CURING AGENT

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to European Patent Application No.

19184421.6, filed on July 4, 2019 and Indian Patent Application No. 201911008314, filed March 4, 2019, the entire contents of which are both incorporated by reference herein.

BACKGROUND

[0001] Thermosetting epoxy resins exhibit excellent properties of toughness, corrosion resistance, and chemical resistance, as well as low cost. The properties make these resins ideal as coating materials in a variety of applications such as automotive coatings, building materials, and household electronic appliances. Commonly used epoxy curing agents such as amines and monoanhydrides often result in cured epoxy resins having limited high heat properties, such as a glass transition temperature (TG) that is less than 160°C. Aromatic dianhydrides are another class of epoxy curing agents than can afford cured epoxy resins having higher T _g. However, most aromatic dianhydride curing agents have a high melting points (e.g., greater than 200°C) with no or limited solubility in liquid epoxy resins and organic solvents. As a result, curable epoxy formulations with these curing agents often have poor processability that limits their use.

[0002] There remains a need for curable epoxy compositions that can provide cured epoxy resins having high temperature stability, good mechanical properties, and improved chemical stability.

BRIEF DESCRIPTION

[0003] Provided is a thermosetting epoxy composition comprising: 100 parts by weight of an epoxy resin composition; 30 to 200 parts by weight of an aromatic dianhydride curing agent; optionally 20 to 100 parts by weight of a liquid monoanhydride curing agent; and optionally a curing catalyst; wherein the amounts are based on the total parts by weight of the epoxy resin composition, the aromatic dianhydride curing agent, and optionally the liquid monoanhydride curing agent when present, wherein an anhydride to epoxy stoichiometric ratio (A/E) is 0.2: 1 to 1.6: 1, preferably 0.5: 1 to 1.3: 1, more preferably 0.6: 1 to 1.2: 1, as determined by molar ratio of total anhydride functionalities to total epoxy functionalities in the thermosetting epoxy composition, wherein the thermosetting epoxy composition after curing has a glass transition temperature of 120 to 320°C, preferably 160 to 320°C, more preferably 180 to 320°C, even more preferably 200 to 320°C, still more preferably 250 to 320°C, as determined by dynamic mechanical analysis (DMA), wherein the aromatic dianhydride curing agent has a maximum absolute particle size of 0.1 to 3,350 micrometers (pm), preferably 0.1 to 1,450 pm, more preferably 0.1 to 600 pm, ever more preferably 0.1 to 355 pm, still more preferably 0.1 to 200 pm or 0.1 to 50 pm, based on a maximum sieve size, and wherein the aromatic dianhydride curing agent is of formula (1)

wherein T is -0-, -S-, -SO2-, -SO-, -C _y H2 _y - wherein y is an integer from 2 to 5 or a halogenated derivative thereof, or -O-Z-O- wherein Z is an aromatic C6-24 monocyclic or polycyclic moiety optionally substituted with 1 to 6 Ci- ₈ alkyl groups, 1 to 8 halogen atoms, or a combination thereof.

[0004] Also provided is a method for the manufacture of a homogenous solution comprising the thermosetting epoxy composition, which includes combining the aromatic dianhydride curing agent and the epoxy resin composition under conditions effective to form the homogenous solution; preferably heating at 50 to 200°C, more preferably at 80 to 200°C, even more preferably at 100 to 200°C to dissolve the aromatic dianhydride curing agent to form the homogenous solution.

[0005] An article comprising a cured product of the thermosetting epoxy composition is also provided.

DETAILED DESCRIPTION

[0006] This disclosure relates to a thermosetting epoxy composition. The thermosetting epoxy composition includes an epoxy resin composition, an aromatic dianhydride curing agent, optionally a liquid monoanhydride curing agent, and optionally a curing catalyst. The inventors have discovered that an aromatic dianhydride, for example bisphenol-A dianhydride (BPA-DA), can be a useful curing agent for making high heat cured epoxy resins. The thermosetting epoxy composition including the aromatic dianhydride as an epoxy curing agent can provide a cured thermoset product, for example as a powder coating on a substrate, having good high heat resistance properties, such as a glass transition temperature of 230°C or greater.

[0007] Provided herein is a thermosetting epoxy composition including an epoxy resin composition, an aromatic dianhydride curing agent, optionally a liquid monoanhydride curing agent, and optionally a curing catalyst. The thermosetting epoxy composition after curing has a glass transition temperature of 120 to 320°C by DMA. The aromatic dianhydride curing agent has a maximum absolute particle size of less than 3,350 pm, based on a maximum sieve size. [0008] The stoichiometric ratio between the aromatic dianhydride curing agent and the epoxy resin composition is 0.1 : 1 to 2.0: 1, preferably 0.2: 1 to 1.6: 1, more preferably 0.5: 1 to 1.3:1, even more preferably 0.6: 1 to 1.2: 1, still more preferably 0.6: 1 to 1 : 1. The stoichiometric ratio is the molar ratio of total anhydride functionalities to the total epoxy functionalities in the thermosetting epoxy resin composition. The stoichiometric ratio is also referred to as the anhydride to epoxy (A/E) ratio.

[0009] The thermosetting epoxy composition includes 100 parts by weight (pbw) of the epoxy resin composition, based on the total parts by weight of the epoxy resin composition, the aromatic dianhydride curing agent, and optionally the a liquid monoanhydride curing agent. The epoxy resin composition can include one or more epoxy resins, such as bisphenol A epoxy resin, a triglycidyl-substituted epoxy resin, a tetraglycidyl-substituted epoxy resin, a bisphenol F epoxy resin, a phenol novolak epoxy resin, a cresol novolak epoxy resin, a cycloaliphatic diglycidyl ester epoxy resin, a cycloaliphatic epoxy resin comprising a ring epoxy group, an epoxy resin containing a spiro-ring, a hydantoin epoxy resin, or a combination thereof. For example, the epoxy resin is bisphenol-A diglycidyl ether (BPA-DGE). In some aspects, the epoxy resin composition can have a melting point of less than or equal to 25°C.

[0010] In some aspects, the epoxy resin composition may include one or more“high heat” epoxy compounds of formulas (I) to (IX):

wherein, in Formulas (I) to (IX), R ¹ and R ² at each occurrence are each independently an epoxide-containing functional group; R ^a and R ^b at each occurrence are each independently halogen, Ci- ₁₂ alkyl, C _2-12 alkenyl, C3-8 cycloalkyl, or Ci- ₁₂ alkoxy; p and q at each occurrence are each independently 0 to 4; R ¹³ at each occurrence is independently a halogen or a Ci- ₆ alkyl group; c at each occurrence is independently 0 to 4; R ¹⁴ at each occurrence is independently a Ci - ₆ alkyl, phenyl, or phenyl substituted with up to five halogens or Ci- ₆ alkyl groups; R ^g at each occurrence is independently Ci- ₁₂ alkyl or halogen, or two R ^g groups together with the carbon atoms to which they are attached form a four-, five, or six-membered cycloalkyl group; and t is 0 to 10.

[0011] In other aspects, the epoxy resin composition does not include a compound of formulas (I) to (IX). That is, the epoxy resin composition, and by extension the thermosetting epoxy composition, is free of the high heat epoxy compounds of formulas (I) to (IX). Preferably, the epoxy resin composition does not include a compound of formulas (I) to (IX).

[0012] The epoxide equivalent weight (EEW) of the epoxy resin composition is generally from 100 to 20,000 grams per equivalent (g/eq), preferably from 100 to 5,000 g/eq, more preferably from 100 to 1,000 g/eq. As used herein the terms“epoxide equivalent weight” refers to the number average molecular weight of the epoxide moiety divided by the average number of epoxide groups present in the molecule.

[0013] The thermosetting epoxy composition includes 30 to 200 parts by weight (pbw) of the aromatic dianhydride curing agent, based on the total parts by weight of the epoxy resin composition, the aromatic dianhydride curing agent, and optionally the a liquid monoanhydride curing agent. For example, the thermosetting epoxy composition can include 50 to 150 pbw, preferably 60 to 140 parts by weight, more preferably 80 to 120 pbw of the aromatic dianhydride curing agent. [0014] The aromatic dianhydride curing agent can be of the formula (1)

wherein r from 1 to 5 or a halogenated derivative thereof, or -O-Z-O- wherein Z is an aromatic C6-24 monocyclic or polycyclic moiety optionally substituted with 1 to 6 Ci- ₈ alkyl groups, 1 to 8 halogen atoms, or a combination thereof. In some aspects, the R ¹ is a monovalent Ci-13 organic group. In some aspects, T is -O- or a group of the formula -O-Z-O- wherein the divalent bonds of the -O- or the -O-Z-O- group are in the 3,3', 3,4', 4,3', or the 4,4' positions. In particular aspects, T is not -0-, -SO2-, or -SO-.

