WO2021096654A1 - Curing composition for high heat adhesive epoxy resin - Google Patents

Abstract

An adhesive composition comprising 100 parts by weight of an epoxy resin composition; 30- 400 pbw of a curing composition comprising a monoanhydride and an aromatic dianhydride of formula (2) as provided herein; and a curing catalyst, wherein the amounts are each based on the total parts by weight of the epoxy resin composition and the curing composition, wherein the adhesive composition after curing has a Tg of 180-260°C, wherein the adhesive composition after curing has an adhesive strength of greater than or equal to 30 MPa.

Description

CURING COMPOSITION FOR HIGH HEAT ADHESIVE EPOXY RESIN

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to European Patent Application No. EP20151425.5, filed January 13, 2020, and Indian Patent Application No. 201911045891, filed November 12, 2019, the entire contents of which are incorporated by reference herein.

BACKGROUND

[0001] Thermoset polymers are used in a wide variety of consumer and industrial products including protective coatings, adhesives, electronic laminates (such as those used in the fabrication of printed circuit boards), flooring and paving, glass fiber-reinforced pipes, and automotive parts (such as leaf springs, pumps, and electrical components). Thermoset epoxies are derived from thermosetting epoxy resins that are polymerized in the presence of a co-reactive curing agent (also referred to in the art as a hardener), a catalytic curing agent (also referred to in the art as a cure accelerator or a catalyst), to afford a cured thermoset polymer.

[0002] 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 (T_G) 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, for examples in adhesives.

[0003] There remains a need for curable epoxy compositions that can provide cured epoxy resins having high temperature stability and improved adhesive properties.

BRIEF DESCRIPTION

[0004] Provided is an adhesive composition including 100 parts by weight of an epoxy resin composition; 30 to 400 part by weight, or 50 to 350 parts by weight, or 50 to 200 parts by weight of a curing composition comprising a monoanhydride and an aromatic dianhydride of formula (2):

, wherein T is -O-, -S-, -SO2-, -SO-, -C_yH_2y- wherein y is an integer 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-g alkyl groups, 1 to 8 halogen atoms, or a combination thereof; and a curing catalyst, wherein the amounts are each based on the total parts by weight of the epoxy resin composition and the curing composition, wherein the adhesive composition after curing has a glass transition temperature of 180 to 260°C, or 200 to 260°C, or 220 to 260°C, as determined by dynamic mechanical analysis, and wherein the adhesive composition after curing has an adhesive strength of greater than or equal to 30 MPa, or greater than or equal to 32 MPa, or greater than or equal to 34 MPa, as determined in accordance with ASTM D1002.

[0005] Also provided is an adhesive composition prepared by contacting the aromatic dianhydride and the monoanhydride under conditions effective to form the curing composition as a substantially homogenous solution; and contacting the curing composition, the epoxy resin composition, and the curing catalyst at a temperature of 20 to 120°C, or 30 to 100°C, or 40 to 80°C, to form the adhesive composition.

[0006] Also provided is a method for the manufacture of the adhesive composition including contacting the aromatic dianhydride and the monoanhydride, preferably at a temperature of 20 to 200°C, or 20 to 180°C, or 30 to 150°C, or 40 to 80°C, to form the curing composition as a substantially homogenous solution, or as a homogenous solution; and contacting the curing composition, the epoxy resin composition, and the curing catalyst under conditions effective to form the adhesive composition. An article including a cured product of the adhesive composition is further provided.

[0007] The above described and other features are exemplified by the following detailed description.

DETAILED DESCRIPTION

[0008] This disclosure relates to a thermosetting epoxy adhesive composition. The adhesive composition includes an epoxy resin composition, a curing composition including an aromatic dianhydride and a monoanhydride, and a curing catalyst. The inventors have discovered that a curing package including an aromatic dianhydride, for example bisphenol-A dianhydride (BPA-DA or BISDA), and a monoanhydride can be a useful curing composition for manufacturing high heat cured epoxy resins having superior adhesive properties. The adhesive composition including the curing composition can provide a cured thermoset product having good high heat resistance properties and adhesive strength, such as a glass transition temperature of up to 230°C or greater and an adhesion strength that exceeds 30 megapascal (MPa).

[0009] Provided is an adhesive composition that includes an epoxy resin composition; a curing composition comprising an aromatic dianhydride of formula (2) and a monoanhydride; and a curing catalyst. The adhesive composition after curing has a glass transition temperature of 160- 260°C and an adhesive strength of greater than or equal to 30 MPa.

[0010] The stoichiometric ratio between anhydride groups of the curing composition and epoxy groups of the epoxy resin composition can be 0.1:1 to 2.0:1. For example, the stoichiometric ratio between anhydride groups of the curing composition and epoxy groups of the epoxy resin composition can be 0.4:1 to 1.2:1 or 0.6:1 to 1:1. The stoichiometric ratio is the molar ratio of anhydride functionalities to the epoxy functionalities in the epoxy resin composition. The stoichiometric ratio is also referred to as the anhydride to epoxy (A/E) ratio. [0011] The adhesive composition includes 100 parts by weight (pbw) of the epoxy resin composition, based on the total parts by weight of the epoxy resin composition and the curing composition. The epoxy resin composition can include a single epoxy resin, or can include two or more epoxy resins that are different from each other.

[0012] The epoxy resin composition can include an epoxy resin of formula (1)

wherein A is an organic or inorganic radical of valence n, X is oxygen or nitrogen, m is 1 or 2 and consistent with the valence of X, R is hydrogen or methyl, n is 1 to 8, or 2 or 3 or 4.

[0013] In an aspect, the epoxy resin is a bisphenol A epoxy resin, a bisphenol F epoxy resin, a bisphenol S epoxy resin, a triglycidyl-substituted epoxy resin, a tetraglycidyl-substituted 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, a biphenyl epoxy resin, a naphthalene epoxy resin, an isocyanurate epoxy resin, triphenylmethane epoxy resin, or a combination thereof. For example, the epoxy resin can be tetraglycidyldiaminodiphenylmethane.

