Curable compositions, thermosetting polymers derived therefrom, and methods of making the same

Abstract

A curable composition comprising at least one cyclic olefin capable of undergoing ring-opening metathesis polymerization, at least one ring-opening olefin metathesis catalyst, and dicumyl peroxide. A thermosetting polymer comprising the cured reaction product of the curable composition. A method of making a thermosetting polymer comprising optionally precuring the curable composition to form a self- supporting structure, and curing the curable composition at a temperature of at least 250 ºC to form the thermosetting polymer, wherein the thermosetting polymer has a Tg in a range of 200 ºC to 400 ºC.

Description

CURABLE COMPOSITIONS, THERMOSETTING POLYMERS DERIVED THEREFROM, AND METHODS OF MAKING THE SAMEBackground

[0001] Ring-Opening Metathesis Polymerization (ROMP) is a well-known process that converts cyclic olefins into polymers using a ROMP catalyst. Metathesis polymerization of cycloolefins typically yields crosslinked polymers having an unsaturated linear backbone. The degree of unsaturation of the repeat backbone unit of the polymer is the same as that of the cycloolefin. For example, with a norbomene reactant in the presence of an appropriate catalyst, the resulting polymer may be represented by:wherein a is the number of repeating cycloolefin units in the polymer chain.

[0002] For another example, with dienes such as dicyclopentadiene in the presence of an appropriate catalyst, the resulting polymer may be represented by:wherein b + c is the number of moles of polymerized cycloolefin, and c / (b + c) is the mole fraction of cycloolefin units which ring -open at both reactive sites. As shown by the above reaction, metathesis polymerization of dienes, trienes, etc. can result in a crosslinked polymer.Summary

[0003] The present disclosure provides curable compositions that utilize ring-opening metathesis polymerization to produce thermosetting polymers that, when fully cured, exhibit high temperature resistance and improved moisture resistance. Such thermosetting polymers may be used in a variety of applications that benefit from such properties, including molded abrasives and electronic components (e.g., adhesives, dielectric insulation, thermal cooling compounds, and encapsulants).

[0004] In one embodiment, the present disclosure provides a curable composition comprising at least one cyclic olefin capable of undergoing nng-opening metathesis polymerization, at least one ringopening olefin metathesis catalyst, and dicumyl peroxide.

[0005] In another embodiment, the present disclosure provides a thermosetting polymer comprising a cured reaction product of the curable composition.

[0006] In a further embodiment, the present disclosure provides articles comprising the thermosetting polymer.

[0007] In yet another embodiments, the present disclosure provide a method of making a thermosetting polymer comprising optionally precuring the curable composition to form a self-supporting structure, and curing the curable composition at a temperature of at least 250 °C to form the thermosetting polymer, wherein the thermosetting polymer has a Tgin a range of 200 °C to 400 °C.

[0008] The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The description that follows more particularly exemplifies illustrative embodiments.Detailed Description

[0009] In the following description of illustrative embodiments, it is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.

[0010] As used herein:

[0011] The term “comprises” and variations thereof do not have a limiting meaning where these terms appear in the description and claims. Such terms will be understood to imply the inclusion of a stated step or element or group of steps or elements but not the exclusion of any other step or element or group of steps or elements. By “consisting of’ is meant including, and limited to, whatever follows the phrase “consisting of.” Thus, the phrase “consisting of’ indicates that the listed elements are required or mandatory, and that no other elements may be present. By “consisting essentially of’ is meant including any elements listed after the phrase, and limited to other elements that do not interfere with or contribute to the activity or action specified in the disclosure for the listed elements. Thus, the phrase “consisting essentially of’ indicates that the listed elements are required or mandatory, but that other elements are optional and may or may not be present depending upon whether or not they materially affect the activity or action of the listed elements.

[0012] The terms “a,” “an,” and “the” are used interchangeably with “at least one” to mean one or more of the components being described.

[0013] The term “and / or” means one or all of the listed elements or a combination of any two or more of the listed elements.

[0014] The term “some embodiments” means that a particular feature, configuration, composition, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of such phrases in various places throughout this specification are not necessarily referring to the same embodiment of the disclosure. Furthermore, the particular features, configurations, compositions, or characteristics may be combined in any suitable manner in one or more embodiments.

[0015] The terms “preferred” and “preferably” refer to embodiments of the disclosure that may afford certain benefits, under certain circumstances; however, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments doesnot imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the disclosure.