[0015] Exemplary groups Z include groups of formula (2)

wherein R ^a and R ^b are each independently the same or different, and are a halogen atom or a monovalent Ci- ₆ alkyl group, for example; p and q are each independently integers of 0 to 4; c is 0 to 4; and X ^a is a bridging group connecting the hydroxy-substituted aromatic groups, where the bridging group and the hydroxy substituent of each Ce arylene group are disposed ortho, meta, or para (specifically para) to each other on the Ce arylene group. The bridging group X ^a can be a single bond, -0-, -S-, -S(O)-, -S(0)2-, -C(O)-, or a Ci-i ₈ organic bridging group. The Ci-is organic bridging group can be cyclic or acyclic, aromatic or non-aromatic, and can further comprise heteroatoms such as halogens, oxygen, nitrogen, sulfur, silicon, or phosphorous. The Ci-18 organic group can be disposed such that the Ce arylene groups connected thereto are each connected to a common alkylidene carbon or to different carbons of the Ci-is organic bridging group. A specific example of a group Z is a divalent group of the formula (3a) or (3b)

wherein Q is -O-, -S-, -C(O)-, -SO2-, -SO-, -P(R ^a )(=0)- wherein R ^a is a Ci- ₈ alkyl or C6-12 aryl, or -C _y Tk _y - wherein y is an integer from 1 to 5 or a halogenated derivative thereof (including a perfluoroalkylene group). In some aspects, Q is 2,2-isopropylidene. In some aspects, T is -O-Z-O-, preferably wherein Z is derived from bisphenol A (i.e., Z is

2,2-(4-phenylene)isopropylidene). [0016] Exemplary aromatic dianhydride include 3,3-bis[4-(3,4- dicarboxyphenoxy)phenyl]propane dianhydride; 4,4'-bis(3,4-dicarboxyphenoxy)diphenyl ether dianhydride; 4,4'-bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride; 4,4'-bis(3,4- dicarboxyphenoxy)benzophenone dianhydride; 4,4'-bis(3,4-dicarboxyphenoxy)diphenyl sulfone dianhydride; 2,2-bis[4-(2,3-dicarboxyphenoxy)phenyl]propane dianhydride; 4,4'-bis(2,3- dicarboxyphenoxy)diphenyl ether dianhydride; 4,4'-bis(2,3-dicarboxyphenoxy)diphenyl sulfide dianhydride; 4,4'-bis(2,3-dicarboxyphenoxy)benzophenone dianhydride; 4,4'-bis(2,3- dicarboxyphenoxy)di phenyl sulfone dianhydride; 4-(2,3-dicarboxyphenoxy)-4'-(3,4- dicarboxyphenoxy)diphenyl-2, 2-propane dianhydride; 4-(2,3-dicarboxyphenoxy)-4'-(3,4- dicarboxyphenoxy)diphenyl ether dianhydride; 4-(2,3-dicarboxyphenoxy)-4'-(3,4- dicarboxyphenoxy)diphenyl sulfide dianhydride; 4-(2,3-dicarboxyphenoxy)-4'-(3,4- dicarboxyphenoxy)benzophenone dianhydride; and 4-(2,3-dicarboxyphenoxy)-4'-(3,4- dicarboxyphenoxy)diphenyl sulfone dianhydride. In particular aspects, the aromatic dianhydride curing agent is bisphenol-A dianhydride (BP AD A).

[0017] The aromatic dianhydride curing agent has a maximum absolute particle size of 0.1 to 3,350 micrometers (pm), based on a maximum sieve size. For example, the maximum absolute particle size can be 0.1 to 1,450 pm, preferably 0.1 to 600 pm, more preferably 0.1 to 355 pm, even more preferably 0.1 to 200 pm, still more preferably 0.1 to 50 pm, based on a maximum sieve size. As used herein,“maximum absolute particle size” is the maximum size of the largest particle and not an average particle size. In other words, the particles have a maximum particle size that is equal to or less than the maximum absolute particle size.

Alternatively, the maximum absolute particle size can be defined as less than or equal to 3,350 pm, less than or equal to 1,450 pm, less than or equal to 600 pm, less than or equal to 355 pm, less than or equal to 200 pm, or less than or equal to 50 pm, based on a maximum sieve size.

[0018] The maximum absolute particle size is based on the size of the sieve(s) used for filtration of the particles. The sieve can be used to exclude particular particles that have a size that is greater than or less than a certain particle size (sieve size). In some aspects, two or more sieves having different sizes can be used to provide the aromatic dianhydride curing agent having a maximum absolute particle size that is within a range and based on sieve size, such as from 600 to 1450 pm, based on sieve size. In this example, a first sieve (or the maximum sieve size) is used to remove particles having a particle size that exceeds 1450 pm, and the particles are subsequently filtered through a second sieve that passes particles having a particle size that is less than 600 mih. The resulting particles have a maximum absolute particle size from 600 to 1450 pm, based on sieve size.

[0019] The aromatic dianhydride curing agent can be soluble in the epoxy resin composition. The term“soluble in the epoxy resin composition” means that there is a temperature range where a combination of the aromatic dianhydride curing agent and the epoxy resin composition can be combined to form a homogeneous phase or a homogenous solution. As used herein,“forming a homogeneous phase” means creating a state where there is no visible separation between the components. The homogeneous phase can be formed in a certain temperature range without regard to any separation that may occur outside of that temperature range, for example, at room temperature. For example, a combination of the aromatic dianhydride curing agent and the epoxy resin composition can be stirred, heated, or heated under stirring to form a homogeneous phase. The solubility can be enhanced by the use of the optional liquid monoanhydride curing agent, a solvent, or a combination thereof, or the aromatic dianhydride curing agent can be soluble in the epoxy resin composition without a solvent or the optional liquid monoanhydride curing agent.

[0020] In some aspects, the aromatic dianhydride curing agent can be soluble in the epoxy resin composition at a temperature from 50 to 200°C. For example, the aromatic dianhydride curing agent can be soluble in the epoxy resin composition from 80 to 200°C, more preferably from 120 to 200°C, even more preferably from 160 to 200°C. The solubility of the aromatic dianhydride in the epoxy resin composition at a given temperature can also vary based on the presence of other components such as liquid monoanhydrides, solvents, or the like.

[0021] In some aspects, the aromatic dianhydride curing agent can be soluble in the epoxy resin composition after an amount of time at a temperature. For example, the aromatic dianhydride curing agent can be soluble in the epoxy resin composition in less than 35 minutes (min), preferably less than 25 min, more preferably less than 20 min, even more preferably less than 10 min upon heating at 160°C. As used herein,“soluble in the epoxy resin composition” means the formation of a homogenous solution, for example a substantially homogenous solution. The substantially homogenous solution can be substantially clear.

[0022] According to another aspect, provided is a substantially homogenous solution comprising or derived from the thermosetting epoxy composition. In an aspect, the substantially homogenous solution can include greater than 0 pbw of aromatic dianhydride particles (e.g., includes one or more particles) having the maximum absolute particle size.

[0023] The amount of time to form a substantially homogenous solution can vary based on the maximum absolute particle size and the temperature. For example, a substantially homogenous solution can be formed at 160°C in 16 to 18 min when the absolute maximum particle size is 1450 to 3350 pm, in 13 to 15 min when the maximum particle size is 600 to 1450 pm, in 11 to 13 minutes when the maximum particle size is 355 to 600 pm, in 8 to 10 min when the particle size is 200 to 355 pm, or in 6 to 8 min when the particle size is less than 200 pm.

