TECHNICAL FIELD

The present disclosure broadly relates to coated abrasive articles and methods of making and using the same.

BACKGROUND

In general, coated abrasive articles have an abrasive layer secured to a backing. The abrasive layer comprises abrasive particles and a binder that secures the abrasive particles to the backing. One type of coated abrasive article has an abrasive layer comprised of a make layer and abrasive particles. In making such a coated abrasive article, a make layer precursor comprising a curable make layer precursor is applied to a major surface of the backing. Abrasive particles are then at least partially embedded into the curable make resin (for example, via electrostatic coating), and the curable make layer precursor is at least sufficiently cured to adhere the abrasive particles to the backing. Often, a size layer precursor comprising a curable size resin is then applied over the at least partially cured curable make resin and abrasive particles, followed by curing of the curable size resin precursor, and optionally, further curing of the curable make resin. Some coated abrasive articles additionally have a supersize layer disposed over the make and/or size layers of the coated abrasive article. The supersize layer typically includes grinding aids and/or antiloading materials.

SUMMARY

Advantageously and unexpectedly, methods of making coated abrasive articles according to the present disclosure can improve abrasive particle pick up and retention of orientation of precisely-shaped abrasive particles during electrostatic deposition onto a make layer precursor.

In a first aspect the present disclosure provides a method of making a coated abrasive article, the method comprising: providing a backing having first and second opposed major surfaces; disposing a make layer precursor comprising water-based animal glue on the first major surface of the backing; partially embedding shaped abrasive particles in the water-based animal glue, wherein the shaped abrasive particles are triangular platelets; and at least partially curing the make layer precursor.

In a second aspect the present disclosure provides a coated abrasive article comprising: a backing having first and second opposed major surfaces; a make layer disposed on the first major surface of the backing, wherein the make layer comprise at least partially cured animal glue; shaped abrasive particles partially embedded in the make layer wherein the shaped abrasive particles are triangular platelets; a size layer disposed over the make layer and shaped abrasive particles, wherein the size layer comprises a thermoset polymer.

The coated abrasive article can be made, for example, according to the method described above.

Features and advantages of the present disclosure will be further understood upon consideration of the detailed description as well as the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side view of an exemplary abrasive article 100 made according one method of the present disclosure.

It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the disclosure. The figures may not be drawn to scale.

DETAILED DESCRIPTION

An exemplary embodiment of a coated abrasive article according to the present disclosure is depicted in FIG. 1. Referring now to FIG. 1, coated abrasive article 100 has backing 120 and abrasive layer 130. Abrasive layer 130 includes shaped abrasive particles 140 secured to major surface 170 of backing 120 (substrate) by make layer 150 and size layer 160.

Coated abrasive articles according to the present disclosure may include additional layers such as, for example, an optional supersize layer 180 that is superimposed on the abrasive layer, or a backing antistatic treatment layer may also be included, if desired.

Useful backings include, for example, those known in the art for making coated abrasive articles. Typically, the backing has two opposed major surfaces, although this is not a requirement. The thickness of the backing generally ranges from about 0.02 to about 5 millimeters, desirably from about 0.05 to about 2.5 millimeters, and more desirably from about 0.1 to about 1.0 millimeter, although thicknesses outside of these ranges may also be useful. Generally, the strength of the backing should be sufficient to resist tearing or other damage during abrading processes. The thickness and smoothness of the backing should also be suitable to provide the desired thickness and smoothness of the coated abrasive article; for example, depending on the intended application or use of the coated abrasive article.

Exemplary backings include: dense nonwoven fabrics (e.g., needletacked, meltspun, spunbonded, hydroentangled, or meltblown nonwoven fabrics), knitted fabrics, stitchbonded and/or woven fabrics; scrims; polymer films; treated versions thereof; and combinations of two or more of these materials.

