Shaped abrasive particles with sharp tips

Abstract

Various embodiments disclosed relate to shaped abrasive particles having sharp tips, methods of making shaped abrasive particles, methods of grinding a substrate with shaped abrasive particles, and coated abrasive articles including shaped abrasive particles. The shaped abrasive particle includes a ceramic having a polygonal cross-sectional shape along a longitudinal axis of the shaped abrasive particle, and at least one tip of the shaped abrasive particle has a radius of curvature less than or equal to about 19.2 microns.

Description

[0001] This patent application is a divisional application of the patent application with application number 201780047542.6, application date July 31, 2017, and invention name “Shaped abrasive particles with sharp tips”. Background Art

[0002] Abrasive grains and abrasive articles made from abrasive grains can be used to grind, dress or dress a variety of materials and surfaces in product manufacturing processes. There remains a need to improve the cost, performance or life of abrasive grains or abrasive articles, such as in a grinding process with low pressure or down force that does not damage the abrasive grains during use of the grains or articles. Summary of the invention

[0003] In various embodiments, the present invention provides a shaped abrasive particle comprising a ceramic. The shaped abrasive particle comprises a polygonal cross-sectional shape along the longitudinal axis of the shaped abrasive particle. The radius of curvature of at least one top end of the shaped abrasive particle is less than or equal to about 19.2 microns.

[0004] In various embodiments, the present invention provides a method of grinding. The method includes grinding a substrate with a plurality of shaped abrasive particles.

[0005] In various embodiments, the present invention provides a method for preparing shaped abrasive particles. The method includes placing a starting material composition in a mold. The method includes curing the starting material composition in the mold to form shaped abrasive particles.

[0006] In various embodiments, the present invention provides a coated abrasive article. The coated abrasive article includes a backing. The coated abrasive article includes a make coat on a first major surface of the backing. The coated abrasive article also includes an abrasive layer on the make coat, the abrasive layer comprising a plurality of shaped abrasive particles.

[0007] In various embodiments, the present invention provides a method of grinding. The method includes grinding a substrate with a coated abrasive article, the coated abrasive article including a plurality of shaped abrasive particles.

[0008] In various embodiments, the present invention provides a coated abrasive article. The coated abrasive article includes a backing and a primer layer on the first major surface of the backing. The coated abrasive article also includes an abrasive layer on the primer layer, the abrasive layer comprising a plurality of shaped abrasive particles. The plurality of shaped abrasive particles account for about 0.5% to about 100% by weight of the abrasive layer. The shaped abrasive particles independently include about 100% by weight of alpha alumina and have a polygonal cross-sectional shape along the longitudinal axis of the shaped abrasive particles. The top of the largest face of each shaped abrasive particle independently has a radius of curvature less than or equal to about 5 microns. The radius of curvature is the radius of the smallest circle, when viewed in a direction orthogonal to the largest face of the shaped abrasive particle, the smallest circle: passing through a point on each side of the two sides of the largest face of the shaped abrasive particle, the two sides come together at the beginning of the curved surface of the top to form a top, wherein each of the two sides transitions from straight to curved and contains the entire top.

[0009] Various embodiments of the present invention have advantages over other shaped particles, methods of preparing shaped particles, articles comprising shaped particles, and methods of grinding using shaped particles, at least some of which are unexpected. For example, in some embodiments, the shaped abrasive particles of the present invention can provide greater wear performance than other abrasive particles. In some embodiments, the shaped abrasive particles of the present invention can provide high removal rates when used to grind a substrate compared to other abrasive particles used under corresponding conditions.

[0010] In some embodiments, methods of making shaped abrasive particles of the present disclosure can provide shaped abrasive particles having sharper tips and more consistently sharp tips compared to other methods of making shaped abrasive particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The drawings show generally by way of example, but not limitation, of the various embodiments discussed in this document.

[0012] Figure 1 Shown is a top view of shaped abrasive particles having a triangular shape according to various embodiments.

[0013] Figure 2 Shown according to various embodiments Figure 1 Side view of a shaped abrasive particle.

[0014] Figure 3 Measurements of the radius of curvature of the tip according to various embodiments are shown.

[0015] Figure 4 According to various embodiments, Figure 1 A coated abrasive product made of shaped abrasive particles.

[0016] Figure 5A -B shows a micrograph of shaped abrasive particles according to various embodiments.

[0017] Figure 6 The total cut for several abrasive grains according to various embodiments is shown. DETAILED DESCRIPTION

[0018] Reference will now be made in detail to some embodiments of the disclosed subject matter, examples of which are partially illustrated in the accompanying drawings.While the disclosed subject matter will be described in conjunction with the enumerated claims, it will be understood that the exemplary subject matter is not intended to limit the claims to the disclosed subject matter.

[0019] In this document, values ​​expressed in a range format should be interpreted in a flexible manner to include not only the explicitly stated values ​​as the limits of the range, but also all individual values ​​or subranges contained within the range, as if the individual values ​​or subranges were explicitly stated. For example, a range of "about 0.1% to about 5%" or "about 0.1% to 5%" should be interpreted to include not only about 0.1% to about 5%, but also the individual values ​​(e.g., 1%, 2%, 3% and 4%) and subranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. Unless otherwise specified, the expression "about X to Y" has the same meaning as "about X to about Y". Similarly, unless otherwise specified, the expression "about X, Y or about Z" has the same meaning as "about X, about Y or about Z".

[0020] In this document, the terms "a", "an" or "the" are used to include one or more than one, unless the context clearly dictates otherwise. Unless otherwise indicated, the term "or" is used to refer to a non-exclusive "or". The expression "at least one of A and B" has the same meaning as "A, B, or A and B". In addition, it should be understood that the words or terms used herein and not otherwise defined are used for descriptive purposes only and not for limiting purposes. Any use of section headings is intended to facilitate the reading of the document and should not be interpreted as limiting; information related to section headings may exist within or outside that particular section. All publications, patents, and patent documents mentioned in this document are incorporated herein by reference in their entirety, as if individually incorporated by reference. If there is an inconsistency in usage between this document and those documents so incorporated by reference, the usage in the cited references should be considered to supplement the usage of this document; for irreconcilable inconsistencies, the usage in this document shall prevail.

[0021] In the methods described herein, the acts may be performed in any order without departing from the principles of the invention, except where a temporal sequence or sequence of operations is explicitly enumerated. In addition, specified acts may be performed simultaneously unless explicit claim language lists them as being performed separately. For example, a claimed act of doing X and a claimed act of doing Y may be performed simultaneously in a single operation, and the resulting method would fall within the literal scope of the claimed process.

[0022] As used herein, the term "about" can allow a degree of variability in a value or range, for example, within 10%, within 5%, or within 1% of the stated value or limit of the stated range, and includes the exact stated value or range.