[0016] The terms “thermosetting polymer” or “thermoset” refer to a polymer or polymer composite obtained by irreversibly hardening (e.g., through curing) a curable composition.

[0017] All numbers are assumed to be modified by the term “about”. As used herein in connection with a measured quantity, the term “about” refers to that variation in the measured quantity as would be expected by the skilled artisan making the measurement and exercising a level of care commensurate with the objective of the measurement and the precision of the measuring equipment used.

[0018] The recitations of numerical ranges by endpoints include all numbers subsumed within that range as well as the endpoints (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.). The phrase “up to” a number (e.g., up to 50) includes the number (e.g., 50).

[0019] Generally, the present disclosure provides a thermosetting polymer derived from a curable composition comprising at least one cyclic olefin capable of undergoing ring-opening metathesis polymerization, at least one ring -opening olefin metathesis catalyst, and dicumyl peroxide. Dicumyl peroxide was found to be a particularly advantageous co-catalyst that enhances the crosslinking of the curable composition upon curing, contributing to a thermosetting polymer having increased temperature resistance and improved moisture resistance. In some embodiments, the curable composition comprises at least 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40 or 0.45 percent by weight dicumyl peroxide. In some embodiments, the curable composition comprises no greater than 0.50, 0.45, 0.40, 0.35. 0.30, 0.25 or 0.20 percent by weight dicumyl peroxide. In some embodiments, the curable composition comprises 0.05 to 0.50, more particularly 0.05 to 0.30 and even more particularly 0.1 to 0.20 percent by weight dicumyl peroxide. Other components of the curable composition are described in greater detail below.

[0020] Cyclic Olefins

[0021] The term "cyclic olefin" or “cycloolefin”, as used herein, refers to an olefin having at least one cyclic group and may include polycyclic cycloolefins (e.g., bicyclic cycloolefms and tricyclic cycloolefins). The term cyclic olefin does not expressly refer to any aromatic ring or fused aromatic rings (i.e., structures that do not undergo ROMP), although such rings may be present in the curable composition as well.

[0022] Exemplary cyclic olefins capable of undergoing ring-opening metathesis polymerization include dicyclopentadiene, norbomene, ethylidenenorbomene, cyclopentene, cyclooctene, tricyclopentadiene, tetracyclopentadiene, norbomadiene, 7-oxobicyclo[2.2. l]hept-2-ene, tetracyclo [6.2.13 ,6.0]dodeca-4,9- diene, hexylnorbomylene, cyclopentadiene, alkyl norbomene, an oligomer thereof, a derivative thereof, or combinations thereof. In some embodiments, the cyclic olefins comprise at least one of dicyclopentadiene or a derivative thereof

[0023] Additional exemplary cyclic olefins include alkyl norbomylenes represented by the formula:wherein R is an alkyl group comprising from 1 to 12 carbon atoms, e.g., 6 carbon atoms.

[0024] Additional examples of useful cyclic olefins include the following polycyclic dienes:wherein X 11is a divalent aliphatic or aromatic group with 0 to 20 carbon atoms; X 9 is a multivalent aliphatic or aromatic group with 0 to 20 carbon atoms; optional group Y ' is a divalent functional group selected from the group consisting of esters, amides, ethers, and silanes; and z is 2 or greater.

[0025] Commercially available cyclic olefins include PROXIMA® HPR 2128 and PROXIMA® HPR 2029 from Materia®, Inc. in Pasadena, CA.

[0026] The amount of cyclic olefins in the curable composition will vary depending upon the application. In some embodiments, the curable composition comprises at least 10, 20, 30, 40, 50, 60, 70, 80, or 90 percent by weight cyclic olefin. In some embodiments, the curable composition comprises no greater than 99, 90, 80, 70, 60, 50 or 40 percent by weight cyclic olefin. When the curable composition is used in abrasive applications, the amount of cyclic olefin is typically on the lower end, for example, 10 to 40 percent by weight based upon the total weight of the curable composition. In other embodiments where there are little to no additives or additives having lower density, the amount of cyclic olefin can be on the higher end. For example, in some embodiments, the amount of cyclic olefin can be at least 96 percent by weight based upon the total weight of the curable composition.

[0027] ROMP Catalysts

[0028] Besides cyclic olefin(s) (e.g., as described above), the curable composition comprises at least one ring-opening metathesis polymerization catalyst. Transition metal carbene catalysts such as ruthenium, osmium, and rhenium catalysts may be used, including versions of Grubbs catalysts and Grubbs- Hoveyda catalysts. See, for example, U. S. Pat. No. 5,849,851 (Grubbs et al.).

[0029] In some embodiments, the ROMP catalyst comprises a compound of the formula:wherein:M is selected from the group consisting of Os and Ru;R and R are independently selected from the group consisting of hydrogen and a substituent group selected from the group consisting of C |-C’2O alkyl, C2-C20 alkenyl, C2-C20 alkoxycarbonyl, aryl, C1-C20 carboxylate, G | -C'20 alkoxy, C2-C20 alkenyloxy, C^-C^Q alkynyloxy and aryloxy; the substituent group optionally substituted with a moiety selected from the group consisting of C1-C5 alkyl, halogen, C 1-C5 alkoxy and phenyl; the phenyl optionally substituted with a moiety selected from the group consisting of halogen, C1-C5 alkyl, and C | -C5 alkoxy; are independently selected from any anionic ligand; andL and k' are independently selected from any phosphine of the formula PR^R^R^, wherein R^ is selected from the group consisting of neopentyl, secondary alkyl and cycloalkyl and wherein R^ and R^ are independently selected from the group consisting of aryl, neopentyl, C | -C | g primary alkyl, secondary alkyl, and cycloalkyl.

[0030] In some embodiments, the ROMP catalyst comprises a compound of the formula:wherein Cyi is a cyclopentyl group, and Ph is a phenyl group.

[0031] Commercially available ROMP catalysts include “PROXIMA® CT-762” from Materia®, Inc. in Pasadena, CA.

[0032] In some embodiments, the curable composition comprises at least 0.05, 0.10, 0.15, 0.20, 0.25, 0.30. 0.35. 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75 and 0.80 percent by weight ROMP catalyst. In some embodiments, the curable composition comprises no greater than 1, 0.95, 0.90, 0.85, 0.80. 0.75, 0.65, 0.60, 0.55 or 0.50 percent by weight ROMP catalyst. In some embodiments, the curable composition comprises 0.05 to 1, more particularly 0.20 to 0.70, and even more particularly 0.40 to 0.60 percent by weight ROMP catalyst based upon the total weight of the curable composition.

[0033] Curable Composition for Abrasive Applications

[0034] When the thermosetting polymer is used in abrasive applications, the curable composition may further comprise abrasive particles, a coupling agent and, optionally, one or more fillers and / or grinding aids.

[0035] Generally, the abrasive particles used herein have surface hydroxyl groups. Examples of suitable abrasive particles include fused aluminum oxide, heat-treated aluminum oxide, white fused aluminum oxide, ceramic aluminum oxide materials such as available as ceramic abrasive grains from 3M Company, brown aluminum oxide, blue aluminum oxide, garnet, fused alumina zirconia, iron oxide, chromia, zirconia, titania, tin oxide, quartz, feldspar, flint, emery, sol-gel-derived abrasive particles (e.g., including both precisely-shaped and crushed forms), and combinations thereof.

[0036] Preferably, the abrasive particles (especially precisely-shaped abrasive platelets) comprise sol- gel-derived alpha-alumina particles.

[0037] 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.).

[0038] Alpha-alumina-based precisely-shaped abrasive particles can be made according to a well-known multistep processes. Briefly, the method comprises the steps of: making either a seeded or non-seeded sol-gel alpha-alumina precursor dispersion that can be converted into alpha-alumina; filling one or more mold cavities having the desired outer shape of the precisely-shaped abrasive particle with the sol-gel and drying the sol-gel to form precursor precisely-shaped ceramic abrasive particles; removing the precursor precisely-shaped ceramic abrasive particles from the mold cavities; calcining the precursor precisely- shaped ceramic abrasive particles to form calcined, precursor precisely-shaped ceramic abrasiveparticles; and, then sintering the calcined, precursor precisely-shaped ceramic abrasive particles to form precisely-shaped ceramic abrasive particles. 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 ). Further examples of sol-gel-derived precisely-shaped alpha-alumina (i.e., ceramic) abrasive particles can be found in U.S. Pat. Nos. 5,201,916 (Berg); 5,366,523 (Rowenhorst (Re 35,570)); 5,984,988 (Berg); 8,142,531 (Adefns 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 (Adefns et al.); 2013 / 0040537 (Schwabel et al.); and 2013 / 0125477 (Adefris).