[0014] Exemplary epoxy resins include those produced by the reaction of epichlorohydrin or epibromohydrin with a phenolic compound. Exemplary phenolic compounds include resorcinol, catechol, hydroquinone, 2,6-dihydroxynaphthalene, 2,7-dihydroxynapthalene, 2- (diphenylphosphoryl)hydroquinone, bis(2,6-dimethylphenol)2,2’-biphenol, 4,4-biphenol, 2, 2’, 6,6’- tetramethylbiphenol, 2,2’,3,3’,6,6’-hexamethylbiphenol, 3,3’,5,5’-tetrabromo-2,2’6,6’- tetramethylbiphenol, 3,3’-dibromo-2,2’,6,6’-tetramethylbiphenol, 2,2’,6,6’-tetramethyl-3,3’5- dibromobiphenol, 4,4’-isopropylidenediphenol, 4,4’-isopropylidenebis(2,6-dibromophenol), 4,4’- isopropybdenebis(2,6-dimethylphenol) (teramethylbisphenol A), 4,4’-isopropylidenebis(2- methylphenol), 4,4’-isopropybdenebis(2-allylphenol), 4,4’-(l,3- phenylenediisopropybdene)bisphenol, 4,4’-isopropybdenebis(3-phenylphenol), 4,4’-(l,4- phenylenediisoproybdene)bisphenol, 4,4’-ethybdenediphenol, 4,4 ’-oxy diphenol, 4,4’-thiodiphenol, 4,4’-thiobis(2,6-dimethylphenol), 4,4’-sulfonyldiphenol, 4,4’-sulfonylbis(2,6-dimethylphenol) 4,4’- sulfmyldiphenol, 4,4’-hexafluoroisoproybdene)bisphenol, 4,4’-(l-phenylethybdene)bisphenol, bis(4- hydroxyphenyl)-2,2-dichloroethylene, bis(4-hydroxyphenyl)methane, bis(2,6-dimethyl-4- hydroxyphenyl)methane, 4,4'-(cyclopentybdene)diphenol, 4,4'-(cyclohexybdene)diphenol, 4,4'- (cyclododecybdene)diphenol 4,4'-(bicyclo[2.2. l]heptylidene)diphenol, 4,4'-(9H-fluorene-9,9- diyl)diphenol, 3,3-bis(4-hydroxyphenyl)isobenzofuran-l(3H)-one, l-(4-hydroxyphenyl)-3,3- dimethyl-2,3-dihydro-lH-inden-5-ol, l-(4-hydroxy-3,5-dimethylphenyl)-l,3,3,4,6-pentamethyl-2,3- dihydro-lH-inden-5-ol, 3,3,3',3'-tetramethyl-2,2',3,3'-tetrahydro-l,r-spirobi[indene]-5,6'-diol (spirobiindane), dihydroxybenzophenone, tris(4-hydroxyphenyl)methane, tris(4- hydroxyphenyl)ethane, tris(4-hydroxyphenyl)propane, tris(4-hydroxyphenyl)butane, tris(3-methyl-4- hydroxyphenyl)methane, tris(3,5-dimethyl-4-hydroxyphenyl)methane, tetrakis(4- hydroxyphenyl)ethane, tetrakis(3,5-dimethyl-4-hydroxyphenyl)ethane, bis(4- hydroxyphenyl)phenylphosphine oxide, dicyclopentadienylbis(2, 6-dimethyl phenol), dicyclopentadienyl bis(2-methylphenol), dicyclopentadienyl bisphenol, or the like, or combinations thereof.

[0015] Other exemplary epoxy resins include /V-glycidyl phthabmide, N- glycidyltetrahydrophthalimide, phenyl glycidyl ether, p-butylphenyl glycidyl ether, styrene oxide, neohexene oxide, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, tetramethyleneglycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, resorcinol-type epoxy compounds, phenol novolac-type epoxy compounds, ortho-cresol novolac-type epoxy compounds, adipic acid diglycidyl ester, sebacic acid diglycidyl ester, phthalic acid diglycidyl ester, or the like, or combinations thereof.

[0016] Other epoxy resins include the glycidyl ethers of phenolic resins such as the glycidyl ethers of phenol-formaldehyde novolac, alkyl substituted phenol-formaldehyde resins including cresol-formaldehyde novolac, /-butyl phenol -formaldehyde novolac, sec-butyl phenol -formaldehyde novolac, /677-octyl phenol -formaldehyde novolac, cumylphenol-formaldehyde novolac, decylphenol- formaldehyde novolac. Other useful epoxies are the glycidyl ethers of bromophenol-formaldehyde novolac, chlorophenolformaldehyde novolac, phenol-bis(hydroxymethyl)benzene novolac, phenol- bis(hydroxymethylbiphenyl) novolac, phenol-hydroxybenzaldehyde novolac, phenol- dicylcopentadiene novolac, naphthol-formaldehyde novolac, naphthol-bis(hydroxymethyl)benzene novolac, naphthol-bis(hydroxymethylbiphenyl) novolac, naphthol-hydroxybenzaldehyde novolac, and naphthol-dicylcopentadiene novolacs, or the like, or combinations thereof.

[0017] Other exemplary epoxy resins include the poly glycidyl ethers of polyhydric aliphatic alcohols. Examples of such polyhydric alcohols include 1 ,4-butanediol, 1,6-hexanediol, polyalkylene glycols, glycerol, trimethylolpropane, 2,2-bis(4-hydroxycyclohexyl)propane, pentaerythritol, or the like, or combinations thereof.

[0018] Further examples of epoxy resins are polyglycidyl esters which are obtained by reacting epichlorohydrin or similar epoxy compounds with an aliphatic, cycloaliphatic, or aromatic polycarboxylic acid, such as oxalic acid, adipic acid, glutaric acid, phthalic, isophthalic, terephthalic, tetrahydrophthalic or hexahydrophthalic acid, 2,6-naphthalenedicarboxylic acid, and dimerized fatty acids. Examples are diglycidyl terephthalate and diglycidyl hexahydrophthalate. Moreover, polyepoxide compounds which contain the epoxide groups in random distribution over the molecule chain and which can be prepared by emulsion copolymerization using olefmically unsaturated compounds that contain these epoxide groups, such as, for example, glycidyl esters of acrylic or methacrylic acid, can be used.

[0019] Other exemplary epoxy resins are those based on heterocyclic ring systems, for example hydantoin epoxy resins, triglycidyl isocyanurate and its oligomers, triglycidyl-p- aminophenol, triglycidyl-p-aminodiphenyl ether, tetraglycidyldiaminodiphenylmethane, tetraglycidyldiaminodiphenyl ether, tetrakis(4-glycidyloxyphenyl)ethane, urazole epoxides, uracil epoxides, and oxazolidinone-modified epoxy resins.

[0020] Other examples are polyepoxides based on aromatic amines, such as aniline, for example /V, /V-diglycidylanil ine, diaminodiphenylmethane and /V, A-di methyl ami nodiphenyl methane or /V, V-di methyl ami nodiphenyl sulfone and cycloaliphatic epoxy resins such as 3,4- epoxycyclohexylmethyl-3, 4-epoxycyclohexane carboxylate, 4,4'-(l,2-epoxyethyl)biphenyl, 4,4'- di(l, 2-epoxy ethyl)diphenyl ether, and bis(2,3-epoxycyclopentyl)ether.

[0021] Examples of mono-functional epoxy include 2-ethylhexyl glycidyl ether, butyl glycidyl ether , phenyl glycidyl ether, t-butyl glycidyl ether, o-cresyl glycidyl ether, and nonyl phenol glycidyl ether.

[0022] Oxazolidinone-modified epoxy resins can also be used, such as those disclosed in Angew. Makromol. Chem., vol. 44, (1975), pages 151-163, and U.S. Patent No. 3,334,110 to Schramm. An example is the reaction product of bisphenol A diglycidyl ether with diphenylmethane diisocyanate in the presence of an appropriate accelerator.

[0023] Epoxy resin oligomers may be prepared by condensation of an epoxy resin with a phenol such as a bisphenol. A typical example is the condensation of bisphenol A with a bisphenol A diglycidyl ether to produce an oligomeric diglycidyl ether. In another example a phenol dissimilar to the one used to derive the epoxy resin may be used. For example, tetrabromobisphenol A may be condensed with bisphenol A diglycidyl ether to produce an oligomeric diglycidyl ether containing halogens.

[0024] The epoxy resin can be a solid at room temperature. Thus, in some aspects, the epoxy resin has a softening point of 25-150°C. The epoxy resin can be a liquid or a softened solid at room temperature. In some aspects, the epoxy resin has a softening point less than 25°C.