Fabric backings can be made from any known fibers, whether natural, synthetic or a blend of natural and synthetic fibers. Examples of useful fiber materials include fibers or yams comprising polyester (for example, polyethylene terephthalate), polyamide (for example, hexamethylene adipamide, polycaprolactam), polypropylene, acrylic (formed from a polymer of acrylonitrile), cellulose acetate, polyvinylidene chloride-vinyl chloride copolymers, vinyl chloride-acrylonitrile copolymers, graphite, polyimide, silk, cotton, linen, jute, hemp, or rayon. Useful fibers may be of virgin materials or of recycled or waste materials reclaimed from garment cuttings, carpet manufacturing, fiber manufacturing, or textile processing, for example. Useful fibers may be homogenous or a composite such as a bicomponent fiber (for example, a co-spun sheath-core fiber). The fibers may be tensilized and crimped, but may also be continuous filaments such as those formed by an extrusion process.

The backing may have any suitable basis weight; typically, in a range of from 100 to 1250 grams per square meter (gsm), more typically 450 to 600 gsm, and even more typically 450 to 575 gsm. In many embodiments (e.g., abrasive belts and sheets), the backing typically has good flexibility; however, this is not a requirement (e.g., vulcanized fiber discs). To promote adhesion of binder resins to the backing, one or more surfaces of the backing may be modified by known methods including corona discharge, ultraviolet light exposure, electron beam exposure, flame discharge, and/or scuffing.

The make layer comprises an at least partially cured make layer precursor that comprises a waterbased animal glue. As used herein, the term "water-based animal glue" refers to an aqueous organic colloid of protein derivation, which is derived primarily from collagenous material present in animal hide or from the extraction of collagen present in animal bones, primarily cattle, or more-commonly derived from recycled gelatin. These protein colloid glues are formed through hydrolysis of the collagen from skins, bones, tendons, and other tissues, similar to gelatin. These proteins form a molecular bond with the glued object. Exemplary types of animal glues include hide glue, hoof glue, bone glue, fish glue, and rabbit-skin glue.

Animal glue is widely available from commercial sources and may be supplied, for example, as granules, flakes, or flat sheets, which have an indefinite shelf life if kept dry. To form water-based animal glue it is dissolved/dispersed in water. In use it is heated and applied warm to the backing, typically around 50-60 °C. Preferably, the water-based animal glue has a viscosity at 60 °C of 1 to 100 cps (1 to 100 mPa’sec), and preferably 10 to 100 cps (10 to 100 mPa’sec). As the water-based animal glue cools, it gels quickly and gradually hardens as it dries/cures until is reaches its ultimate strength. Commercial suppliers of animal glues include, for example, LD Davis of Jenkintown, Pennsylvania and Milligan & Higgins of Johnstown, New York and Incogel - Industria de Cola e Gelatina, Campo Bela - MG, Brazil.

The make layer precursor may be coated on the backing by any suitable technique including, for example, roll coating, gravure roll coating, curtain coating, knife coating, notch bar coating, and/or spraying,

Once the make layer precursor has been applied to the backing, and before it is gelled, the shaped abrasive particles are applied; resulting in the shaped abrasive particles being deposited on the make layer precursor standing largely upright. The abrasive particles may be deposited on the make layer precursor (whether partially cured or not) by any method known in the abrasive arts, for example. Examples include drop coating, electrostatic coating, magnetic coating, and transfer from a production tool as described in U.S. Pat. Nos. 10,611,001 (Adefris et al.) and 9776302 (Keipert). Being shaped as triangular platelets the shaped abrasive particles are influenced by gravity to tip over, but advantageously make layer precursor is sufficiently cooled immediately after deposition of the shaped abrasive particles that the water-based animal glue gels and holds the shaped abrasive particles in their upright position.

