WO2020028803A1

WO2020028803A1 - High heat diepoxy compounds, processes of making, and uses thereof

Info

Publication number: WO2020028803A1
Application number: PCT/US2019/044908
Authority: WO
Inventors: Prakash Sista
Original assignee: Sabic Global Technologies B.V.
Priority date: 2018-08-03
Filing date: 2019-08-02
Publication date: 2020-02-06

Abstract

A diepoxy phthalimidine of formula (2) wherein R¹, R², R^a, R^b, R¹³, R¹⁴, p, q, and c are as provided herein, wherein the diepoxy phthalimidine of formula (2) has a purity of greater than 60%, preferably greater than 70%, preferably greater than 80%, preferably greater than 90%, preferably greater than 95%, preferably greater than 98%, and preferably greater than 99% as determined by high performance liquid chromatography, or wherein the diepoxy phthalimidine of formula (2) has an epoxy equivalent weight of 1.0 to 1.5, preferably 1.0 to 1.2, more preferably 1.0 to 1.15, even more preferably 1.0 to 1.1 times relative to the theoretical EEW, or a combination of the purity and epoxy equivalent weight.

Description

HIGH HEAT DIEPOXY COMPOUNDS, PROCESSES OF MAKING, AND USES THEREOF BACKGROUND

[0001] Epoxy thermosets are generally formed from a mixture of one or more multifunctional epoxide compounds, which react with a hardening agent. This reaction allows for the growth of linear molecular weight of the polymer. The polymer thus formed can be cast into a specific shape and permanently hardened (cured) at a certain temperature. In their cured form, epoxy resins offer desirable properties including good adhesion to other materials, excellent resistance to corrosion and chemicals, high tensile strength, and good electrical resistance.

[0002] It is desirable to have epoxy resins of low viscosities, for example, for the production of articles using resin transfer molding processes to allow for short mold fill time. There remains a need for high heat epoxy resins having low viscosity for processability and high purity, as well as a need for methods for preparing such high heat epoxy resins.

BRIEF DESCRIPTION

[0003] Provided is a diepoxy phthalimidine of formula (2)

wherein R¹ and R² are each independently an epoxide-containing functional group; R^a and R^b at each occurrence are each independently halogen, C1-C12 alkyl, C2-C12 alkenyl, C₃-C₈ cycloalkyl, or C1-C12 alkoxy; p and q at each occurrence are each independently 0 to 4; R¹³ at each occurrence is independently a halogen or a Ci-C₆ alkyl group; c at each occurrence is independently 0 to 4; and R ¹⁴ is a Ci-C₆ alkyl; wherein the diepoxy phthalimidine of formula (2) has a purity of greater than 60%, preferably greater than 70%, preferably greater than 80%, preferably greater than 90%, preferably greater than 95%, preferably greater than 98%, and preferably greater than 99% as determined by high performance liquid chromatography, or wherein the diepoxy phthalimidine of formula (2) has an epoxy equivalent weight of 1.0 to 1.5, preferably 1.0 to 1.2, more preferably 1.0 to 1.15, even more preferably 1.0 to 1.1 times relative to the theoretical EEW, or a combination of the purity and epoxy equivalent weight.

[0004] Provided is a curable epoxy composition comprising: a diepoxy phthalimidine; and optionally an additional high heat epoxy compound, an auxiliary epoxy compound, or a combination thereof; and optionally further comprising an additive, preferably wherein the additive is a particulate filler, fibrous filler, antioxidant, heat stabilizer, light stabilizer, ultraviolet light stabilizer, ultraviolet light-absorbing compound, near infrared light-absorbing compound, infrared light- absorbing compound, plasticizer, lubricant, release agent, antistatic agent, anti-fog agent, antimicrobial agent, colorant, surface effect additive, radiation stabilizer, flame retardant, anti-drip agent, fragrance, a polymer different from the thermoset polymer, or a combination thereof.

[0005] A cured epoxy thermoset can be obtained by curing the curable epoxy

composition, preferably wherein the cured epoxy thermoset has a glass transition temperature of greater than or equal to 220 °C, preferably greater than or equal to 250 °C, even more preferably greater than or equal to 260 °C, as measured by differential scanning calorimetry. An article including the cured epoxy thermoset is also provided, preferably wherein the article is a composite, a foam, a fiber, a layer, a coating, an encapsulant, an adhesive, a sealant, a sizing resin, a prepreg, a casing, a component, or a combination thereof.

[0006] Also provided is a process for preparing a diepoxy phthalimidine of formula (2), the process including reacting a bisphenol of formula (1)

with epichlorohydrin or an epichlorohydrin analog in the presence of a phase transfer catalyst for a time and at a temperature to provide a first reaction mixture; adding a base to the first reaction mixture to provide a second reaction mixture; and agitating the second reaction mixture for a time and a temperature so as to provide an as-synthesized diepoxy phthalimidine of formula (2) and optionally purifying the as- synthesized diepoxy phthalimidine to result in a higher purity material or a change in the state of the material.

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

DETAILED DESCRIPTION

[0008] Disclosed are high heat diepoxy compounds, particularly diepoxy phthalimidine compounds, processes for making the high heat diepoxy compounds, epoxy resin compositions including the same, and thermosets prepared from the epoxy resin compositions. The processes for making the high heat diepoxy compound results in a compound of high purity. Certain diepoxy phthalimidine compounds further have low viscosity rendering them more processable than higher viscosity epoxy resins.

[0009] The diepoxy phthalimidine is of formula (2)

wherein R¹ and R² are each independently an epoxide-containing functional group; R^a and R^b at each occurrence are each independently halogen, C1-C12 alkyl, C2-C12 alkenyl, C₃-C₈ cycloalkyl, or C1-C12 alkoxy; p and q at each occurrence are each independently 0 to 4; R¹³ at each occurrence is independently a halogen or a Ci-C₆ alkyl group; c at each occurrence is independently 0 to 4; and R ¹⁴ is a Ci-C₆ alkyl; wherein the diepoxy phthalimidine of formula (2) has a purity of greater than 95%, preferably greater than 98%, and preferably greater than 99% as determined by high performance liquid chromatography (HPLC), or wherein the diepoxy phthalimidine of formula (2) has an epoxy equivalent weight of 1.0 to 1.5, preferably 1.0 to 1.2, more preferably 1.0 to 1.15, even more preferably 1.0 to 1.1 times relative to the theoretical EEW, or a combination of the purity and epoxy equivalent weight.

