Monofunctional benzoxazine phthalonitrile resin compostion

Abstract

The present disclosure provides a polymerizable thermosetting compositions comprising monofunctional benzoxazine bearing unsaturated functional group, and a monophthalonitrile resin containing unsaturated or amine functional group. The compositions may be cured to form thermoset polymers having improved thermal and mechanical properties, such as a low melting and low viscosity monobenzoxazine. The cured thermoset polymers having excellent thermal and mechanical properties, such as high thermal stability, heat resistance, high char yield, and enhanced structural rigidity.

Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application Serial Number 63 / 627,111, filed January 31, 2024, the entire contents of which are expressly incorporated herein by reference. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable. FIELD

[0003] The present disclosure generally relates to a a low viscosity, curable, high Tg composition composed of monofunctional benzoxazine and monofunctional phthalonitrile resins, and their use for applications in various industries, such as, but not limited to, the building and construction, electronics packaging, energy and power generation, aerospace, transportation and medical device industries. BACKGROUND

[0004] Phthalonitrile monomers are a class of high-performance monomers developed for high temperature applications, such as in the production of prepregs, laminates and structural composite parts. For example, US Pat. No. 6,420,464, US Pat. No. 8,039,576, US Pat. No. 8,853,343, US Pat. No. 9,920,165 and US Pat. Publ. No. 2019 / 0047946 disclose various phthalonitrile monomers derived from phenols, aromatic diols reacted with diphenyl acetylenes, polyphenols from renewable sources, and bisphenols. These phthalonitrile monomers, after curing, have been found to possess excellent thermal and thermo-oxidative stability with initial decomposition temperatures greater than 450°C, as well as a myriad of other highly attractive performance properties, such as enhanced flame-resistance, the absence of a glass transition temperature before thermal decomposition, good mechanical properties at high temperatures, low water uptake, excellent corrosion resistance and advanced UV-shielding behavior.

[0005] However, state of the art phthalonitrile monomers are known to suffer from brittleness due to the rigidity of the monomeric precursors and the high degree of crosslinking in the final cured product. Typical phthalonitrile monomers are solid at room temperature with a melting point well above 150°C and need higher processing temperature to melt so as it can be used in liquid process. The initial cure temperature of phthalonitrile is above 250°C and higher curing temperatures and extended time are needed to achieve full cure. Although the addition of multiple catalysts has been found to improve the curing behavior to a certain extent, the processing temperature, curing temperatures and cure times remains higher than those of other high-performance thermosets.

[0006] To overcome these drawbacks, attempts have been made to adjust the chain length of the moi eties between the phthalonitrile monomer units in order to reduce their melting point and improve the flexibility of the cured product. Different types of catalysts have also been used to improve the curing behavior of these phthalonitrile monomers. Finally, in order to improve the processability, curing behavior and final properties of the cured phthalonitrile product, US Pat. No. 5,939,508, and WO 2017105890, disclose particular phthalonitrile monomers copolymerized with an epoxy or benzoxazine resin; however, such compositions can still require higher than desired curing temperatures (e.g., well above 250°C) and longer times to fully cure, and have insufficient char yield for carbon-carbon composite applications.

[0007] Thermoset resin-based composites with high glass transition temperatures (“Tg”) are desired in high temperature applications, such as aerospace structural components. Additionally, resins with high Tg and char yield are indicative of good thermal stability and thus suitable for engine components or thermal protection systems.

[0008] Benzoxazines are a special type of phenolic resin. They are made from a phenol or bisphenol with an amine reacted with formaldehyde. During the curing process, it is believed that the oxazine ring opens and attacks the amino group or hydroxy group of another ring opened product to form a thermoset polymer with high Tg. Often, this process needs a catalyst or very high temperature to promote the complete reaction. On the other hand, the cured samples of monobenzoxazine monomer generally provide low Tg and high temperature resistance. Additionally, char yields are about 30 to 40% and thermal stability is much lower than other resin. It is believed that a Tg above 300°C and char above 60% would be more favored.

[0009] Benzoxazine resin and phthalonitrile resin are prime targets for high Tg or high char yield composites. However, both resins can be difficult to process due to high viscosity and long cure cycle.