[0023] As used herein, the term "substantially" means mostly or predominantly, such as 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%.

[0024] Shaped abrasive particles.

[0025] In various embodiments, the present invention provides shaped abrasive particles. The shaped abrasive particles may include ceramics. The shaped abrasive particles may include a polygonal cross-sectional shape along the longitudinal axis of the shaped abrasive particles. At least one top of the shaped abrasive particles may have a radius of curvature less than or equal to about 19.2 microns.

[0026] The cross-sectional shape of the shaped abrasive particles can be any suitable polygonal shape, such as a triangle, rectangle, trapezoid, or pentagon.

[0027] The shaped abrasive grains may include a volume aspect ratio greater than about 1.15, wherein the volume aspect ratio is the ratio of the maximum cross-sectional area through the centroid of the shaped abrasive grains divided by the minimum cross-sectional area through the centroid of the shaped abrasive grains. In various embodiments of the present invention, the volume aspect ratio of the shaped abrasive grains may be greater than about 1.15, or greater than about 1.50, or greater than about 2.0, or between about 1.15 to about 10.0, or between about 1.20 to about 5.0, or between about 1.30 to about 3.0.

[0028] The shaped abrasive particles may include a first face and a second face connected to each other by a sidewall, the first face and the second face being separated by a thickness t. The shaped abrasive particles may include a draft angle α between the second face and the sidewall. The draft angle α may be other than 90 degrees, for example, from about 95 degrees to about 130 degrees.

[0029] In various embodiments, the perimeter of the first face and the second face may be any suitable polygonal shape, such as a triangle, rectangle, trapezoid, or pentagon.The perimeter of the first face and the second face may be substantially triangular.

[0030] See also Figure 1 and Figure 2 , shows an embodiment of a shaped abrasive particle 20. In some embodiments, the shaped abrasive particle includes a sidewall 22 having a draft angle α different from 90 degrees, and is hereinafter referred to as a sloped sidewall. Figure 1 is a top view of the open face of the particle 20, and Figure 2 is along Figure 1 The material from which the shaped abrasive particles 20 are made includes alpha alumina.

[0031] Typically, the shaped abrasive particles 20 include a thin body having a first face 24 and a second face 26 and having a thickness t. In some embodiments, the thickness t ranges from about 25 microns to about 500 microns. The first face 24 and the second face 26 are connected to each other by at least one sidewall 22, which may be an inclined sidewall. In some embodiments, there may be more than one inclined sidewall 22, and the inclination or angle of each inclined sidewall 22 may be the same or different. In some embodiments, the first face 24 is generally flat, the second face 26 is generally flat, or both faces are generally flat. Alternatively, the face may be concave or convex. In addition, there may be an opening or hole through the face.

[0032] In one embodiment, the first face 24 and the second face 26 are substantially parallel to each other. In other embodiments, the first face 24 and the second face 26 can be non-parallel, such that one face is inclined relative to the other face, and an imaginary line tangent to each face will intersect at a point. The sidewall 22 of the shaped abrasive particle 20 can vary, and it generally forms a perimeter 29 of the first face 24 and the second face 26. In one embodiment, the perimeter 29 of the first face 24 and the second face 26 are selected to be a selected geometry, and the first face 24 and the second face 26 are selected to have the same geometry; however, they are different in size, with one side being larger than the other. In one embodiment, the perimeter 29 of the first face 24 and the perimeter 29 of the second face 26 are triangular, as shown.

[0033] Return to reference Figure 1 The shaped abrasive particle 20 includes a longitudinal axis 50 extending from a base 52 to a dressing tip 54. In a coated abrasive article, the sidewall 22 of the base 52 is typically attached to the backing 42 in the coated abrasive article 40 by a make coat 44.

[0034] The radius of curvature of the at least one apex is the radius of the smallest circle that, when viewed in a direction normal to the face of the shaped abrasive particle containing the apex, passes through a point on each of the two sides of the face of the shaped abrasive particle that come together at the beginning of the curve of the apex to form the apex, wherein each of the two sides transitions from straight to curved. Figure 3 A method for determining the radius of curvature of the tip of a shaped abrasive particle is shown. Figure 3 A segment of a shaped abrasive particle 100 is shown. Figure 3 100, wherein only a segment of the shaped abrasive particle 100 is shown, with the remainder of the particle represented by the wavy lines 110. The shaped abrasive particle includes a face 105 having two sides 115 and 130 of the face 105 that come together to form a tip 120. A circle 140 is drawn through point 125, where the side 115 transitions from straight to curved to form the tip 120. The circle 140 also passes through point 135, where the side 130 transitions from straight to curved to form the tip 120. The circle is drawn so that it is the smallest possible circle at the location of the face 105 that passes through the two points 125 and 135 and also completely contains the tip 120, such that no portion of the tip crosses the boundary of the circle 140. The radius (r) 145 of the circle 140 represents the radius of curvature of the tip 120.

[0035] The maximum radius of curvature can be any suitable value so that the abrasive grain is effective for grinding applications. For example, the radius of curvature can be less than or equal to about 19.2 microns, less than or equal to about 15 microns, less than or equal to about 5 microns, less than or equal to about 3 microns, or less than, equal to or greater than about 19 microns, 18, 17, 16, 15, 14, 13, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4.5, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.5, 0.4, 0.3, 0.2, 0.1, 0.05 or about 0.01 micron or less.

[0036] In various embodiments, the maximum radius of curvature can be defined by the average radius of curvature of all the tops of the shaped abrasive particles or the average radius of curvature of all the tops of a plurality of shaped abrasive particles. For example, the average radius of curvature of the tops of a plurality of shaped abrasive particles is less than or equal to about maximum value, for example about 19.2 microns.

[0037] At least one top with the maximum radius of curvature can be on an open face of the particle, for example, the face of the particle with the largest surface area, or the face of the particle at the open end of a mold for forming the particle (for example, the largest end forming the largest face). For example, at least one top with the maximum radius of curvature can be a top on the largest face of the shaped abrasive particle, wherein the radius of curvature is the radius of the smallest circle, when viewed in a direction orthogonal to the largest face of the shaped abrasive particle, the smallest circle: passes through a point on each of the two sides of the largest face of the shaped abrasive particle, the two sides come together at the beginning of the curved surface of the top to form a top, wherein each of the two sides transitions from straight to curved and contains the entire top.

[0038] In various embodiments, the maximum radius of curvature can be defined by the average radius of curvature of all open face tops of shaped abrasive particles or the average radius of curvature of all open face tops of a plurality of shaped abrasive particles.For example, the average radius of curvature of the open face tops of a plurality of shaped abrasive particles is less than or equal to about maximum value, such as about 19.2 microns.Shaped abrasive particles may include a first face and a second face connected to each other by a sidewall, wherein the first face and the second face are substantially parallel to each other, and the first face has a surface area larger than the second face.The first face may have the maximum surface area of ​​any face (for example, open face) of shaped abrasive particles.Shaped abrasive particles may include a top with a maximum radius of curvature on the first face, or all tops on the first face may have a maximum radius of curvature, such as about 19.2 microns.

