60 degrees relative to the first major surface of the backing, and wherein at least 50% of the precisely shaped abrasive flakes each overhang a corresponding plurality of the diluted abrasive grains; as well as A double-glue layer is disposed on the base glue layer and the abrasive layer.

12. The coated abrasive article of claim 11, wherein the precisely shaped abrasive flakes are aligned relative to a longitudinal axis of the coated abrasive article.

13. The coated abrasive article of claim 11, wherein the precisely shaped abrasive flakes are aligned relative to an axis of rotation of the coated abrasive article.

14. The coated abrasive article of claim 11, wherein the precisely shaped abrasive flakes comprise triangular shaped flakes.

15. The coated abrasive article of claim 11, wherein the precisely shaped abrasive flakes comprise rectangular flakes.

16. The coated abrasive article of claim 11, wherein the diluted abrasive particles comprise crushed abrasive particles.

17. The coated abrasive article of claim 11, wherein the precisely shaped abrasive flakes and the diluted abrasive grains form a closed abrasive coating.

18. The coated abrasive article of claim 11, wherein the precisely shaped abrasive flakes and the diluted abrasive grains form an open abrasive coating.

19. The coated abrasive article of claim 11, wherein the precisely shaped abrasive flakes are positioned according to a predetermined pattern.

20. A coated abrasive article comprising: a backing having a major surface; a primer layer, the primer layer being disposed on the backing and fixed to the backing; an abrasive layer contacting and secured to the make coat, wherein the abrasive layer includes islands, each island containing at least one precisely shaped abrasive flake and diluted abrasive grains transferred to the make coat by a production tool including a carrier member having a dispensing surface and having precisely shaped cavities therein, and wherein the islands are separated from one another; as well as A double-glue layer is disposed on the base glue layer and the abrasive layer.

21. The coated abrasive article of claim 20, wherein at least 50% of the precisely shaped abrasive flakes overhang a corresponding plurality of the diluted abrasive particles.

22. The coated abrasive article of claim 20, wherein the islands are separated from one another by a distance that is at least twice the smallest distance between the closest precisely shaped abrasive flakes of adjacent islands.

23. The coated abrasive article of claim 20, wherein the precisely shaped abrasive flakes are positioned according to a predetermined pattern.

24. The coated abrasive article of claim 20, wherein the precisely shaped abrasive flakes are aligned relative to a longitudinal axis of the coated abrasive article.

25. The coated abrasive article of claim 20, wherein the precisely shaped abrasive flakes are aligned relative to an axis of rotation of the coated abrasive article.

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