[0010] A solution to improve the Tg and char yield of a benzoxazine is to add a pendant unsaturated functional group, such as alkynyl, furfuryl, alkenyl or cyano group. WO 199918092 disclosed the synthesis and char yields of such a group of benzoxazine with additional unsaturated functional groups, especially the acetylene group and cyano group, which also included phthalonitriles. The acetylene bearing benzoxazine are made from 3-aminophenyl acetylene and phenol or bisphenols. The char yield could be as high as 81% for the monobenzoxazine derived from phenol, however, no curing conditions were disclosed. Except a few comments on the Dynamic Scanning Calorimetry (“DSC “) scan and enthalpy, no information was given about mechanical properties. In the same patent mentioned above, a benzoxazine bearing phthalonitrile moiety was also disclosed. It is shown there are two DSC peaks: one is believed to account for benzoxazine ring opening, another for the reaction of the cyano group of the phthalonitrile. However, not all benzoxazines with pendant unsaturated functional group provide high Tg or char yield. For example, the low viscosity benzoxazine made from allylphenol and aniline, which contains pendant alkenyl group had a poor Tg and char yield of ~100°C and 45% char at 800°C as shown in Agag,T., Takeichi, T., Macromolecules, 2003, 6010-6017.

[0011] Some methods to improve upon the drawbacks of phthalonitrile resins include adding pendant functional groups to lower the melting point of the phthalonitrile or synthesizing phthalonitrile with an internal amine catalyst to decrease cure temperature. Han, Y., et al., European Polymer Journal, 2019, 104-113, discloses monomers and formulations that target both lower melting temperature and cure temperature through a combination of the above pendant functional group and internal catalyst approach. No single phthalonitrile resin had a melting temperature below 150°C and cure temperature below 250°C. Attempts to improve both melting and cure temperatures by formulating with multiple phthalonitriles still required high final cure of 375°C. Tg and Char yields were typically high, as expected, reaching a maximum of about 485°C and 69% char.

[0012] The co-curing of benzoxazine / phthalonitrile blend have also been reported. Normally, the benzoxazine involved in those blends are without any additional functional group (Xu, Y-L.; Dayor, A. D.; etc. Copolymerization of bisphthalonitrile / benzoxazine blends: Curing behavior, thermomechanical and thermal properties; Reactive and Functional Polymers, 123 (2018), 97-105.) orthose phthalonitrile derived natural product with additional allyl group attached. (Dayor, A.D.; Wang, A-R.; etc. Copolymerization of mono and difunctional benzoxazine monomers with bio-based phthalonitrile monomer: Curing behaviour, thermal, and mechanical properties; Reactive and Functional Polymers, 131 (2018), 156-163; Wang, A-R.; Dayor, A. D. etc. Bio-based phthalonitrile compounds: Synthesis, curing behavior, thermomechanical and thermal properties; Reactive and Functional Polymers, 127 (2018), 1-9). In those blends, the DSC show that two distinct reactions corresponded to the benzoxazine ring opening and the reactions of the cyano groups.

[0013] WO2017105890A disclosed a phthalonitrile and benzoxazine blend which has improved curing behavior. Such formulations demonstrated higher temperature thermal and oxidative-degradation resistance than polybenzoxazine alone, however, the cured polymer performance barely reaches the potential of polyphthalonitrile.

[0014] Overall, the blends tend to use a dibenzoxazine without any unsaturated functional group that generally have high viscosity at around 65°C, which in turn gives overall high viscosity for the blend. The examples also use difunctional phthalonitriles without any pendant functionality such as alkenyl or methoxy group.

[0015] WO 2021 / 087197, which is hereby incorporated by reference, provides a polymerizable thermosetting composition comprising (i) an acetylene-bearing benzoxazine compound, and (ii) a phthalonitrile monomer. WO 2021 / 087193, hereby incorporated by reference provides a functionalized phthalonitrile monomer obtained from the reaction of (i) a polyhydric phenol compound comprising at least one furan group or thiophene group and (ii) 4-nitrophthalonitrile. The present invention improves upon the previous inventions by simultaneously incorporating monofunctional resin(s) with low viscosity and good processability compared to a di-, or multifunctional resin while also obtaining high thermomechanical performance that is difficult to achieve without multifunctional resins.

[0016] It would be desirable to further improve the curing cycle in the copolymerization of thermosetting compositions that can be readily processed while exhibiting even better processability and curing behavior and produce cured products having improved thermal and mechanical properties. SUMMARY

[0017] The present disclosure generally provides a low viscosity, curable, high Tg composition composed of monofunctional benzoxazine and monofunctional phthalonitrile resins.

[0018] The monofunctional benzoxazine and monofunctional phthalonitrile resins compositions of the present disclosure may be cured to form thermoset polymers having improved thermal and mechanical properties. The novel compositions provided in this disclosure include a low melting and low viscosity monobenzoxazine bearing unsaturated functional group, and a monophthalonitrile resin containing unsaturated or amine functional group. Accordingly, these compositions can find use in a variety of applications, such as, but not limited to, the building and construction, electronics packaging, military, energy and power generation, aerospace, transportation and medical device industries. DETAILED DESCRIPTION

[0019] The polymerizable thermosetting compositions of the present disclosure are composed of a low melting and low viscosity monobenzoxazine(s) bearing unsaturated functional group, and a monophthalonitrile resins containing an unsaturated or amine functional group. Upon mixing, the compositions exhibit low viscosity, with a viscosity below 1.5 Pascal second (1500 centipoise) at 75°C. In certain embodiments, the low viscosity monobenzoxazine is allylphenol benzoxazine (Huntsman’s LME 11353) and / or phenol 3-aminophenyl acetylene benzoxazine. The mixture of this monophthalonitrile(s) made from a combination of allylphenol, eugenol, propargyl alcohol, and aminophenol displays a low viscosity at 75°C. Optionally, a catalyst may be added from 1-10% to improve the curing characteristics. These compositions may also be cured to a thermoset polymer with improved performance characteristics, including higher thermal resistance and mechanical performance, low water absorption, and higher char yield. These combinations produce cured articles with exceptionally high Tg above 300°C and char yield over 65% with great processability. The low viscosity of the composition makes it suitable for liquid processing of composites including Resin Transfer Molding (“RTM”), wet compression molding, and Vacuum Assisted RTM (“VARTM”).

[0020] The combination of low viscosity and high Tg, high char is desirable for various applications including, but not limited to, use in building and construction materials, electronics packaging, energy and power generation, aerospace, transportation and medical devices. The pendant alkenyl functionality on the monomers in the polymerizable thermosetting compositions of the present disclosure provides good performance in viscosity, Tg, and high char, as opposed to poor Tg & char yield when used as a single resin (e.g., alylphenol benzoxazine). These monofunctional resins give highly crosslinked networks with high Tg and char yield.

[0021] The following terms shall have the following meanings:

[0022] The term “comprising” and derivatives thereof are not intended to exclude the presence of any additional component, step or procedure, whether or not the same is disclosed herein. In order to avoid any doubt, all compositions claimed herein through use of the term “comprising” may include any additional additive or compound, unless stated to the contrary. In contrast, the term, “consisting essentially of’ if appearing herein, excludes from the scope of any succeeding recitation any other component, step or procedure, excepting those that are not essential to operability and the term “consisting of’, if used, excludes any component, step or procedure not specifically delineated or listed. The term “or”, unless stated otherwise, refers to the listed members individually as well as in any combination.

[0023] The articles “a” and “an” are used herein to refer to one or 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.

[0024] The phrases “in one aspect”, “according to one aspect” and the like generally mean the particular feature, structure, or characteristic following the phrase is included in at least one aspect of the present disclosure and may be included in more than one aspect of the present disclosure. Importantly, such phases do not necessarily refer to the same aspect.

[0025] If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.

[0026] In certain embodiments, the polymerizable thermosetting composition of the present disclosure includes: (i) one or more monofunctional benzoxazine resins with pendant unsaturated functionality; and (ii) one or more monofunctional phthalonitrile resins.

[0027] In one aspect, the one or more monofunctional benzoxazine resins with pendant unsaturated functionality are represented by the following structure: r9 In this structure each of RI through R9 is independently selected from a hydrogen atom, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, a substituted or unsubstituted C2-C20 heteroaryl group, a substituted or unsubstituted C2-C20 heterocyclic group, or a C3-C8 cycloalkyl group; and at least one of RI through R9 consists of an alkenyl or alkynyl substituted C1-C20 alkyl group, an alkenyl or alkynyl substituted C6-C20 aryl group, an alkenyl or alkynyl substituted C2-C20 heteroaryl group, an alkenyl or alkynyl substituted C2-C20 heterocyclic group, or an alkenyl or alkynyl substituted C3-C8 cycloalkyl group.

[0028] In certain embodiments, the benzoxazines resins of polymerizable thermosetting compositions are represented by one or both of the following structures: Benzoxazines (!!!) Ally! pheno! benzoxazine (V!) Pheno! 3-aminopheny! acetylene benzoxazine

[0029] In one aspect, the monofunctional phthalonitrile resins of the present disclosure is one or more compounds represented by the following structure:

[0030] In this structure, R10 is independently selected from an alkenyl or alkynyl substituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, a substituted or unsubstituted C2-C20 heteroaryl group, a substituted or unsubstituted C2-C20 heterocyclic group, or a substituted or unsubstituted C3-C8 cycloalkyl group.

[0031] In certain embodiments, the phthalonitrile resins of the polymerizable thermosetting composition of the present disclosure are represented by one or more of the following structures: Phthalonitriles {I) Eugenol Phthalonitrile (IV) Aminophenol phthalonitrile (II) Allyipherol phthalonitrile (V) Propargyl phthalonitrile

[0032] According to one aspect, the polymerizable thermosetting compositions include benzoxazine and phthalonitrile in ratios from 10:1 up to 1:3.

[0033] In other embodiments, the polymerizable thermosetting composition includes: (i) one or more monofunctional benzoxazine resins with pendant unsaturated functionality; (ii) one or more monofunctional phthalonitrile resins; and (iii) a catalyst. In certain embodiments the catalyst may be added from 0.1-10% of the total weight of the polymerizable thermosetting composition to improve the curing characteristics. In preferred embodiments, 2-Phenylimidazole, 4,4’-Thiodiphenol, and / or 3,3’-Thiodipropionic acid are used as a catalyst. Alternatively, one or a combination of the following may act as a potential catalyst: aromatic amines, primary amines, secondary amines, diamines, polyamines, amine-substituted phosphazenes, phenols, imidazoles, strong acids, organic acids, strong organic acids, inorganic acids.

[0034] The polymerizable thermosetting compositions of the present disclosure may be cured into a thermoset polymer. In certain embodiments, a thermoset polymer may be obtained by curing the thermosetting compositions to yield a cured polymer with a Tg of 300°C and char yield at 1000°C (in N2 atmosphere) of at least 65% wt.

[0035] The polymerizable thermosetting compositions of the present disclosure may also be used in forming fiber-reinforced composite materials. The present disclosure provides processes for generating fiber-reinforced composite materials that include: (a) contacting reinforcement fiber with the polymerizable thermosetting compositions of the present invention; (b) curing the polymerizable thermosetting composition in contact with the reinforcement fiber.

[0036] The curable compositions of the present disclosure contain low viscosity monobenzoxazine resin(s) with pendant unsaturated functionality and monophthalonitrile resin(s) containing pendant unsaturated functionality and / or amine. The composition itself also has low viscosity for liquid processes and provides high heat resistance with Tg above 300°C and char yield over 65%. It is the combination of the resins, not a single resin alone, that give the most desirable performance characteristics.

[0037] The compositions of the present disclosure contain several benzoxazine and phthalonitrile moieties that are monofunctional in nature or contain internal amine functionality. The combination of these components yields low melting blends suitable for liquid processing with lower cure temperatures than typical phthalonitrile resins and cured articles with high Tg and char yield. It is believed that the combination of pendant functional groups also enables benzoxazine and phthalonitrile to react with each other to form a more complicated cross-linking system, further contributing to high Tg. These reactions may include Diels-Alder or ene reactions among the cyano, alkenyl, and the alkynyl functional group. The heat release from those reaction will further complete the reaction at a relatively lower temperature than a typical complete cure of phthalonitriles. Additionally, though single resins, such as allyl phenol benzoxazine, may have poor Tg and char yield, it is shown in this disclosure that combination with other monofunctional resins can have a positive additive effect on both properties.

[0038] According to one embodiment, the polymerizable thermosetting composition comprises the one or more monofunctional benzoxazine compound and the one or more monofunctional phthalonitrile compounds in a weight ratio of between about 1:1 to about 10:1, or from about 1.5:1 to about 10:1, or from about 2:1 to about 10:1.

[0039] The amount of the phthalonitrile monomer present in the polymerizable thermosetting composition may be in an amount of at least about 1% by weight, at least about 5% by weight, or at least about 10% by weight, or at least about 20% by weight, or at least about 30% by weight, or at least about 40% by weight, or at least about 50% by weight, or at least about 60% by weight, or at least about 70% by weight, or at least about 80% by weight, or at least about 90% by weight, or at least about 99% by weight, based on the total weight of the polymerizable thermosetting composition. In other embodiments, the amount of phthalonitrile monomer present in the polymerizable thermosetting composition may be in an amount of between about 1% by weight to about 99% by weight, or between about 5% by weight to about 90% by weight, or between about 10% by weight to about 80% by weight, or between about 20% by weight to about 70% by weight, or between about 30% by weight to about 60% by weight, based on the total weight of the polymerizable thermosetting composition.

[0040] The polymerizable thermosetting composition of the present disclosure may be cured by sufficient heating the polymerizable thermosetting composition so as to form a thermoset polymer. For instance, the presently disclosed compositions may require a staged cure at a temperature up to 200°C to 220°C followed by a post-cure at a temperature ranging from 250°C to 260°C. By comparison, a phthalonitrile monomer, alone, generally requires a curing temperature of at least 350°C.