[0025] The epoxy resin can have an average epoxy functionality of 1.5 to 10 epoxy groups per molecule. For example, the average epoxy functionality can be 2 to 8 epoxy groups per molecule, specifically 3 to 6 epoxy groups per molecule. In an aspect, the adhesive composition includes at least one epoxy resin having a mean epoxy functionality of about 2 or greater than 2, that is to say having on average about two or more than two epoxy groups per molecule, such as, for example, corresponding polyglycidyl ethers or polyglycidyl esters.

[0026] The epoxide equivalent weight (EEW) of the epoxy resin can be from 100 to 20,000 grams per equivalent (g/eq), or from 100 to 5,000 g/eq, or from 100 to 1,000 g/eq. Within the range of 90 to 1,000 g/eq, the EEW can be 100 to 500 g/eq, specifically 150 to 300 g/eq. As used herein, the term “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.

[0027] The adhesive composition further includes 30 to 400 parts by weight (pbw) of a curing composition comprising an aromatic dianhydride of formula (2) and a monoanhydride, based on the total parts by weight of the epoxy resin composition and the curing composition. For example, the adhesive composition can include 50 to 350 pbw, or 50 to 200 pbw, or 50 to 150 pbw, or 60 to 140 pbw, or 80 to 120 pbw of the curing composition, based on the total parts by weight of the epoxy resin composition and the curing composition.

[0028] The aromatic dianhydride is a compound of formula (2)

wherein T is -0-, -S-, -SO2-, -SO-, -C_yH_2y- wherein y is an integer from 1 to 5 or a halogenated derivative thereof, or -O-Z-O- wherein Z is an aromatic C_6-24 monocyclic or polycyclic moiety optionally substituted with 1 to 6 Ci-g alkyl groups, 1 to 8 halogen atoms, or a combination thereof. In some aspects, the R¹ 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. Exemplary groups Z include groups of formula (3)

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 G, arylene group are disposed ortho, meta, or para (specifically para) to each other on the G, arylene group. The bridging group X^a can be a single bond, -O-, -S-, -S(O)-, -S(0)₂-, -C(O)-, or a C _S organic bridging group. The C _S 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 C _S organic group can be disposed such that the G, arylene groups connected thereto are each connected to a common alkylidene carbon or to different carbons of the C _S organic bridging group. A specific example of a group Z is a divalent group of the formula (4a) or (4b)

wherein Q is -0-, -S-, -C(O)-, -SO₂-, -SO-, -P(R^c)(=0)- wherein R^c is a Ci-g alkyl or C6-12 aryl, or - C_yH_2y- 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 (for example, Z is 2,2-(4-phenylene)isopropylidene).

[0029] 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)diphenyl 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 (BPADA or BISDA).

[0030] The curing composition further includes a monoanhydride. Exemplary monoanhydrides include norbomene dicarboxybc anhydrides (e.g., methyl-5-norbomene-2,3- dicarboxybc anhydride, or the like), hexahydrophthalic anhydrides (e.g., 1,2- cyclohexanedicarboxybc anhydride, 4-methylhexahydrophthalic anhydride, 5- methylhexahydrophthabc anhydride, or the like), tetrahydrophthalic anhydrides (e.g., 1, 2,3,6- tetrahydrophthabc 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. In an aspect, the monoanhydride is maleic anhydride, phthalic anhydride, hexahydro-o-phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyl-5-norbomene-2,3-dicarboxylic anhydride, cis-5- norbomene-endo-2, 3 -dicarboxybc anhydride, tetrachlorophthalic anhydride, trimellitic anhydride, hexahydrophthalic anhydride, or a combination thereof. Preferably, the monoanhydride is methyltetrahydrophthalic anhydride.

[0031] In some aspects, the monoanhydride can be a liquid. As used herein, “liquid monoanhydride” refers to a monoanhydride compound that is a liquid at a temperature from 15 to 45°C, or 20 to 40°C, or 20 to 30°C, or 20 to 25°C.

[0032] Within the curing composition, the anhydride equivalent ratio of the aromatic dianhydride to the monoanhydride can be 0.01:1 to 1:0.01. For example, the anhydride equivalent ratio can be 0.05:1 to 4:1, or preferably 0.11:1 to 1:1. In an aspect, the anhydride equivalent ratio can be 1 : 10 to 1 : 7, or 1 : 9 to 3 : 7. As used herein, the term “anhydride equivalent ratio” refers to the ratio of the anhydride equivalents of the aromatic dianhydride to the anhydride equivalents of monoanhydride.

[0033] The aromatic dianhydride can be soluble in the monoanhydride. The term “soluble in the monoanhydride” means that there is a temperature range where a combination of the aromatic dianhydride and the monoanhydride 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 and the monoanhydride can be stirred, heated, or heated under stirring to form a homogeneous phase. The solubility can be enhanced using a solvent, when the monoanhydride is a liquid, or a combination thereof. In some aspects, the aromatic dianhydride can be soluble in the monoanhydride without a solvent.

[0034] The adhesive composition further includes an effective amount of a curing catalyst.

In an aspect, the adhesive composition can include 0.01 to 5 weight percent (wt%) of a curing catalyst, based on the total weight of the composition. For example, the adhesive composition can include 0.04 to 4 wt%, or 0.06 to 3 wt%, or 0.07 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 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. Preferably, the curing catalyst includes 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, the curing catalyst comprises a C3.4 five-membered ring wherein the ring heteroatoms are one or two nitrogen atoms.

[0035] 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, l-cyanoethyl-2-ethyl-4-methylimidazole, l-cyanoethyl-2-undecylimidazole, 1- 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, diazabicycloundecene, 2-phenyl imidazoline, or the like; N,N-dimethylaminopyridine; sulfamidate; or a combination thereof.

[0036] The curing catalyst can be an amine curing catalyst. Amine curing catalysts include isophoronediamine, tri ethyl enetetraamine, 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- 1,4-diamine, dicyanamide, diamide diphenylmethane, diamide diphenylsulfonic acid (amine adduct), 4,4’-methylenedianiline, diethyltoluenediamine, 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, l,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 1,4- 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, a-methylbenzyldimethylamine, A, /V-di methyl ami noethanol,

/V, /V-di methyl ami nocresol , tri(/V, /V-di methyl ami nomethyl (phenol, or a combination thereof. Amine curing catalysts also include acid-base complexes such as a boron trifluoride-trialkylamine complex.

[0037] 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.

[0038] 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 [(R¹⁰)(Rⁿ)I]⁺ X , wherein R¹⁰ and R¹¹ 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 [(R¹⁰)(Rⁿ)I]⁺ SbF₆ , wherein R¹⁰ and R¹¹ 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 acetylacetonate.

[0039] In some aspects, the adhesive composition includes 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. For example, the additive composition can include 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. The amount of the optional additive composition can be from 0 to 99 wt%, or 0.001 to 95 wt%, or 0.01 to 10 wt%, or 0.05 to 5 wt%, based on total weight of the adhesive composition.