[0039] The ceramic can be any suitable ceramic suitable for grinding applications. The ceramic can be an inorganic non-metallic oxide, nitride or carbide material, such as an oxide, nitride or carbide material of aluminum, titanium, zinc, boron, tungsten, silicon or a combination thereof. The ceramic can be kaolinite, aluminum oxide, zirconium oxide, silicon carbide, silicon nitride, tungsten carbide, boron nitride, boron oxide, titanium carbide or a combination thereof. The ceramic can be aluminum oxide, such as alpha-aluminum oxide. The ceramic can be any suitable proportion of the shaped abrasive particles, such as about 50% to about 100% by weight of the shaped abrasive article, about 100% by weight of the shaped abrasive article, or about 50% by weight or less, or less than, equal to or greater than about 55% by weight, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 99.9, 99.99% by weight or about 99.999% by weight or more.

[0040] The shaped abrasive particles can have any suitable particle size (e.g., the maximum dimension of the particles). The particle size of the shaped abrasive particles can be from about 4 microns (e.g., about P6000) to about 1800 microns (e.g., about P12), or from about 25 microns (e.g., about P600) to about 70 microns (e.g., about P220), or about 4 microns or less, or less than, equal to, or greater than about 5 microns, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 45, 50, 55, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550, 560, 570, 580, 590, 610 1,500, 1,600, 1,700, 1,800, 1,900, 2,000, 2,000, 3,000, 4,000, 5, 10, 20, 30, 40, 500, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 18, 20, 22, 25, 27, 30, 35, 40, 45, 50, 60, 70, 80, 900, 1,000, 1,200, 1,400, 1,600 micrometers or about 1,800 micrometers or more.

[0041] A method of making shaped abrasive particles.

[0042] In various embodiments, the present invention provides a method for preparing shaped abrasive particles. The method can be any suitable method for forming an embodiment of a shaped abrasive article having a maximum radius of curvature as described herein. The method can include placing a starting material composition in a mold. The method can include curing the starting material composition in the mold to form shaped abrasive particles. As used herein, "curing" refers to any chemical or physical transformation that causes a material to harden. Curing can include heating the starting material composition until it is converted into a ceramic.

[0043] Placing the starting material composition into the mold can be performed in any suitable manner. In some embodiments, a scraper or a pull rod can be used to force the starting material composition completely into the cavity of the mold.

[0044] The starting material composition can be any suitable starting material composition that can be cured to form a shaped abrasive particle, such as a ceramic. The starting material composition can include a dispersion of a material in a volatile component that can be heated to form a ceramic. The volatile component can be water. The dispersed material can be a precursor to the ceramic. For example, for an alumina ceramic, the starting material composition can be a hydrosol or gel of alumina monohydrate (e.g., bemisite).

[0045] The method may further include placing a release coating in a mold before the starting material composition is placed in the mold. The release coating can demould the shaped abrasive particles formed from the mold with little or no adhesion to the mold. Adhesion to the mold may make it difficult to remove the shaped abrasive particles from the mold, and may cause particle rupture when the particles are removed from the mold. In other embodiments, during placement and curing of the starting material composition in the mold, the mold may be substantially free of a release agent.

[0046] The anti-stick coating may include any suitable material that facilitates the demoulding of the shaped abrasive particles from the mold. For example, the anti-stick coating may include a release agent such as peanut oil, mineral oil, fish oil, silicone, polytetrafluoroethylene, zinc stearate, graphite, or a combination thereof. In some embodiments, applying the anti-stick coating may include applying about 0.1 wt % to about 5 wt % of an anti-sticking agent (such as peanut oil) in a liquid (such as water or alcohol) to the mold.

[0047] Accumulation of anti-stick coating or release agent in the corners of the mold can result in blunt tips. Although not using a release agent will produce an extremely sharp tip, the resulting cured particles often break, forming abrasive particle fragments. By controlling the amount of release agent in the corners of the production tool, the sharpness of the tip can be controlled. The concentration of the anti-stick coating and release agent on the surface is sufficient to avoid, reduce or minimize the formation of non-uniform areas in the corners of the mold during placement and curing of the starting material composition in the mold, which may result in blunt tips. The release agent can be distributed substantially uniformly on the mold, such as in a substantially uniform anti-stick coating; in other embodiments, the release agent can be distributed in an uneven manner. In some embodiments, the concentration of the release agent on the mold may be about 0.001 mg / in 2 To about 5.0mg / in 2 , or about 0.01 mg / in 2 To about 3.0mg / in 2 , or about 0.001 mg / in 2 or less, or less than, equal to or greater than about 0.005 mg / in 2 , 0.01, 0.05, 0.1, 0.5, 1, 1.5, 2, 2.5 or about 3.0 mg / in 2The thickness of the release coating can be from about 0.001 micron to about 1 millimeter, or from about 0.050 micron to about 5 microns, or from about 1 micron to about 10 microns, or from about 0.001 micron or less, or less than, equal to or greater than about 0.005 micron, 0.01, 0.05, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 50, 100, 200, 500, about 750 microns or about 1 millimeter. The release coating can be applied in any suitable manner, such as by brushing, spraying, inkjet, gravure printing, slit die or blade, notch rod, tentering, squeeze roller, roller coating, 5 roller coatings, 3 roller coatings, Meyer rod coating, curtain coating, slide coating or their combination.

[0048] Coated abrasive articles.

[0049] In various embodiments, the present invention provides a coated abrasive article. The coated abrasive article may include a backing having a make coat on a first major surface of the backing. The coated abrasive article may include an abrasive layer on the make coat, the abrasive layer comprising a plurality of shaped abrasive particles having a maximum radius of curvature as described herein.

[0050] The shaped abrasive particles can comprise any suitable proportion of the abrasive layer or the total amount of abrasive particles in the abrasive layer, such as from about 0.001 wt % to about 100 wt %, from about 0.5 wt % to about 60 wt %, from about 8 wt % to about 15 wt %, or about 0.001 wt % or less, or less than, equal to, or greater than about 0.01 wt %, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 24, 26, 28, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 99.9, 99.99, or about 99.999 wt % or more.