[0010] The process for preparing a diepoxy phthalimidine of formula (2) includes reacting a bisphenol of formula (1)

with epichlorohydrin or an epichlorohydrin analog in the presence of a phase transfer catalyst for a time and at a temperature to provide a first reaction mixture; adding a base to the first reaction mixture to provide a second reaction mixture, e.g. over a period of 15 minutes to 3 hours; and agitating the second reaction mixture for a time and a temperature so as to provide an as- synthesized diepoxy phthalimidine of formula (2), e.g. for 2 to 5 hours at 40 to 60°C; wherein the definitions for R^a, R^b, R¹³, R¹⁴, c, p, and q are as previously described. The resulting diepoxy phthalimidine of formula (2) has a purity of greater than 95%, greater than 98%, greater than 99.0%, preferably greater than 99.3%, preferably greater than 99.5%, and preferably greater than 99.6% as determined by HPLC.

[0011] For example, the process for preparing a diepoxy phthalimidine comprises reacting a bisphenol of formula (1) with epichlorohydrin or an epichlorohydrin analog in the presence of a phase transfer catalyst at a temperature of 40 to 60°C, preferably 40 to 50°C for 10 to 48 hours, preferably 15 to 36 hours, and more preferably 20 to 28 hours to form a first intermediate reaction mixture; removing unreacted epichlorohydrin/epichlorohydrin analog from the first intermediate reaction mixture by vacuum distillation to form a second intermediate reaction mixture; suspending the second intermediate reaction mixture in a water immiscible organic solvent, particularly a water immiscible organic solvent such as dichloromethane, followed by the slow addition of an aqueous alkali hydroxide or alkaline earth metal hydroxide solution to form a third intermediate reaction mixture; heating the third intermediate reaction mixture to 40 to 60°C, preferably 45 to 55°C for a time sufficient to convert any chlorohydrins present to epoxides to form a reaction mixture comprising diepoxy phthalimidine of formula (2), cooling the reaction mixture to ambient temperature or 17 to 25 °C and washing the reaction mixture with water until a neutral pH is achieved to form a neutralized solution; and isolating the diepoxy phthalimidine of formula (2) from the neutralized solution; wherein in formulas (1) and (2) R¹ and R² are each independently an epoxide-containing functional group; R^a and R^b at each occurrence are each independently halogen, C1-C12 alkyl, C2-C12 alkenyl, C₃-C₈ cycloalkyl, or C1-C12 alkoxy; p and q at each occurrence are each independently 0 to 4; R¹³ at each occurrence is independently a halogen or a Ci-C₆ alkyl group; c at each occurrence is independently 0 to 4; and R ¹⁴ is a Ci-C₆ alkyl.

[0012] In an embodiment, R¹ and R² are each independently

wherein R’ and R^3b are each independently hydrogen or C 1-12 alkyl, preferably hydrogen.

[0013] In an embodiment, the diepoxy phthalimidine compound has the formula (2a).

The diepoxy phthalimidine compound of formula (2a) is in the form of a white amorphous solid having a glass transition temperature (T_g) in the range of 50 to 55°C, for example 52°C. This compound demonstrates high heat properties upon curing in the presence of 4-aminophenyl sulfone and has lower viscosity compared to the high heat epoxy l,l-bis(4-epoxyphenyl)-N- phenylphthalimidine epoxy. In another embodiment, the diepoxy phthalimidine compound of formula (2a) is in the form of a liquid.

[0014] Prior methods of making the diepoxy phthalimidine compound of formula (2a) yield a product that is a viscous yellow liquid, indicative of low purity. The EEW of this lower purity material is 233 vs a theoretical value of 221 (ratio of 1.06). In comparison to this prior material, the diepoxy phthalimidine compound of formula (2a) prepared by the methods described herein yield a product of much higher purity, even without the need for column chromatography.

[0015] In an embodiment, isolating the diepoxy phthalimidine comprises removing the water immiscible organic solvent from the neutralized solution to form a mixture of diepoxy phthalimidine of formula (2) and an aqueous layer; and separating the diepoxy phthalimidine of formula (2) from the mixture and washing the diepoxy phthalimidine with a polar organic solvent, preferably an alkyl alcohol such as methanol, to obtain purified diepoxy phthalimidine of formula (2).

[0016] In another embodiment, isolating the diepoxy phthalimidine comprises concentrating the neutralized solution and isolating the diepoxy phthalimidine of formula (2), with optional purification by column chromatography.

[0017] In an embodiment, the reaction is conducted with epichlorohydrin or an epichlorohydrin analog, preferably epichlorohydrin. Exemplary epichlorohydrin analogs include epichlorohydrin substituted with one or two C_M 2 alky] groups at the carbon sharing the chlorine atom or the bromine analog thereof.

[0018] Suitable phase transfer catalysts include quaternary ammonium salts such as tetrabutylammonium bromide, methyltrioctylammonium chloride, methyltrialkyl(C₈- Cio)ammonium chloride, hexaethylguanidinium chloride (HEGC1) or hexa-n-propylguanidinium chloride (HPGC1), and the like. Suitable amounts of catalyst include 1 to 60 mole percent based on the moles of bisphenol of formula (1), preferably 3 to 50 mole percent, preferably 5 to 40 mole percent, preferably 10 to 30 mole percent, and preferably 15 to 20 mole percent.

[0019] The reaction step of removing unreacted epichlorohydrin or epichlorohydrin analog from the first intermediate reaction mixture by vacuum distillation can be conducted at a temperature of 40 to 60°C, preferably 45 to 55°C, and more preferably 50°C.

[0020] Suitable water immiscible organic solvents for use in the reaction include halogenated alkyls such as dichloromethane. [0021] In the step of heating the third intermediate reaction mixture in the presence of an aqueous alkali hydroxide or alkaline earth metal hydroxide for a time sufficient to convert any chlorohydrins present to epoxides, the completion of the conversion can be monitored using any suitable analytical method, e.g. HPLC.

[0022] The alkali hydroxide or alkaline earth metal hydroxide used to prepare the aqueous alkali hydroxide or alkaline earth metal hydroxide solution can be sodium or potassium hydroxide, or barium hydroxide.

[0023] The diepoxy phthalimidine compounds can have a metal impurity content of 3 ppm or less, 2 ppm or less, 1 ppm or less, 500 ppb or less, 400 ppb or less, 300 ppb or less, 200 ppb or less, or 100 ppb or less. The metal impurities may be iron, calcium, zinc, aluminum, or a combination thereof. The diepoxy phthalimidine compounds can have an unknown impurities content of 0.1 wt% or less. The diepoxy phthalimidine compounds can have a color APHA value of 40 or less, 30 or less, 20 or less, 18 or less, 16 or less, or 15 or less, as measured according to ASTM D1209. The diepoxy phthalimidine can have a residual halide content of less than 2 wt%, preferably less than 1 wt%, more prepferably less than 0.5 wt% based on the total weight of the diepoxy phthalimidine.