[0040] The adhesive composition can include a filler. Exemplary fillers include, for example, alumina, silica (including fused silica, fumed silica, colloidal silica, and crystalline silica), boron nitride (including spherical boron nitride), aluminum nitride, silicon nitride, titania, titanium dioxide, titanium diboride, magnesia, magnesium oxide, magnesium silicate, glass fibers (chopped, milled and cloth), glass bubbles, hollow glass microsphere, aramid fibers, glass mat, talc, fly ash, kaolin, clay (aluminum silicate), antimony trioxide, calcium carbonate, calcium oxide, carbon black, zinc oxide, or a combination thereof. Exemplary glass fibers include those based on E, A, C, ECR,

R, S, D, and NE glasses, as well as quartz.

[0041] Glass fibers include quartz glass fibers and glass fibers other than quartz glass fibers, such as E glass fibers, D glass fibers, S glass fibers, R glass fibers, NE glass fibers, or T glass fibers. Suitable glass styles include, but are not limited to, 106, 1080, 2112, 2113, 2116, and 7628, wherein the term glass style is known to those skilled in the art and refers to the size of glass fibers and number of fibers in a bundle. The filler can further include inorganic fibers other than glass fibers, polypropylenes, polyimides, polyamides, polyesters, carbon fibrils, acrylic fibers, or cellulose fibers. In some aspects, the adhesive composition further includes a reinforcing structure that is a fibrous preform that includes a woven or non-woven glass or carbon fabric, or comprises glass cloth. Additional reinforcing structures include co-woven structures comprising at least two types of fibers, including glass fiber-carbon fiber, carbon fiber-aromatic polyimide (aramid) fiber, and aromatic polyimide fiber-glass fiber. Reinforcing structures further include non-woven fibrous reinforcements such as continuous strand mat, chopped strand mat, tissues, papers, felts, three-dimensional woven reinforcements, preforms, and braids.

[0042] In an aspect, the adhesive composition further comprises a poly(phenylene ether) copolymer. The poly(phenylene ether) copolymer is ideally suited as a reactive component in the adhesive composition because it is bifunctional, with two reactive phenolic groups. For example, the adhesive composition can include 1 to 100 parts by weight of a poly(phenylene ether) copolymer.

[0043] In the adhesive composition, the curing composition can be manufactured by contacting the aromatic dianhydride and the monoanhydride to form the curing composition. For example, the aromatic dianhydride and the monoanhydride can be contacted at a temperature of 20 to 200°C, or 20 to 180°C, or 30 to 150°C, or 40 to 80°C to provide the curing composition. In an aspect, the aromatic dianhydride and the monoanhydride are combined under conditions effective to provide the curing composition as a substantially homogenous solution. For example, the aromatic dianhydride and the monoanhydride can be combined under conditions effective to provide the curing composition as a homogenous solution. For example, a substantially homogenous solution can be formed when the aromatic dianhydride and the monoanhydride are combined at a temperature of 20 to 200°C, or 20 to 180°C, or 30 to 150°C, or 40 to 80°C. For example, a substantially homogenous solution can be formed when the aromatic dianhydride and the monoanhydride are combined at a temperature of 20 to 200°C, or 20 to 180°C, or 30 to 150°C, or 40 to 80°C in the absence of a solvent (or reactive diluent). For example, a homogenous solution can be formed when the aromatic dianhydride and the monoanhydride are combined at a temperature of 20 to 200°C, or 20 to 180°C, or 30 to 150°C, or 40 to 80°C. For example, a homogenous solution can be formed when the aromatic dianhydride and the monoanhydride are combined at a temperature of 20 to 200°C, or 20 to 180°C, or 30 to 150°C, or 40 to 80°C in the absence of a solvent (or reactive diluent).

[0044] The curing composition can then be contacted with the epoxy resin composition and the curing catalyst under conditions effective to form the adhesive composition. For example, the curing composition can be contacted with the epoxy resin composition and the curing catalyst at a temperature of 20 to 120°C, or 30 to 100°C, or 40 to 80°C.

[0045] The inventors have discovered that when a curing composition is prepared as a homogenous solution by contacting the aromatic dianhydride provided herein and a monoanhydride, the subsequent reaction of the curing composition with the epoxy resin composition and the curing catalyst at a temperature of 20 to 120°C, or 30 to 100°C, or 40 to 80°C affords an adhesive composition that provides a cured product having superior adhesive strength relative to a comparative curing composition that is prepared by combining the same monoanhydride, the same epoxy resin composition, and the same curing catalyst to form a comparative adhesive composition at the same temperature and subsequent curing, but in the absence of the aromatic dianhydride.

[0046] The curing composition can be prepared using a solvent. For example, the curing composition can be prepared using a solvent that is subsequently removed after combining the aromatic dianhydride and the monoanhydride. In an aspect, the curing composition includes a solvent, for example, the curing composition includes at least a portion of the solvent used to prepare the curing composition. In another aspect, the curing composition includes no solvents, reactive diluents, or both (i.e., is free of solvents, reactive diluents, or both).

[0047] The adhesive composition can be prepared using an optional solvent. For example, the adhesive composition can be prepared from the curing composition, the epoxy resin composition, the curing catalyst, and a solvent, where the solvent is optionally removed prior to forming the adhesive composition. In an aspect, the adhesive composition includes a solvent, for example, the adhesive composition includes at least a portion of the solvent used to prepare the curing composition. In another aspect, the adhesive composition includes no solvents, reactive diluents, or both (i.e., is free of solvents, reactive diluents, or both).

[0048] Exemplary solvents include, but are not limited to, C3.8 ketones, C4.8 /V, /V-dialkylamides, C4-16 dialkyl ethers, C6-12 aromatic hydrocarbons, C3.6 alkyl alkanoates, C2-6 alkyl nitriles, C2-6 dialkyl sulfoxides, or a combination thereof. Examples of C3.8 ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, and combinations thereof. Examples of C4.8 N,N- dialkylamides include dimethylformamide, dimethyl acetamide, /V-methyl-2-pyrrolidone, and combinations thereof. Examples of C4-16 dialkyl ethers include tetrahydrofuran, dioxane, and combinations thereof. The C4-16 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 C4-16 dialkyl ether can be ethylene glycol monomethyl ether. The aromatic hydrocarbon solvent can be an ethylenically unsaturated solvent. Examples of C6-12 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). Combinations of two or more solvents can also be used.

[0049] The adhesive composition can be cured to form a cured product. There is no particular limitation on the method by which the composition can be cured. The adhesive composition can be cured thermally or by using irradiation techniques, including ultraviolet (UV) irradiation and electron beam irradiation. Heat curing can be at 80 to 300°C, and preferably 120 to 260°C. The heat curing can be for 1 minute to 10 hours, for example 1 minute to 6 hours, or 4 minutes to 4 hours, or 15 minutes to 4 hours. The curing can be staged to produce a partially cured and often tack-free resin, which then can be fully cured by heating for longer periods or temperatures within the aforementioned ranges.

[0050] The adhesive composition can be cured by compression molding, injection molding, transfer molding, pultrusion, resin casting, or a combination thereof. For example, the adhesive composition can be disposed in, for example injected into, a mold and then cured at 80 to 300°C, or 120 to 260°C in the mold. Various molded articles or components can be prepared in this manner, including those described herein.

[0051] The cured product of the adhesive composition has a glass transition temperature (T_g) of 180 to 260°C, or 200 to 260°C, or 220 to 260°C. The T_g can be measured by dynamic mechanical analysis (DMA).