[0024] The aromatic dianhydride curing agent can be soluble in the epoxy resin composition without the inclusion of any additives or solvents to improve the solubility of the dianhydride. In an aspect, the thermosetting epoxy composition is substantially free of solvent or reactive diluents. Reactive diluents can include, for example, liquid monoanhydrides or other compounds. In a particular aspect, the thermosetting epoxy composition is free of solvent. The term“substantially free of solvent” means that the thermosetting epoxy composition contains less than 500 parts per million (ppm) by weight of solvent. A“solvent free” thermosetting epoxy composition can have greater than 0 to 450 ppm by weight, preferably greater than 0 to 300 ppm by weight, more preferably greater than 0 to 200 ppm by weight, even more preferably greater than 0 to 100 ppm by weight of solvent, based on the total weight of the thermosetting epoxy composition.

[0025] The thermosetting epoxy composition optionally includes an effective amount of curing catalyst. In an aspect, the thermosetting epoxy composition can include 0.1 to 5 weight percent (wt%) of a curing catalyst, based on the total weight of the composition. For example, the thermosetting epoxy composition can include 0.4 to 4 wt%, preferably 0.6 to 3 wt%, more preferably 0.7 to 2 wt% of the curing catalyst, based on the total weight of the composition. The term“curing catalyst” as used herein encompasses compounds whose roles in curing epoxy resins are variously described as those of a hardener, a hardening accelerator, a curing accelerator, a curing catalyst, and a curing co-catalyst, among others. Exemplary curing catalysts can include, for example, amines, dicyandiamide, polyamides, amidoamines, Mannich bases, anhydrides, phenol-formaldehyde resins, carboxylic acid functional polyesters, polysulfides, polymercaptans, isocyanates, cyanate esters, and combinations thereof.

[0026] The curing catalyst can be a heterocyclic curing catalyst. Heterocyclic curing catalysts include benzotriazoles; triazines; piperazines such as aminoethylpiperazine, N-(3- aminopropyl)piperazine, or the like; imidazoles such as 1-methylimidazole, 2-methylimidazole, 3-methyl imidazole, 4-methylimidazole, 5-methylimidazole, 1-ethylimidazole, 2-ethylimidazole, 3-ethylimidazole, 4-ethylimidazole, 5-ethylimidazole, 1-n-propylimidazole, 2-n- propylimidazole, 1-isopropylimidazole, 2-isopropylimidazole, 1-n-butylimidazole, 2-n- butylimidazole, 1-isobutylimidazole, 2-isobutylimidazole, 2-undecyl-lH-imidazole, 2- heptadecyl-lH-imidazole, 1,2-dimethylimidazole, 1,3-dimethylimidazole, 2,4- dimethylimidazole, 2-ethyl-4-methylimidazole, 1-phenylimidazole, 2-phenyl-lH-imidazole, 4- methyl-2-phenyl-lH-imidazole, 2-phenyl-4-methylimidazole, 1 -benzyl-2 -methylimidazole, 1- benzyl-2-phenylimidazole, 1 -cyanoethyl-2 -methylimidazole, 1 -cyanoethyl-2-ethyl-4- methylimidazole, 1 -cyanoethyl-2 -undecylimidazole, l-cyanoethyl-2-phenylimidazole, 2-phenyl- 4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 1 -cyanoethyl-2 - phenyl-4, 5-di(2-cyanoethoxy)methylimidazole; cyclic amidine such as 4- diazabicyclo(2,2,2)octane (DABCO), diazabicycloundecene (DBU), 2-phenyl imidazoline, or the like; N,N-dimethylaminopyridine (DMAP); sulfamidate; or a combination thereof. In a particular aspect, the thermosetting epoxy composition does not include a heterocyclic curing catalyst.

[0027] The curing catalyst can be an amine curing catalyst. Amine curing catalysts include isophoronediamine, triethylenetetraamine, diethylenetriamine, 1,2- and

1.3-diaminopropane, 2,2-dimethylpropylenediamine, 1,4-diaminobutane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,12-diaminododecane, 4- azaheptamethylenediamine, N,N’-bis(3-aminopropyl)butane-l, 4-diamine, dicyanamide, diamide diphenylmethane, diamide diphenylsulfonic acid (amine adduct), 4,4’-methylenedi aniline, di ethy It oluenedi amine, m-phenylenediamine, p-phenylenediamine, melamine formaldehyde resins, urea formaldehyde resins, tetraethylenepentamine, 3-diethylaminopropylamine,

3,3’-iminobispropylamine, 2,4-bis(p-aminobenzyl)aniline, tetraethylenepentamine,

3-diethylaminopropylamine, 2,2,4- and 2,4,4- trimethylhexamethylenediamine, 1,2- and 1,3- diaminocyclohexane, l,4-diamino-3,6-diethylcyclohexane, l,2-diamino-4-ethylcyclohexane,

1.4-diamino-3,6-diethylcyclohexane, l-cyclohexyl-3,4-diminocyclohexane,

4,4’-diaminondicyclohexylmethane, 4,4’-diaminodicyclohexylpropane, 2,2-bis(4- aminocyclohexyl)propane, 3,3’ -dimethyl-4, 4’-diaminodicyclohexylmethane,

3-amino-l-cyclohexaneaminopropane, 1,3- and l,4-bis(aminomethyl)cyclohexane, m- and p- xylylenediamine, diethyl toluene diamines, or a combination thereof. The amine compound can be a tertiary amine hardening accelerator. The tertiary amine curing catalyst can be

triethylamine, tributylamine, dimethylaniline, diethylaniline, benzyldimethylamine (BDMA), a-methylbenzyldimethylamine, A', A -di methyl a i noethanol , A', A-di m ethyl am i nocresol , tri(A( A- dimethylaminomethyl)phenol, or a combination thereof. Amine curing catalysts also include acid-base complexes such as a boron trifluoride-trialkylamine complex.

[0028] The curing catalyst can be a phenolic curing catalyst. Exemplary phenols include novolac type phenol resins, resole type phenol resins, aralkyl type phenol resins, dicyclopentadiene type phenol resins, terpene modified phenol resins, biphenyl type phenol resins, bisphenols, triphenylmethane type phenol resins, or a combination thereof.

[0029] The curing catalyst can be a latent cationic cure catalyst such as diaryliodonium salts, phosphonic acid esters, sulfonic acid esters, carboxylic acid esters, phosphonic ylides, triarylsulfonium salts, benzylsulfonium salts, aryldiazonium salts, benzylpyridinium salts, benzylammonium salts, isoxazolium salts, or a combination thereof. The diaryliodonium salt can have the structure [(R ¹⁰ )(R ^U )I] ⁺ X , wherein R ¹⁰ and R ¹¹ are each independently a C6-C14 monovalent aromatic hydrocarbon radical, optionally substituted with from 1 to 4 monovalent radicals selected from C1-C20 alkyl, C1-C20 alkoxy, nitro, and chloro; and wherein X is an anion. The curing catalyst can have the structure [(R ¹⁰ )(R ^U )I] ⁺ SbF ₆ , wherein R ¹⁰ and R ¹¹ are each independently a C6-C14 monovalent aromatic hydrocarbon radical, optionally substituted with from 1 to 4 monovalent radicals selected from C1-C20 alkyl, C1-C20 alkoxy, nitro, and chloro.

For example, curing catalyst can be a latent cationic cure catalyst comprising 4-octyloxyphenyl phenyl iodonium hexafluoroantimonate. The latent cationic cure catalysts also include metal salts including copper (II), tin (II), and aluminum (III) salts of an aliphatic or aromatic carboxylic acid, such as acetate, stearate, gluconate, citrate, benzoate, or combinations thereof; copper (II), tin (II), or aluminum (III) b-diketonates such as acetyl acetonate. In particular aspects, the thermosetting epoxy composition does not include a latent cationic cure catalyst

[0030] The thermosetting epoxy composition can optionally include a liquid

monoanhydride curing agent. Exemplary liquid monoanhydride curing agents include norbornene dicarboxylic anhydrides (e.g., methyl-5-norbornene-2,3-dicarboxylic anhydride, or the like), hexahydrophthalic anhydrides (e.g., 1,2-cyclohexanedicarboxylic anhydride, 4- methylhexahydrophthalic anhydride, 5-methylhexahydrophthalic anhydride, or the like), tetrahydrophthalic anhydrides (e.g., 1,2,3,6-tetrahydrophthalic anhydride, l,2,3,6-tetrahydro-4- methylphthalic anhydride, or the like), phthalic anhydrides (e.g., 3-fluorophthalic anhydride), maleic anhydrides (e.g., 2-methylmaleic anhydride, dimethylmaleic anhydride, or the like), succinic anhydrides (e.g., dodecenylsuccinic anhydride, hexadecenylsuccinic anhydride, or the like), trimellitic anhydride, perfluoroglutaric anhydride, or the like. When used, the liquid monoanhydride curing agent can be present in an amount of 10 to 100 parts by weight, preferably 20 to 100 parts by weight, more preferably 20 to 80 parts by weight, based on the total parts by weight of the epoxy resin composition, the aromatic dianhydride curing agent, and the liquid monoanhydride curing agent. As used herein,“liquid monoanhydride” refers to a monoanhydride compound that is a liquid at a temperature from 15 to 45°C, preferably 20 to 40°C, more preferably 20 to 30°C, even more preferably 20 to 25°C at atmospheric pressure. [0031] The liquid monoanhydride curing agent can act as a flux to help solubilize the aromatic dianhydride in the epoxy resin composition, thereby decreasing the dissolution time. For example, when the liquid monoanhydride curing agent is used, a homogenous solution can be formed at 120°C in 28 to 36 min when the maximum particle size is 1450 to 3350 pm, in 21 to 27 min when the maximum particle size is 600 to 1450 pm, in 17 to 21 min when the maximum particle size is 355 to 600 pm, in 12 to 17 min when the particle size is 200 to 355 pm, or in 6 to 12 min when the particle size is less than 200 pm.