[0051] The abrasive layer can further include non-shaped abrasive particles (e.g., crushed grinding filler particles, such as crushed aluminum oxide, having a substantially random shape). The unshaped abrasive particles can have any suitable particle size (e.g., the maximum dimension of the particles), such as about 4 microns (e.g., about P6000) to about 1800 microns (e.g., about P12), or about 25 microns (e.g., about P600) to about 70 microns (e.g., about P220), or about 4 microns or less, or less than, equal to, or greater than about 5 microns, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 120, 140, 160, 180, 200, 250, 300, 350, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1400, 1600, 1800, 2000, 2500, 3000, 3500, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 1 , 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 160, 180, 200, 225, 250, 275, 300, 350, 400, 450, 500, 600, 700, 800, 900, 1,000, 1,200, 1,400, 1,600 microns or about 1,800 microns or more. In an abrasive layer comprising shaped abrasive particles, the unshaped abrasive particles can form the remainder of the abrasive layer or any suitable proportion of the abrasive layer, for example, about 0.001 wt % to about 99.999 wt % of the abrasive layer, about 40 wt % to about 99.5 wt % of the abrasive layer, about 85 wt % to about 92 wt % of the abrasive layer.

[0052] The shaped abrasive particles can be adhered to the make coat through the sidewalls of the shaped abrasive particles. The shaped abrasive particles adhered to the make coat through the sidewalls can have an orientation angle β of about 50 degrees to about 85 degrees. The coated abrasive article can also include a size coat on the abrasive layer.

[0053] See also Figure 4 , the shaped abrasive particles 20 can be used to prepare a coated abrasive article 40 having a first major surface 41 of a backing 42 covered by an abrasive layer including a plurality of shaped abrasive particles 20. The coated abrasive article 40 includes a make size layer 44 on the first major surface 41 and a plurality of shaped abrasive particles 20 attached to the make size layer 44, for example, by the sidewalls 22. A size coat 46 can be applied to further attach or adhere the shaped abrasive particles 20 to the backing 42. An optional top size layer known to those skilled in the art can also be applied.

[0054] See also Figure 4, the coated abrasive article 40 includes a backing 42 having a first binder layer (hereinafter referred to as the base layer 44), which is applied to the first major surface 41 of the backing 42. A plurality of shaped abrasive particles 20 are attached to or partially embedded in the base layer 44 to form an abrasive layer. Located above the shaped abrasive particles 20 is a second binder layer (hereinafter referred to as the double layer 46). The purpose of the base layer 44 is to fix the shaped abrasive particles 20 to the backing 42, while the purpose of the double layer 46 is to reinforce the shaped abrasive particles 20. An optional top layer known to those skilled in the art may also be applied. Most of the shaped abrasive particles 20 are oriented so that the top 48 ( Figure 1 The grinding tip 54 or apex in FIG. 5 is located on the sidewall 22. If an inclined sidewall is used, the shaped abrasive particles 20 are generally inverted or inclined, as shown.

[0055] To further optimize the tilted orientation, shaped abrasive particles with inclined sidewalls are coated in the backing in the sparse coating abrasive layer. As used herein, the closed coating abrasive layer is defined as the maximum weight of abrasive particles or abrasive particle blends that can be applied to the abrasive article primer layer in a single pass through the preparation machine. The sparse coating is a certain amount of abrasive particles or abrasive particle blends, and its weight is less than the maximum weight (in grams) that can be applied to the primer layer of the coated abrasive article. The sparse coating abrasive layer will result in a coverage of the abrasive particles of the primer layer of less than 100%, thereby leaving open areas and visible resin layers between the abrasive particles. In various embodiments of the present invention, the percentage of open areas in the abrasive layer can be from about 10% to about 90%, or from about 30% to about 80%, or from about 40% to about 70%.

[0056] In some embodiments, if too many shaped abrasive particles with sloping sidewalls are applied to the backing, insufficient space between the particles may result to allow the abrasive particles to tilt or flip before curing the make coat and size coat. In various embodiments of the present invention, greater than 50%, 60%, 70%, 80%, or 90% by weight of the shaped abrasive particles in the coated abrasive article having an open-coated abrasive layer are flipped or tilted, and the orientation angle β ( Figure 4 ) is less than 90 degrees.

[0057] Without wishing to be bound by theory, it is believed that an orientation angle β of less than 90 degrees results in enhanced cutting performance of shaped abrasive particles having sloped sidewalls. Surprisingly, this effect occurs regardless of the rotational orientation of the shaped abrasive particles about the Z axis within the coated abrasive article. Figure 4Ideally all of the particles are shown aligned in the same direction, but in reality the particles of a coated abrasive disc will be randomly distributed and rotated. Because the abrasive disc is rotating and the shaped abrasive particles are randomly distributed, some of the shaped abrasive particles will be driven into the workpiece at an orientation angle β of less than 90 degrees and the workpiece will initially impact the second face 26, while the adjacent shaped abrasive particles will be exactly rotated 180 degrees and the workpiece will impact the back of the shaped abrasive particle and the first face 24. Due to the random distribution of the particles and the rotation of the disc, less than half of the shaped abrasive particles will cause the workpiece to initially impact the second face 26 instead of the first face 24. However, for an abrasive belt having a defined direction of rotation and a defined point of contact with the workpiece, shaped abrasive particles having inclined sidewalls can be aligned on the belt to ensure that each shaped abrasive particle runs at an orientation angle β of less than 90 degrees and the workpiece is first as Figure 4 is driven into the second face 26 as shown in the idealized view. In various embodiments of the present invention, the orientation angle β of at least a majority of the shaped abrasive particles having inclined sidewalls in the abrasive layer of the coated abrasive article can be between about 50 degrees and about 85 degrees, or between about 55 degrees and about 85 degrees, or between about 60 degrees and about 85 degrees, or between about 65 degrees and about 85 degrees, or between about 70 degrees and about 85 degrees, or between about 75 degrees and about 85 degrees, or between about 80 degrees and about 85 degrees.

[0058] Primer layer 44 and adhesive layer 46 comprise resin adhesive.The resin adhesive of primer layer 44 and the resin adhesive of adhesive layer 46 can be identical or different.The example of the resin adhesive that is applicable to these coatings comprises phenolic resin, epoxy resin, urea-formaldehyde resin, acrylate resin, amino plastic resin, melamine resin, acrylated epoxy resin, polyurethane resin and their combination.Except the resin adhesive, primer layer 44 or adhesive layer 46 or these two layers can also comprise additive known in the art, such as for example filler, grinding aid, wetting agent, surfactant, dye, pigment, coupling agent, tackifier and their combination.The example of filler comprises calcium carbonate, silica, talcum, clay, calcium metasilicate, dolomite, aluminum sulfate and their combination.