[0052] The adhesive composition after curing (i.e., the cured product) has an adhesive strength of greater than or equal to 30 megapascal (MPa), or greater than or equal to 32 MPa, or greater than or equal to 34 MPa, as determined in accordance with ASTM D1002. For example, the cured product can have an adhesive strength of 30 to 100 MPa, or 30 to 75 MPa, or 32 to 60 MPa, or 34 to 60 MPa, as determined in accordance with ASTM D1002.

[0053] The resulting cured product of the adhesive composition after curing can be clear and/or transparent. For example, adhesive composition after curing can have a total transmission of greater than 50%, or greater than 70%, or greater than 90%. [0054] In an aspect, the adhesive composition includes 100 pbw of an epoxy resin composition, preferably a bisphenol A epoxy resin, a bisphenol F epoxy resin, a bisphenol S epoxy resin, a triglycidyl-substituted epoxy resin, a tetraglycidyl-substituted 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, a biphenyl epoxy resin, a naphthalene epoxy resin, an isocyanurate epoxy resin, triphenylmethane epoxy resin, or a combination thereof, more preferably tetraglycidyldiaminodiphenylmethane; 50 to 350 pbw of a curing composition comprising an aromatic dianhydride and a monoanhydride; wherein the monoanhydride is maleic anhydride, phthalic anhydride, hexahydro-o-phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyl-5-norbomene-2,3- dicarboxylic anhydride, cis-5-norbomene-endo-2,3-dicarboxylic anhydride, tetrachlorophthalic anhydride, trimellitic anhydride, hexahydrophthalic anhydride, or a combination thereof, preferably methyltetrahydrophthalic anhydride; wherein the aromatic dianhydride is of formula (2) wherein T is -O- or a group of the formula -0-Z-0-; wherein an anhydride equivalent ratio of the aromatic dianhydride to the monoanhydride is 0.05:1 to 4:1, or 0.11:1 to 1:1; wherein a stoichiometric ratio between anhydride groups of the curing composition and epoxy groups of the epoxy resin composition is 0.4:1 to 1.2:1, or 0.6:1 to 1:1; and a curing catalyst; 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, preferably a C3.4 five-membered ring wherein the ring heteroatoms are one or two nitrogen atoms; wherein the adhesive composition after curing has a glass transition temperature of 180 to 260°C, or 200 to 260°C, or 220 to 260°C, as determined by DMA; and wherein the adhesive composition after curing has an adhesive strength of greater than or equal 32 MPa, or greater than or equal to 34 MPa, as determined in accordance with ASTM D1002, and wherein the adhesive composition is prepared by contacting the aromatic dianhydride and the monoanhydride under conditions effective to form the curing composition; and contacting the curing composition, the epoxy resin composition, and the curing catalyst at a temperature of 40 to 80°C to form the adhesive composition.

[0055] In another aspect, the adhesive composition includes 100 pbw of an epoxy resin composition, wherein the epoxy resin composition includes a bisphenol A epoxy resin, a bisphenol F epoxy resin, a bisphenol S epoxy resin, a triglycidyl-substituted epoxy resin, a tetraglycidyl- substituted 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, a biphenyl epoxy resin, a naphthalene epoxy resin, or a combination thereof, preferably tetraglycidyldiaminodiphenylmethane; 50 to 350 pbw of a curing composition comprising an aromatic dianhydride and a monoanhydride; wherein the monoanhydride is maleic anhydride, phthalic anhydride, hexahydro-o-phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, tetrachlorophthalic anhydride, trimellitic anhydride, hexahydrophthalic anhydride, or a combination thereof, preferably methyltetrahydrophthalic anhydride; wherein the aromatic dianhydride is of formula (2) wherein T is a group of the formula -0-Z-0-; wherein an anhydride equivalent ratio of the aromatic dianhydride to the monoanhydride is 0.05:1 to 4:1, or 0.11:1 to 1:1; wherein a stoichiometric ratio between anhydride groups of the curing composition and epoxy groups of the epoxy resin composition is 0.4:1 to 1.2:1, or 0.6:1 to 1:1; and a curing catalyst; wherein the curing catalyst comprises a substituted or unsubstituted C_3.6 heterocycle comprising 1 to 4 ring heteroatoms, wherein each heteroatom is independently the same or different, and is nitrogen or oxygen, preferably a C3.4 five- membered ring wherein the ring heteroatoms are one or two nitrogen atoms; wherein the adhesive composition after curing has a glass transition temperature of 200 to 260°C, or 220 to 260°C, as determined by DMA; and wherein the adhesive composition after curing has an adhesive strength of greater than or equal 32 MPa, or greater than or equal to 34 MPa, as determined in accordance with ASTM D1002, and wherein the adhesive composition is prepared by contacting the aromatic dianhydride and the monoanhydride under conditions effective to form the curing composition; and contacting the curing composition, the epoxy resin composition, and the curing catalyst at a temperature of 40 to 80°C to form the adhesive composition.

[0056] In another aspect, the adhesive composition includes 100 pbw of an epoxy resin composition, wherein the epoxy resin composition includes a bisphenol A epoxy resin, a bisphenol F epoxy resin, a bisphenol S epoxy resin, a triglycidyl-substituted epoxy resin, a tetraglycidyl- substituted epoxy resin, or a combination thereof, preferably tetraglycidyldiaminodiphenylmethane; 50 to 350 pbw of a curing composition comprising an aromatic dianhydride and a monoanhydride; wherein the monoanhydride is maleic anhydride, phthalic anhydride, hexahydro-o-phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, tetrachlorophthalic anhydride, trimellitic anhydride, hexahydrophthalic anhydride, or a combination thereof, preferably methyltetrahydrophthalic anhydride; wherein the aromatic dianhydride is of formula (2) wherein T is a group of the formula - O-Z-O-; wherein an anhydride equivalent ratio of the aromatic dianhydride to the monoanhydride is 0.11:1 to 1:1; wherein a stoichiometric ratio between anhydride groups of the curing composition and epoxy groups of the epoxy resin composition is 0.6:1 to 1:1; and a curing catalyst; wherein the curing catalyst comprises a C3.4 five-membered ring wherein the ring heteroatoms are one or two nitrogen atoms; wherein the adhesive composition after curing has a glass transition temperature of 220 to 260°C, as determined by DMA; and wherein the adhesive composition after curing has an adhesive strength of greater than or equal 32 MPa, or greater than or equal to 34 MPa, as determined in accordance with ASTM D1002, and wherein the adhesive composition is prepared by contacting the aromatic dianhydride and the monoanhydride under conditions effective to form the curing composition; and contacting the curing composition, the epoxy resin composition, and the curing catalyst at a temperature of 40 to 80°C to form the adhesive composition.