[0032] In some aspects, the thermosetting epoxy composition is substantially free of a monoanhydride such as a liquid monoanhydride curing agent, a monoanhydride compound, or a combination thereof. The term“substantially free of a monoanhydride” means that the thermosetting epoxy composition contains less than 500 ppm by weight of monoanhydride. For example, a“monoanhydride free” thermosetting epoxy composition can have less than 450 ppm by weight, preferably less than 300 ppm by weight, more preferably less than 200 ppm by weight, even more preferably less than 100 ppm by weight of monoanhydride, based on the total weight of the thermosetting epoxy composition.

[0033] The curable epoxy composition can further include an additive composition. The additive composition can include an antioxidant, a heat stabilizer, a light stabilizer, a ultraviolet light stabilizer, a ultraviolet light-absorbing compound, a near infrared light-absorbing compound, an infrared light-absorbing compound, a plasticizer, a lubricant, a release agent, an antistatic agent, a surfactant, an anti-fog agent, an antimicrobial agent, colorants such as pigments and dyes, a high temperature pigment, a surface effect additive, a radiation stabilizer, a flame retardant, flame retardant synergists such as antimony pentoxide, an anti-drip agent, a corrosion inhibiting agent, a defoaming or degassing agent, diluents, an adhesion promoter, fillers and reinforcing agents, a flow control agent, a stress-relief additive, a coating additive, a polymer different from the thermoset (epoxy resin) polymer, or a combination thereof. In a preferred aspect, the curable epoxy composition is substantially free of any polymer other than the thermoset (epoxy resin) polymer. The amount of the optional additives used can range generally from 0 to 99 wt%, preferably 0.001 to 95 wt%, more preferably 0.01 to 10 wt%, even more preferably 0.05 to 5 wt%, based on total weight of the thermosetting epoxy composition.

[0034] The thermosetting epoxy composition can be manufactured by combining the epoxy resin composition, the aromatic dianhydride curing agent, optionally the curing catalyst, and optionally the liquid monoanhydride curing agent at a temperature of 50 to 200°C, preferably 80 to 200°C, more preferably 100 to 200°C to provide the thermosetting epoxy composition. The method for the manufacture of a substantially homogenous solution comprising the thermosetting epoxy composition can include combining the aromatic dianhydride curing agent and the epoxy resin composition under conditions effective to form the homogenous solution, preferably by heating at 50 to 200°C, preferably 80 to 200°C, more preferably 100 to 200°C to form the homogenous solution comprising the thermosetting epoxy composition. The homogenous solution can be derived from the aromatic dianhydride curing agent having a maximum absolute particle size of 0.1 to 3,350 pm, preferably 0.1 to 1,450 pm, more preferably 0.1 to 600 pm, ever more preferably 0.1 to 355 pm, still more preferably 0.1 to 200 pm or 0.1 to 50 pm, based on sieve size.

[0035] The method can include combining the aromatic dianhydride curing agent, the liquid monoanhydride curing agent, and the epoxy resin composition under conditions effective to form the homogenous solution comprising the thermosetting epoxy composition, preferably by heating at 50 to 200°C, preferably 80 to 200°C, more preferably 100 to 200°C. For example, the liquid monoanhydride curing agent and the epoxy resin composition can be combined to form a precursor homogenous solution, and then the precursor homogenous solution and the aromatic dianhydride curing agent can be combined at 50 to 200°C, preferably 80 to 200°C, more preferably 100 to 200°C to form the substantially homogenous solution.

[0036] In an aspect, the method can include contacting the aromatic dianhydride curing agent and the liquid monoanhydride curing agent under conditions effective to form a precursor homogenous solution; and combining the precursor homogenous solution and the epoxy resin composition under conditions effective to form the substantially homogenous solution. For example, the aromatic dianhydride curing agent and the liquid monoanhydride curing agent can be combined at 50 to 200°C, preferably 80 to 200°C, more preferably 100 to 200°C to form a precursor homogenous solution. The precursor homogenous solution and the epoxy resin composition can then be combined to form the substantially homogenous solution, for example at a temperature of 25 to 200°C, preferably 40 to 200°C, more preferably 60 to 200°C.

[0037] In another aspect, the method can include contacting the aromatic dianhydride curing agent and a solvent under conditions effective to form a precursor homogenous solution; and combining the precursor homogenous solution and the epoxy resin composition under conditions effective to form the homogenous solution. For example, the aromatic dianhydride curing agent and the solvent can be combined at 25 to 120°C, preferably 40 to 100°C, more preferably 50 to 180°C to form the precursor homogenous solution. The precursor homogenous solution and the epoxy resin composition can then be combined at 25 to 200°C, preferably 40 to 200°C, more preferably 60 to 200°C to form the substantially homogenous solution. [0038] Exemplary solvents include C _3-8 ketones, C _4-8 Af./V-dialkylamides, C _4-16 dialkyl ethers, Ce-u aromatic hydrocarbons, C _3-6 alkyl alkanoates, C _2-6 alkyl nitriles, C _2-6 dialkyl sulfoxides, or a combination thereof. Examples of C _3-8 ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, and combinations thereof. Examples of C _4-8 A ^f , A'-dialkylamides include dimethylformamide, dimethylacetamide, A-m ethyl -2-pyrrol i done, and combinations thereof. Examples of C _4-16 dialkyl ethers include tetrahydrofuran, dioxane, and combinations thereof. The C _4-16 dialkyl ether can optionally further include one or more ether oxygen atoms within the alkyl groups and one or more hydroxy substituents on the alkyl groups, for example the C _4-16 dialkyl ether can be ethylene glycol monomethyl ether. The aromatic hydrocarbon solvent can be an ethylenically unsaturated solvent. Examples of C _6-12 aromatic hydrocarbons include benzene, toluene, xylenes, styrene, divinylbenzenes, and combinations thereof.

Examples of C3-6 alkyl alkanoates include methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, and combinations thereof. Examples of C2-6 alkyl cyanides include acetonitrile, propionitrile, butyronitrile, and combinations thereof. Examples of C2-6 dialkyl sulfoxides include dimethyl sulfoxide, methyl ethyl sulfoxide, diethyl sulfoxide, and combinations thereof. In some aspects, the solvent comprises acetone, methyl ethyl ketone, /V-methyl-2-pyrrolidone, toluene, or a combination thereof. In still other aspects, the solvent can be a halogenated solvent such as methylene chloride, chloroform, 1,1,1-trichloroethane, chlorobenzene, or the like. In a particular aspect, the solvent comprises methyl ethyl ketone (MEK) and dimethylformamide (DMF).

[0039] When used, the curing catalyst can be added to the other components at any time. For example, a curing catalyst can be added to the substantially homogenous solution, the precursor homogenous solution, the liquid monoanhydride curing agent, or the solvent.

[0040] There is no particular limitation on the method by which the composition can be cured. The thermosetting epoxy composition can, for example, be cured thermally or by using irradiation techniques, including UV irradiation and electron beam irradiation. Heat curing can be at 80 to 300°C, and preferably 120 to 250°C. The heat curing can be for 1 min to 10 hours (h), for example 1 min to 6 h, preferably 4 min to 4 h, more preferably 15 min to 4 h. Such curing may be staged to produce a partially cured and often tack-free resin, which then is fully cured by heating for longer periods or temperatures within the aforementioned ranges.