[0024] The diepoxy phthalimidine compounds can be substantially free of epoxide oligomer impurities. These epoxides can have an oligomer impurity content of less than or equal to 3%, less than or equal to 2%, less than or equal to 1%, less than or equal to 0.5%, less than or equal to 0.4%, less than or equal to 0.3%, less than or equal to 0.2%, or less than or equal to 0.1%, as determined by high performance liquid chromatography. The diepoxy phthalimidine compounds can have an epoxy equivalent weight corresponding to purity of the bisepoxide of 95% purity or greater, 96% purity or greater, 97% purity or greater, 98% purity or greater, 99% purity or greater, or 100% purity. Epoxy equivalent weight (EEW) is the weight of material in grams that contains one mole of epoxy groups. It is also the molecular weight of the compound divided by the number of epoxy groups in one molecule of the compound. The diepoxy phthalimide compounds can have an epoxy equivalent weight of 1.0 to 1.5, preferably 1.0 to 1.2, more preferably 1.0 to 1.15, even more preferably 1.0 to 1.1 times relative to the theoretical EEW.

[0025] The diepoxy phthalimidine compound can be formed into an epoxy resin composition, optionally in combination with other additional high heat epoxy compounds, auxiliary epoxy compounds, or a combination thereof to form resin blends. In an embodiment, the epoxy resin composition forms a homogenous amorphous blend with a single glass transition temperature. Exemplary additional high heat epoxy compounds include those of formulas (11) to (17)

wherein R¹ and R² are each independently an epoxide-containing functional group; R^c and R^d are each independently a C_1-12 alkyl, C_2-12 alkenyl, C_3-8 cycloalkyl, or C_1-12 alkoxy; each R^f is hydrogen or both R_f together are a carbonyl group; each R³ is independently Ci_-6 alkyl; each R⁴ is independently hydrogen, Ci_-6 alkyl, or phenyl optionally substituted with 1 to 5 Ci_-6 alkyl groups; R¹⁵ is hydrogen or phenyl optionally substituted with 1 to 5 Ci_-6 alkyl groups; R⁶ is independently C_1-3 alkyl, or phenyl, preferably methyl; X^a is a C₆-i₂ polycyclic aryl, C_3-18 mono- or polycycloalkylene, C_3-18 mono- or polycycloalkylidene, -C(R^f)(R^g)- wherein R^f is hydrogen, C_1-12 alkyl, or C₆-i₂ aryl and R^g is C₆-io alkyl, C₆-s cycloalkyl, or C₆-i₂ aryl, or -(Q^a)_x-G-(Q^b)_y- group, wherein Q^a and Q^b are each independently a C_1-3 alkylene, G is a C_3-10 cycloalkylene, x is 0 or 1, and y is 0 or 1, and j, m, and n are each independently 0 to 4.

[0026] In an embodiment, R¹ and R² are each independently

wherein R^Ja and R ^b are each independently hydrogen or€_1-12 alkyl, preferably hydrogen.

[0027] In an embodiment, R^c and R^d are each independently a C_1-3 alkyl, or C_1-3 alkoxy, each R⁶ is methyl, each R³ is independently C_1-3 alkyl, R⁴ and R¹⁵ is phenyl, each R⁶ is independently C_1-3 alkyl, or phenyl, preferably methyl, X^a is a C₆-i₂ polycyclic aryl, C_3-18 mono- or polycycloalkylene, C_3-18 mono- or polycycloalkylidene, -C(R^f)(R^g)- wherein R^f is hydrogen, Ci-i₂ alkyl, or C₆-i₂ aryl and R^g is C₆-io alkyl, C₆-s cycloalkyl, or C₆-i₂ aryl, or -(Q¹)_x-G-(Q²)_y- group, wherein Q¹ and Q² are each independently a Ci_-3 alkylene and G is a C_3-10 cycloalkylene, x is 0 or 1, and y is 0 or 1, and j, m, and n are each independently 0 or 1.

[0028] Exemplary additional high heat epoxy compounds include those of formula (5a) and (7a) to (l7j)

wherein R¹, R², R^c, and R^d are the same as defined for formulas (1) to (7), each R⁷ is independently hydrogen or Ci_-4 alkyl, m and n are each independently 0 to 4, , R¹⁵ is phenyl optionally substituted with 1 to 5 Ci_-6 alkyl groups, and g is 0 to 10. In a specific embodiment each bond of the divalent group is located para to the linking group that is X^a.

[0029] In an embodiment, R^c and R^d are each independently a Ci_-3 alkyl, or Ci_-3 alkoxy, each R⁷ is methyl, each R⁸ is methyl, R¹⁵ is phenyl, and g is 0 to 4, and m and n are each independently 0 or 1.

[0030] In a preferred embodiment, the additional high heat epoxy compound is of formula (5b)

wherein R¹ and R² are as defined for formulas (1) to (7), R^c and R^d are each independently hydrogen or methyl, and R¹⁵ is phenyl. Preferably R¹ and R² are each independently of the formula

wherein R^3a and R^3b are each independently hydrogen or Ci_-4 alkyl, preferably hydrogen.

[0031] In an embodiment, the additional high heat epoxy compound has the formula (5c) or (7c).

[0032] The additional high heat epoxy compound can be prepared by methods described in, for example, WO2016/014536.

[0033] In certain embodiments, the additional high heat compound has a purity that is 95% or greater, preferably 97% or greater, preferably 99% or greater, as determined by high performance liquid chromatography (HPLC). WO 2016/014536A1 and US Publication

2015/041338 disclose that high purity epoxy with low oligomer content exhibits lower viscosity, which can facilitate fiber wet out during processing to make prepregs and laminates.

[0034] The additional high heat epoxy compound can have a metal impurity content of 3 ppm or less, 2 ppm or less, 1 ppm or less, 500 ppb or less, 400 ppb or less, 300 ppb or less, 200 ppb or less, or 100 ppb or less. The metal impurities may be iron, calcium, zinc, aluminum, or a combination thereof. The additional high heat epoxy compounds can have an unknown impurities content of 0.1 wt% or less. The additional high heat epoxy compounds can have a color APHA value of 40 or less, 35 or less, 30 or less, 25 or less, 20 or less, 19 or less, 18 or less, 17 or less, 16 or less, or 15 or less, as measured using test method ASTM D1209.

[0035] The additional high heat epoxy compounds can be substantially free of epoxide oligomer impurities. These epoxides can have an oligomer impurity content of less than or equal to 3%, less than or equal to 2%, less than or equal to 1%, less than or equal to 0.5%, less than or equal to 0.4%, less than or equal to 0.3%, less than or equal to 0.2%, or less than or equal to 0.1%, as determined by high performance liquid chromatography. The additional high heat epoxy compounds can have an epoxy equivalent weight corresponding to purity of the bisepoxide of 95% purity or greater, 96% purity or greater, 97% purity or greater, 98% purity or greater, 99% purity or greater, or 100% purity.

[0036] In embodiments, the auxiliary epoxy compound is an aliphatic epoxy compound, cycloaliphatic epoxy compound, aromatic epoxy compound, bisphenol A epoxy compound, bisphenol-F epoxy compound, phenol novolac epoxy polymer, cresol-novolac epoxy polymer, biphenyl epoxy compound, triglycidyl p-aminophenol, tetraglycidyl diamino diphenyl methane, polyfunctional epoxy compound, naphthalene epoxy compound, divinylbenzene dioxide compound, 2-glycidylphenylglycidyl ether, dicyclopentadiene-type epoxy compound, multi aromatic type epoxy polymer, bisphenol-S type epoxy compound, isocyanurate type epoxy compound, hydantoin type epoxy compound or a combination thereof. In embodiments, the auxiliary epoxy compound is a bisphenol A diglycidyl ether, a bisphenol F diglycidyl ether, a neopentylglycol diglycidyl ether, a 3, 4-epoxycyclohexylmethyl-3, 4-epoxycyclohexane carboxylate, a N,N-diglycidyl-4-glycidyloxyaniline, a N,N,N',N'-tetraglycidyl-4,4'- diaminodiphenylmethane, or a combination thereof.

[0037] The auxiliary epoxy compound can have formula

wherein A is an organic or inorganic radical of valence n, X^b is oxygen or nitrogen, u is 1 or 2 and consistent with the valence of X, R is hydrogen or methyl, v is 1 to 1000, specifically 1 to 8, more specifically 2 or 3 or 4.

[0038] Other auxiliary epoxy compounds include, for example, halogenated hydantoin epoxy compounds, triphenylmethane epoxy compounds, tetra phenyl-glycidyl-ether of tetraphenyl ethane (4 functionality epoxy compound), and novolac type epoxy compounds.

[0039] Auxiliary epoxy compounds include those having the following structures

wherein each occurrence of R is independently hydrogen or methyl; each occurrence of M is independently Ci-Cis hydrocarbylene optionally further comprising an oxirane, carboxy, carboxamide, ketone, aldehyde, alcohol, halogen, or nitrile; each occurrence of X is independently hydrogen, chloro, fluoro, bromo, or Ci-Cis hydrocarbyl optionally further comprising a carboxy, carboxamide, ketone, aldehyde, alcohol, halogen, or nitrile; each occurrence of B is independently a carbon-carbon single bond, Ci-Cis hydrocarbyl, C₁-C₁₂ hydrocarbyloxy, C₁-C₁₂ hydrocarbylthio, carbonyl, sulfide, sulfonyl, sulfinyl, phosphoryl, silane, or such groups further comprising a carboxyalkyl, carboxamide, ketone, aldehyde, alcohol, halogen, or nitrile; y is 1 to 20; and each occurrence of P and q is independently 0 to 20.

[0040] Auxiliary epoxy compounds for many applications include those produced by the reaction of epichlorohydrin or epibromohydrin with a phenolic compound. Suitable 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 (bisphenol A), 4,4’- isopropylidenebis(2,6-dibromophenol) (tetrabromobisphenol A), 4,4’-isopropylidenebis(2,6- dimethylphenol) (teramethylbisphenol A), and the like and mixtures thereof. In some embodiments, the auxiliary epoxy compound comprises a bisphenol A diglycidylether epoxy compound.

[0041] Other exemplary auxiliary epoxy compounds include /V-glycidyl phthalimide, 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, and phthalic acid diglycidyl ester.

[0042] Other auxiliary epoxy compounds include the glycidyl ethers of phenolic compounds such as the glycidyl ethers of phenol-formaldehyde novolac, alkyl substituted phenol-formaldehyde compounds including cresol-formaldehyde novolac, i-butylphenol- formaldehyde novolac, e c - b u t y 1 p h c n o 1 - fo m aldehyde novolac, / _<? r / - oc t y 1 p h c n o 1 - fo m aldehyde novolac, cumylphenol-formaldehyde novolac, decylphenol-formaldehyde novolac. Other useful auxiliary epoxy compounds 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, and the like, and mixtures thereof.

[0043] Other exemplary auxiliary epoxy compounds include the polyglycidyl ethers of polyhydric aliphatic alcohols. Examples of such polyhydric alcohols include l,4-butanediol, l,6-hexanediol, polyalkylene glycols, glycerol, trimethylolpropane, 2,2-bis(4- hydroxycyclohexyl)propane, and pentaerythritol.

[0044] Further exemplary auxiliary epoxy compounds 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 olefinically unsaturated compounds that contain these epoxide groups, such as, for example, glycidyl esters of acrylic or methacrylic acid, can be used.

[0045] Examples of further auxiliary epoxy compounds that can be used are those based on heterocyclic ring systems, for example hydantoin epoxy compounds, 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 compounds.

[0046] Other examples of auxiliary epoxy compounds are polyepoxides based on aromatic amines, such as aniline, for example N,N-diglycidylaniline, diaminodiphenylmethane and cycloaliphatic epoxy compounds such as 3,4-epoxycyclohexylmethyl-3,4- epoxycyclohexane carboxylate, 4,4'-(l,2-epoxyethyl)biphenyl, 4,4'-di(l,2-epoxyethyl)diphenyl ether, and bis(2,3-epoxycyclopentyl)ether.

[0047] Other examples of auxiliary epoxy compounds are mixed multifunctional epoxy compounds obtained from compounds that contain a combination of functional groups mentioned above, for example 4-aminophenol.

[0048] Examples of mono-functional auxiliary epoxy compounds include 2-ethylhexyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, t-butyl glycidyl ether, o-cresyl glycidyl ether, and nonyl phenol glycidyl ether.

[0049] Oxazolidinone-modified auxiliary epoxy compounds 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.

[0050] Auxiliary epoxy compounds can be prepared by condensation of an epoxy compound with a phenol such as a bisphenol. An 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 compound can be used. For example tetrabromobisphenol A can be condensed with bisphenol A diglycidyl ether to produce an oligomeric diglycidyl ether containing halogens.

[0051] The auxiliary epoxy compound can be a solid at room temperature. Thus, in some embodiments, the epoxy compound has a softening point of 25°C to l50°C. The auxiliary epoxy compound can be a liquid or a softened solid at room temperature. Thus, in some embodiments, the auxiliary epoxy compound has a softening point less than 25°C.

[0052] The epoxy resin composition comprising the diepoxy phthalimidine compound can further include a curing promoter. The term“curing promoter” as used herein encompasses compounds whose roles in curing epoxy compounds are variously described as those of a hardener, a hardening accelerator, a curing catalyst, and a curing co-catalyst, among others. The curing promoter can be an aromatic diamine compound.

[0053] In an embodiment, the epoxy resin composition includes a hardener. In an embodiment, the hardener is an amine compound. In embodiments, the amine compound can be 4-aminophenyl sulfone (DDS), 4,4’-methylenedianiline, diethyltoluenediamine, 4,4'- methylenebis(2,6-diethylaniline), m-phenylenediamine, p-phenylenediamine, 2,4-bis(p- aminobenzyl)aniline, 3, 5-diethyltoluene-2, 4-diamine, 3, 5-diethyltoluene-2, 6-diamine, m- xylylenediamine, p-xylylenediamine, a diethyl toluene diamine, or a combination thereof. In embodiments, the amine compound can be 4-aminophenyl sulfone (DDS), 4,4'-methylenebis- (2,6-diethylaniline) (MDEA), or a combination thereof. In an embodiment, the hardener is methyl-5-norbornene-2,3-dicarboxylic anhydride (NMA). The amount of curing promoter will depend on the type of curing promoter, as well as the identities and amounts of the other components of the epoxy resin composition. For example, when the curing promoter is an aromatic diamine amine compound, it can be used in an amount of 10 to 30 weight percent of the epoxy resin composition.

[0054] The curing promoter can be an aromatic dianhydride. In embodiments, the

aromatic dianhydride compound has the general structure

ean be a single bond,

, other bisphenols, -C(CF₃)₂-, -0-, or -C(=0)-.

[0055] Examples of curing promotors include 4,4'-(4,4'-isopropylidenediphenoxy)bis- (phthalic anhydride) (CAS Reg. No. 38103-06-9), 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (CAS Reg. No. 1107-00-2), 4,4'-oxydiphthalic anhydride (CAS Reg. No. 1823-59-2), benzophenone-3,3',4,4'-tetracarboxylic dianhydride (CAS Reg. No. 2421-28-5), and 3,3 ',4,4'- biphenyltetracarboxylic dianhydride (CAS Reg. No. 2420-87-3), and specifically compounds having the formulas below.

[0056] The curing promoter can be a bicyclic anhydride. In embodiments, the bicyclic anhydride compound can be methyl-5 -norbomene-2, 3 -dicarboxylic anhydride (CAS Reg. No. 25134-21-8) and cis-5-norbornene-endo-2,3-dicarboxylic anhydride (CAS Reg. No. 129-64-6) and specifically compounds having the formulas below.

[0057] In an embodiment, a cured sample of the epoxy resin composition including the diepoxy phthalimidine has a glass transition temperature of greater than or equal to 220 °C, preferably greater than or equal to 250 °C, even more preferably greater than or equal to 260 °C, as measured by differential scanning calorimetry. In an embodiment, a cured sample of the epoxy resin composition has a glass transition temperature between l50°C to 280°C as measured by differential scanning calorimetry. In an embodiment, a cured sample of the epoxy resin composition has a glass transition temperature between l70°C to 275°C as measured by differential scanning calorimetry. In an embodiment, a cured sample of the epoxy resin composition has a glass transition temperature between l75°C to 275°C, as measured by dynamic mechanical thermal analyzer. In an embodiment, a cured sample of the epoxy resin composition has a glass transition temperature between l90°C to 275°C, as measured by dynamic mechanical thermal analyzer. [0058] In an embodiment, the epoxy resin composition comprising diepoxy phthalimidine does not contain a solvent. The epoxy resin compositions can include a solvent to prepare homogeneous epoxy blends and then the solvent can be removed.

[0059] A method for curing the curable composition includes polymerizing and crosslinking the curable composition including the diepoxy phthalimidine described herein he curable compositions can be subjected to various treatments to cure the composition (e.g., initiate reaction of the diglycidyl ether with a curing promoter, such as a polyamine). There is no particular limitation on the method by which the composition can be cured. The composition can, for example, be cured thermally or by irradiation, including ultraviolet (UV) irradiation and electron beam irradiation. When heat curing is used, the temperature can be 80 to 300°C, and preferably 120 to 240°C. The heating can be for 1 minute to 10 hours, preferably 1 minute to 6 hours, more preferably 3 hours to 5 hours. The curing can be staged to produce a partially cured and often tack-free polymer, which then can be fully cured by heating for longer periods or temperatures within the aforementioned ranges.

[0060] The curable compositions can be used in a variety of forms for various purposes, including a composite (e.g. composite materials such as those using carbon fiber and fiberglass reinforcements), a foam, a fiber, a layer, a coating, an encapsulant, an adhesive, a sealant, a sizing resin, a prepreg, a casing, a component, or a combination comprising one or more of the foregoing. The cured epoxy thermosets can be used to form a number of articles in the aerospace, automobile, and other industries. In certain embodiments, the composite is a glass fiber based composite, a carbon fiber based composite, or a combination thereof.

[0061] Methods of forming a composite can include impregnating a reinforcing structure with a curable composition such as the epoxy resin composition; partially curing the curable composition to form a prepreg; and laminating a plurality of prepregs; wherein the curable composition comprises a disclosed compound, a curing promoter, optionally, an auxiliary co monomer, and optionally, one or more additional additives.

[0062] Applications for the epoxy resin compositions comprising diepoxy phthalimidine compound 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 toners 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] The compositions and methods described herein are further illustrated by the following non-limiting examples.

EXAMPLES

[0064] The materials used in the Examples are described in Table 1.

Table 1.

[0065] Compositions were tested using the test methods listed in Table 2. Unless indicated otherwise, all test methods are the test methods in effect as of the filing date of this application.

Table 2.

Example 1. Synthesis of N-methyl phenolphthalein diglycidyl ether (MPP-DGE)

[0066] MPPBP was reacted with epichlorohydrin in the presence of phase transfer catalyst ADOGEN at 50°C for 24 hours. Epichlorohydrin was removed by vacuum distillation at 50°C. The viscous liquid was diluted with DCM and 50% NaOH solution was added dropwise for 30-45 minutes. The reaction was heated to 50°C and continued until all the chlorohydrins were consumed based on monitoring the reaction process using HPLC. When the reaction is complete, the reaction mixture was cooled to room temperature, washed with water until a neutral pH is achieved. The organic layer was heated with 20% sodium sulfite solution at 100- l20°C to remove DCM to leave a viscous liquid floating in the aqueous layer. The viscous liquid was separated from aqueous layer. This viscous liquid can either be allowed to solidify or can be washed with MeOH to obtain a white powder of MPP-DGE with a purity of 98.9% measured using HPLC. The EEW of MPP-DGE was measured (by 'H NMR) to be 225.6 which is 1.02 times relative to the theoretical EEW. No column chromatography was used.

Example 2. Synthesis of N-methyl phenolphthalein diglycidyl ether (MPP-DGE)

[0067] MPPBP was reacted with epichlorohydrin in the presence of phase transfer catalyst ADOGEN at 50°C for 24 hours. Epichlorohydrin was removed by vacuum distillation at 50°C. The viscous liquid was diluted with DCM and 50% NaOH solution was added dropwise for 30-45 minutes. The reaction was heated to 50°C and continued until all the chlorohydrins were consumed based on monitoring the reaction progress using HPLC. When the reaction is complete, the reaction mixture was cooled to room temperature, washed with water until a neutral pH was achieved. The reaction mixture was concentrated and a solid product was obtained, which is purified by column chromatography to obtain a purity of 99.63% measured using HPLC. The EEW of MPP-DGE was measured (by 'H NMR) to be 223 which is 1.01 times relative to the theoretical EEW.

[0068] A further advantage of MPP-DGE obtained by the disclosed processes is that a targeted material state can be achieved. By tuning the synthesis, the MPP-DGE can be obtained as a crystalline material, an amorphous material, or a material exhibiting some degree of crystallinity.

[0069] Table 3 shows the product purity.

Table 3.

* Bl is mostly amorphous, contains small amount of crystalline fraction

** B2 has significantly higher crystallinity than Bl

Sample Preparation

[0070] In a general procedure to prepare test specimen castings, the high heat diepoxy compound is melted under nitrogen with an additional high heat epoxy compound or auxiliary epoxy compound, if used, to form an epoxy melt. Curing promoters are then mixed into to the epoxy melt and then treated to three cycles of vacuum/N₂ to form an epoxy resin composition. Viscosity measurements are made on the epoxy resin composition. To form the test specimen castings, the epoxy resin composition is poured into a mold and cured. The cured samples are removed from the mold and tested for T_g.

[0071] Table 4 reports the viscosity growth in castings maintained at l76.67°C (350°F) for blends of MPP-DGE and DDS compared to other blends. As shown, the viscosity of MPP- DGE + DDS is much lower than the viscosity of PPPBP-Epoxy + DDS. At the temperature studied, the viscosity increases quickly with time for TGDDM+DDS followed by of PPPBP- Epoxy + DDS and then MPP-DGE+DDS. A higher viscosity can translate to decreased flow, inadequate wetting of fiber reinforcing material in a composite material, a decrease in pot-life, and premature gelation, for example. Table 5 reports the thermal property comparision of cured castings of MPP-DGE and DDS compared to other blends. MPP-DGE demonstrates higher Tg and slower viscosity growth which leads to improved processability (longer high temperature pot-life) and better thermal properties.

Table 4.

Table 5.

[0072] The disclosure is further illustrated by the following non-limiting aspects.

[0073] Aspect 1. A diepoxy phthalimidine of formula (2) as provided herein, wherein R¹ and R² are each independently an epoxide-containing functional group; R^a and R^b at each occurrence are each independently halogen, C1-C12 alkyl, C2-C12 alkenyl, C₃-Cs cycloalkyl, or Ci-C 12 alkoxy; p and q at each occurrence are each independently 0 to 4; R¹³ at each occurrence is independently a halogen or a Ci-C₆ alkyl group; c at each occurrence is independently 0 to 4; and R¹⁴ is a Ci-C₆ alkyl; wherein the diepoxy phthalimidine of formula (2) has a purity of greater than 95%, preferably greater than 98%, and preferably greater than 99% as determined by high performance liquid chromatography, or wherein the diepoxy phthalimidine of formula (2) has an epoxy equivalent weight of 1.0 to 1.5, preferably 1.0 to 1.2, more preferably 1.0 to 1.15, even more preferably 1.0 to 1.1 times relative to the theoretical EEW, or a combination of the purity and epoxy equivalent weight.

[0074] Aspect 2. The diepoxy phthalimidine of Aspect 1, wherein R¹ and R² at each

occurrence are each independently

wherein R^3a and R^3b are each independently hydrogen or C1-12 alkyl, R¹⁴ is C1-2 alkyl, and c, p, and q are each 0; preferably wherein the

diepoxy phthalimidine is of formula

[0075] Aspect 3. The diepoxy phthalimidine of Aspect 1 or 2 in powder form or liquid form.

[0076] Aspect 4. The diepoxy phthalimidine of Aspect 1 or 2 in crystalline form or amorphous form.

[0077] Aspect 5. An epoxy composition comprising: a diepoxy phthalimidine of any one of Aspects 1 to 4; and optionally an additional high heat epoxy compound, an auxiliary epoxy compound, or a combination thereof; and optionally further comprising an additive, preferably wherein the additive is a particulate filler, fibrous filler, antioxidant, heat stabilizer, light stabilizer, ultraviolet light stabilizer, ultraviolet light- absorbing compound, near infrared light absorbing compound, infrared light-absorbing compound, plasticizer, lubricant, release agent, antistatic agent, anti-fog agent, antimicrobial agent, colorant, surface effect additive, radiation stabilizer, flame retardant, anti-drip agent, fragrance, a polymer different from the thermoset polymer, or a combination comprising one or more of the foregoing.

[0078] Aspect 6. The composition of Aspect 5, comprising 5 to 95 wt%, preferably 5 to 50 wt%, more preferably 5 to 25 wt%, even more preferably 5 to 10 wt% of the additional high heat epoxy compound, an auxiliary epoxy compound, or a combination thereof.

[0079] Aspect 7. The composition of Aspect 6, wherein the auxiliary epoxy compound is an aliphatic epoxy compound, cycloaliphatic epoxy compound, aromatic epoxy compound, bisphenol A epoxy compound, bisphenol-F epoxy compound, phenol novolac epoxy polymer, cresol-novolac epoxy polymer, biphenyl epoxy compound, triglycidyl p-aminophenol, tetraglycidyl diamino diphenyl methane, polyfunctional epoxy compound, naphthalene epoxy compound, divinylbenzene dioxide compound, 2-glycidylphenylglycidyl ether,

dicyclopentadiene epoxy compound, multi aromatic type epoxy polymer, or a combination thereof; preferably wherein the auxiliary epoxy compound is a bisphenol A diglycidylether, a bisphenol F diglycidylether, a neopentylglycol diglycidyl ether, a 3,4-epoxycyclohexylmethyl- 3, 4-epoxycyclohexane carboxylate, a /V,/V-diglycidyl-4-glycidyloxyaniline, a N,N,N',N'- tetraglycidyl-4,4'-diaminodiphenylmethane, or a combination thereof.

[0080] Aspect 8. The composition of any one of Aspects 5 to 7 wherein the composition forms a homogenous amorphous blend with a single glass transition temperature.

[0081] Aspect 9.The composition of any one of Aspect 5 to 7, further comprising a hardener, preferably wherein the hardener is an amine compound, an aromatic dianhydride, or a bicyclic anhydride, more preferably wherein the hardener is 4-aminophenyl sulfone, 4,4'- methylenebis-(2,6-diethylaniline), 4,4’- methylenedianiline, diethyltoluenediamine, 4,4'- methylenebis-(2,6-dimethylaniline), m-phenylenediamine, p-phenylenediamine, 2,4-bis(p- aminobenzyl)aniline, 3, 5-diethyltoluene-2, 4-diamine, 3, 5-diethyltoluene-2, 6-diamine, m- xylylenediamine, p-xylylenediamine, diethyl toluene diamines, methyl-5-norbornene-2,3- dicarboxylic anhydride, more preferably wherein the hardener is 4-aminophenyl sulfone, 4,4'- methylenebis-(2,6-diethylaniline), or a combination thereof.

[0082] Aspect 10. A cured epoxy thermoset obtained by curing the curable epoxy composition of any one of Aspects 5 to 9, preferably wherein the cured epoxy thermoset has a glass transition temperature of greater than or equal to 220 °C, preferably greater than or equal to 250 °C, even more preferably greater than or equal to 260 °C, as measured by differential scanning calorimetry.

[0083] Aspect 11. The cured epoxy thermoset of composition of Aspect 10, wherein the curing is at a temperature of 80 to 300°C for 1 minute to 10 hours.

[0084] Aspect 12. An article comprising the cured epoxy thermoset of Aspect 10 or 11, preferably wherein the article is a composite, a foam, a fiber, a layer, a coating, an encapsulant, an adhesive, a sealant, a sizing resin, a prepreg, a casing, a component, or a combination comprising one or more of the foregoing.

[0085] Aspect 13. A process for preparing a diepoxy phthalimidine of any one of Aspects 1 to 4, the process comprising reacting a bisphenol of formula (1) with epichlorohydrin or an epichlorohydrin analog in the presence of a phase transfer catalyst for a time and at a temperature to provide a first reaction mixture; adding a base to the first reaction mixture to provide a second reaction mixture, e.g. over a period of 15 minutes to 3 hours; and agitating the second reaction mixture for a time and a temperature so as to provide an as-synthesized diepoxy phthalimidine of formula (2) and optionally purifying the as-synthesized diepoxy phthalimidine to result in a higher purity material or a change in the state of the material.

[0086] Aspect 13A. The process of Aspect 13, wherein the reacting of the bisphenol with the epichlorohydrin analog is at 40 to 60°C, preferably 40 to 50°C for 10 to 48 hours, preferably 15 to 36 hours, and more preferably 20 to 28 hours.

[0087] Aspect l4.The process according to Aspect 13 or 13A, wherein the process optionally further comprises removing unreacted epichlorohydrin/epichlorohydrin analog from the first reaction mixture before adding the base, preferably by vacuum distillation, optionally at a temperature of 40 to 70°C, preferably 45 to 55°C, and more preferably 50°C.

[0088] Aspect 15. The method of any one of Aspect 13 or 14, wherein R¹ and R² at each

occurrence are each independently

diepoxy phthalimidine is of formula

[0089] The compositions, methods, and articles disclosed herein can alternatively comprise, consist of, or consist essentially of, any appropriate components or steps herein disclosed. The compositions, methods, and articles can additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any steps, components, materials, ingredients, adjuvants, or species that are otherwise not necessary to the achievement of the function and/or objectives of the compositions, methods, and articles.

[0090] All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. “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“an embodiment” means that a particular element described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. The described elements may be combined in any suitable manner in the various embodiments. 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.

[0091] 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 invention belongs. All cited patents, patent applications, and other references are incorporated herein by reference in their entirety.

[0092] 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.

[0093] 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, -C_nH_2n-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. “Alkylarylene” means an arylene group substituted with an alkyl group. “Arylalkylene” means an alkylene group substituted with an aryl group (e.g., benzyl). 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. “Substituted” means that the compound or group is substituted with at least one (e.g., 1, 2, 3, or 4) substituents that can each independently be a C_1-9 alkoxy, a C_1-9 haloalkoxy, a nitro (-NO₂), a cyano (-CN), a C_1-6 alkyl sulfonyl (-S(=0)₂-alkyl), a C₆-i₂ aryl sulfonyl (-S(=0)₂-aryl)a thiol (-SH), a thiocyano (-SCN), a tosyl (CH3C6H4SO2-), a C3-12 cycloalkyl, a C2-12 alkenyl, a C5-12 cycloalkenyl, a C₆-i2 aryl, a C-_7-13 arylalkylene, a C_4-12 heterocycloalkyl, and a C_3-12 heteroaryl instead of hydrogen, provided that the substituted atom’s normal valence is not exceeded. The number of carbon atoms indicated in a group is exclusive of any substituents. For example -CH₂CH₂CN is a C₂ alkyl group substituted with a nitrile.

[0094] 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 (-NO₂), 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-i2 aryl, C_7-i3 arylalkylene (e.g., benzyl), C_7-i2 alkylarylene (e.g., toluyl), C_4-12 heterocycloalkyl, C_3-12 heteroaryl, Ci_-6 alkyl sulfonyl (-S(=0)₂-alkyl), C₆-i₂ arylsulfonyl (-S(=0)₂-aryl), or tosyl (CH₃C₆H₄SO₂-), 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.

[0095] While particular embodiments 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. A diepoxy phthalimidine of formula (2)

wherein

R¹ and R² are each independently an epoxide-containing functional group;

R^a and R^b at each occurrence are each independently halogen, C1-C12 alkyl, C2-C12 alkenyl, C₃-Cs cycloalkyl, or C1-C12 alkoxy;

p and q at each occurrence are each independently 0 to 4;

R¹³ at each occurrence is independently a halogen or a Ci-C₆ alkyl group;

c at each occurrence is independently 0 to 4; and

R¹⁴ is a Ci-Ce alkyl;

wherein the diepoxy phthalimidine of formula (2) has a purity of greater than 95%, preferably greater than 98%, and preferably greater than 99% as determined by high performance liquid chromatography, or

wherein the diepoxy phthalimidine of formula (2) has an epoxy equivalent weight of 1.0 to 1.5, preferably 1.0 to 1.2, more preferably 1.0 to 1.15, even more preferably 1.0 to 1.1 times relative to the theoretical EEW, or a combination of the purity and epoxy equivalent weight.

2. The diepoxy phthalimidine of claim 1, wherein R¹ and R² at each occurrence are each independently

wherein R^3a and R^3b are each independently hydrogen or C1-12 alkyl, R¹⁴ is C1-2 alkyl, and c, p, and q are each 0;

preferably wherein the diepoxy phthalimidine is of formula (2a)

3. The diepoxy phthalimidine of claim 1 or 2 in powder form or liquid form.

4. The diepoxy phthalimidine of claim 1 or 2 in crystalline form or amorphous form.

5. A curable epoxy composition comprising:

a diepoxy phthalimidine of any one of claims 1 to 4; and

optionally an additional high heat epoxy compound, an auxiliary epoxy compound, or a combination thereof; and

optionally further comprising an additive, preferably wherein the additive is a particulate filler, fibrous filler, antioxidant, heat stabilizer, light stabilizer, ultraviolet light stabilizer, ultraviolet light- absorbing compound, near infrared light-absorbing compound, infrared light absorbing compound, plasticizer, lubricant, release agent, antistatic agent, anti-fog agent, antimicrobial agent, colorant, surface effect additive, radiation stabilizer, flame retardant, anti drip agent, fragrance, a polymer different from the thermoset polymer, or a combination thereof.

6. The composition of claim 5, comprising 5 to 95 wt%, preferably 5 to 50 wt%, more preferably 5 to 25 wt%, even more preferably 5 to 10 wt% of the additional high heat epoxy compound, an auxiliary epoxy compound, or a combination thereof.

7. The composition of claim 6,

wherein the auxiliary epoxy compound is an aliphatic epoxy compound, cycloaliphatic epoxy compound, aromatic epoxy compound, bisphenol A epoxy compound, bisphenol-F epoxy compound, phenol novolac epoxy polymer, cresol-novolac epoxy polymer, biphenyl epoxy compound, triglycidyl p-aminophenol, tetraglycidyl diamino diphenyl methane, polyfunctional epoxy compound, naphthalene epoxy compound, divinylbenzene dioxide compound,

2-glycidylphenylglycidyl ether, dicyclopentadiene epoxy compound, multi aromatic type epoxy polymer, or a combination thereof;

preferably wherein the auxiliary epoxy compound is a bisphenol A diglycidylether, a bisphenol F diglycidylether, a neopentylglycol diglycidyl ether, a 3,4-epoxycyclohexylmethyl- 3, 4-epoxycyclohexane carboxylate, a /V,/V-diglycidyl-4-glycidyloxyaniline, a N,N,N',N'- tetraglycidyl-4,4'-diaminodiphenylmethane, or a combination thereof.

8. The composition of any one of claims 5 to 7 wherein the composition forms a homogenous amorphous blend with a single glass transition temperature.

9. The composition of any one of claims 5 to 7, further comprising a hardener, preferably wherein the hardener is an amine compound, an aromatic dianhydride, or a bicyclic anhydride,

more preferably wherein the hardener is 4-aminophenyl sulfone, 4,4'-methylenebis-(2,6- diethylaniline), 4,4’- methylenedianiline, diethyltoluenediamine, 4,4'-methylenebis-(2,6- dimethylaniline), m-phenylenediamine, p-phenylenediamine, 2,4-bis(p-aminobenzyl)aniline,

3, 5-diethyltoluene-2, 4-diamine, 3, 5-diethyltoluene-2, 6-diamine, m-xylylenediamine, p- xylylenediamine, diethyl toluene diamines, methyl-5-norbomene-2,3-dicarboxylic anhydride, more preferably wherein the hardener is 4-aminophenyl sulfone, 4,4'-methylenebis-(2,6- diethylaniline), or a combination thereof.

10. A cured epoxy thermoset obtained by curing the curable epoxy composition of any one of claims 5 to 9, preferably wherein the cured epoxy thermoset has a glass transition temperature of greater than or equal to 220 °C, preferably greater than or equal to 250 °C, even more preferably greater than or equal to 260 °C, as measured by differential scanning

calorimetry.

11. The cured epoxy thermoset of composition of claim 10, wherein the curing is at a temperature of 80 to 300°C for 1 minute to 10 hours.

12. An article comprising the cured epoxy thermoset of claim 10 or 11, preferably wherein the article is a composite, a foam, a fiber, a layer, a coating, an encapsulant, an adhesive, a sealant, a sizing resin, a prepreg, a casing, a component, or a combination thereof.

13. A process for preparing a diepoxy phthalimidine of any one of claims 1 to 4, the process comprising

reacting a bisphenol of formula (1)

with epichlorohydrin or an epichlorohydrin analog in the presence of a phase transfer catalyst for a time and at a temperature to provide a first reaction mixture;

adding a base to the first reaction mixture to provide a second reaction mixture; and agitating the second reaction mixture for a time and a temperature so as to provide an as- synthesized diepoxy phthalimidine of formula (2) and optionally purifying the as-synthesized diepoxy phthalimidine to result in a higher purity material or a change in the state of the material.

14. The process according to claim 13, wherein the process optionally further comprises removing unreacted epichlorohydrin/epichlorohydrin analog from the first reaction mixture before adding the base, preferably by vacuum distillation.

15. The method of any one of claims 13 or 14,

wherein R¹ and R² at each occurrence are each independently

preferably wherein the diepoxy phthalimidine is of formula (2a)