[0057] In another aspect, the adhesive composition includes 100 pbw of an epoxy resin composition, wherein the epoxy resin composition includes a triglycidyl-substituted epoxy resin, a tetraglycidyl-substituted epoxy resin, or a combination thereof, preferably tetraglycidyldiaminodiphenylmethane; 50 to 350 pbw of a curing composition comprising an aromatic dianhydride and a monoanhydride; wherein the monoanhydride is hexahydro-o-phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, or a combination thereof, preferably methyltetrahydrophthalic anhydride; wherein the aromatic dianhydride is of formula (2) wherein T is a group of the formula -0-Z-0-; wherein an anhydride equivalent ratio of the aromatic dianhydride to the monoanhydride is 0.11 : 1 to 1:1; wherein a stoichiometric ratio between anhydride groups of the curing composition and epoxy groups of the epoxy resin composition is 0.6:1 to 1:1; and a curing catalyst; wherein the curing catalyst comprises a C_3.4 five-membered ring wherein the ring heteroatoms are one or two nitrogen atoms; wherein the adhesive composition after curing has a glass transition temperature of 220 to 260°C, as determined by DMA; and wherein the adhesive composition after curing has an adhesive strength of greater than or equal 32 MPa, or greater than or equal to 34 MPa, as determined in accordance with ASTM D1002, and wherein the adhesive composition is prepared by contacting the aromatic dianhydride and the monoanhydride under conditions effective to form the curing composition; and contacting the curing composition, the epoxy resin composition, and the curing catalyst at a temperature of 40 to 80°C to form the adhesive composition.

[0058] In another aspect, the adhesive composition includes 100 pbw of an epoxy resin composition including a tetraglycidyl-substituted epoxy resin, preferably tetraglycidyldiaminodiphenylmethane, more preferably wherein the epoxy resin composition consists of tetraglycidyldiaminodiphenylmethane; 50 to 350 pbw of a curing composition comprising an aromatic dianhydride and a monoanhydride; wherein the monoanhydride is methyltetrahydrophthalic anhydride; wherein the aromatic dianhydride is bisphenol-A dianhydride; wherein an anhydride equivalent ratio of the aromatic dianhydride to the monoanhydride is 1:9 to 3:7; wherein a stoichiometric ratio between anhydride groups of the curing composition and epoxy groups of the epoxy resin composition is 0.7:1 to 0.9:1, or 0.8:1; and a curing catalyst; wherein the curing catalyst is 2-ethyl-4-methylimidazole; wherein the adhesive composition after curing has a glass transition temperature of 220 to 260°C, as determined by DMA; and wherein the adhesive composition after curing has an adhesive strength of greater than or equal 32 MPa, or greater than or equal to 34 MPa, as determined in accordance with ASTM D1002, and wherein the adhesive composition is prepared by contacting the aromatic dianhydride and the monoanhydride under conditions effective to form the curing composition; and contacting the curing composition, the epoxy resin composition, and the curing catalyst at a temperature of 40 to 80°C to form the adhesive composition.

[0059] The adhesive composition or cured product thereof can be used in a variety of applications and articles, including any applications where conventional epoxide adhesives are 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, such as to provide an adhesive layer, the adhesive composition can be deposited on a surface of a variety of underlying substrates. For example, the adhesive composition can be deposited on a surface of metals, plastics, glass, fiber sizings, ceramics, stone, wood, or any combination thereof. The adhesive composition 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 aspects, the coated metal is aluminum or steel.

[0060] Articles can be manufactured by shaping the adhesive composition; and curing the adhesive composition as provided herein. Exemplary methods for shaping and/or curing the adhesive 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 adhesive composition into a mold, and curing the composition at 150 to 250°C in the mold.

[0061] Articles that can be prepared using the adhesive compositions include, for example, electrical components and computer components. Other 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 adhesive compositions can be used for the production of composite materials for use in the aerospace industry. The adhesive compositions can be used in forming composites used for printed circuit boards. Methods of forming composites for use in printed circuit boards 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.

[0062] Additional applications and uses 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 electrorefming 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.

[0063] Methods of forming a composite can include impregnating a reinforcing structure with the adhesive 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 adhesive 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, “Famborough 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.

[0064] The method of forming the composite comprises partially curing the adhesive 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 adhesive 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 adhesive composition” refer to an adhesive 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 achieved, for example, by subjecting the adhesive composition-impregnated reinforcing structure to a temperature of 133 to 140°C for 4 to 10 minutes.

[0065] Commercial-scale methods of forming composites are known in the art, and the adhesive 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 adhesive 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. [0066] While the above-described articles and 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.

[0067] The method for the manufacture of the article can include shaping the adhesive 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, such as epoxy adhesive 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.

[0068] This disclosure is further illustrated by the following examples, which are non- limiting.

EXAMPLES

[0069] Materials used in the examples are described in Table 1.

Table 1

[0070] Glass transition temperature (T_g) was measured on an RDA III dynamic mechanical analyzer (DMA) from TA Instruments. The samples with 40 mm ^c 4 mm ^c 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. Adhesion strength was evaluated by means of a lab shear strength test according to ASTM D1002. Example 1

[0071] BISDA was combined with MTHPA at an anhydride equivalent ratio of 1:9, and mixed well at 23 °C. The mixture was held in an oil bath at 120°C and stirred to form a clear solution. Example 2

[0072] The same procedure as in Example 1 was used, except the anhydride equivalent ratio was 2:8.

Example 3

[0073] The same procedure as in Example 1 was used, except the anhydride equivalent ratio was 3:7.

Example 4

[0074] The blend of BISDA -MTHPA prepared in Example 1 was combined with TGDDM at an anhydride to epoxy ratio (A/E ratio) of 0.8:1 with mixing at 50°C. 1 wt% of 2,4-EMI was added while stirring. The resulting mixture was poured into a preheated mold (130°C) and then cured in the mold at 220°C for 90 minutes.

Example 5

[0075] The blend of BISDA-MTHPA prepared in Example 2 was combined with TGDDM at an A/E ratio of 0.8 with mixing at 50°C. 1 wt% of 2,4-EMI was added while stirring. The resulting mixture was poured into a preheated mold (130°C) and then cured in the mold at 220°C for 90 minutes.

Comparative Example 1

[0076] BTDA was combined with MTHPA at an anhydride equivalent ratio of 1:9, and mixed well at 23 °C. The mixture was held in an oil bath at 120°C and stirred, but no clear solution was obtained due to the poor solubility of BTDA in MTHPA. The resulting blend was not used for curing the epoxy resin.

Comparative Example 2

[0077] BPDA was combined with MTHPA at an anhydride equivalent ratio of 1:9, and mixed well at 23 °C. The mixture was held in an oil bath at 120°C and stirred, but no clear solution was obtained due to the poor solubility of BPDA in MTHPA. The resulting blend was not used for curing the epoxy resin.

Comparative Example 3

[0078] PMDA was combined with MTHPA at an anhydride equivalent ratio of 1:9, and mixed well at 23 °C. The mixture was held in an oil bath at 120°C and stirred, but no clear solution was obtained due to the poor solubility of PMDA in MTHPA. The resulting blend was not used for curing the epoxy resin.

Comparative Example 4

[0079] MTHPA was combined with TDGGM at an A/E ratio of 0.8 with mixing at 50°C. 1 wt% of 2,4-EMI was added while stirring. The resulting mixture was poured into a preheated mold (130°C) and then cured in the mold at 220°C for 90 minutes to afford a rigid and clear casting. Summary of Curing Packages [0080] Table 2 shows the components of the curing packages of Examples 1 to 3 and Comparative Examples 1 to 3.