[0041] The cured product of the thermosetting epoxy composition after curing has a glass transition temperature (T _g ) of 120 to 320°C, preferably 160 to 320°C, more preferably 180 to 320°C, even more preferably 200 to 320°C, still more preferably 250 to 320°C, as determined by dynamic mechanical analysis (DMA). [0042] The thermosetting epoxy composition or cured product thereof can be used in a variety of applications and articles, including any applications where conventional epoxides are currently used. Exemplary uses and applications include coatings such as protective coatings, sealants, weather resistant coatings, scratch resistant coatings, and electrical insulative coatings; adhesives; binders; glues; composite materials such as those using carbon fiber and fiberglass reinforcements. When used as a coating, the compounds and compositions can be deposited on a surface of a variety of underlying substrates. For example, the compositions can be deposited on a surface of metals, plastics, glass, fiber sizings, ceramics, stone, wood, or any combination thereof. The disclosed compositions can be used as a coating on a surface of a metal container, such as those commonly used for packaging and containment in the paint and surface covering industries. In some instances, the coated metal is aluminum or steel.

[0043] For example, articles can be manufactured by shaping the thermosetting epoxy composition; and curing the thermosetting epoxy composition as provided herein. Exemplary methods for shaping and/or curing the thermosetting epoxy composition include compression molding, injection molding, transfer molding, pultrusion, resin casting, or a combination thereof. In a particular aspect, the shaping and curing comprises disposing the thermosetting epoxy composition into a mold, and curing the composition at 150°C to 250°C in the mold.

[0044] Articles that can be prepared using the disclosed thermosetting epoxy

compositions include, for example, electrical components and computer components. Articles that can be prepared can include, for example, automotive, aircraft, and watercraft exterior and interior components. In some aspects, the article is in the form of in the form of a composite, a foam, a fiber, a layer, a coating, an encapsulant, an adhesive, a sealant, a component, a prepreg, a casing, or a combination thereof. The compositions are used for the production of composite materials for use in the aerospace industry. The compositions can be used in forming

composites used for printed circuit boards. Methods of forming composites for use in printed circuit boards are known in the art and are described in, for example, U.S. Pat. No. 5,622,588 to Weber, U.S. Pat. No. 5,582,872 to Prinz, and U.S. Pat. No. 7,655,278 to Braidwood.

[0045] Additional applications include, for example, acid bath containers; neutralization tanks; aircraft components; bridge beams; bridge deckings; electrolytic cells; exhaust stacks; scrubbers; sporting equipment; stair cases; walkways; automobile exterior panels such as hoods and trunk lids; floor pans; air scoops; pipes and ducts, including heater ducts; industrial fans, fan housings, and blowers; industrial mixers; boat hulls and decks; marine terminal fenders; tiles and coatings; building panels; business machine housings; trays, including cable trays; concrete modifiers; dishwasher and refrigerator parts; electrical encapsulants; electrical panels; tanks, including electrorefining tanks, water softener tanks, fuel tanks, and various filament-wound tanks and tank linings; furniture; garage doors; gratings; protective body gear; luggage; outdoor motor vehicles; pressure tanks; printed circuit boards; optical waveguides; radomes; railings; railroad parts such as tank cars; hopper car covers; car doors; truck bed liners; satellite dishes; signs; solar energy panels; telephone switchgear housings; tractor parts; transformer covers; truck parts such as fenders, hoods, bodies, cabs, and beds; insulation for rotating machines including ground insulation, turn insulation, and phase separation insulation; commutators; core insulation and cords and lacing tape; drive shaft couplings; propeller blades; missile

components; rocket motor cases; wing sections; sucker rods; fuselage sections; wing skins and flarings; engine narcelles; cargo doors; tennis racquets; golf club shafts; fishing rods; skis and ski poles; bicycle parts; transverse leaf springs; pumps, such as automotive smog pumps;

electrical components, embedding, and tooling, such as electrical cable joints; wire windings and densely packed multi-element assemblies; sealing of electromechanical devices; battery cases; resistors; fuses and thermal cut-off devices; coatings for printed wiring boards; casting items such as capacitors, transformers, crankcase heaters; small molded electronic parts including coils, capacitors, resistors, and semiconductors; as a replacement for steel in chemical processing, pulp and paper, power generation, and wastewater treatment; scrubbing towers; pultruded parts for structural applications, including structural members, gratings, and safety rails; swimming pools, swimming pool slides, hot-tubs, and saunas; drive shafts for under the hood applications; dry toner resins for copying machines; marine tooling and composites; heat shields; submarine hulls; prototype generation; development of experimental models; laminated trim; drilling fixtures; bonding jigs; inspection fixtures; industrial metal forming dies; aircraft stretch block and hammer forms; vacuum molding tools; flooring, including flooring for production and assembly areas, clean rooms, machine shops, control rooms, laboratories, parking garages, freezers, coolers, and outdoor loading docks; electrically conductive compositions for antistatic applications; for decorative flooring; expansion joints for bridges; injectable mortars for patch and repair of cracks in structural concrete; grouting for tile;

machinery rails; metal dowels; bolts and posts; repair of oil and fuel storage tanks, and numerous other applications.

[0046] Methods of forming a composite can include impregnating a reinforcing structure with thermosetting epoxy composition; partially curing the composition to form a prepreg; and laminating a plurality of prepregs. Reinforcing structures suitable for prepreg formation are known in the art. Suitable reinforcing structures include reinforcing fabrics. Reinforcing fabrics include those having complex architectures, including two or three-dimensional braided, knitted, woven, and filament wound. The thermosetting epoxy composition is capable of permeating such complex reinforcing structures. The reinforcing structure can comprise fibers of materials known for the reinforcement of plastics material, for example fibers of carbon, glass, metal, and aromatic polyamides. Suitable reinforcing structures are described, for example, in Anonymous (Hexcel Corporation),“Prepreg Technology”, March 2005, Publication No. FGU 017b;

Anonymous (Hexcel Corporation),“Advanced Fibre Reinforced Matrix Products for Direct Processes”, June 2005, Publication No. ITA 272; and Bob Griffiths,“Farnborough Airshow Report 2006”, CompositesWorld.com, September 2006. The weight and thickness of the reinforcing structure are chosen according to the intended use of the composite using criteria well known to those skilled in the production of fiber reinforced resin composites. The reinforced structure can contain various finishes suitable for the epoxy matrix.

[0047] The method of forming the composite comprises partially curing the

thermosetting epoxy composition after the reinforcing structure has been impregnated with it. Partial curing is curing sufficient to reduce or eliminate the wetness and tackiness of the thermosetting epoxy composition but not so great as to fully cure the composition. The resin in a prepreg is customarily in the partially cured state, and those skilled in the thermoset arts, and particularly the reinforced composite arts, understand the concept of partial curing and how to determine conditions to partially cure a resin without undue experimentation. References herein to properties of the“cured composition” refer to a composition that is substantially fully cured. For example, the resin in a laminate formed from prepregs is typically substantially fully cured. One skilled in the thermoset arts can determine whether a sample is partially cured or substantially fully cured without undue experimentation. For example, one can analyze a sample by differential scanning calorimetry to look for an exotherm indicative of additional curing occurring during the analysis. A sample that is partially cured will exhibit an exotherm. A sample that is substantially fully cured will exhibit little or no exotherm. Partial curing can be effected by subjecting the curable-composition-impregnated reinforcing structure to a temperature of 133 to 140°C for 4 to 10 minutes.

[0048] Commercial-scale methods of forming composites are known in the art, and the thermosetting epoxy compositions described herein are readily adaptable to existing processes and equipment. For example, prepregs are often produced on treaters. The main components of a treater include feeder rollers, a resin impregnation tank, a treater oven, and receiver rollers.

The reinforcing structure (E-glass, for example) is usually rolled into a large spool. The spool is then put on the feeder rollers that turn and slowly roll out the reinforcing structure. The reinforcing structure then moves through the resin impregnation tank, which contains the thermosetting epoxy composition. The varnish impregnates the reinforcing structure. After emerging from the tank, the coated reinforcing structure moves upward through the vertical treater oven, which is typically at a temperature of 175 to 200°C, and the solvent of the varnish is boiled away. The resin begins to polymerize at this time. When the composite comes out of the tower it is sufficiently cured so that the web is not wet or tacky. The cure process, however, is stopped short of completion so that additional curing can occur when laminate is made. The web then rolls the prepreg onto a receiver roll.