[0059] Grinding aids can be applied to coated abrasive articles. As used herein, a grinding aid is a particulate material whose addition has a significant effect on the chemical and physical processes of grinding, resulting in improved performance. Grinding aids encompass a wide variety of different materials and can be inorganic or organic. Examples of chemical groups of grinding aids include waxes, organic halides, halide salts, metals, and their alloys. Organic halides will typically decompose during the grinding process and release halogen acids or gaseous halides. Examples of such materials include chlorinated waxes, such as tetrachloronaphthalene, pentachloronaphthalene; and polyvinyl chloride. Examples of halide salts include sodium chloride, potassium cryolite, sodium cryolite, ammonium cryolite, potassium tetrafluoroborate, sodium tetrafluoroborate, silicon fluoride, potassium chloride, magnesium chloride. Examples of metals include tin, lead, bismuth, cobalt, antimony, cadmium, iron, and titanium. Other grinding aids include sulfur, organic sulfur compounds, graphite, and metal sulfides. The present invention also encompasses the use of a combination of different grinding aids; in some cases, this can produce a synergistic enhancement effect. In one embodiment, the grinding aid is cryolite or potassium tetrafluoroborate. The amount of such additives can be adjusted to impart the desired properties. The present invention also encompasses the use of a top glue layer. The top glue layer typically comprises a binder and a grinding aid. The binder can be formed from materials such as phenolic resins, acrylate resins, epoxy resins, urea-formaldehyde resins, melamine resins, urethane resins, and combinations thereof.

[0060] It is also contemplated that the shaped abrasive particles 20 can be used in bonded abrasive articles, nonwoven abrasive articles, or abrasive brushes. Bonded abrasives can include a plurality of shaped abrasive particles 20 bonded together by a binder to form a shaped mass. The binder used for bonded abrasives can be a metallic binder, an organic binder, or a vitreous binder. Nonwoven abrasives include a plurality of shaped abrasive particles 20 bonded to a fibrous nonwoven web by an organic binder.

[0061] A method of making a coated abrasive article.

[0062] In various embodiments, the present invention provides a method of preparing a coated abrasive article. The method can be any suitable method of producing an embodiment of a coated abrasive article described herein, wherein the coated abrasive article includes shaped abrasive particles having a maximum radius of curvature. The method can include applying a plurality of shaped abrasive particles to a make coat on a first major surface of a backing.

[0063] Grinding method.

[0064] In various embodiments, the present invention provides a grinding method. The method includes grinding a substrate with a plurality of shaped abrasive particles described herein having a maximum radius of curvature. The method can be any suitable method, which includes grinding a substrate with an embodiment of shaped abrasive particles described herein. In some embodiments, the method can be a method of grinding a substrate with a coated abrasive article, and the coated abrasive article includes a plurality of shaped abrasive particles described herein having a maximum radius of curvature.

[0065] In some embodiments, during grinding (e.g., during a grinding cycle from start to finish), most of the shaped abrasive particles do not break. In such applications, the sharpness of the abrasive particles can surprisingly have a significant impact on the abrasive properties of the abrasive particles, such as the amount of substrate removed using a given amount of pressure in a given amount of time. The substrate can be any suitable substrate, such as metal (e.g., steel), paint, filler, primer, wood, or a combination thereof.

[0066] Example

[0067] Various embodiments of the present invention may be better understood by reference to the following examples which are provided by way of illustration.The present invention is not limited to the examples given herein.

[0068] Unit abbreviations used in the examples: °C: degrees Celsius; cm: centimeters; g / m 2 : grams per square meter; mm: millimeter; rpm: revolutions per minute

[0069] Materials. Unless otherwise specified, all parts, percentages, ratios, etc. in the examples and the rest of this specification are by weight. The materials used in the examples are shown in Table 1.

[0070] Table 1: Materials.

[0071]

[0072]

[0073] General measurement of radius of curvature. The average radius of curvature of a shaped abrasive particle is determined as the average radius of curvature of the open face apex of the particle. The radius of curvature is determined as the radius of the smallest circle that passes through a point on each of the two sides of the open face of the shaped abrasive particle when viewed in a direction orthogonal to the open face of the shaped abrasive particle containing the open face apex, the two sides coming together at the beginning of the curved surface of the apex to form the apex, where each of the two sides transitions from straight to curved. Take the average of the 12 radii of four particles.

[0074] Example 1: Formation of shaped abrasive particles.

[0075] Boehmite sol-gel samples were prepared using the following recipe: Alumina monohydrate powder (1600 parts) sold under the brand name "DISPERAL" was dispersed by high shear mixing a solution containing water (2400 parts) and 70% aqueous nitric acid (72 parts) for about 11 minutes. The resulting sol-gel was aged for at least 1 hour before coating. The sol-gel was forced into a production tool having a triangular mold cavity with a depth of 2.67 mils (69 microns) and a side length of 8 mils (203 microns). The draft angle α between the sidewalls and the bottom of the mold was 98 degrees. The sol-gel was forced into the cavity with a putty knife so that the opening of the production tool was completely filled. A release agent, 0.2% peanut oil in methanol, was used to coat the production tool with a brush to fill the open cavity in the production tool. Excess methanol was allowed to evaporate in a hood at room temperature. The sol-gel coated production tool was air dried at room temperature for at least 10 minutes to obtain a 0.08 mg / in 2 (after evaporation of methanol) and an average coating thickness of 138 microns (before evaporation of methanol). The precursor shaped abrasive particles are removed from the production tool by passing them over an ultrasonic horn. The shaped abrasive particle precursor is calcined at about 650°C and then saturated with a mixed nitrate solution of the following concentrations (recorded as oxides): 1.8% each of MgO, Y2O3, Nd2O3 and La2O3. The excess nitrate solution is removed and the saturated open precursor shaped abrasive particles are dried, then the particles are calcined again at 650°C and sintered at about 1400°C. A tubular rotary kiln is used for both calcination and sintering. The fired shaped abrasive particles (micrographs of which are shown in Figure 5A -B) is about 0.12 mm (side length) x 0.04 mm thick. According to the general measurement method of the radius of curvature described in the examples, the average radius of curvature of the obtained shaped abrasive particles is 2.0 μm.

[0076] Example 2: Preparation of primer resin and secondary glue resin.

[0077] A primer resin was prepared according to the composition listed in Table 2. AMOX, EP1, EP2, CHDM and PEP were metered directly into a twin screw extruder running at 300 rpm and compounded at a rate of 26-40 kg / hour in temperature zones of 30° C., 105° C., 110° C., 100° C., 65° C. and 60° C. The compounded resin was then fed into a pin mixer running at 1750 rpm, and ACR, PC2, PC3, PC4 and PPC were metered directly into the pin mixer and mixed for about 10 minutes.

[0078] Table 2: Primer resin composition.