Table 2

[0081] As shown in Table 2, a series of physical blends of MTHPA with different dianhydrides (BTDA, PMDA, BPDA, and BISDA) were prepared. The dianhydrides BTDA, PMDA, and BPDA had poor solubility in MTHPA, even at a loading of only 10%, and therefore could not be introduced into the curing package for the epoxy adhesive formulations. BISDA had good solubility in MTHPA at 120°C at A/E ratios of 1:9, 2:8, and 3:7, and the resulting curing packages were used for making the adhesive formulations of Examples 4 and 5, shown below. Adhesive Formulations

[0082] Table 3 shows the A/E ratio, T_g, and adhesion strength of the adhesive formulations of Examples 4 and 5, and Comparative Example 4.

Table 3

[0083] The high heat and adhesive properties of BISDA-containing adhesive formulations were characterized by glass transition temperature (T_g) and adhesion strength, respectively. As shown in Table 3, the samples including the BISDA-MTHPA curing packages (Examples 4 and 5) provided cured samples having increased T_g and adhesion strength compared to the cured sample prepared using a curing package of MTHPA alone (Comparative Example 4). Further increases to both T_g and adhesion strength were achieved in Example 5 using the higher loading of BISDA (20%) in the BISDA-MTHPA curing package. These results show the curing packages including BISDA and MTPHA can be used to provide epoxy adhesive formulations for high temperature applications, having high heat and adhesive properties that exceed those of epoxy adhesive formulations having MTHPA as a curing agent.

[0084] This disclosure further encompasses the following Aspects.

[0085] Aspect 1. An adhesive composition comprising: 100 parts by weight of an epoxy resin composition; 30-400 pbw, or 50-350 pbw, or 50-200 pbw of a curing composition comprising a monoanhydride and an aromatic dianhydride of formula (2) as provided herein; and a curing catalyst; wherein the adhesive composition after curing has a T_g of 180-260°C, or 200-260°C, or 220-260°C, as determined by DMA, wherein the adhesive composition after curing has an adhesive strength of greater than or equal to 30 MPa, or greater than or equal to 32 MPa, or greater than or equal to 34 MPa, as determined in accordance with ASTM D1002.

[0086] Aspect 2. wherein the adhesive composition is prepared by contacting the aromatic dianhydride and the monoanhydride under conditions effective to form the curing composition; and contacting the curing composition, the epoxy resin composition, and the curing catalyst at a temperature of 20 to 120°C, or 30 to 100°C, or 40 to 80°C, to form the adhesive composition.

[0087] Aspect 3. The adhesive composition of Aspect 2, wherein the contacting to form the curing composition is at a temperature of 50 to 200°C, or 80 to 180°C, or 100 to 160°C.

[0088] Aspect 4. The adhesive composition of Aspect 2 or 3, wherein the curing composition is a homogenous solution.

[0089] Aspect 5. The adhesive composition of any one of the preceding Aspects, wherein a stoichiometric ratio between anhydride groups of the curing composition and epoxy groups of the epoxy resin composition is 0.1:1 to 2.0:1, or 0.4:1 to 1.2:1, or 0.6:1 to 1:1.

[0090] Aspect 6. The adhesive composition of any one of the preceding Aspects, wherein an anhydride equivalent ratio of the aromatic dianhydride to the monoanhydride is 0.01:1 to 1:0.01, or 0.05:1 to 4:1, or 0.11:1 to 1:1.

[0091] Aspect 7. The adhesive composition of any one of the preceding Aspects, wherein the epoxy resin composition comprises an epoxy resin of formula (1) as provided herein; preferably wherein the epoxy resin is a bisphenol A epoxy resin, a bisphenol F epoxy resin, a bisphenol S epoxy resin, a triglycidyl-substituted epoxy resin, a tetraglycidyl-substituted 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, a biphenyl epoxy resin, a naphthalene epoxy resin, an isocyanurate epoxy resin, triphenylmethane epoxy resin, or a combination thereof; more preferably wherein the epoxy resin is tetraglycidyldiaminodiphenylmethane.

[0092] Aspect 8. The adhesive composition of any one of the preceding Aspects, wherein T is -O- or a group of the formula -O-Z-O- wherein Z is of the formula (3) as provided herein; even more preferably wherein the aromatic dianhydride is bisphenol-A dianhydride.

[0093] Aspect 9. The adhesive composition of any one of the preceding Aspects, wherein the monoanhydride is maleic anhydride, phthalic anhydride, hexahydro-o-phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyl-5-norbomene-2,3-dicarboxylic anhydride, cis-5-norbomene-endo-2,3- dicarboxylic anhydride, tetrachlorophthalic anhydride, trimellitic anhydride, hexahydrophthalic anhydride, or a combination thereof; preferably wherein the monoanhydride is methyltetrahydrophthalic anhydride.

[0094] Aspect 10. The adhesive composition of any one of the preceding Aspects, 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 C_3.6 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.

[0095] Aspect 11. The adhesive composition of any one 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.

[0096] Aspect 12. An adhesive composition, comprising: 100 parts by weight of an epoxy resin composition; 30 to 400 part by weight, or 50 to 350 parts by weight, or 50 to 200 parts by weight of a curing composition comprising a monoanhydride and an aromatic dianhydride of formula (2) as disclosed herein, and a curing catalyst, wherein the amounts are each based on the total parts by weight of the epoxy resin composition and the curing composition, and wherein the adhesive composition is prepared by: contacting the aromatic dianhydride and the monoanhydride under conditions effective to form the curing composition as a substantially homogenous solution; and contacting the curing composition, the epoxy resin composition, and the curing catalyst at a temperature of 20 to 120°C, or 30 to 100°C, or 40 to 80°C, to form the adhesive composition.

[0097] Aspect 13. The adhesive composition of Aspect 12, wherein the aromatic dianhydride and the monoanhydride are contacted at a temperature of 20 to 200°C, or 20 to 180°C, or 30 to 150°C, or 40 to 80°C to provide the curing composition as a homogenous solution.

[0098] Aspect 14. A method of manufacturing an adhesive composition of any one of Aspects 1 to 11, the method comprising: contacting the aromatic dianhydride and the monoanhydride at a temperature of 20 to 200°C, or 20 to 180°C, or 30 to 150°C, or 40 to 80°C to form the curing composition as a substantially homogenous solution, or as a homogenous solution; contacting the curing composition, the epoxy resin composition, and the curing catalyst under conditions effective to form the adhesive composition.

[0099] Aspect 15. An article comprising a cured product of the adhesive composition of any one of the preceding Aspects.

[0100] Aspect 16. The article of Aspect 15, 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.

[0101] 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.

[0102] All ranges are inclusive of the endpoints, and the endpoints are independently combinable with each other and are inclusive of the endpoints and all intermediate values. “Combinations” is inclusive of blends, mixtures, alloys, reaction products, and the like. The terms “a” and “an” and “the” do not denote a limitation of quantity and are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. “Or” means “and/or” unless clearly stated otherwise. Reference throughout the specification to “some aspects”, “an aspect”, and so forth, 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] The term "alkyl" means a branched or straight chain, unsaturated aliphatic hydrocarbon group. “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-). "Alkylene" means a straight or branched chain, saturated, divalent aliphatic hydrocarbon group (e.g., methylene (-CH₂-) or, propylene (-(CH₂)₃-)). “Cycloalkylene” means a divalent cycloalkyl group. “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. "Aryl" means an aromatic hydrocarbon group containing the specified number of carbon atoms. “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.