[0049] While the above-described curing methods rely on thermal curing, it is also possible to effect curing with radiation, including ultraviolet light and electron beams.

Combinations of thermal curing and radiation curing can also be used.

[0050] The method for the manufacture of the article can include shaping the

thermosetting epoxy composition and curing. Shaping and curing can be by compression molding, injection molding, transfer molding, pultrusion, resin casting, or a combination thereof. Processes useful for preparing the articles and materials include those known to the art for the processing of thermosetting resins, as described in, for example, Engineered Materials

Handbook, Volume 1, Composites, ASM International Metals Park, Ohio, copyright 1987 Cyril A. Dostal Senior Ed, pp. 105-168 and 497-533, and“Polyesters and Their Applications” by Bjorksten Research Laboratories, Johan Bjorksten (pres.) Henry Tovey (Ch. Lit. Ass.), Betty Harker (Ad. Ass.), James Henning (Ad. Ass.), Reinhold Publishing Corporation, New York, 1956. Processing techniques include resin transfer molding; sheet molding; bulk molding;

pultrusion; injection molding, including reaction injection molding (RIM); atmospheric pressure molding (APM); casting, including centrifugal and static casting open mold casting; lamination including wet or dry lay-up and spray lay up; also included are contact molding, including cylindrical contact molding; compression molding; including vacuum assisted resin transfer molding and chemically assisted resin transfer molding; matched tool molding; autoclave curing; thermal curing in air; vacuum bagging; pultrusion; Seeman's Composite Resin Infusion

Manufacturing Processing (SCRIMP); open molding, continuous combination of resin and glass; and filament winding, including cylindrical filament winding. In certain aspects, an article can be prepared via a resin transfer molding process.

[0051] This disclosure is further illustrated by the following examples, which are non limiting.

EXAMPLES

[0052] Materials used in the examples are described in Table 1.

Table 1.

[0053] Glass transition temperature (T _g ) was measured on a RDA III dynamic mechanical analyzer from TA Instruments. The samples with 40 mm x 4 mm x 3 mm dimensions were heated in the range of -40°C to 300°C at a heating rate of 3°C/min and a frequency of 6.283 radians per second. T _g was determined as the temperature of the tan d maximum.

[0054] Examples 1 to 5. BP AD A flakes were ground into a fine powder by Jet-milling and then sieved to a maximum particle size range (in micrometers, pm) as provided in Table 2. The resulting BP ADA powder (28 wt%) was added to MTHPA to obtain a slurry (total weight of 25 g) at 23°C. The slurry was held in an oil bath at 120°C and stirred well with a magnetic stirrer. The amount of time for the slurry to form a clear solution was reported as dissolution time in minutes (min).

[0055] Comparative Example 1. BP ADA flakes (28 wt%) were added to MTHPA to obtain a slurry (total weight of 25 g) at 23°C. The slurry was held in an oil bath set at 120°C and stirred well with a magnetic stirrer. The amount of time for the slurry to form a clear solution was reported as dissolution time (min).

[0056] Table 2 shows the components, particle sizes, and dissolution times for Examples 1 to 5 and Comparative Example 1.

Table 2.

[0057] Examples 6 to 10. BPADA flakes were ground into a fine powder by Jet-milling and then sieved to a maximum particle size range (in micrometers, pm) as provided in Table 3. The resulting BPADA powder (19 wt%) was added to BPA-DGE to obtain a slurry (total weight of 37 g) at 23°C. The slurry was held in an oil bath at 160°C and stirred well with a magnetic stirrer. The amount of time for the slurry to form a clear solution was reported as dissolution time in minutes (min). [0058] Comparative Example 2. BP ADA flakes (19 wt%) were added to BPA-DGE to obtain a slurry (total weight of 37 g) at 23°C. The slurry was held in an oil bath set at 160°C and stirred well with a magnetic stirrer. The amount of time for the slurry to form a clear solution was reported as dissolution time (min).

[0059] Table 3 shows the components, particle sizes, and dissolution times for Examples 6 to 10 and Comparative Example 2.

Table 3.

[0060] As shown in Tables 2 and 3he rate of dissolution for BP ADA powders into the liquid monoanhydride flux MTHPA or the epoxy resin BPA-DGE was faster that for BP ADA flakes. It was discovered that the particle size of BP ADA powder influenced dissolution time into both MTHPA and BPA-DGE. Among these powdered samples of BP AD A, dissolution time decreased based on maximum particle size range of BP AD A, with faster dissolution achieved for smaller particle sizes.

[0061] Examples 11 to 15. BP AD A flakes were ground into a fine powder by

mechanical grinding and then sieved to specific maximum particle size range (pm) as provided in Table 4. The resulting BP ADA powder (13 wt%) was added to a mixture of MTHPA and BPA-DGE to obtain a slurry (total weight of 60 g) at 23°C. The anhydride to epoxy ratio (A/E ratio) is 0.8. The slurry was held in an oil bath at 120°C and stirred well with a magnetic stirrer. The amount of time for the slurry to form a clear solution was reported as dissolution time (min).

[0062] Comparative Example 3. BPADA flakes (13 wt%) were added to a mixture of MTHPA and BPAD-DGE to obtain a slurry (total weight of 60 g) at 23°C. The anhydride to epoxy ratio (A/E ratio) is 0.8. The slurry was held in an oil bath set at 120°C and stirred well with a magnetic stirrer. The amount of time for the slurry to form a clear solution was reported as dissolution time (min).

[0063] Table 4 shows the components, average particle sizes, and dissolution times for Examples 11 to 15 and Comparative Example 3.

Table 4.

[0064] BP ADA was added to the combination of epoxy resin BPA-DGE and MTHPA flux to obtain a clear solution of a curable formulation. The maximum particle size of the solid aromatic dianhydride BP ADA powder influenced dissolution time in the mixture of BPA-DGE and MTHPA. As shown in Table 4, BPADA flakes of Comparative Example 3 take longer to dissolve as compared to the powder forms of BPADA of Examples 11 to 15. Among these powdered samples, dissolution time decreased based on maximum particle size of BPADA, with faster dissolution achieved for smaller particle sizes.

[0065] These results show that compared to BPADA flakes, BPADA powders are easier to process due to faster dissolution in the liquid epoxy formulations.

[0066] Comparative Example 4A. BTDA flakes (19 wt%) were added to MTHPA to obtain a slurry (total weight of 25 g) at 23°C. The slurry was held in an oil bath set at 120°C and stirred well with a magnetic stirrer. The amount of time for the slurry to form a clear solution was reported as dissolution time (min).

[0067] Comparative Example 4B. BTDA flakes were ground into a fine powder by Jet milling and then sieved to a maximum particle size range (in micrometers, pm) as provided in Table 5. The resulting BTDA powder (19 wt%) was added to MTHPA to obtain a slurry (total weight of 25 g) at 23°C. The slurry was held in an oil bath at 120°C and stirred well with a magnetic stirrer. The amount of time for the slurry to form a clear solution was reported as dissolution time (min).

[0068] Table 5 shows the particle size and dissolution time for Comparative Examples 4 A and 4B.

Table 5.

[0069] Comparative Example 5 A. BTDA flakes (13 wt%) were added to BPA-DGE to obtain a slurry (total weight of 35 g) at 23°C. The slurry was held in an oil bath set at 160°C and stirred well with a magnetic stirrer. The amount of time for the slurry to form a clear solution was reported as dissolution time (min). [0070] Comparative Example 5B. BTDA flakes were ground into a fine powder by Jet milling and then sieved to a maximum particle size range (in micrometers, pm) as provided in Table 3. The resulting BTDA powder (13 wt%) was added to BPA-DGE to obtain a slurry (total weight of 35 g) at 23°C. The slurry was held in an oil bath at 160°C and stirred well with a magnetic stirrer. The amount of time for the slurry to form a clear solution was reported as dissolution time in minutes (min).

[0071] Table 6 shows the particle size and dissolution time for Comparative Examples 5 A and 5B.

Table 6.