[0079] Components Weight Percent EP1 24.0 EP2 32.0 PEP 28.0 ACR 10.0 CHDM 2.8 PC2 0.5 PC3 0.7 PC4 0.3 PPC 1.1 AMOX 0.6

[0080] A size resin premix was prepared by mixing 70% EP3 and 30% ACR. To 55.06% of this premix, 0.59% W985, 39.95% Minex, 3% PC1, 1% IRG and 0.40% PP were added. The formulation was stirred at 24°C for 30 minutes until homogeneous.

[0081] Example 3A: Preparation of coated abrasive article.

[0082] Use 135-142g / m 2 Basis weight paper backing (obtained from Neenah Paper Inc., Neenah, Wisconsin) was used with a 10 g / m 2 The primer resin prepared as above is coated. The coating is exposed to an ultraviolet curing device (derived from Fusion UV Systems, Gaithersburg, Maryland), wherein a set of D bulbs and a set of V bulbs are operated at 600 watts / inch (236 watts / cm). The abrasive grain blend is prepared by mixing 10% of the shaped abrasive grains prepared by the above method and 90% ALO. Then the abrasive grain blend is coated with 37g / m 2 The web was then exposed to an infrared heater for about 7 seconds at a nominal web temperature setting of 100°C. The size resin was then applied at a nominal coating weight of 37 g / m 2 The resulting article was exposed to a UV curing unit (obtained from Fusion UV Systems, Gaithersburg, Maryland) with one set of H bulbs and two sets of D bulbs, all three sets operating at 600 watts / inch (236 watts / cm). It was then processed through an infrared oven with a target exit web temperature of 125°C. The calcium stearate top size was applied using a roll coating technique at 10 g / m 2 A coating weight of 1000 g was applied on top and then dried in a temperature setting zone of 60-90°C. After drying, the coated abrasive strips were converted into discs having a diameter of 6 inches (15.24 cm) as known in the art. The resulting coated abrasive articles were then maintained at 24°C and 40-60% relative humidity until testing.

[0083] Example 3B: Comparative. Preparation of coated abrasive article.

[0084] The procedure generally described in Example 1 was repeated, except that the shaped abrasive particles used were prepared according to the instructions of the method described in U.S. Patent 8,142,531. The shaped abrasive particles were 0.12 mm (side length) x 0.04 mm thick. The average radius of curvature of the resulting shaped abrasive particles was 4.45 microns, measured according to the method described in the specification.

[0085] Example 3C: Comparative. Preparation of coated abrasive article.

[0086] A coated abrasive disc was obtained from 3M Company, Saint Paul, Minnesota under the trade designation "PURPLE CLEAN SANDING HOOKIT DISC 334U" 6 inch, P320 grit.

[0087] Example 4: Characterization of the sharpness of shaped abrasive particles.

[0088] The 6 inch (15.24 cm) diameter abrasive disc to be tested was mounted on a dual action sander tool available from 3M Company under the trade designation "RANDOM ORBITAL SANDER ELITE SERIES" in a self-generating vacuum 3 / 16 in track. The tool was set on an XY table with an automotive test panel (available from ACT, Hillsdale, Michigan as "59597"), measuring 18 inches (45.7 cm) x 24 inches (61.0 cm) x 0.036 inches (0.09 cm), secured to the XY table. The rotary tool was activated to rotate at 5250 rpm under no load. The abrasive article was then pushed at an angle of 2.5 degrees relative to the panel under a load of 13 pounds (5.90 kg) of downward force. The tool was then set to move along the length of the panel in the Y direction at a rate of 3.50 inches / minute (8.9 cm / minute) and along the width of the panel in the X direction at a rate of 3.50 inches / minute (8.9 cm / minute). This process along the length of the panel was completed 7 times in each cycle, for a total of 3 cycles. The mass of the panel was measured before and after each cycle to determine the mass loss of the clear coating from the OEM panel after each cycle, in grams. The total amount of cut was determined as the cumulative mass loss at the end of the test. The surface finish was measured using a contact profilometer (such as the Mahr Perthometer M2 from Mahr Federal Inc., Providence, Rhode Island) as an average surface roughness in microinches (1 microinch is 25.4 nanometers). The test results are shown in Tables 3 and Figure 6 middle.

[0089] Table 3: Performance measurements.

[0090]

[0091] Although the terms and expressions employed are used as terms of description rather than limitation, and it is not intended that the use of such terms and expressions exclude any equivalents of the features shown and described or portions thereof, it should be recognized that various modifications within the scope of the embodiments of the present invention are possible. Therefore, it should be understood that although the present invention has been specifically disclosed through specific embodiments and optional features, modifications and variations of the concepts disclosed herein may be deduced by those skilled in the art, and such modifications and variations are considered to be within the scope of the embodiments of the present invention.

[0092] Additional Implementations

[0093] The following exemplary embodiments are provided, the numbering of which should not be construed as designating a level of importance:

[0094] Embodiment 1 provides a shaped abrasive particle, comprising:

[0095] Ceramics; and

[0096] a polygonal cross-sectional shape along the longitudinal axis of the shaped abrasive particle;

[0097] Wherein at least one apex of the shaped abrasive particles has a radius of curvature less than or equal to about 19.2 microns.

[0098] Embodiment 2 provides the shaped abrasive particles according to embodiment 1, wherein the radius of curvature of the at least one apex is the radius of a smallest circle, when viewed in a direction normal to the face of the shaped abrasive particle containing the apex, the smallest circle:

[0099] passing a point on each of the two sides of the face of the shaped abrasive particle where the two sides of the face of the shaped abrasive particle come together at the beginning of the curve of the tip to form a tip where each of the two sides transitions from straight to curved, and

[0100] Includes the entire top.

[0101] Embodiment 3 provides a shaped abrasive particle according to any one of embodiments 1-2, wherein the at least one apex is a apex on the largest face of the shaped abrasive particle, wherein the radius of curvature is the radius of a smallest circle, when viewed in a direction orthogonal to the largest face of the shaped abrasive particle, the smallest circle:

[0102] The two sides of the largest face of the shaped abrasive particle come together at the beginning of the curve of the tip to form the tip, passing a point on each of the two sides of the largest face of the shaped abrasive particle, where each of the two sides transitions from straight to curved, and

[0103] Includes the entire top.

[0104] Embodiment 4 provides a plurality of shaped abrasive particles according to any one of embodiments 1-3, wherein an average radius of curvature of the top ends of the plurality of shaped abrasive particles is less than or equal to about 19.2 micrometers.

[0105] Embodiment 5 provides a shaped abrasive particle according to any one of embodiments 1-4, comprising

[0106] a first face and a second face connected to each other by a side wall, the first face and the second face being substantially parallel to each other, the first face having a larger surface area than the second face;

[0107] The at least one apex having a radius of curvature less than or equal to about 19.2 micrometers is a apex on the first face of the shaped abrasive particle.

[0108] Embodiment 6 provides a plurality of shaped abrasive particles according to embodiment 5, wherein an average radius of curvature of the top of the first face of the plurality of shaped abrasive particles is less than or equal to about 19.2 micrometers.