Preferably, the shaped abrasive particles comprise sol-gel-derived polycrystalline alpha alumina particles. Such abrasive particles composed of crystallites of alpha alumina, magnesium alumina spinel, and a rare earth hexagonal aluminate may be prepared using sol-gel precursor alpha alumina particles according to methods described in, for example, U.S. Pat. No. 5,213,591 (Celikkaya et al.) and U.S. Publ. Pat. Appln. Nos. 2009/0165394 Al (Culler et al.) and 2009/0169816 Al (Erickson et al.). Further details concerning methods of making sol-gel-derived abrasive particles can be found in, for example, 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 in U.S. Publ. Pat. Appln. No. 2009/0165394 Al (Culler et al.).

Useful shaped abrasive particles having the shape of triangular platelets can be found in U.S. Pat. Nos. 5,201,916 (Berg); 5,366,523 (Rowenhorst (Re 35,570)); and 5,984,988 (Berg). In some embodiments, the shaped abrasive particles are precisely-shaped (i.e., the particles have shapes that are at least partially determined by the shapes of mold cavities in a production tool used to make them. Details concerning such abrasive particles and methods for their preparation can be found, for example, in U.S. Pat. Nos. 8,142,531 (Adefris et al.); 8,142,891 (Culler et al.); and 8,142,532 (Erickson et al.); and in U.S. Pat. Appl. Publ. Nos. 2012/0227333 (Adefris et al.); 2013/0040537 (Schwabel et al.); and 2013/0125477 (Adefris). One particularly useful precisely-shaped abrasive particle shape is that of a platelet having three-sidewalls, any of which may be straight or concave, and which may be vertical or sloping with respect to the platelet base; for example, as set forth in U.S. Pat. Nos. 9,771,504 and 10,301,518, both to Adefris.

In some embodiments, the shaped abrasive particles may be selected to have a length and/or width in a range of from 0.1 micrometers to 3.5 millimeters (mm), more typically 0.05 mm to 3.0 mm, and more typically 0.1 mm to 2.6 mm, although other lengths and widths may also be used.

In some embodiments, the shaped abrasive particles may be selected to have a thickness in a range of from 0.1 micrometer to 1.6 mm, more typically from 1 micrometer to 1.2 mm, although other thicknesses may be used. In some embodiments, abrasive particles may have an aspect ratio (length to thickness) of at least 2, 3, 4, 5, 6, or more.

Optionally, the shaped abrasive particles may be combined with diluent abrasive particles (typically crushed). If present, the diluent abrasive particles are preferably coated onto the make layer precursor after the shaped abrasive particles.

Suitable diluent abrasive particles include, for example, crushed abrasive particles comprising fused aluminum oxide, heat-treated aluminum oxide, white fused aluminum oxide, ceramic aluminum oxide materials such as those commercially available as 3M CERAMIC ABRASIVE GRAIN from 3M Company, St. Paul, Minnesota, brown aluminum oxide, blue aluminum oxide, silicon carbide (including green silicon carbide), titanium diboride, boron carbide, tungsten carbide, garnet, titanium carbide, diamond, cubic boron nitride, fused alumina zirconia, iron oxide, chromia, zirconia, titania, tin oxide, quartz, feldspar, flint, emery, sol-gel-derived ceramic (e.g., alpha alumina), and combinations thereof. Examples of sol-gel-derived abrasive particles from which the abrasive particles can be isolated, and methods for their preparation can be found, in U.S. Pat. Nos. 4,314,827 (Leitheiser et al.); 4,623,364 (Cottringer et al.); 4,744,802 (Schwabel), 4,770,671 (Monroe et al.); and 4,881,951 (Monroe et al.). It is also contemplated that the abrasive particles could comprise abrasive agglomerates such, for example, as those described in U.S. Pat. Nos. 4,652,275 (Bloecher et al.) or 4,799,939 (Bloecher et al.). In some embodiments, the abrasive particles may be surface-treated with a coupling agent (e.g., an organosilane coupling agent) or other physical treatment (e.g., iron oxide or titanium oxide) to enhance adhesion of the crushed abrasive particles to the binder. The abrasive particles may be treated before combining them with the binder, or they may be surface treated in situ by including a coupling agent to the binder.