The prefix "halo" means a group or compound including one more of a fluoro, chloro, bromo, or iodo substituent. 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.

[0107] 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 (-N0₂), 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, cycloalkyl, C_5.18 cycloalkenyl, C_6-12 aryl, C_7-13 arylalkyl (e.g., benzyl), C₇ _i₂ alkylaryl (e.g., toluyl), C_4- heterocycloalkyl, C_3- heteroaryl, Ci_₆ alkyl sulfonyl (-S(=0)₂-alkyl), C_6-12 arylsulfonyl (-S(=0)₂-aryl), or tosyl (CTfCeTL_tSCh-), provided that the substituted atom’s normal valence is not exceeded. When a compound is substituted, the indicated number of carbon atoms is the total number of carbon atoms in the compound or group, excluding those of any substituents.

[0108] 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.

Claims

CLAIMS What is claimed is:

1. An adhesive composition, comprising:

100 parts by weight of an epoxy resin composition;

30 to 400 part by weight, or 50 to 350 parts by weight, or 50 to 200 parts by weight of a curing composition comprising a monoanhydride and an aromatic dianhydride of formula (2)

wherein T is -0-, -S-, -SO2-, -SO-, -C_yH_2y- wherein y is an integer 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-g alkyl groups, 1 to 8 halogen atoms, or a combination thereof; and a curing catalyst, wherein the amounts are each based on the total parts by weight of the epoxy resin composition and the curing composition, wherein the adhesive composition after curing has a glass transition temperature of 180 to 260°C, or 200 to 260°C, or 220 to 260°C, as determined by dynamic mechanical analysis, wherein the adhesive composition after curing has an adhesive strength of greater than or equal to 30 MPa, or greater than or equal to 32 MPa, or greater than or equal to 34 MPa, as determined in accordance with ASTM D1002.

2. The adhesive composition of claim 1, wherein the adhesive composition is prepared by contacting the aromatic dianhydride and the monoanhydride under conditions effective to form the curing composition; and contacting the curing composition, the epoxy resin composition, and the curing catalyst at a temperature of 20 to 120°C, or 30 to 100°C, or 40 to 80°C, to form the adhesive composition.

3. The adhesive composition of claim 2, wherein the contacting to form the curing composition is at a temperature of 50 to 200°C, or 80 to 180°C, or 100 to 160°C.

4. The adhesive composition of claim 2 or 3, wherein the curing composition is a homogenous solution.

5. The adhesive composition of any one of the preceding claims, wherein a stoichiometric ratio between anhydride groups of the curing composition and epoxy groups of the epoxy resin composition is 0.1:1 to 2.0:1, or 0.4:1 to 1.2:1, or 0.6:1 to 1:1.

6. The adhesive composition of any one of the preceding claims, wherein an anhydride equivalent ratio of the aromatic dianhydride to the monoanhydride is 0.01:1 to 1:0.01, or 0.05:1 to 4:1, or 0.11:1 to 1:1.

7. The adhesive composition of any one of the preceding claims, wherein the epoxy resin composition comprises an epoxy resin of formula (1)

wherein A is an organic or inorganic radical of valence n, X is oxygen or nitrogen, m is 1 or 2 and consistent with the valence of X, R is hydrogen or methyl, n is 1 to 8, or 2 or 3 or 4; preferably wherein the epoxy resin is a bisphenol A epoxy resin, a bisphenol F epoxy resin, a bisphenol S epoxy resin, a triglycidyl-substituted epoxy resin, a tetraglycidyl-substituted 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, a biphenyl epoxy resin, a naphthalene epoxy resin, an isocyanurate epoxy resin, triphenylmethane epoxy resin, or a combination thereof; more preferably wherein the epoxy resin is tetraglycidyldiaminodiphenylmethane.

8. The adhesive composition of any one of the preceding claims, wherein T is -O- or a group of the formula -O-Z-O- wherein Z is of the formula (3)

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; X^a is a single bond, -0-, -S-, -S(O)-, -S(0)₂-, -C(O)-, or a C _S organic bridging group, and p, q, and c are each independently integers of 0 to 4; more preferably wherein T is a group of the formula -O-Z-O- wherein Z is a divalent group of formulas (4a) or (4b)

wherein Q is -0-, -S-, -C(O)-, -SO₂-, -SO-, -P(R^c)(=0)- wherein R^c is a Ci-g alkyl or C_6-12 aryl, or -C_yH_2y- wherein y is an integer from 1 to 5 or a halogenated derivative thereof; even more preferably wherein the aromatic dianhydride is bisphenol-A dianhydride.

9. The adhesive composition of any one of the preceding claims, wherein the monoanhydride is maleic anhydride, phthalic anhydride, hexahydro-o-phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyl-5-norbomene-2,3-dicarboxylic anhydride, cis-5-norbomene-endo-2,3- dicarboxylic anhydride, tetrachlorophthalic anhydride, trimellitic anhydride, hexahydrophthalic anhydride, or a combination thereof; or wherein the monoanhydride is methyltetrahydrophthalic anhydride.

10. The adhesive composition of any one of the preceding claims, 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; or wherein the curing catalyst comprises a substituted or unsubstituted C_3.6 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.

11. The adhesive composition of any one of the preceding claims, further comprising an additive; or 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.

12. An adhesive composition, comprising:

100 parts by weight of an epoxy resin composition;

30 to 400 part by weight, or 50 to 350 parts by weight, or 50 to 200 parts by weight of a curing composition comprising a monoanhydride and an aromatic dianhydride of formula (2)

wherein T is -0-, -S-, -SO₂-, -SO-, -C_yH_2y- wherein y is an integer from 1 to 5 or a halogenated derivative thereof, or -O-Z-O- wherein Z is an aromatic C_6-24 monocyclic or polycyclic moiety optionally substituted with 1 to 6 Ci-g alkyl groups, 1 to 8 halogen atoms, or a combination thereof; and a curing catalyst, wherein the amounts are each based on the total parts by weight of the epoxy resin composition and the curing composition, and wherein the adhesive composition is prepared by: contacting the aromatic dianhydride and the monoanhydride under conditions effective to form the curing composition as a substantially homogenous solution; and contacting the curing composition, the epoxy resin composition, and the curing catalyst at a temperature of 20 to 120°C, or 30 to 100°C, or 40 to 80°C, to form the adhesive composition.

13. The adhesive composition of claim 12, wherein the aromatic dianhydride and the monoanhydride are contacted at a temperature of 20 to 200°C, or 20 to 180°C, or 30 to 150°C, or 40 to 80°C to provide the curing composition as a homogenous solution.

14. A method of manufacturing an adhesive composition of any one of claims 1 to 11, the method comprising: contacting the aromatic dianhydride and the monoanhydride, preferably at a temperature of 20 to 200°C, or 20 to 180°C, or 30 to 150°C, or 40 to 80°C, to form the curing composition as a substantially homogenous solution, or as a homogenous solution; and contacting the curing composition, the epoxy resin composition, and the curing catalyst under conditions effective to form the adhesive composition.

15. An article comprising a cured product of the adhesive composition of any one of the preceding claims, preferably wherein the article is a composite, a foam, a fiber, a layer, a coating, an encapsulant, an adhesive, a sealant, a prepreg, a casing, or a combination thereof.