[0109] Embodiment 7 provides shaped abrasive particles according to any of Embodiments 1-6, wherein the ceramic comprises from about 50 weight percent to about 100 weight percent of the shaped abrasive article.

[0110] Embodiment 8 provides shaped abrasive particles according to any one of Embodiments 1-7, wherein the ceramic comprises about 100 weight percent of the shaped abrasive article.

[0111] Embodiment 9 provides shaped abrasive particles according to any one of embodiments 1-8, wherein the ceramic is kaolinite, aluminum oxide, zirconium oxide, silicon carbide, silicon nitride, tungsten carbide, boron nitride, boron oxide, titanium carbide, or a combination thereof.

[0112] Embodiment 10 provides shaped abrasive particles according to any one of Embodiments 1-9, wherein the ceramic is aluminum oxide.

[0113] Embodiment 11 provides shaped abrasive particles according to any one of Embodiments 1-10, wherein the ceramic is alpha-alumina.

[0114] Embodiment 12 provides a shaped abrasive particle according to any one of Embodiments 1-11, wherein the at least one apex is a apex on an open face of the shaped abrasive particle.

[0115] Embodiment 13 provides the shaped abrasive particles according to any one of Embodiments 1-12, wherein the shaped abrasive particles include at least one tip having a radius of curvature less than or equal to about 15 micrometers.

[0116] Embodiment 14 provides the shaped abrasive particles according to any one of Embodiments 1-13, wherein the shaped abrasive particles include at least one tip having a radius of curvature less than or equal to about 5 micrometers.

[0117] Embodiment 15 provides the shaped abrasive particles according to any one of Embodiments 1-14, wherein the shaped abrasive particles include at least one tip having a radius of curvature less than or equal to about 3 micrometers.

[0118] Embodiment 16 provides shaped abrasive particles according to any one of Embodiments 1-15, wherein the shaped abrasive particles have a particle size of about 4 microns to about 1800 microns.

[0119] Embodiment 17 provides shaped abrasive particles according to any one of Embodiments 1-16, wherein the shaped abrasive particles have a particle size of about 25 microns to about 70 microns.

[0120] Embodiment 18 provides a shaped abrasive particle according to any one of Embodiments 1-17, wherein the cross-sectional shape is triangular, rectangular, trapezoidal, or pentagonal.

[0121] Embodiment 19 provides a shaped abrasive particle according to any one of embodiments 1-18, comprising a volume aspect ratio greater than about 1.15, wherein the volume aspect ratio is the ratio of the maximum cross-sectional area through the centroid of the shaped abrasive particle divided by the minimum cross-sectional area through the centroid of the shaped abrasive particle.

[0122] Embodiment 20 provides a shaped abrasive particle according to any one of embodiments 1-19, comprising

[0123] A first face and a second face connected to each other by a side wall, the first face and the second face being separated by a thickness t; and

[0124] A draft angle α between the second face and the sidewall.

[0125] Embodiment 21 provides a shaped abrasive particle according to Embodiment 20, wherein the perimeters of the first face and the second face are generally triangular.

[0126] Embodiment 22 provides shaped abrasive particles according to any of Embodiments 20-21, wherein the draft angle α is from about 95 degrees to about 130 degrees.

[0127] Embodiment 23 provides a grinding method, comprising:

[0128] A substrate is ground with a plurality of shaped abrasive particles according to any one of Embodiments 1-22.

[0129] Embodiment 24 provides a method according to embodiment 23, wherein a majority of the shaped abrasive particles do not break during the grinding.

[0130] Embodiment 25 provides a method according to any one of embodiments 23-24, wherein the substrate comprises metal, paint, filler, primer, wood, or a combination thereof.

[0131] Embodiment 26 provides a method for preparing shaped abrasive particles according to any one of embodiments 1-25, the method comprising:

[0132] placing the starting material composition in a mold; and

[0133] The starting material composition in the mold is cured to form shaped abrasive particles according to any one of Embodiments 1-25.

[0134] Embodiment 27 provides a method according to embodiment 26, wherein the starting material composition is a sol.

[0135] Embodiment 28 provides a method according to any one of embodiments 26-27, wherein the mold is substantially free of a release agent during placement and curing of the starting material composition.

[0136] Embodiment 29 provides a method according to any one of embodiments 26-28, further comprising placing a release coating in the mold before placing the starting material composition in the mold.

[0137] Embodiment 30 provides a method according to embodiment 29, wherein the release coating is applied to the mold in a substantially uniform coating.

[0138] Embodiment 31 provides a method according to any of Embodiments 29-30, wherein the coating has a thickness sufficient to avoid or minimize the formation of non-uniform areas of the anti-stick coating in the corners of the mold during placement and curing of the starting material composition.

[0139] Embodiment 32 provides a method according to any one of embodiments 29-31, wherein the coating has a thickness of about 0.001 micrometers to about 1 millimeter.

[0140] Embodiment 33 provides a coated abrasive article, comprising:

[0141] Backing;

[0142] a primer layer on the first major surface of the backing; and

[0143] An abrasive layer on the base layer, the abrasive layer comprising a plurality of shaped abrasive particles according to any one of embodiments 1-22.

[0144] Embodiment 34 provides a coated abrasive article according to Embodiment 33, wherein the shaped abrasive particles are from about 0.001 weight percent to about 100 weight percent of the abrasive layer.

[0145] Embodiment 35 provides a coated abrasive article according to any one of Embodiments 33-34, wherein the shaped abrasive particles are from about 0.5 weight percent to about 60 weight percent of the abrasive layer.

[0146] Embodiment 36 provides a coated abrasive article according to any one of Embodiments 33-35, wherein the shaped abrasive particles are about 8 weight percent to about 15 weight percent of the abrasive layer.

[0147] Embodiment 37 provides a coated abrasive article according to any one of Embodiments 33-36, wherein the abrasive layer further comprises unformed abrasive particles.

[0148] Embodiment 38 provides the coated abrasive particles according to Embodiment 37, wherein the unshaped abrasive particles comprise from about 0.001 wt % to about 99.999 wt % of the abrasive layer.

[0149] Embodiment 39 provides coated abrasive particles according to any one of Embodiments 37-38, wherein the unshaped abrasive particles comprise from about 40 weight percent to about 99.5 weight percent of the abrasive layer.

[0150] Embodiment 40 provides the coated abrasive particles according to any one of Embodiments 37-39, wherein the unshaped abrasive particles comprise from about 85 weight percent to about 92 weight percent of the abrasive layer.

[0151] Embodiment 41 provides a coated abrasive article according to any one of Embodiments 33-40, wherein a majority of the shaped abrasive particles are adhered to the make layer through sidewalls of the shaped abrasive particles.