Any size of shaped and optional diluent abrasive particles may be used. In some embodiments, the abrasive particles can be graded to a nominal screened grade using U.S.A. Standard Test Sieves conforming to ASTM E-l 1 "Standard Specification for Wire Cloth and Sieves for Testing Purposes". ASTM E-l 1 prescribes the requirements for the design and construction of testing sieves using a medium of woven wire cloth mounted in a frame for the classification of materials according to a designated particle size. A typical designation may be represented as -18+20 meaning that the shaped abrasive particles pass through a test sieve meeting ASTM E-l 1 specifications for the number 18 sieve and are retained on a test sieve meeting ASTM E-l 1 specifications for the number 20 sieve. 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, 25, 30, 35, 40, 45, or 50 mesh test sieve. In various embodiments, the shaped abrasive particles can have a nominal screened grade comprising: 18+20, 20+25, 25+30, 30+35, 35+40, 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 could be used such as 90+100.

Alternatively, shaped and optional diluent abrasive particles may be independently sized according to an abrasives industry recognized specified nominal grade. Exemplary abrasive industry recognized grading standards include those promulgated by ANSI (American National Standards Institute), FEPA (Federation of European Producers of Abrasives), and JIS (Japanese Industrial Standard). Such industry accepted grading standards include, for example: ANSI 4, ANSI 6, ANSI 8, ANSI 16, ANSI 24, ANSI 30, ANSI 36, ANSI 40, ANSI 50, ANSI 60, ANSI 80, ANSI 100, ANSI 120, ANSI 150, ANSI 180, ANSI 220, ANSI 240, ANSI 280, ANSI 320, ANSI 360, ANSI 400, and ANSI 600; FEPA P8, FEPA P12, FEPA P16, FEPA P24, FEPA P30, FEPA P36, FEPA P40, FEPA P50, FEPA P60, FEPA P80, FEPA P100, FEPA P120, FEPA P150, FEPA P180, FEPA P220, FEPA P320, FEPA P400, FEPA P500, FEPA P600, FEPA P800, FEPA P1000, FEPA P1200; FEPA F8, FEPA F12, FEPA F16, and FEPA F24;.and JIS 8, JIS 12, JIS 16, JIS 24, JIS 36, JIS 46, JIS 54, JIS 60, JIS 80, JIS 100, JIS 150, JIS 180, JIS 220, JIS 240, JIS 280, JIS 320, JIS 360, JIS 400, JIS 500, JIS 600, JIS 800, JIS 1000, JIS 1500, JIS 2500, JIS 4000, JIS 6000, JIS 8000, and JIS 10,000. More typically, the crushed aluminum oxide particles and the non-seeded sol-gel derived alumina-based abrasive particles are independently sized to ANSI 60 and 80, or FEPA F36, F46, F54 and F60 or FEPA P60 and P80 grading standards.

The shaped and optional diluent abrasive particles should have sufficient hardness and surface roughness to function as crushed abrasive particles in abrading processes. Preferably, 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.

Suitable diluent abrasive particles include, for example, crushed abrasive particles comprising fused aluminum oxide, heat-treated aluminum oxide, white fused aluminum oxide, ceramic aluminum oxide materials such as those commercially available as 3M CERAMIC ABRASIVE GRAIN from 3M Company, St. Paul, Minnesota, brown aluminum oxide, blue aluminum oxide, silicon carbide (including green silicon carbide), titanium diboride, boron carbide, tungsten carbide, garnet, titanium carbide, diamond, cubic boron nitride, fused alumina zirconia, iron oxide, chromia, zirconia, titania, tin oxide, quartz, feldspar, flint, emery, sol-gel-derived ceramic (e.g., alpha alumina), and combinations thereof. Examples of sol-gel-derived abrasive particles from which the abrasive particles can be isolated, and methods for their preparation can be found, in U.S. Pat. Nos. 4,314,827 (Leitheiser et al.); 4,623,364 (Cottringer et al.); 4,744,802 (Schwabel), 4,770,671 (Monroe et al.); and 4,881,951 (Monroe et al.). It is also contemplated that the abrasive particles could comprise abrasive agglomerates such, for example, as those described in U.S. Pat. Nos. 4,652,275 (Bloecher et al.) or 4,799,939 (Bloecher et al.). In some embodiments, the abrasive particles may be surface-treated with a coupling agent (e.g., an organosilane coupling agent) or other physical treatment (e.g., iron oxide or titanium oxide) to enhance adhesion of the crushed abrasive particles to the binder. The abrasive particles may be treated before combining them with the binder, or they may be surface treated in situ by including a coupling agent to the binder.

The size layer comprises an at least partially cured precursors size layer that may be the same as, or more typically different than the make layer precursor. Examples of suitable size layer precursor compositions included in the size layer precursor include, for example, animal glues, free-radically polymerizable monomers and/or oligomers, epoxy resins, acrylic resins, urethane resins, phenolic resins, urea-formaldehyde resins, melamine-formaldehyde resins, aminoplast resins, cyanate resins, or combinations thereof. Additional details concerning size layer precursors may be found in U.S. Pat. No. 4,588,419 (Caul et al.), U.S. Pat. No. 4,751,138 (Tumey et al.), and U.S. Pat. No. 5,436,063 (Follett et al.).

The size layer precursor may be coated on the backing by any suitable technique including, for example, roll coating, gravure roll coating, curtain coating, knife coating, notch bar coating, and/or spraying, Coating weights will depend on the size layer precursor used, and are within the capability of those skilled in the art. Heat energy (e.g., from an oven, heated roll, microwave radiation, and/or infrared radiation) and electromagnetic radiation (e.g., ultraviolet light and/or visible light), may be applied to advance curing of the size layer precursor; however, other sources of energy may also be used. The selection will generally be dictated by the particular resin system selected.

Make and size layers and their precursors may contain filler materials, diluent abrasive particles (e.g., as described hereinbelow), and/or or grinding aids, typically in the form of a particulate material. Typically, the particulate materials are inorganic materials. Examples of useful fillers for this disclosure include: metal carbonates (e.g., calcium carbonate (e.g., chalk, calcite, marl, travertine, marble and limestone), calcium magnesium carbonate, sodium carbonate, magnesium carbonate), silica (e.g., quartz, glass beads, glass bubbles and glass fibers) silicates (e.g., talc, clays, (montmorillonite) feldspar, mica, calcium silicate, calcium metasilicate, sodium aluminosilicate, sodium silicate) metal sulfates (e.g., calcium sulfate, barium sulfate, sodium sulfate, aluminum sodium sulfate, aluminum sulfate), gypsum, vermiculite, wood flour, aluminum trihydrate, carbon black, metal oxides (e.g., calcium oxide (lime), aluminum oxide, titanium dioxide), and metal sulfites (e.g., calcium sulfite).

A grinding aid is a material that has a significant effect on the chemical and physical processes of abrading, which results in improved performance. Grinding aids encompass a wide variety of different materials and can be inorganic or organic based. Examples of chemical groups of grinding aids include waxes, organic halide compounds, halide salts and metals and their alloys. The organic halide compounds will typically break down during abrading and release a halogen acid or a gaseous halide compound. Examples of such materials include chlorinated waxes like tetrachloronaphthalene, pentachloronaphthalene, and polyvinyl chloride. Examples of halide salts include sodium chloride, potassium cryolite, sodium cryolite, ammonium cryolite, potassium tetrafluoroborate, sodium tetrafluoroborate, silicon fluorides, potassium chloride, and magnesium chloride. Examples of metals include tin, lead, bismuth, cobalt, antimony, cadmium, iron, and titanium.

Other miscellaneous grinding aids include sulfur, organic sulfur compounds, graphite, and metallic sulfides. A combination of different grinding aids may be used, and in some instances, this may produce a synergistic effect.

Grinding aids can be particularly useful in coated abrasives. In coated abrasive articles, grinding aid is typically used in a supersize coat, which is applied over the surface of the abrasive particles. Sometimes, however, the grinding aid is added to the size coat. Typically, the amount of grinding aid incorporated into coated abrasive articles are about 50-800 grams per square meter (g/m^), preferably about 80-475 g/n

The optional supersize layer may comprise at least one of a grinding aid, lubricant, or antiloading agent, and optionally a polymeric binder.

Further details regarding coated abrasive articles and methods of their manufacture 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.); 5,436,063 (Follett et al.); 5,496,386 (Broberg et al.); 5,609,706 (Benedict et al.); 5, 520,711 (Helmin); 5,961,674 (Gagliardi et al.), and 5,975,988 (Christianson).

Coated abrasive articles according to the present disclosure are useful, for example, for abrading a workpiece. Such a method may comprise: frictionally contacting an abrasive articles according to the present disclosure with a surface of the workpiece, and moving at least one of the abrasive article and the surface of the workpiece relative to the other to abrade at least a portion of the surface of the workpiece. Methods for abrading with abrasive articles according to the present disclosure include, for example, snagging (i.e., high-pressure high stock removal) to polishing (e.g., polishing medical implants with coated abrasive belts), wherein the latter is typically done with finer grades (e.g., ANSI 220 and finer) of abrasive particles. The size of the abrasive particles used for a particular abrading application will be apparent to those skilled in the art.

Abrading may be carried out dry or wet. For wet abrading, the liquid may be introduced supplied in the form of a light mist to complete flood. Examples of commonly used liquids include: water, water- soluble oil, organic lubricant, and emulsions. The liquid may serve to reduce the heat associated with abrading and/or act as a lubricant. The liquid may contain minor amounts of additives such as bactericide, antifoaming agents, and the like.

Examples of workpieces include aluminum metal, carbon steels, mild steels (e.g., 1018 mild steel and 1045 mild steel), tool steels, stainless steel, hardened steel, titanium, glass, ceramics, wood, woodlike materials (e.g., plywood and particle board), paint, painted surfaces, and organic coated surfaces. The applied force during abrading typically ranges from about 1 to about 100 kilograms (kg), although other pressures can also be used.

SELECT EMBODIMENTS OF THE PRESENT DISCLOSURE

In a first embodiment, the present disclosure provides a method of making a method of making a coated abrasive article, the method comprising: providing a backing having first and second opposed major surfaces; disposing a make layer precursor comprising water-based animal glue on the first major surface of the backing; partially embedding shaped abrasive particles in the water-based animal glue, wherein the shaped abrasive particles comprise three-sided platelets; and at least partially curing the make layer precursor.

In a second embodiment, the present disclosure provides a method according to the first embodiment, wherein the animal glue comprises hide glue.

In a third embodiment, the present disclosure provides a method according to the first or second embodiment, wherein the animal glue has a viscosity of 100 to 200 cps (100 to 200 mPa’sec) at 21 °C.

In a fourth embodiment, the present disclosure provides a method according to any of the first to third embodiments, wherein the shaped abrasive particles comprise alpha alumina. In a fifth embodiment, the present disclosure provides a method according to any of the first to fourth embodiments, wherein the make layer precursor further comprises filler.

In a sixth embodiment the present disclosure provides a method according to any of the first to fifth embodiments, further comprising: disposing size layer precursor on the further cured make layer precursor and the abrasive particles; and at least partially curing the size layer precursor.

In a seventh embodiment, the present disclosure provides a method according to the sixth embodiment, further comprising disposing a supersize layer on the at least partially cured size layer precursor.