[0072] Comparative Example 6A. BTDA flakes (8.5 wt%) were added to a mixture of MTHPA and BPAD-DGE to obtain a slurry (total weight of 50 g) at 23°C. The anhydride to epoxy ratio (A/E ratio) is 0.8. The slurry was held in an oil bath set at 120°C and stirred well with a magnetic stirrer. The amount of time for the slurry to form a clear solution was reported as dissolution time (min.).

[0073] Comparative Example 6B. BTDA flakes were ground into a fine powder by mechanical grinding and then sieved to specific maximum particle size range (pm) as provided in Table 4. The resulting BTDA powder (8.5 wt%) was added to a mixture of MTHPA and BPA-DGE to obtain a slurry (total weight of 50 g) at 23°C. The anhydride to epoxy ratio (A/E ratio) is 0.8. The slurry was held in an oil bath at 120°C and stirred well with a magnetic stirrer. The amount of time for the slurry to form a clear solution was reported as dissolution time (min).

[0074] Table 7 shows the particle size and dissolution time for Comparative Examples 6 A and 6B.

Table 7.

[0075] Examples 16 to 20. BP ADA flakes were ground into a fine powder by

mechanical grinding and then sieved to specific maximum particle size range (pm) as provided in Table 8. The resulting BP ADA powder (20 w/v%) was added to a mixture of MEK-DMF (1 : 1 v/v) (total solvent volume 20 ml) at 23 °C. The slurry was held in an oil bath set at 60°C and stirred well with a magnetic stirrer. The amount of time for the slurry to form a clear solution was reported as dissolution time (min.).

[0076] Comparative Example 7. BPADA flakes (20 w/v%) were added to a mixture of MEK-DMF (1 : 1 v/v) (total solvent volume 20 ml) at 23°C. The slurry was held in an oil bath set at 60°C and stirred well with a magnetic stirrer. The amount of time for the slurry to form a clear solution was reported as dissolution time (min.).

Table 8.

[0077] Comparative Example 8A. BTDA flakes were ground into a fine powder by mechanical grinding and then sieved to specific maximum particle size range (pm) as provided in Table 9. The resulting BTDA powder (20 w/v%) was added to a mixture of MEK-DMF (1 : 1 v/v) (total solvent volume 20 ml) at 23°C. The slurry was held in an oil bath set at 70°C and stirred well with a magnetic stirrer. The amount of time for the slurry to form a clear solution was reported as dissolution time (min.).

[0078] Comparative Example 8B. BTDA flakes (20 w/v%) were added to a mixture of MEK-DMF (1 : 1 v/v) (total solvent volume 20 ml) at 23°C. The slurry was held in an oil bath set at 70°C and stirred well with a magnetic stirrer. The amount of time for the slurry to form a clear solution was reported as dissolution time (min.).

Table 9.

[0079] This disclosure further encompasses the following aspects.

[0080] Aspect 1. A thermosetting epoxy composition, comprising: 100 parts by weight of an epoxy resin composition; 30 to 200 parts by weight of an aromatic dianhydride curing agent; optionally 20 to 100 parts by weight of a liquid monoanhydride curing agent; and optionally a curing catalyst; wherein an anhydride to epoxy stoichiometric ratio (A/E) is 0.2: 1 to 1.6:1, preferably 0.5: 1 to 1.3: 1, more preferably 0.6: 1 to 1.2: 1, wherein the thermosetting epoxy composition after curing has a glass transition temperature of 120 to 320°C, preferably 160 to 320°C, more preferably 180 to 320°C, even more preferably 200 to 320°C, still more preferably 250 to 320°C by DMA, wherein the aromatic dianhydride curing agent has a maximum absolute particle size of 0.1 to 3,350 pm, preferably 0.1 to 1,450 pm, more preferably 0.1 to 600 pm, even more preferably 0.1 to 355 pm, still more preferably 0.1 to 200 pm or 0.1 to 50 pm, by sieve size, and wherein the aromatic dianhydride curing agent is of formula (1) as provided herein.

[0081] Aspect la. A thermosetting epoxy composition, comprising: 100 parts by weight of an epoxy resin composition; 30 to 200 parts by weight of an aromatic dianhydride curing agent; optionally 20 to 100 parts by weight of a liquid monoanhydride curing agent; and optionally a curing catalyst; wherein an anhydride to epoxy stoichiometric ratio (A/E) is 0.2: 1 to 1.6: 1, preferably 0.5: 1 to 1.3: 1, more preferably 0.6: 1 to 1.2: 1, wherein the thermosetting epoxy composition after curing has a glass transition temperature of 120 to 320°C, preferably 160 to 320°C, more preferably 180 to 320°C, even more preferably 200 to 320°C, still more preferably 250 to 320°C by DMA, wherein the aromatic dianhydride curing agent has a maximum absolute particle size of 0.1 to 3,350 pm, preferably 0.1 to 1,450 pm, more preferably 0.1 to 600 pm, even more preferably 0.1 to 355 pm, still more preferably 0.1 to 200 pm or 0.1 to 50 pm, by sieve size, wherein the aromatic dianhydride curing agent is of formula (1) as provided herein, and wherein the epoxy resin composition does not include a high heat epoxy compound of formulas (I) to (IX) as provided herein.

[0082] Aspect 2. The thermosetting epoxy composition of aspect 1, wherein upon heating at 160°C, preferably at 140°C, more preferably at 120°C, the composition forms a homogenous solution in less than 35 minutes, preferably less than 25 minutes, more preferably less than 20 minutes, even more preferably less than 10 minutes.

[0083] Aspect 2a. The thermosetting epoxy composition of any one or more of the preceding aspects, wherein the thermosetting epoxy composition does not comprise a solvent or a liquid monoanhydride, and wherein upon heating at 160°C, the composition forms a homogenous solution in less than 35 minutes, preferably less than 25 minutes, more preferably less than 20 minutes, even more preferably less than 10 minutes.

[0084] Aspect 2b. The thermosetting epoxy composition of any one or more of the preceding aspects, wherein the thermosetting epoxy composition consists essentially of or consists of the epoxy resin composition and the aromatic dianhydride curing agent, and wherein upon heating at 160°C, the composition forms a homogenous solution in less than 35 minutes, preferably less than 25 minutes, more preferably less than 20 minutes, even more preferably less than 10 minutes.

[0085] Aspect 3. The thermosetting epoxy composition of aspect 1 or 2, wherein the composition further comprises a solvent.

[0086] Aspect 4. The thermosetting epoxy composition of any one or more of the preceding aspects, wherein the epoxy resin composition comprises an epoxy resin having a melting point of less than or equal to 25°C; preferably wherein the epoxy resin is a bisphenol A epoxy resin, a triglycidyl-substituted epoxy resin, a tetraglycidyl-substituted epoxy resin, a bisphenol F epoxy resin, a phenol novolak epoxy resin, a cresol novolak epoxy resin, a cycloaliphatic diglycidyl ester epoxy resin, a cycloaliphatic epoxy resin comprising a ring epoxy group, an epoxy resin containing a spiro-ring, a hydantoin epoxy resin, or a combination thereof; more preferably wherein the epoxy resin composition comprises bisphenol-A diglycidyl ether.

[0087] Aspect 5. The thermosetting epoxy composition of any one or more of the preceding aspects, wherein T is -O- or a group of the formula -O-Z-O- wherein Z is of the formula (2) as provided herein; preferably wherein T is a group of the formula -O-Z-O- wherein Z is a divalent group of formulas (3a) or (3b) as provided herein; more preferably wherein the aromatic dianhydride curing agent comprises bisphenol-A dianhydride.

[0088] Aspect 6. The thermosetting epoxy composition of any one or more of the preceding aspects, further comprising a curing catalyst; wherein the curing catalyst is an amine, a dicyandiamide, a polyamide, an amidoamine, a Mannich base, an anhydride, a

phenol-formaldehyde resin, a carboxylic acid functional polyester, a polysulfide, a

polymercaptan, an isocyanate, a cyanate ester, or a combination thereof; preferably wherein the curing catalyst comprises a substituted or unsubstituted C3-6 heterocycle comprising 1 to 4 ring heteroatoms, wherein each heteroatom is independently the same or different, and is nitrogen, oxygen, phosphorus, silicon, or sulfur; more preferably wherein the curing catalyst comprises a C3-4 five-membered ring wherein the ring heteroatoms are one or two nitrogen atoms.