[0152] Embodiment 42 provides a coated abrasive article according to Embodiment 41, wherein the shaped abrasive particles adhered to the make layer by the sidewalls have an orientation angle β of about 50 degrees to about 85 degrees.

[0153] Embodiment 43 provides a coated abrasive article according to any one of Embodiments 33-42, further comprising a size layer on the abrasive layer.

[0154] Embodiment 44 provides a grinding method, comprising:

[0155] A substrate is ground using the coated abrasive article according to any one of Embodiments 33-43.

[0156] Embodiment 45 provides a method according to embodiment 44, wherein a majority of the shaped abrasive particles do not break during the grinding.

[0157] Embodiment 46 provides a method according to any one of embodiments 44-45, wherein the substrate comprises metal, paint, filler, primer, wood, or a combination thereof.

[0158] Embodiment 47 provides a method for preparing a coated abrasive article according to any one of Embodiments 33-43, the method comprising:

[0159] A plurality of the shaped abrasive particles are applied to a make layer on the first major surface of a backing to form a coated abrasive article according to any one of Embodiments 33-43.

[0160] Embodiment 48 provides a coated abrasive article, comprising:

[0161] Backing;

[0162] a primer layer on the first major surface of the backing; and

[0163] An abrasive layer on the make coat layer, the abrasive layer comprising a plurality of shaped abrasive particles, wherein the plurality of shaped abrasive particles account for about 0.5 wt % to about 100 wt % of the abrasive layer, and each of the shaped abrasive particles independently comprises:

[0164] about 100 weight percent alpha alumina; and

[0165] a polygonal cross-sectional shape along the longitudinal axis of the shaped abrasive particle;

[0166] wherein the radius of curvature of the top of the largest face of the shaped abrasive particle is less than or equal to about 5 microns, wherein the radius of curvature is the radius of the smallest circle when in contact with the shaped abrasive particle

[0167] When viewed in a direction orthogonal to the largest face of the particle, the smallest circle:

[0168] The two sides of the largest face of the shaped abrasive particle come together at the beginning of the curve of the tip to form the tip, passing a point on each side of the largest face of the shaped abrasive particle, where each side transitions from straight to curved, and

[0169] Includes the entire top.

[0170] Embodiment 49 provides a shaped abrasive particle, a coated abrasive article, or a method according to any one or any combination of Embodiments 1-48, optionally configured so that all of the elements or options described are available for use or selection.

Claims

1. A shaped abrasive particle comprising: ceramics; and a polygonal cross-sectional shape along the longitudinal axis of the shaped abrasive particle; Wherein at least one apex of the shaped abrasive particles has a radius of curvature less than or equal to about 19.2 microns.

2. The shaped abrasive particle of claim 1 , wherein the radius of curvature of the at least one apex is the radius of a smallest circle, when viewed in a direction normal to the face of the shaped abrasive particle containing the apex: The two sides of the face of the shaped abrasive particle come together at the beginning of the curve of the tip to form the tip through a point on each of the two sides of the face of the shaped abrasive particle, wherein each of the two sides transitions from straight to curved and encompasses the entire tip.

3. The shaped abrasive particle of claim 1 , wherein the at least one apex is a apex on a largest face of the shaped abrasive particle, wherein the radius of curvature is the radius of a smallest circle, when viewed in a direction normal to the largest face of the shaped abrasive particle: The two sides of the largest face of the shaped abrasive particle come together at the beginning of the curve of the tip to form the tip, passing a point on each of the two sides of the largest face of the shaped abrasive particle, where each of the two sides transitions from straight to curved, and Includes the entire top.

4. A plurality of shaped abrasive particles according to claim 1, wherein the average radius of curvature of the top ends of the plurality of shaped abrasive particles is less than or equal to about 19.2 microns.

5. The shaped abrasive particles according to claim 1, comprising a first face and a second face connected to each other by a side wall, the first face and the second face being substantially parallel to each other, the first face having a larger surface area than the second face; The at least one apex having a radius of curvature less than or equal to about 19.2 micrometers is a apex on the first face of the shaped abrasive particle.

6. The shaped abrasive particle of claim 1, wherein the at least one apex is a apex on an open face of the shaped abrasive particle.

7. The shaped abrasive particle of claim 1, wherein the shaped abrasive particle comprises at least one tip having a radius of curvature less than or equal to about 15 microns.

8. The shaped abrasive particles of claim 1, wherein the shaped abrasive particles have a particle size of about 4 microns to about 1800 microns.

9. The shaped abrasive particles of claim 1, comprising a volume aspect ratio greater than about 1.15, wherein the volume aspect ratio is the ratio of the maximum cross-sectional area through the centroid of the shaped abrasive particles divided by the minimum cross-sectional area through the centroid of the shaped abrasive particles.

10. A grinding method comprising: A substrate is ground using a plurality of shaped abrasive particles according to claim 1.

11. The method of claim 10, wherein a majority of the shaped abrasive particles do not break during the grinding.

12. A coated abrasive article comprising: Backing; a primer layer on the first major surface of the backing; and An abrasive layer on the base layer, wherein the abrasive layer comprises a plurality of shaped abrasive particles according to claim 1.

13. The coated abrasive article of claim 12, wherein the abrasive layer further comprises unformed abrasive particles.

14. The coated abrasive article of claim 12, wherein a majority of the shaped abrasive particles are adhered to the make layer through sidewalls of the shaped abrasive particles.

15. The coated abrasive article of claim 14, wherein the shaped abrasive particles adhered to the make layer by the sidewalls have an orientation angle β of about 50 degrees to about 85 degrees.

16. A grinding method comprising: A substrate is abraded using the coated abrasive article of claim 12.

17. The method of claim 16, wherein a majority of the shaped abrasive particles do not break during the grinding.

18. A coated abrasive article comprising: Backing; a primer layer on the first major surface of the backing; and An abrasive layer on the make coat layer, the abrasive layer comprising a plurality of shaped abrasive particles, wherein the plurality of shaped abrasive particles account for about 0.5 wt % to about 100 wt % of the abrasive layer, and each of the shaped abrasive particles independently comprises: about 100 weight percent alpha alumina; and a polygonal cross-sectional shape along the longitudinal axis of the shaped abrasive particle; wherein the radius of curvature of the apex on the largest face of the shaped abrasive particle is less than or equal to about 5 micrometers, wherein the radius of curvature is the radius of the smallest circle, when viewed in a direction normal to the largest face of the shaped abrasive particle, the smallest circle: The two sides of the largest face of the shaped abrasive particle come together at the beginning of the curve of the tip to form the tip, passing a point on each of the two sides of the largest face of the shaped abrasive particle, where each of the two sides transitions from straight to curved, and Includes the entire top.

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