[0039] In some embodiments, the base and the top of the precisely-shaped abrasive particles are substantially parallel, resulting in prismatic or truncated pyramidal shapes, although this is not a requirement. In some embodiments, the sides of a truncated trigonal pyramid have equal dimensions and form dihedral angles with the base of about 82 degrees. However, it will be recognized that other dihedral angles (including 90 degrees) may also be used. For example, the dihedral angle between the base and each of the sides may independently range from 45 to 90 degrees, typically 70 to 90 degrees, more typically 75 to 85 degrees.

[0040] 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.), 4,799,939 (Bloecher et al.), 6,521,004 (Culler et al ), or 6,881,483 (McArdle et al.).

[0041] In some embodiments, the abrasive particles have a Mohs hardness of at least 4, at least 5, at least 6, at least 7, or even at least 8.

[0042] In some preferred embodiments, the abrasive particles comprise shaped ceramic abrasive particles (e.g., shaped sol-gel-derived polycrystalline alpha alumina particles) that are generally triangularly-shaped (e.g., a triangular prism or a truncated three-sided pyramid).

[0043] The abrasive particles are typically selected to have a length in a range of from 1 micron to 4 millimeters, more typically 10 microns to about 3 millimeter, and still more typically from 150 to 2,600 microns, although other lengths may also be used.

[0044] The abrasive particles are typically selected to have a width in a range of from 0.1 micron to 3,500 microns, more typically 100 microns to 3,000 microns, and more typically 100 microns to 2,600 microns, although other lengths may also be used.

[0045] The abrasive particles are typically selected to have a thickness in a range of from 0.1 micron to 1,600 microns, more typically from 1 micron to 1,200 microns, although other thicknesses may be used.

[0046] In some embodiments, the abrasive particles may have an aspect ratio (length to thickness) of at least 2, 3, 4, 5, 6, or more.

[0047] The 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 EuropeanProducers of Abrasives), and JIS (Japanese Industrial Standard). ANSI grade designations (i.e., specified nominal grades) include, for example: ANSI 4, ANSI 6, ANSI 8, ANSI 16, ANSI 24, ANSI 36, ANSI 46, ANSI 54, ANSI 60, ANSI 70, ANSI 80, ANSI 90, ANSI 100, ANSI 120, ANSI 150, ANSI 180, ANSI 220, ANSI 240, ANSI 280, ANSI 320, ANSI 360, ANSI 400, and ANSI 600. FEPA grade designations include F4, F5, F6, F7, F8, F10, F12, F14, F16, F16, F20, F22, F24, F30, F36, F40, F46, F54, F60, F70, F80, F90, F100, F120, F150, F180, F220, F230, F240, F280, F320, F360, F400, F500, F600, F800, F1000, F1200, F1500, and F2000. JIS grade designations include JIS8, JIS 12, JIS 16, JIS24, JIS36, JIS46, JIS54, JIS60, JIS80, JIS 100, JIS150, JIS180, JIS220, JIS240, JIS280, JIS320, JIS360, JIS400, JIS600, JIS800, JIS1000, JIS 1500, JIS2500, JIS4000, JIS6000, JIS8000, and JIS10,000.

[0048] According to an embodiment of the present disclosure, the average diameter of the abrasive particles may be within a range of from 260 to 4,000 microns in accordance with FEPA grades F60 to F24.

[0049] Alternatively, the abrasive particles can be graded to a nominal screened grade using U.S.A. Standard Test Sieves conforming to ASTM El 1-17 "Standard Specification for Woven Wire Test Sieve Cloth and Test Sieves". ASTM El l-17 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 abrasive particles pass through a test sieve meeting ASTM El 1-17 specifications for the number 18 sieve and are retained on a test sieve meeting ASTM El l-17 specifications for the number 20 sieve. In one embodiment, the 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 abrasive particles can have a nominal screened grade of: -18+20, -20+25, - 25+30, -30+35, -35+40, 5 -40+45, -45+50, -50+60, -60+70, -70+80, -80+100, -100+120, -120+140, - 140+170, -170+200, -200+230, -230+270, -270+325, -325+400, -400+450, -450+500, or -500+635. Alternatively, a custom mesh size can be used such as -90+100.

[0050] In some embodiments, the abrasive particles are 40 to 80, more particularly 55 to 65 percent by weight based upon the total weight of the curable composition.

[0051] In addition to the abrasive particles, the curable composition may also include coupling agents. Coupling agents typically improve compatibility between the abrasive particles and resin in the cured composition. In some embodiments, the coupling agents are polyfimctional coupling agents. Exemplary polyfimctional coupling agents include polyurethane-methoxy silane available under the trade designation VESTANAT EP-M 95 from Evonik, tris-(trimethoxysilylpropyl)isocyanurate, l,3,5-tris(3- (trimethoxysilyl)propyl)-!, 3, 5-triazinane-2, 4, 6-trione, and tris(3-(trimethoxysilyl)propyl)amine.

[0052] In other embodiments, the coupling agents include difunctional coupling agents represented by the structure Z-X-Z. Each Z independently represents a group that is chemically reactive with at least one of the surface hydroxyl groups of one of the abrasive particles thereby forming at least one covalent bond. Examples include isocyanate groups (i.e., -N=C=O) and silyl groups having one to 3 hydrolyzable groups bonded thereto. Exemplary silyl groups include those represented by the formula -wherein each L independently represents a hydrolyzable group (e.g., Cl, Br, acetoxy, methoxy, ethoxy, and / or hydroxyl), whereinrepresents an alkyl group having from 1 to 4 carbon atoms, and wherein a is 0, 1, or 2. In preferred embodiments a is 0. Each X independently represents a divalent organic linking group have a number average molecular weight (Mn) of 500 to 10,000 grams per mole, preferably 600 to 6,000 grams per mole. For example, the X may have an Mnof 500, 600,700, 800, 900, or 1000 grams / mole up to 6000, up to 7000, up to 8000, up to 9000, or up to 10000 grams / mole in any combination.

[0053] In some preferred embodiments, the difunctional coupling agent comprises an isocyanate- terminated polyurethane prepolymer; for example, a diphenylmethane diisocyanate (e.g., 4,4'- methylenebis(phenyl isocyanate))-terminated polyether prepolymer based on a polytetramethylene ether glycol. Exemplary polyalkylene ether diols include polyethylene glycol, polypropylene glycol, polytrimethylene ether glycol (i.e., HOfCH CH CLhOfiqH . and polytetramethylene ether glycol (i.e., HO(CH2CH2CH2CH2O)nH). The resulting prepolymers may have poly oxyalkylene divalent segments such as, for example, a polyoxyethylene segment, a polyoxypropylene segment, and / or a polyoxybutylene segment.

[0054] One preferred isocyanate-terminated polyurethane prepolymer is a modified diphenylmethane diisocyanate (MDI)-terminated polyether prepolymer based on polytetramethylene ether glycol (PTMEG) available under the trade designation BAYTEC ME-230 from Covestro, Pittsburg, Pennsylvania.

[0055] Isocyanate-terminated polybutadiene prepolymers can be prepared, for example, by reaction of a diisocyanate with a hydroxyl-terminated poly oxyalkylene or a hydroxyl-terminated polybutadiene. Polyoxyalkylene polymers having hydrolyzable silyl end groups can be prepared , for example, by reaction of a corresponding hydroxyl-terminated polyoxyalkylene with an isocyanate functional hydrolysable organosilane (e.g., isocyanatoethyltnmethoxysilane or isocyanatoethyltriethoxysilane).

[0056] Commercially available OH-terminated polybutadienes include those under the trade designation POLYVEST HT (Mn = 2,900 g / mole) available from Evonik Industries AG in Essen, Germany, and those under the trade designations POLY BD R-45HTLO (Mn= 2800 g / mol), POLY BD R-20LM (Mn= 1200), KRASOL LBH 2000 (2100 g / mol) and KRASOL LBH 3000 (3000 g / mol) available from Cray Valley in Exton, Pennsylvania.

[0057] Silane-terminated poly butadienes can be prepared by anionic polymerization and capping the living end of die polybutadiene with a hydrolyzable silane (e.g., tetramethoxysilane or tetraethoxysilane). Suitable hydrolyzable silane-terminated liquid polybutadienes are also commercially available, for example, under the trade designation POLYVEST EP ST-M 60 (Mn-3300 g / mole) from Evonik in Marl, Germany and under the trade designation RICON 603 silane-functional polybutadiene (Mn= 3300 g / mole, difunctional) from Total Cray Valley in Exton, Pennsylvania

[0058] In some embodiments, the coupling agent is 0.01 to 2 percent by weight based upon the total weight of the curable composition.

[0059] In addition to the abrasive particles and coupling agent, the curable composition may, optionally, further include one or more grinding aids and / or fillers, typically in the form of a particulate material. Typically, the particulate materials are inorganic materials. Examples of useful fillers 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).

[0060] In general, the addition of a grinding aid increases the useful life of the abrasive article. 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, and iron 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. In some embodiments, the curable composition for abrasive applications comprises 10 to 30 percent by weight of grinding aids and / or fillers.

[0061] Additives

[0062] The curable composition may comprise one or more optional additives, depending upon the intended application. Exemplary classes of additives include adhesion promoters, thermal fillers, reinforcing fillers, coupling agents, plasticizers, antioxidants, UV stabilizers, colorants, and polymeric and / or inorganic fibers.

[0063] In some embodiments, the curable composition may comprise an adhesion promoter to facilitate bonding to various surfaces (e g., metal oxide surfaces). An exemplary adhesion promoter is trimethoxysilane-functionalized polybutadiene (e.g., as available from Evonik Corp. Parsippany, New Jersey under the trade designation Polyvest EP ST-M) In some embodiments, the adhesion promoter is 0.01 to 2 percent by weight based on the total weight of curable composition.

[0064] In some embodiments, the curable composition may comprise thermal fillers, including at least one of alumina, alumina trihydrate, boron nitride, zinc oxide, tin oxide, aluminum nitride, magnesium oxide, silicon carbide, graphene, carbon nanotubes, carbon black, or diamond. In some embodiments, thethermal filler (often in the form of particles) comprises at least 10 percent, at least 20 percent, at least 30 percent, at least 40 percent, at least 50 percent, at least 60 percent, or even at least 70 percent by weight up to about 80 percent by weight, based on the total weight of the curable composition.

[0065] In some embodiments, the curable composition may comprise reinforcing fillers, including reinforcing fibers, solid glass microspheres, solid ceramic microspheres, solid polymeric microspheres, hollow glass microspheres, hollow ceramic microspheres, hollow polymeric microspheres, expandable polymeric microspheres, or combinations thereof. If present, reinforcing filler may be present in amounts of at least 10 percent, at least 20 percent, at least 30 percent, at least 40 percent, at least 50 percent, at least 60 percent, or even at least 70 percent by weight up to about 80 percent by weight, based on the total weight of the curable composition.

[0066] In one preferable embodiment, the curable composition comprises at least one cyclic olefin capable of undergoing ring-opening metathesis polymerization, at least one ring-opening metathesis catalyst, dicumyl peroxide, abrasive particles, silane-terminated polybutadiene, fused white aluminum oxide, carbon black potassium aluminum fluoride and, optionally, magnesium hydroxide. In some embodiments, the ring-opening metathesis catalyst comprises a compound of the formula:wherein Cys is a cyclopentyl group, and Ph is a phenyl group. In some embodiments, the cyclic olefin is dicyclopentadiene .

[0067] Method of Making

[0068] The curable compositions disclosed herein may be cured to form a thermosetting polymer that is useful in a variety of high temperature applications. Generally, the thermosetting polymer is made by precuring the curable composition to form a self-supporting structure, and further curing the curable composition at a temperature of at least 250 °C to form the thermosetting polymer. Alternatively, the precuring step may be bypassed and the curable composition cured at a temperature of at least 250 °C to form the thermosetting polymer in a single step.

[0069] The optional precuring step may be conducted at temperatures below 250 °C and for a sufficient period of time to create a self-supporting structure. For example, in some embodiments, the precuring step is conducted at 130 °C for 15-30 minutes. If using a mold to form the thermosetting polymer into a particular shape, the curable composition may be removed from the mold after the precuring step and prior to the curing step.

[0070] The curing step is conducted at temperatures of at least 250 °C for up to 10, 15, 20 hours. In some embodiments, the curing is performed at 250 °C for 16 hours. Although the curing may be performed in an inert atmosphere, it was unexpectedly found that ambient gas (i.e., in the presence ofoxygen) worked similarly well. It was expected that the presence of oxygen in such high temperature processes would result in oxidative degradation of the cured product. However, only minimal oxidation was noted at the surface, which did not sufficiently impact the performance of the cured polymer.

[0071] The resultant thermosetting polymers of the present disclosure can be configured into a variety of form factors, including free-standing films, protective coatings and molded components. In some embodiments, the thermosetting polymers can be provided in the form of a sheet (e.g., disc-shape), a strip, a gasket, or a roll.

[0072] Surprisingly, the presence of dicumyl peroxide in the curable composition in combination with the high curing temperatures and long curing times provide thermosetting polymers with increased crosslinking. The increased crosslinking leads to polymers with higher glass transition temperatures and improved moisture resistance. In some embodiments, the thermosetting polymer exhibits glass transition temperatures of at least 200 °C, 250 °C, 300 °C. In some embodiments, the glass transition temperature ranges from 200 °C to 400 °C. For this reason, the thermosetting polymers of the present invention can by used in high temperature applications.

[0073] The thermosetting polymers of the present application can be used in a variety of applications that require high temperature performance, including molded abrasives (e.g., cut-off wheels) and electronic components (e.g., dielectric insulation, thermal cooling materials, encapsulants and sensor protection). In some embodiments, the thermosetting polymer is an abrasive article, more particularly a bonded abrasive article used in cutting wheels.Examples

[0074] Objects and advantages of this invention are further illustrated by the following 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 invention. These examples are merely for illustrative purposes only and are not meant to be limiting on the scope of the appended claims.

[0075] Table 1. Materials

[0076] Cutting Test Method

[0077] A 40-inch (1 m) long sheet of 0.12 inch (3 mm) thick stainless steel was secured with its major surface inclined at a 35-degree angle relative to horizontal. A guide rail was secured along the downward-sloping top surface of the inclined sheet. A DeWalt Model DWE43114N 4.5-inch (11.4- cm) / 5-inch ( 12.7-cm) cut-off wheel angle grinder was secured to the guide rail such that the tool was guided in a downward path under the force of gravity. A cut-off wheel for evaluation was mounted on the tool such that the cut-off wheel encountered the full thickness of the stainless steel sheet when the cut-off wheel tool was released to traverse downward, along the rail under gravitational force. The cutoff wheel tool was activated to rotate the cut-off wheel at 10000 rpm, the tool was released to begin its descent, and the length of the resulting cut in the stainless steel sheet was measured after 60 seconds. Dimensions of the cut-off wheel were measured before and after the cutting test to determine wear. Cut rate is the distance the wheel cut in one minute [mm / min] . Wear rate [mm3 / min] is the rate of volume removal of the wheel as it cuts. Performance is the cut rate per wear rate [mm / mm3] .

[0078] As shown in Table 2, all cut-off wheels made with dicumyl peroxide (Ex 1-7) show reduction of wear rate compared to the comparative example made without dicumyl peroxide (Comparative Examples A-C). Examples 3 and 4 demonstrate repeatability.

[0079] Comparative Example A

[0080] HPR 2128 (36.445g) was weighed in a small glass jar. ST-M ( 1 ,4g) was added to and mixed with a tongue depressor. PP (41.6g) was added to the mixture and stirred by hand. The RMP catalyst CT-762 (0.555g) was blended into the mixture. SAP (120g) was added and mixed using a tongue depressor.

[0081] Mold release was added on a 5 -inch (127-mm) diameter metal mold cavity with a mold inner diameter of 23-mm. SCRIM was placed in the bottom of mold. The cut-off wheel fill mixture (35g) was then placed on top of the SCRIM and spread with a tongue depressor until it is relatively flat. The filled mold is placed on the IKA AS 130 agitator [1 / min] 320 for 5 minutes to aid flatness. A second SCRIM was then placed on top of the fill mixture. A hovering top plate is placed on the mold for thermal stability. The entire mold and wheel precursors are precured for 15 minutes at 130C. The mold was opened, and the wheel was transferred onto a release liner on top of an aluminum plate in stack and placed in the oven. The wheels are cured at 250C for 16 hours. The final thickness of the wheel was 1.5mm. Three replicates of Comparative Example A were made for a total of four wheels.

[0082] Example 1

[0083] Comparative Example A was repeated, except that the amount of HPR 2128 was reduced (36.075g), and DP (0.370g) was added to the olefin resin and ST-M prior to the PP add. The DP is dissolved with mild agitation for IKA AS130.1 by IKA®KS130 Basic Mot at a speed of 320 rpm for 5 minutes.

[0084] Comparative Example B

[0085] Comparative Example A was repeated, except that HPR 2029 was used in place of HPR 2128. Final wheel thicknesses were approximately 1.55mm. Two replicates of Comparative Example B were made for a total of three wheels.

[0086] Example 2

[0087] Example 1 was repeated, except that HPR 2128 was replaced with HPR 2029. One replicate of Example 2 was made for a total of two wheels.

[0088] Comparative Example C

[0089] Comparative Example B was repeated, but because EXP 2008 is a lower viscosity resin, less total resin was used in the cut-off wheel compared to the inorganic compounds. Therefore, the mixture was made of EXP 2008 (32.802g), ST-M (1.26g), PP (37.44g), CT-762 (0.500g) and SAP (128g). In addition, each wheel was made with 35.5g mixture. The resulting wheels were 1.6mm thickness.

[0090] Example 3

[0091] Comparative Example C was repeated, except that EXP 2008 (32.469g) and DP (0.333g) replaced the EXP 2008 (32.802g).

[0092] Example 4

[0093] Example 3 was repeated.

[0094] Example 5

[0095] Comparative Example C was repeated, except that EXP 2008 (32.136g) and DP (0.67) replacedthe EXP 2008 (32.802g).

[0096] Example 6

[0097] Comparative Example C was repeated, except that EXP 2008 (31.803g) and DP (1.00g) replaced the EXP 2008 (32.802g).

[0098] Example 7

[0099] Comparative Example C was repeated, except that EXP 2008 (31 470g) and DP (1 33g) replaced the EXP 2008 (32.802g).

[0100] Table 2. Performance Data of Cut-off Wheels

[0101] Thus, the present disclosure provides, among other things, curable compositions, thermosetting polymers derived therefrom, and methods of making the same. Various features and advantages of the present disclosure are set forth in the following claims.

Claims

What is claimed is:

1. A curable composition comprising: at least one cyclic olefin capable of undergoing ring-opening metathesis polymerization; at least one ring-opening olefin metathesis catalyst; and dicumyl peroxide.

2. The curable composition of claim 1, wherein the at least one cyclic olefin capable of undergoing ring-opening metathesis polymerization comprises dicyclopentadiene, norbomene, ethylidenenorbomene, cyclopentene, cyclooctene, tricyclopentadiene, tetracyclopentadiene, norbomadiene, 7-oxobicyclo[2.

2. l]hept-2-ene, tetracyclo [6.2.13.6.0]dodeca-4,9-diene, hexylnorbomylene, cyclopentadiene, alkyl norbomene, an oligomer thereof, a derivative thereof, or combinations thereof.

3. The curable composition of claim 1, wherein the at least one cyclic olefin capable of undergoing ring-opening metathesis polymerization comprises at least one of dicyclopentadiene or a derivative thereof.

4. The curable composition of any one of claims 1 to 3, wherein the at least one ringopening olefin metathesis catalyst iswherein Cy is a cyclopentyl group and Ph is a phenyl group.

5. The curable composition of any one of claims 1 to 4 further comprising an adhesion promoter.

6. The curable composition of any one of claims 1 to 5 further comprising a thermal filler comprising at least one of alumina, alumina trihydrate, boron nitride, zinc oxide, tin oxide, aluminum nitride, magnesium oxide, silicon carbide, graphene, carbon nanotubes, carbon black, or diamond.

7. The curable composition of any one of claims 1 to 6 further comprising at least one of reinforcing fibers, solid glass microspheres, solid ceramic microspheres, solid polymeric microspheres,hollow glass microspheres, hollow ceramic microspheres, hollow polymeric microspheres, or expandable polymeric microspheres.

8. The curable composition of any one of claims 1 to 7, further comprising: abrasive particles having surface hydroxyl groups; and a coupling agent9. The curable composition of claim 8, wherein the coupling agent is a polyfunctional coupling agent.

10. The curable composition of claim 8, wherein the coupling agent is a difunctional coupling agent represented by the structure Z-X-Z, wherein each Z independently represents a group that is chemically reactive with at least one of the surface hydroxyl groups of one of the abrasive particles thereby forming at least one covalent bond, and wherein X represents a divalent organic linking group have a number average molecular weight of 500 to 10,000 grams per mole.

11. The curable composition of claim 10, wherein the difunctional coupling agent is a silane- terminate polybutadiene.

12. The curable composition of any one of claims 8 to 11, further comprising grinding aid particles.

13. A thermosetting polymer comprising a cured reaction product of the curable composition of any one of claims 1 to 12.

14. The thermosetting polymer of claim 13 in the form of a sheet, a strip, a gasket, or a roll.

15. An article comprising the thermosetting polymer of claim 13 or claim 14.

16. The article of claim 15, wherein the thermosetting polymer is a cutting wheel.

17. A method of making a thermosetting polymer comprising: optionally precuring the curable composition of any one of claims 1 to 12 to form a self- supporting structure; and curing the curable composition at a temperature of at least 250 °C to form the thermosetting polymer,wherein the thermosetting polymer has a Tgin a range of 200 °C to 400 °C.

18. The method of claim 17, wherein the optional precuring and curing are done in the presence of oxygen.

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