[0089] Aspect 7. The thermosetting epoxy composition of any one or more of the preceding aspects, further comprising an additive; preferably wherein the additive is an antioxidant, a filler, a reinforcing agent, a heat stabilizer, a light stabilizer, a ultraviolet light stabilizer, a ultraviolet light-absorbing compound, a near infrared light-absorbing compound, an infrared light-absorbing compound, a plasticizer, a lubricant, a release agent, a antistatic agent, an anti-fog agent, an antimicrobial agent, a surface effect additive, a radiation stabilizer, a flame retardant, an anti-drip agent, a fragrance, an adhesion promoter, a coating additive, a degassing agent, or a combination thereof. [0090] Aspect 8. The thermosetting epoxy composition of any one or more of the preceding aspects, wherein the glass transition temperature after curing is greater than or equal to 160°C, preferably greater than or equal to 180°C, more preferably greater than or equal to 200°C, even more preferably greater than or equal to 220°C, still more preferably greater than 260°C.

[0091] Aspect 9. A method for the manufacture of a homogenous solution comprising the thermosetting epoxy composition of aspect 1, the method comprising: combining the aromatic dianhydride curing agent and the epoxy resin composition under conditions effective to form the homogenous solution; preferably heating at 50 to 200°C, more preferably at 80 to 200°C, even more preferably at 100 to 200°C to dissolve the aromatic dianhydride curing agent to form the homogenous solution.

[0092] Aspect 10. The method of aspect 9, further comprising: contacting the aromatic dianhydride curing agent and the liquid monoanhydride curing agent under conditions effective to form a precursor homogenous solution; and combining the precursor homogenous solution and the epoxy resin composition under conditions effective to form the homogenous solution.

[0093] Aspect 11. The method of aspect 9, further comprising: contacting the aromatic dianhydride curing agent and a solvent under conditions effective to form a precursor homogenous solution; and combining the precursor homogenous solution and the epoxy resin composition under conditions effective to form the homogenous solution.

[0094] Aspect 12. The method of any one or more of the preceding aspects, further comprising adding a curing catalyst to the homogenous solution, the precursor homogenous solution, the liquid monoanhydride curing agent, the solvent, or a combination thereof.

[0095] Aspect 13. The method of any one or more of the preceding aspects, further comprising curing the thermosetting epoxy composition under conditions effective to form a cured thermosetting epoxy composition.

[0096] Aspect 14. An article comprising a cured product of the thermosetting epoxy composition of any one or more of the preceding aspects.

[0097] Aspect 15. The article of aspect 14, wherein the article is in the form of a composite, a foam, a fiber, a layer, a coating, an encapsulant, an adhesive, a sealant, a component, a prepreg, a casing, or a combination thereof.

[0098] The compositions, methods, and articles can alternatively comprise, consist of, or consist essentially of, any appropriate materials, steps, or components herein disclosed. The compositions, methods, and articles can additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any materials (or species), steps, or components, that are otherwise not necessary to the achievement of the function or objectives of the compositions, methods, and articles.

[0099] All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other (e.g., ranges of“up to 25 wt%, or, more specifically,

5 wt% to 20 wt%”, is inclusive of the endpoints and all intermediate values of the ranges of“5 wt% to 25 wt%,” etc.). Disclosure of a narrower range or more specific group in addition to a broader range is not a disclaimer of the broader range or larger group.

[0100] The singular forms“a”“an,” and“the” include plural referents unless the context clearly dictates otherwise. “Combination” is inclusive of blends, mixtures, alloys, reaction products, and the like. The terms“first,”“second,” and the like, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. “Or” means“and/or” unless clearly stated otherwise. Reference throughout the specification to“an aspect” means that a particular element described in connection with the aspect is included in at least one aspect described herein and may or may not be present in other aspects. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various aspects. A“combination thereof’ is open and includes any combination comprising at least one of the listed components or properties optionally together with a like or equivalent component or property not listed.

[0101] Unless specified to the contrary herein, all test standards are the most recent standard in effect as of the filing date of this application, or, if priority is claimed, the filing date of the earliest priority application in which the test standard appears. Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this application belongs. All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference.

[0102] Compounds are described using standard nomenclature. For example, any position not substituted by any indicated group is understood to have its valency filled by a bond as indicated, or a hydrogen atom. A dash that is not between two letters or symbols is used to indicate a point of attachment for a substituent. For example, -CHO is attached through carbon of the carbonyl group.

[0103] The term“hydrocarbyl” refers to a monovalent group containing carbon and hydrogen. Hydrocarbyl can be alkyl, cycloalkyl, alkenyl, cycloalkenyl, aryl, alkylaryl, or arylalkyl as defined below. The term“hydrocarbylene” refers to a divalent group containing carbon and hydrogen. Hydrocarbylene can be alkylene, cycloalkylene, arylene, alkylarylene, or arylalkylene as defined below. The term "alkyl" means a branched or straight chain, unsaturated aliphatic hydrocarbon group, e.g., methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, t-butyl, n- pentyl, s-pentyl, and n- and s-hexyl. “Alkenyl” means a straight or branched chain, monovalent hydrocarbon group having at least one carbon-carbon double bond (e.g., ethenyl (-HC=CH2)). “Alkoxy” means an alkyl group that is linked via an oxygen (i.e., alkyl-O-), for example methoxy, ethoxy, and sec-butyloxy groups. "Alkylene" means a straight or branched chain, saturated, divalent aliphatic hydrocarbon group (e.g., methylene (-CH2-) or, propylene (-(CH2)3- )). “Cycloalkylene” means a divalent cyclic alkylene group, -CiTUn-x, wherein x is the number of hydrogens replaced by cyclization(s). “Cycloalkenyl” means a monovalent group having one or more rings and one or more carbon-carbon double bonds in the ring, wherein all ring members are carbon (e.g., cyclopentyl and cyclohexyl). "Aryl" means an aromatic hydrocarbon group containing the specified number of carbon atoms, such as phenyl, tropone, indanyl, or naphthyl. “Arylene” means a divalent aryl group.“Alkylaryl” means an aryl group substituted with an alkyl group. “Arylalkyl” means an alkyl group substituted with an aryl group (e.g., benzyl). “Aryloxy” means an aryl group with the indicated number of carbon atoms attached through an oxygen bridge (-0-). “Amino” means a monovalent radical of the formula— NRR' wherein R and R' are independently hydrogen or a Ci-30 hydrocarbyl, for example a Ci-20 alkyl group or a C6-30 aryl group.“Halogen” or“halogen atom” means a fluorine, chlorine, bromine, or iodine atom. The prefix "halo" means a group or compound including one more of a fluoro, chloro, bromo, or iodo substituent. A combination of different halo groups (e.g., bromo and fluoro), or only chloro groups can be present. The prefix“hetero” means that the compound or group includes at least one ring member that is a heteroatom (e.g., 1, 2, or 3 heteroatom(s)), wherein the heteroatom(s) is each independently N, O, S, Si, or P.

[0104] Unless substituents are otherwise specifically indicated, each of the foregoing groups can be unsubstituted or substituted, provided that the substitution does not significantly adversely affect synthesis, stability, or use of the compound. “Substituted” means that the compound, group, or atom is substituted with at least one (e.g., 1, 2, 3, or 4) substituents instead of hydrogen, where each substituent is independently nitro (-NO ₂ ), cyano (-CN), hydroxy (-OH), halogen, thiol (-SH), thiocyano (-SCN), Ci- ₆ alkyl, C _2-6 alkenyl, C _2-6 alkynyl, Ci- ₆ haloalkyl, C _1-9 alkoxy, Ci- ₆ haloalkoxy, C3-12 cycloalkyl, C5-18 cycloalkenyl, C6-12 aryl, C7-13 arylalkyl (e.g., benzyl), C _7-12 alkylaryl (e.g., toluyl), C _4-12 heterocycloalkyl, C _3-12 heteroaryl, Ci- ₆ alkyl sulfonyl (-S(=0) ₂ -alkyl), C _6-12 arylsulfonyl (-S(=0) ₂ -aryl), or tosyl (CH ₃ C ₆ H ₄ SO ₂ -), provided that the substituted atom’s normal valence is not exceeded, and that the substitution does not significantly adversely affect the manufacture, stability, or desired property of the compound. When a compound is substituted, the indicated number of carbon atoms is the total number of carbon atoms in the compound or group, including those of any substituents.

[0105] While particular aspects have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or may be presently unforeseen may arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they may be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents.