Phthalonitrile resins, methods of making and compositions thereof

Abstract

The invention provides a functionalized phthalonitrile monomer obtained from a polyhydric phenol compound containing at least one furan or thiophene group and 4-nitrophthalonitrile. The functionalized phthalonitrile monomer can be used in a variety of thermoset compositions that can be cured to form thermoset polymers having good thermal and mechanical properties such as high thermal stability, heat resistance, high char yield, and enhanced structural rigidity.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 928,466, filed October 31, 2019, the entire contents of which are hereby expressly incorporated by reference.

[0003] Statement as to Federally Sponsored Research or Development

[0004] Not Applicable. TECHNICAL FIELD

[0005] The present invention relates generally to new phthalonitrile resins, methods of making such phthalonitrile resins, and their use in polymerizable thermoset compositions that can be used in a variety of industries, such as, but not limited to, the construction and structure, electronics packaging, energy and power generation, aerospace, transportation, and medical device industries. BACKGROUND

[0006] Phthalonitrile monomers are a new class of high performance monomers that are being developed for high temperature applications, such as the production of prepregs, laminates, and structural composite parts. For example, US 6,420,464, US 8,039,576, US 8,853,343, US 9,920,165, and US Patent Publication No. 2019 / 0047946 disclose various phthalonitrile monomers that are derived from the reaction of phenolic, aromatic diols with diphenylacetylene, polyphenols, and bisphenols from renewable sources. These phthalonitrile monomers have been found to possess excellent thermal and thermal-oxidative stabilities after curing, with initial decomposition temperatures greater than 450°C, and many other highly attractive performance characteristics, such as enhanced flame retardancy, the absence of a glass transition temperature before thermal decomposition, good mechanical properties at high temperatures, low absorption, good corrosion resistance, and favorable UV shielding properties.

[0007] However, due to the rigidity of the monomer precursors and the high degree of crosslinking in the final cured product, it is known that phthalonitrile monomers in the prior art are brittle. In addition, these phthalonitrile monomers are typically solids at room temperature and must therefore be melted prior to use. Furthermore, they can require higher than desired curing temperatures (e.g., greater than 250°C) and longer times to fully cure.

[0008] In an attempt to overcome these shortcomings, there have been attempts to adjust the chain length of the moieties between the phthalonitrile monomer units to lower their melting points and improve the flexibility of the cured product. Different types of catalysts have also been applied to improve the curing profile of these phthalonitrile monomers. Finally, to improve the processability, curing behavior, or final properties of the cured phthalonitrile product, US 5,939,508 and WO 2017105890 disclose the use of phthalonitrile monomers with epoxy resins or benzoxazine monomers to form hybrid systems. particular phthalonitrile monomer that copolymerizes with the zine resin.

[0009] It is desirable to further improve upon the art of phthalonitrile monomers by developing new phthalonitrile monomers that can be used in polymerizable thermoset compositions that exhibit better processability and cure behavior and result in cured products having improved thermal and mechanical properties. SUMMARY

[0010] The present invention provides, inter alia, a functionalized phthalonitrile monomer obtained from the reaction of (i) a polyphenolic compound comprising at least one furanyl or thienyl group and (ii) 4-nitrophthalonitrile.

[0011] According to another embodiment, there is provided a thermoset composition comprising a functionalized phthalonitrile monomer and a curing agent. In another embodiment, the thermoset composition can further comprise a second thermoset resin comprising at least one of a vinyl group, an ethynyl group, a maleimide group, an imino group, a cyano group, a zine group, or an epoxy group, wherein the functionalized phthalonitrile monomer is a "first" thermoset resin.

[0012] The thermoset composition of the present invention can be cured to form a thermoset polymer having improved thermal and mechanical properties. Accordingly, the thermoset composition can find use in a variety of applications, such as, but not limited to, the construction and structural, electronics packaging, military, energy and power generation, aerospace, transportation, and medical device industries. DETAILED DESCRIPTION

[0013] The present invention provides, inter alia, a functionalized phthalonitrile monomer obtained from the reaction of (i) a polyphenolic compound comprising at least one furanyl or thienyl group and (ii) 4-nitrophthalonitrile. It has been surprisingly discovered that the functionalized phthalonitrile monomers of the present invention provide several advantages over the prior art phthalonitrile monomers. For example, the functionalized phthalonitrile monomers of the present invention comprise furanyl / thienyl groups that are capable of homopolymerization and crosslinking to form a thermoset polymerization product having improved thermal and mechanical properties, such as increased thermal stability, heat resistance, char yield, and enhanced structural rigidity when cured. In addition, the functionalized phthalonitrile monomers of the present invention are capable of reacting with other unsaturated thermoset resins to further improve processability, cure behavior, and properties of the final cured product. Accordingly, the functionalized phthalonitrile monomers of the present invention exhibit a good balance of physical, mechanical, and thermal properties in both the uncured state and the cured state compared to the prior art phthalonitrile monomers.

[0014] The following terms shall have the following meanings:

[0015] ​The terms "comprising" and variations thereof as used in referring to a list of elements of steps, optionally does not preclude the presence or addition of one or more other elements, steps, or groups thereof. To the extent that any term in the present application, including the claims, is defined using alone or in combination with the term "comprising," also includes any other additional, standalone or auxiliary elements, steps, processes, etc. not specifically recited in the definition or referred to using the term "comprising" or variations thereof. To the extent that any term in the present application, including the claims, is defined using the term "comprising" or variations thereof, also includes the terms "consisting of" and "consisting essentially of."

[0016] The articles "a" and "an" are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. By way of example, "a functionalized phthalonitrile monomer" means one functionalized phthalonitrile monomer or more than one functionalized phthalonitrile monomer.

[0017] The phrases "in one aspect," "according to one aspect," etc. as used herein generally mean the particular feature, structure, or characteristic following the phrase is included in at least one aspect of the application, and can be included in more than one aspect of the application. Important

[0018] If the specification states a component or feature "may," "can," "might," or "could" be included or consist of or have a certain property, that particular component or feature is not required to be included or to have the property.

[0019] According to one aspect, the application provides a functionalized phthalonitrile monomer obtained from the reaction of (i) a polyphenolic compound comprising at least one furanyl or thiophenyl group and (ii) 4-nitrophthalonitrile.

[0020] The polyphenolic compound comprising at least one furanyl or thiophenyl group includes those obtained from a phenolic compound and a compound of general formula (1):

[0021]

[0022] wherein X is oxygen or sulfur, Q is hydrogen or a C1-C5 alkyl group, and j is an integer from 1 to 3. The compounds of general formula (1) include, but are not limited to, furfural, 3-furfural, 3-methylfurfural, 5-methylfurfural, 5-ethylfurfural, 2-thiophene- carboxaldehyde, 3-thiophene-carboxaldehyde, 3-methyl-2-thiophene-carboxaldehyde, and the like.

[0023] The phenolic compound can include, but is not limited to, phenol, cresol, xylenol (dimethyl phenol) such as 2,6-xylenol, trimethyl phenol, 2,5-alkyl phenol such as 2-tert-butyl-5-methyl-phenol or 2-tert-butyl-4-methyl phenol, allyl phenol, acetylenic phenol, octyl phenol, phenyl phenol, diphenyl phenol, guaiacol, hydroquinone, resorcinol, catechol, naphthol, dihydroxynaphthalene, methyl naphthol, bisphenol A, bisphenol F, and the like.

[0024] The compound of general formula (1) and the phenolic compound are not limited to those specifically cited above. In addition, the compound of general formula (1) and the phenolic compound can each be used alone or as a mixture of two or more.

[0025] The polyphenol compound containing at least one furan group or thiophene group can be prepared by a method generally known to one skilled in the art. For example, the phenolic compound can be condensed with the compound of general formula (1) in the presence of a base and optionally an alcohol or a monosubstituted benzene at a temperature of about 30 to 150°C or about 60 to 90°C. Generally, the amount of the phenolic compound and the compound of general formula (1) present during the condensation can be about 1.5 to 20 moles of the phenolic compound per 1 mole of the compound of general formula (1). In some embodiments, the amount of the phenolic compound and the compound of general formula (1) present during the condensation can be about 1.8 to 10 moles of the phenolic compound per 1 mole of the compound of general formula (1).

[0026] Examples of the base that can be used include, but are not limited to, alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide, and the like; alkaline earth metal hydroxides such as magnesium hydroxide, calcium hydroxide, and the like; alkali metal alkoxides such as sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, potassium tert-butoxide, and the like; and alkaline earth metal alkoxides such as magnesium methoxide, magnesium ethoxide, and the like. These bases can be used alone or in combination of two or more. The amount of these bases can be about 0.005 to 2.0 moles per 1 mole of the phenolic compound or about 0.01 to 1.1 moles per 1 mole of the phenolic compound.

[0027] The alcohol or monosubstituted benzene solvent that can be used includes, but is not limited to, methanol, ethanol, propanol, isopropanol, toluene, xylene, and the like, which can be used alone or as a mixture. When desired, the amount of such a solvent can be about 5 to 500 parts by weight per 100 parts by weight of the phenolic compound or about 10 to 300 parts by weight per 100 parts by weight of the phenolic compound.

[0028] The reaction can be carried out by adding a base to a mixture of the phenolic compound and the compound of formula (1) (and optionally an alcohol or monosubstituted benzene solvent) and heating the resulting mixture. Alternatively, the compound of formula (1) can be added to a mixture of the phenolic compound and a base (and optionally an alcohol or monosubstituted benzene solvent) under heating. The reaction time can be about 5 to 100 hours. After the reaction has run to completion, the reaction mixture can be neutralized. Any unreacted material can then be removed by filtration or under vacuum with heating.

[0029] According to one embodiment, the polyphenolic compound comprising at least one furanyl or thiophenyl group is selected from the group consisting of compounds of formulas (2) to (10):

[0030]

[0031] wherein n is an integer from about 3 to 3.2.

[0032] In another embodiment, the polyphenolic compound comprising at least one furanyl or thiophenyl group is derived from bisphenol A or bisphenol F and a compound of formula (1), wherein X is oxygen, and Q and j are as defined above.

[0033] The polyphenolic compound comprising at least one furanyl or thiophenyl group is then reacted with 4-nitrophthalonitrile to form the functionalized phthalonitrile monomer of the present application.

[0034] According to one embodiment, the polyphenolic compound comprising at least one furanyl or thiophenyl group is reacted with 4-nitrophthalonitrile in the presence of a catalyst and optionally a solvent. Examples of catalysts include, but are not limited to, the bases described above, as well as alkali metal salts such as cesium carbonate, potassium carbonate or sodium carbonate, organolithium reagents such as methyl or n-butyllithium, Grignard reagents, or any combination thereof. Examples of solvents that can be used include, but are not limited to, any polar or non-polar solvent such as acetone, acetonitrile, an alcohol, methyl ethyl ketone, methyl isobutyl ketone, dimethylformamide, n-methylpyrrolidinone, dimethylsulfoxide, hexamethylphosphoramide, or a combination thereof. In another embodiment, the solvent can be one that is capable of forming an azeotrope with water, such as toluene or xylene. It has been surprisingly found that these solvents can be used to aid in the removal of water present in the compounds forming the reaction mixture (i.e., the polyphenolic compound comprising at least one furan or thiophenyl group, 4-nitrophthalonitrile, and the base), as well as water formed during the reaction of the polyphenolic compound comprising at least one furanyl or thiophenyl group with 4-nitrophthalonitrile. The functionalized phthalonitrile can be purified by recrystallization from a mixture of the solvent and water to enrich the monomer content in the resulting product.

[0035] According to another embodiment, the polyphenolic compound comprising at least one furanyl or thiophenyl group and the functionalized phthalonitrile monomer can be formed in the same reaction vessel to improve overall process time and efficiency. In this embodiment, in a first step, a polyphenol comprising at least one furanyl or thiophenyl group is formed in a reaction vessel as described above. In a second step, 4-nitrophthalonitrile is added to the polyphenol comprising at least one furanyl or thiophenyl group in the reaction vessel to form the functionalized phthalonitrile monomer. The base, catalyst, and solvent applied in the reactions of the first and second steps can be the same or different. In some embodiments, the solvent is toluene or xylene.

[0036] The functionalized phthalonitrile monomers of the present application can be cured thermally to form thermoset polymers having a good balance of chemical, mechanical, and thermal properties. A curing agent can be applied to accelerate the formation of the thermoset polymer. Thus, according to one embodiment, a thermoset composition comprising a functionalized phthalonitrile monomer and a curing agent is provided.

[0037] The functionalized phthalonitrile monomer can be present in the thermoset composition in an amount of at least about 1 wt%, at least about 5 wt%, or at least about 10 wt%, or at least about 20 wt%, or at least about 30 wt%, or at least about 40 wt%, or at least about 50 wt%, or at least about 60 wt%, or at least about 70 wt%, or at least about 80 wt%, or at least about 90 wt%, or at least about 99 wt%, based on the total weight of the thermoset composition. In other embodiments, the functionalized phthalonitrile monomer can be present in the thermoset composition in an amount of about 1 wt% to about 99 wt%, or about 5 wt% to about 90 wt%, or about 10 wt% to about 80 wt%, or about 20 wt% to about 70 wt%, or about 30 wt% to about 60 wt%, based on the total weight of the thermoset composition.

[0038] Curing agents that can be applied include, but are not limited to, aromatic amines, primary amines, secondary amines, diamines, polyamines, amine-substituted phosphazenes, phenols, strong acids, organic acids, strong organic acids, inorganic acids, metals, metal salts, metal salt hydrates, metal compounds, halogen-containing aromatic amines, clays, and chemically modified clays. The application of clays or chemically modified clays can improve the mechanical and flammability properties of the thermoset. Typically, the chemical modification of clays involves the replacement of sodium ions with ammonium to form quaternary ammonium salts.

[0039] Specific curing agents include, but are not limited to, bis(4-(4- aminophenoxy)phenyl sulfone (p-BAPS), bis(4-(3-aminophenoxy)phenyl sulfone (m-BAPS), 1,4-bis(3-aminophenoxy)benzene (p-APB), 1,12-diaminododecane, diphenylamine, epoxy amine curing agents, 1,6-hexanediamine, 1,3- phenylenediamine, 1,4-phenylenediamine, p-toluenesulfonic acid, cuprous iodide, cuprous bromide, 1,3-bis(3-aminophenoxy)benzene (m-APB), 3,3'-dimethyl-4,4'- diaminodiphenyl sulfone, 3,3'-diethoxy-4,4'-diaminodiphenyl sulfone, 3,3'-dicarboxy-4,4'- diaminodiphenyl sulfone, 3,3'-dihydroxy-4,4'-diaminodiphenyl sulfone, 3,3'-disulfo-4,4'- diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'- dimethyl-4,4'-diaminobenzophenone, 3,3'-dimethoxy-4,4'-diaminobenzophenone, 3,3'- dicarboxy-4,4'-diaminobenzophenone, 3,3'-dihydroxy-4,4'-diaminobenzophenone, 3,3'- disulfo-4,4'-diaminobenzophenone, 4,4'-diaminodiphenyl ethyl phosphine oxide, 4,4'- diaminodiphenyl phenyl phosphine oxide, bis(3-aminophenoxy-4'-phenyl)phenyl phosphine oxide, methylene diphenylamine, hexakis(4-aminophenoxy)cyclotriphosphazene, 3,3'- dichloro-4,4'-diaminodiphenyl sulfone, 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl, 2,2'- bis(4-aminophenyl)hexafluoropropane, bis[4-(4-aminophenoxy)phenyl] 2,2'-hexafluoropropane, 1,1-bis(4-aminophenyl)-1-phenyl-2,2,2-trifluoroethane, 3,3'-dichloro-4,4'- diaminobenzophenone, 3,3'-dibromo-4,4'-diaminobenzophenone, aniline-2-sulfonic acid, 8- aniline-1-naphthalene sulfonic acid, benzenesulfonic acid, butylsulfonic acid, 10-camphorsulfonic acid, 2,5-diaminobenzenesulfonic acid, 6-dimethylamino-4-hydroxy-2- naphthalenesulfonic acid, 5-dimethylamino-1-naphthalenesulfonic acid, 4-hydroxy-3- nitroso-1-naphthalenesulfonic acid tetrahydrate, 8-hydroxyquinoline-5-sulfonic acid, methanesulfonic acid, phenylboronic acid, 1-naphthalenesulfonic acid, 2-naphthalenesulfonic acid, 1,5- naphthalenedisulfonic acid, 2,6-naphthalenedisulfonic acid, 2,7-naphthalenedisulfonic acid, picrylsulfonic acid hydrate, 2-pyridineethanesulfonic acid, 4-pyridineethanesulfonic acid, 3- pyridinesulfonic acid, 2-pyridylhydroxymethanesulfonic acid, aminobenzenesulfonic acid, 2- sulfobenzoic acid hydrate, 5-sulfosalicylic acid hydrate, 2,4-dimethylsulfonic acid, sulfonic acid-containing dyes, organic phosphorus-containing acids, phenyl phosphinic acid, diphenyl phosphinic acid, propyl phosphinic acid, 1-aminoethyl phosphinic acid, 4- aminophenyl phosphinic acid, butyl phosphinic acid, t-butyl phosphinic acid, 2-carboxyethyl phosphinic acid, 2-chloroethyl phosphinic acid, dimethyl phosphinic acid, ethyl phosphinic acid, methylenediphosphinic acid, methyl phosphinic acid, phosphonoacetic acid, bis(hydroxymethyl) phosphinic acid, chloromethyl phosphinic acid, di-n-butyl phosphinic acid, dichloromethyl phosphinic acid, diphenyl dithiophosphinic acid, 1,2-ethylenediphosphinic acid, n-hystaderyl phosphinic acid, hydroxymethyl phosphinic acid, n-octadecyl phosphinic acid, n-octyl phosphinic acid, phenyl phosphinic acid, propylenediphosphinic acid, n-tetradecyl phosphinic acid, concentrated sulfuric acid, phenyl phosphinic acid, copper, iron, zinc, nickel, chromium, molybdenum, vanadium, beryllium, silver, mercury, tin, lead, antimony, calcium, barium, manganese, magnesium, cobalt, palladium, platinum, cuprous bromide, cuprous cyanide, cuprocyanide, zinc chloride, zinc bromide, zinc iodide, zinc cyanide, zinc ferrocyanide, zinc acetate, zinc sulfide, silver chloride, ferrous chloride, ferric chloride, ferrocyanide, ferri chloride, cobalt chloride, cobalt sulfate, cobalt cyanide, nickel chloride, nickel cyanide, nickel sulfate, nickel carbonate, tin chloride, stannous chloride hydrate, stannous chloride dihydrate, aluminum nitrate hydrate, aluminum nitrate nonahydrate, triphenylphosphine oxide complex, montmorillonite, chemically modified montmorillonite, 4,4'-(1,3-phenylenedioxy)dianiline, 4,4'-(1,4-phenylenedioxy)dianiline, bis(4-(4- aminophenoxy)phenyl]sulfone, 4,4'-(4,4'-isopropylidenediphenyl-1,1'-diyldioxy)dianiline, 4,4'-(1,3- phenylenediisopropylidene)dianiline, 4,4'-(1,4-phenylenediisopropylidene)dianiline, 4,4'-(1,1'- biphenyl-4,4'-diyl dioxy)dianiline, 4,4'-methylene dianiline, 4,4'-sulfonyl dianiline, 4,4'- methylene-bis(2-methylaniline), 3,3'-methylene dianiline, 3,4'-methylene dianiline, 4,4'- oxydianiline, 4,4'-(isopropylidene)dianiline, 4,4'-(hexafluoroisopropylidene)dianiline, 4,4'- (hexafluoroisopropylidene)bis(p-phenyleneoxy)dianiline, 4,4'-diaminobenzophenone, the following compound:

[0040]

[0041] and mixtures thereof.

[0042] The curing agent can be present in the thermoset composition in an amount of at least about 0.5 wt%, or at least about 1 wt%, or at least about 2 wt%, or at least about 5 wt%, or at least about 10 wt%, at least about 15 wt%, or even at least about 20 wt%, based on the total weight of the thermoset composition. In other embodiments, the curing agent can be present in an amount of less than about 40 wt%, or less than about 35 wt%, or less than about 30 wt%, or less than about 25 wt%, based on the total weight of the thermoset composition. In other embodiments, the curing agent can be present in an amount of about 0.25 wt% to about 45 wt%, or about 1 wt% to about 40 wt%, based on the total weight of the thermoset composition.

[0043] The thermoset composition can also include a second phthalonitrile monomer other than those of the present application and optional additives to impart desired structural and / or thermal properties. The additives can include, but are not limited to, fillers such as carbon nanotubes, clays, carbon nanofibers, metal oxides, zinc oxide, diatomaceous earth, barium sulfate, talc, silica, calcium carbonate, calcium fluoride, and combinations thereof; colorants, antioxidants, stabilizers, thermal degradation stabilizers, light stabilizers, flow agents, thickening agents, leveling agents, adhesion agents, blowing agents, fungicides, bactericides, surfactants, plasticizers, rubber toughening agents, and other additives known to those skilled in the art. If present, these additives are added in an amount effective for the intended purpose.

[0044] The curing agent (and optional other phthalonitrile monomers and / or additives) can be added to the functionalized phthalonitrile monomer in any desired order and mixed using conventional equipment such as stirred vessels, stir rods, ball mills, sample mixers, static mixers, or ribbon mixers to form the thermoset composition. The composition can then be cured to form a thermoset polymer. As used herein, the term "curing" refers to the conversion of the above-described thermoset composition into an insoluble and infusible crosslinked product, either by shaping to form a shaped article such as a molded, pressed, or laminated article, or by forming a two-dimensional structure such as a coating, glaze, or adhesive layer. Typical curing methods include ambient temperature curing to high temperature curing using heat, radiation, or any combination of energy sources. Additionally, curing can be performed in one or more curing stages. Typical curing temperatures can range from about 50°C to about 500°C, such as from about 75°C to about 375°C, or from about 80°C to about 300°C, for a time sufficient to at least partially, or substantially, or completely cure the composition, for example, for a time ranging from 4 hours to 20 hours, or from 4 hours to 16 hours, or from 6 hours to 12 hours.

[0045] In another embodiment, the thermoset composition can include a curing agent that includes a vinyl group, an ethynyl group, a maleimide group, an imino group, a cyano group, a second thermoset resin having at least one of a triazine or an epoxy group. Combining the functionalized phthalonitrile monomer of the present invention with such a second thermoset resin will allow the thermoset composition to have a lower viscosity, a fast curing matrix, and a thermoset polymer after curing that has a variety of improved properties such as higher heat resistance, improved mechanical properties, lower water absorption, flame retardancy, and high char yield.

[0046] Thus, according to one particular embodiment, the functionalized phthalonitrile monomer of the present invention can be combined with a monofunctional benz triazine or a multifunctional benz triazine and any one or more curing agents and optional additives or a second phthalonitrile monomer other than the functionalized phthalonitrile monomer of the present invention to form a thermoset composition.

[0047] According to one embodiment, the monofunctional benz triazine is an ethynyl-containing benz triazine compound. Such ethynyl-containing benz triazine compounds are described in WO 1999 / 18092, the contents of which are incorporated herein by reference. Specifically, the ethynyl-containing benz triazine compound can be prepared from the reaction of a monophenolic compound, an aldehyde, and a primary amine.

[0048] The phenolic compound can be a monophenolic compound such as, but not limited to, phenol, cresol, 2-bromo-4-methylphenol, 2-allylphenol, 1,4- aminophenol, and the like. In one particular embodiment, the phenolic compound is phenol.

[0049] The aldehyde compound can be, but is not limited to, formaldehyde, oligomeric formaldehyde, polymeric formaldehyde, or a compound having the general formula R a CHO, wherein R a is a C1-C 12 aliphatic group. In one particular embodiment, the aldehyde compound is formaldehyde.

[0050] The primary amine can be an amine having 2 to 40 carbons and having one or more carbon-carbon triple bond groups and optionally O, N, S, or halogen heteroatoms. The intermediate between the nitrogen of the primary amine and the carbon-carbon triple bond group can optionally be a C1-C6alkyl group optionally substituted with an aromatic group having 6 to 12 carbons or an aromatic group having 6 to 12 carbons optionally substituted with a C1-C6alkyl group. The carbon-carbon triple bond group includes those having the general formula: -C≡CR d , -CH2-C≡CR d ,

[0051]

[0052] wherein Rd hydrogen, CrC5alkyl optionally substituted with an aromatic group having 6 to 12 carbons, or an aromatic group having 6 to 12 carbons optionally substituted with CrC5alkyl. In a particular embodiment, the primary amine having one or more carbon-carbon triple bonds is 3-aminophenylacetylene.

[0053] According to another embodiment, the polyfunctional benz oxazine is a compound having the general formula:

[0054]

[0055] wherein b is an integer from 2 to 4; each R is independently hydrogen, substituted or unsubstituted CrC 20 alkyl, substituted or unsubstituted C2-C 20 alkenyl, substituted or unsubstituted C6-C 20 aryl, substituted or unsubstituted C2-C 20 heteroaryl, substituted or unsubstituted C4-C 20 carbocyclic group, substituted or unsubstituted C2-C 20 heterocyclic group, or C3-C8cycloalkyl; each R1is independently hydrogen, CrC 20 alkyl, C2-C 20 alkenyl, or C6-C 20 aryl; and when b is 2, Z is a direct bond, substituted or unsubstituted CrC 20 alkyl, substituted or unsubstituted C6-C 20 aryl, substituted or unsubstituted C2-C 20 heteroaryl, O, S, S=O, O=S=O, or C=O; and when b is 3 or 4, Z is substituted or unsubstituted CrC 20 alkyl, substituted or unsubstituted C6-C 20 aryl, substituted or unsubstituted C2-C 20 heteroaryl. The substituents include, but are not limited to, hydroxy, CrC 20 alkyl, C2-C 10 alkoxy, thiol, C3-C8cycloalkyl, C6-C 14 heterocyclyl, C6-C 14 aryl, C6-C 14 heteroaryl, halogen, cyano, nitro, nitrone, amino, amido, acyl, oxyacyl, carboxyl, carbamato, sulfonyl, sulfonamide, and thioacyl.

[0056] According to one embodiment, the above polyfunctional benz oxazine compound is a compound obtained from the reaction of a polyfunctional phenolic compound, an aldehyde such as formaldehyde, and a primary amine.

[0057] The multifunctional phenolic compound can be, but is not limited to, resorcinol, bisphenol A, bisphenol F, bisphenol E, bisphenol S, 1,2,2,2-tetraphenyl ethane, thiodiphenol, phenolphthalein, dicyclopentadienyl diphenol, 1,8-hydroxyanthraquinone, 1,6-dihydroxynaphthalene, 2-2'-dihydroxyazobenzene, and 1,3,5-trihydroxybenzene.

[0058] The primary amine can be, but is not limited to, those primary amines having at least one carbon-carbon triple bond group as described above, as well as aniline, o-, m- and p-phenylenediamine, benzidine, 4,4'-diaminodiphenyl methane, cyclohexylamine, 1,4-diaminocyclohexyl, butylamine, methylamine, hexylamine, allylamine, furfurylamine, ethylene diamine, propylene diamine, and diamino diphenyl sulfone.

[0059] According to one embodiment, the thermoset composition can comprise a monofunctional benz oxazine or a multifunctional benz oxazine or a combination thereof and a functionalized phthalonitrile monomer, wherein the total weight ratio of benz oxazine to functionalized phthalonitrile monomer is about 1:1 to 10:1, or about 1.5:1 to 10:1, or about 2:1 to 10:1.

[0060] The thermoset composition can be prepared as described above, wherein the thermoset composition is formed by mixing at least one monofunctional benz oxazine or a multifunctional benz oxazine with a functionalized phthalonitrile monomer and, optionally, a curing agent, other phthalonitrile monomers other than the functionalized phthalonitrile monomer of the present application, and additives, using conventional equipment such as a stirred vessel, a stirring rod, a ball mill, a sample mixer, a static mixer, or a ribbon blender, in any order. The thermoset composition can then be cured as described above to form a thermoset polymer.

[0061] In another embodiment, a thermoset polymer is provided, which is obtained by contacting any suitable substrate with any one of the thermoset compositions described above, and curing the substrate / thermoset composition by subjecting the substrate / thermoset composition to heat, radiation, or a combination of various energy sources. In one embodiment, the thermoset composition of the present application can be used to bond one or more substrates together by contacting one or more surfaces of the same or different substrates to be bonded with the thermoset composition under conditions sufficient to cure the thermoset composition.

[0062] In an alternative embodiment, by curing the thermosetting composition of the present application, composite articles can be obtained by techniques well known in the industry, such as pultrusion, infusion, molding, encapsulation or coating. Thus, the thermosetting composition of the present application can be used in a process for the production of composite articles, such as castings, prepregs, bonded plates, laminates and metal foil clad laminates.

[0063] For certain applications, the properties of the composite article can be adjusted by the addition of reinforcing fibers. Examples of reinforcing fibers include glass, quartz, carbon, alumina, ceramic, metal, aramid, natural fibers (such as flax, jute, sisal, hemp), paper, acrylic and polyethylene fibers and mixtures thereof. The reinforcing fibers can be in any of a variety of patterns, such as, for example, tows or rovings formed of continuous fibers or discontinuous fibers (short fibers) in parallel in one direction, cloth such as woven or knitted mats, braids, unidirectional, bidirectional, random, pseudo-isotropic or three-dimensionally dispersed mats, non-homogeneous lattices or reticulated materials, and three-dimensional materials such as tri-axial woven fabrics.

[0064] Thus, in another embodiment, a process for the production of a composite article is provided, comprising the steps of: contacting a layer of reinforcing fibers with a thermosetting composition to coat and / or impregnate the reinforcing fibers; and curing the coated and / or impregnated reinforcing fibers to obtain a composite article.

[0065] Coating and / or impregnation can be carried out by a wet or hot melt process. In a wet process, the thermosetting composition is first dissolved in a solvent to reduce the viscosity, coating and / or impregnation of the reinforcing fibers is then carried out, and the solvent is evaporated using an oven or the like.

[0066] In a hot melt process, coating and / or impregnation can be carried out by directly coating and / or impregnating the reinforcing fibers with the thermosetting composition, which can be heated to reduce its viscosity, or alternatively, a coated film of the thermosetting composition is first obtained on a release paper or the like, and the film is placed on one or both sides of the reinforcing fibers, and heat and pressure are applied to carry out the coating and / or impregnation.

[0067] According to another aspect, a process for the production of a composite article in an RTM system is provided. The process comprises the steps of: a) introducing a fibrous preform comprising reinforcing fibers into a mold; b) injecting a thermosetting composition into the mold; c) allowing the thermosetting composition to impregnate the fibrous preform; d) heating the resin-impregnated preform for a period of time to obtain an at least partially cured solid article; and optionally e) further heating the partially cured solid article.

[0068] In another embodiment, a method of forming a composite article in a VaRTM system is provided. The method comprises the steps of: a) introducing a fiber preform comprising reinforcing fibers into a mold; b) injecting a thermoset composition into the mold; c) reducing the pressure within the mold; d) maintaining the mold at about the reduced pressure; e) allowing the thermoset composition to impregnate the fiber preform; f) heating the resin-impregnated preform to obtain an at least partially cured solid article; and optionally g) further heating the at least partially cured solid article.

[0069] In addition to RTM and VaRTM systems, the thermoset composition can be applied in other methods and systems to produce composite articles, including hot-pressing pre-preg, sheet molding compound, molding, casting, pultrusion, and filament winding.

[0070] In another embodiment, a thermoset polymer having a good balance of physical, mechanical, and thermal properties is provided by curing the thermoset composition. The properties of the thermoset polymer having a good balance according to the present application can include at least two of: a glass transition temperature (T g ) greater than about 250°C, or greater than about 270°C, or greater than about 290°C; a storage modulus greater than 3500 MPa, or greater than 3750 MPa, or greater than 4000 MPa; a viscosity at 75°C of less than 250 centipoise, or less than 200 centipoise, or less than 175 centipoise; and a char yield of at least 60%, or at least 65%, or at least 70%.

[0071] The thermoset composition and composite articles of the present application can be used in a variety of applications, for example, in aerospace applications, they can be used as primary structural materials for aircraft (main wings, tail wings, floor beams, etc.), secondary structural materials (flaps, ailerons, fairings, interior trim, etc.), rocket engine casings, satellites or other moving objects such as cars, boats, and train cars, for drive shafts, fuel cells, leaf springs, wind turbine blades, pressure vessels, flywheels, papermaking rolls, and civil engineering and construction materials (roofing materials, cables, rebar, retrofit materials, etc.).

[0072] Embodiments:

[0073] Example 1: Synthesis of Tetramethyl Bisphenol Furan

[0074]

[0075] To a 500 ml four necked round bottom flask equipped with a mechanical stirrer and reflux cooler was added 61.08 grams of 2,6-dimethylphenol and 32.04 grams of methanol. Then 2 grams of sodium hydroxide was added and stirred to dissolve. The resulting mixture was heated to reflux and 24.0 grams of furfural was added drop wise over a 2 hour time interval at reflux. The mixture was then refluxed for an additional 15 hours and conversion was monitored by HPLC, after which the mixture was neutralized with 35 grams of a 20% aqueous solution of sodium phosphate dibasic. The precipitated crystals were collected by filtration, washed with a 1 : 1 methanol / water solution and dried in a vacuum drying oven. 72.6 grams of tetramethyl bisphenol furan (90.8%) was obtained. The product was very pure (99.7%) as determined by HPLC.

[0076] Example 2: Synthesis of tetramethyl bisphenol furan terephthalonitrile

[0077]

[0078] To a 1000 mL four necked round bottom flask equipped with a thermometer, Dean-Stark trap with condenser and nitrogen inlet was added tetramethyl bisphenol furan from example 1 (32.2 grams, 0.1 moles), powdered K2CO3(33.2 grams, 0.24 moles), toluene (100 mL) and N,N-dimethylformamide (DMF) (146.1 grams). The resulting mixture was degassed with nitrogen and the mixture was heated to reflux at 140 °C for 10-12 hours. The toluene was then removed by distillation and the reaction mixture was cooled to 30 °C. 4-nitroterephthalonitrile (35.3 grams, 0.204 moles) was then added in one portion and the reaction mixture was heated at 80 °C and conversion was monitored by HPLC. The mixture was then cooled to ambient temperature and poured into cold deionized water to form a solid. The precipitated crystals were collected by filtration, washed with cold deionized water until neutral, and then washed with a 1 : 1 methanol / water solution. The resulting dark yellow solid was dried under vacuum to obtain 54.5 grams (95%) of the functionalized terephthalonitrile monomer product. The structure of this product was confirmed by analysis with LC-MS, GPC, NMR and FTIR. The LC-MS chromatogram, GPC scan, NMR and FT-IR spectra were all consistent with the target tetramethyl bisphenol furan terephthalonitrile product. The melting point of tetramethyl bisphenol furan terephthalonitrile was 219.6 °C.

[0079] Example 3: Functionalized terephthalonitrile monomer / benzoxazine

[0080] To a 4 oz glass jar was added 20 grams of phenol 3-aminophenyl acetylene benzoxazine ​benzoxazine. The glass jar was then placed in an 80 °C oven until the material melted, and then 6 grams of o-phthalonitrile (4,4'-(((furan-2-ylmethylene)bis(2,6-dimethyl-4,1- phenylene))bis(oxy))diphthalonitrile) was added to the glass jar with stirring. The resulting mixture was stirred occasionally until the added material was all dissolved in the melted benzoxazine. About 14 grams of the mixture was then transferred to an aluminum pan. After degassing at 65 °C, the mixture was step cured at 120 °C for 2 hours, 150 °C for 2 hours, 180 °C for 2 hours, and 200 °C for 2 hours. DSC of the freshly prepared sample and DMA, TGA of half of the cured product were determined. The other half of the cured product was further post cured at 250 °C for 3 hours, and DMA and TGA of this cured product were also determined. The results are shown in Table 1 below. benzoxazine. The glass jar was then placed in an 80 °C oven until the material melted, and then 6 grams of o-phthalonitrile (4,4'-(((furan-2-ylmethylene)bis(2,6-dimethyl-4,1- phenylene))bis(oxy))diphthalonitrile) was added to the glass jar with stirring. The resulting mixture was stirred occasionally until the added material was all dissolved in the melted benzoxazine. About 14 grams of the mixture was then transferred to an aluminum pan. After degassing at 65 °C, the mixture was step cured at 120 °C for 2 hours, 150 °C for 2 hours, 180 °C for 2 hours, and 200 °C for 2 hours. DSC of the freshly prepared sample and DMA, TGA of half of the cured product were determined. The other half of the cured product was further post cured at 250 °C for 3 hours, and DMA and TGA of this cured product were also determined. The results are shown in Table 1 below.

[0081] Example 4: Functionalized o-phthalonitrile monomer / benzoxazine benzoxazine

[0082] A 4 oz glass jar was charged with 12 grams of phenol 3-aminophenyl acetylene benzoxazine. The glass jar was then placed in an 80 °C oven until the material melted, and then 2.4 grams of o-phthalonitrile (4,4'-(((furan-2-ylmethylene)bis(2,6-dimethyl-4,1- phenylene))bis(oxy))diphthalonitrile) was added to the glass jar with stirring. The resulting mixture was stirred occasionally until the added material was all dissolved in the melted benzoxazine. About 12.5 grams of the mixture was then transferred to an aluminum pan. After degassing at 65 °C, the mixture was step cured at 120 °C for 2 hours, 150 °C for 2 hours, 180 °C for 2 hours, and 200 °C for 2 hours. DSC of the freshly prepared sample and DMA, TGA of half of the cured product were determined. The other half of the cured product was further post cured at 250 °C for 3 hours, and DMA and TGA of this cured product were also determined. The results are shown in Table 1 below. Example 4: Functionalized o-phthalonitrile monomer / benzoxazine benzoxazine

[0083] A 4 oz glass jar was charged with 12 grams of phenol 3-aminophenyl acetylene benzoxazine. The glass jar was then placed in an 80 °C oven until the material melted, and then 2.4 grams of o-phthalonitrile (4,4'-(((furan-2-ylmethylene)bis(2,6-dimethyl-4,1- phenylene))bis(oxy))diphthalonitrile) was added to the glass jar with stirring. The resulting mixture was stirred occasionally until the added material was all dissolved in the melted benzoxazine. About 12.5 grams of the mixture was then transferred to an aluminum pan. After degassing at 65 °C, the mixture was step cured at 120 °C for 2 hours, 150 °C for 2 hours, 180 °C for 2 hours, and 200 °C for 2 hours. DSC of the freshly prepared sample and DMA, TGA of half of the cured product were determined. The other half of the cured product was further post cured at 250 °C for 3 hours, and DMA and TGA of this cured product were also determined. The results are shown in Table 1 below.

[0084] Example 4: Functionalized o-phthalonitrile monomer / benzoxazine benzoxazine ​In a aziridine, approximately 12.5 g of the mixture was transferred into an aluminum dish. After degassing at 65°C, the mixture was cured stepwise under the following conditions: 120°C for 2 hours, 150°C for 2 hours, 180°C for 2 hours, and 200°C for 2 hours. The DSC of the freshly prepared sample and the DMA and TGA of half of the cured product were determined. The other half of the cured product was further post-cured at 250°C for 3 hours, and the DMA and TGA of this cured product were also determined. The results are shown in Table 1 below.

[0085] Example 6: Comparative Example

[0086] Add 14 grams of slightly polymerized phenol-3-aminophenylacetylenebenzylene to an aluminum pan. The aluminum disk was then placed in an 80°C vacuum oven for melting and degassing for 1 hour. After degassing, the material was cured stepwise under the following conditions: 120°C for 2 hours, 150°C for 2 hours, 180°C for 2 hours, and 200°C for 2 hours. The DSC of the newly prepared sample and the DMA and TGA of half of the cured product were determined. The other half of the cured product was further post-cured at 250°C for 3 hours, and the DMA and TGA of this cured product were also determined. The results are shown in Table 1 below.

[0087] Table 1

[0088]

[0089] While the preparation and application of various embodiments of the present invention have been described in detail, it should be understood that the present invention provides many applicable inventive concepts, which can be embodied in many specific contexts. The specific embodiments discussed herein are merely examples of specific methods for the preparation and application of the present invention and do not constitute a limitation thereof.

Claims

1. A thermosetting composition comprising: a functionalized phthalonitrile monomer; a thermosetting resin selected from a monofunctional benzoxazine or a mixture of a monofunctional benzoxazine and a polyfunctional benzoxazine; and a curing agent; wherein the functionalized phthalonitrile monomer is obtained from the reaction of (i) a polyphenolic compound containing at least one furanyl or thienyl group and (ii) 4-nitrophthalonitrile, wherein the polyphenolic compound is obtained from a phenolic compound and a compound of formula (1): ###0001### wherein X is oxygen or sulfur, Q is hydrogen or a C1-C5 alkyl group, and j is an integer from 1 to 3, wherein the phenolic compound includes cresol, xylenol, 2-tert-butyl-5-methyl- phenol, 2-tert-butyl-4-methylphenol, allylphenol, alkynylphenol, octylphenol, phenylphenol, diphenylphenol, guaiacol, hydroquinone, resorcinol, catechol, naphthol, dihydroxynaphthalene, methyl naphthol, bisphenol A, or bisphenol F, wherein the molar ratio of the phenolic compound to the compound of formula (1) is from 1.5 to 10, and wherein the monofunctional benzoxazine is an ethynyl group-containing benzoxazine compound.

2. The thermosetting composition according to claim 1, further comprising at least one of a second phthalonitrile monomer different from the functionalized monomer according to claim 1 and an additive.

3. The thermosetting composition according to claim 1, wherein the polyfunctional benzoxazine is a compound having the following formula: ###0002### 4. The thermosetting composition according to claim 1, wherein the polyphenolic compound containing at least one furanyl or thienyl group is a compound selected from the group consisting of formulae (2), (5), (6), (7), and (9): ###0003### ###0004### ###0005### ###0006### ###0007### wherein n is an integer from 3 to 3.

2. wherein b is an integer from 2 to 4; each R is independently hydrogen, substituted or unsubstituted C1-C 20 alkyl, substituted or unsubstituted C2-C 20 alkenyl, substituted or unsubstituted C6-C 20 aryl, substituted or unsubstituted C2-C 20 heteroaryl, substituted or unsubstituted C4-C 20 carbocyclyl, substituted or unsubstituted C2-C 20 heterocyclyl, or C3-C8 cycloalkyl; each R1is independently hydrogen, C1-C 20 alkyl, C2-C 20 alkenyl, or C6-C 20 aryl; and when b is 2, Z is a direct bond, substituted or unsubstituted C1-C 20 alkyl, substituted or unsubstituted C6-C 20 aryl, substituted or unsubstituted C2-C 20 heteroaryl, or O, S, S=O, O=S=O, or C=O, and when b is 3 or 4, Z is substituted or unsubstituted C1-C 20 alkyl, substituted or unsubstituted C6-C 20 aryl, substituted or unsubstituted C2-C 20 heteroaryl.

5. A thermoset polymer obtained by curing the thermosetting composition according to claim 1. contacting a layer of reinforcing fibers with the thermosetting composition according to claim 1 to coat and / or impregnate the reinforcing fibers; and curing the coated and / or impregnated reinforcing fibers to obtain a composite article.

6. A method of producing a composite article, comprising:

7. A method for producing a composite article in an RTM system, the method comprising the steps of: a) introducing a fibrous preform comprising reinforcing fibers into a mold; b) injecting the thermosetting composition according to claim 1 into the mold; c) impregnating the thermosetting composition into the fibrous preform; d) heating the resin-impregnated preform for a period of time to obtain an at least partially cured solid article; and optionally e) further heating the partially cured solid article. d) maintaining the mold under reduced pressure; e) impregnating the thermosetting composition into the fibrous preform; f) heating the resin-impregnated preform to obtain an at least partially cured solid article; and optionally g) further heating the at least partially cured solid article.

8. A method of forming a composite article in a VaRTM system, the method comprising the steps of: a) introducing a fibrous preform comprising reinforcing fibers into a mold; b) injecting into the mold a thermosetting composition according to claim 1 ; c) reducing the pressure within the mold; ​ ​

Images