In an eighth embodiment, the present disclosure provides a coated abrasive article comprising: a backing having first and second opposed major surfaces; a make layer disposed on the first major surface of the backing, wherein the make layer comprise at least partially cured animal glue; shaped abrasive particles partially embedded in the make layer wherein the shaped abrasive particles are triangular platelets; a size layer disposed over the make layer and shaped abrasive particles, wherein the size layer comprises a thermoset polymer.

In a ninth embodiment, the present disclosure provides a coated abrasive article, wherein the animal glue comprises hide glue.

In a tenth embodiment, the present disclosure provides a coated abrasive article according to the eighth or ninth embodiment, wherein the shaped abrasive particles comprise alpha alumina.

In an eleventh embodiment, the present disclosure provides a coated abrasive article according to any of the eighth to tenth embodiments, wherein the make layer further comprises filler. wherein the make layer further comprises filler.

In a twelfth embodiment, the present disclosure provides a coated abrasive article according to any of the eighth to eleventh embodiments, further comprising a supersize layer disposed on the size layer.

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.

EXAMPLES

Unless stated otherwise, all other reagents were obtained, or are available from fine chemical vendors such as Sigma- Aldrich Company, St. Louis, Missouri, or may be synthesized by known methods. Table 1, below, reports abbreviation ns and materials used in the Examples. EXAMPLES 1 - 3

A make layer precursor consisting of animal glue (33 weight percent solids in water, obtained as 88 MPS from Incogel - Industria de Cola e Gelatina, Campo Bela - MG, Brazil) heated to 60 °C was applied using a wire-wound rod to a paper backing (basis weight 180 grams per meter (g/m ² )) in amounts shown in Table 1. Next, triangular platelet-shaped (truncate trigonal pyramids) abrasive mineral was deposited electrostatically onto the still warm make layer precursor.

The shaped abrasive particles were prepared according to the disclosure of U.S. Pat. No. 8,142,531 (Adefris et al.). The shaped abrasive particles were prepared by molding alumina sol gel in equilateral triangle-shaped polypropylene mold cavities. The draft angle between the sidewall and bottom of the mold was 98 degrees. After drying and firing, the resulting shaped abrasive particles were about 0.52 millimeter (mm) x 0.13 millimeter (thickness).

The make resin was allowed to cool and dried and a size layer precursor composed on a resole phenolic resin in water diluted with water to a viscosity of 200 cps (200 mPa’sec) at ambient temperature was applied onto the resulting make layer and abrasive particles in amounts shown in Table 1 (below).

TABLE 1

The resultant coated abrasive articles were converted into 5 -inch (12.7 cm) discs and tested for abrading performance and peak count (a measure of upright abrasive particle tips).

Abrasive Cut Test

A 5-inch (12.7-cm) diameter abrasive disc to be tested was mounted on an electric random orbital tool (available as Servo 5 mm random orbital sander from PushCorp, Garland, Texas) that was disposed over an X-Y table. A 6063R aluminum alloy panel measuring 400 mm x 60 mm was secured to the X-Y table. The tool was then set to traverse at a rate of 20 inches/second (508 mm/second) in the Y direction along the length of the panel; and a traverse along the width of the panel at a rate of 1.6 inches/second (406 mm/second). Thirteen such passes along the length of the panel were completed in each cycle. The Servo motor of the tool was then set to rotate at 10,000 revolutions per minute under no load. The abrasive article was then urged at an angle of 0 degrees (flat sanding) against the panel at a load of 10 pounds (4.54 kilograms). The tool was then activated to move through the prescribed path. The mass of the panel was measured before and after each cycle to determine the mass loss in grams after each cycle. Total cut was measured as the cumulative mass loss in grams at the end of the test. Besides the Examples 1-3 specimens, 3M Cubitron II Hookit Paper Disc 950U (127 mm, no hole 80+ grit size triangular shaped grain, E-weight paper backing ) was used as a comparative commercial product. Table 2, below, reports cut test results. TABLE 2

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