[0041] A curing agent may be used to speed up thermoset formation of the thermoset polymer. Thus, according to another embodiment, the polymerizable thermosetting composition further comprises a curing agent.

[0042] The curing agent which may be used includes, but is 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, metallic salts, metallic salt hydrates, metallic compounds, halogencontaining aromatic amines, clays, and chemically modified clays. The use of clays or chemically modified clays may improve the mechanical and flammability properties of the thermoset. Typically, chemical modification of a clay involves replacing sodium ions with ammonium to form quaternary ammonium salts.

[0043] Specific curing agents include, but are not limited to, bis(4-(4-aminophenoxy)phenyl sulfone (p-BAPS), bis(4-(3-aminophenoxy)phenylsulfone (m-BAPS), l,4-bis(3-aminophenoxy )benzene (p-APB), 1,12-diaminododecane, diphenylamine, epoxy amine hardener, 1,6-hexanediamine, 1,3-phenylenediamine, 1,4-phenylenediamine, p-toluene sulfonic acid, cuprous iodide, cuprous bromide, 1,3-bis(3-aminophenoxy)benzene (m-APB), 3,3'-dimethyl-4,4'-diaminodiphenylsulfone, 3,3'-di ethoxy-4,4'-diaminodiphenylsulfone, 3,3'-dicarboxy-4,4'-diaminodiphenylsulfone, 3,3'-dihydroxy-4,4'-diaminodiphenylsulfone,                         3,3'-disulfo-4,4'- di aminodiphenyl sulfone, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-dimethyl-4,4'-diaminobenzophenone, 3,3'-dimethoxy-4,4'-diaminobenzophenone, 3,3'-di carboxy-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 dianiline, hexakis(4-aminophenoxy)cyclotriphosphazene, 3,3'-dichloro-4,4'-diaminodiphenylsulfone,              2,2'-bis(trifluoromethyl)-4,4'- diaminobiphenyl, 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-l-naphthalenesulfonic acid, benzene sulfonic acid, butylsulfonic acid, 1 O-camphorsulfonic acid, 2,5-diaminobenzenesulfonic acid, 6-dimethylamino-4-hydroxy-2-naphthalenesulfonic acid, 5-dimethylamino-l-naphthalene sulfonic acid, 4-hydroxy-3 -nitroso-1-naphthalenesulfonic acid tetrahydrate, 8-hydroxyquinoline-5-sulfonic acid, methylsulfonic acid, phenylboric acid, 1-naphthalenesulfonic acid, 2-naphthalenesulfonic acid, 1,5-naphthalenedisulfonic acid, 2,6-naphthalenedisulfonic acid, 2.7-naphthalenedisulfonic acid, picrylsulfonic acid hydrate, 2-pyridineethane sulfonic acid, 4-pyridineethanesulfonic acid, 3-pyridine sulfonic acid, 2-pyridinylhydroxymethanesulfonic acid, sulfanilic acid, 2-sulfobenzoic acid hydrate, 5-sulfosalicylic acid hydrate, 2,4-xylenesulfonic acid, sulfonic acid containing dyes, organic phosphorus-containing acids, phenylphosphinic acid, diphenylphosphinic acid, propylphosphonic acid, 1-aminoethylphosphonic acid, 4-aminophenylphosphonic acid, butylphosphonic acid, t-butylphosphonic acid, 2-carboxyethylphosphonic acid, 2-chloroethylphosphonic acid, dimethylphosphonic acid, ethylphosphonic acid, methylenediphosphonic acid, methylphosphonic acid, phosphonoacetic acid, bis(hydroxymethyl) phosphonic acid, chloromethylphosphonic acid, di-n-butylphosphonic acid, dichloromethylphosphonic acid, diphenyldithiophosphonic acid, 1,2-ethylenediphosphonic acid, n-hystaderylphosphonic acid, hydroxymethylphosphonic acid, n-octadecylphosphonic acid, n-octylphosphonic acid, phenylphosphonic acid, propylenediphosphonic acid, n-tetradecylphosphonic acid, concentrated sulfuric acid, phenylphosphonic 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, cuprous ferricyanide, zinc chloride, zinc bromide, zinc iodide, zinc cyanide, zinc ferrocyanide, zinc acetate, zinc sulfide, silver chloride, ferrous chloride ferric chloride, ferrous ferricyanide, ferrous chloroplatinate, ferrous fluoride, ferrous sulfate, cobaltous chloride, cobaltic sulfate, cobaltous cyanide, nickel chloride, nickel cyanide, nickel sulfate, nickel carbonate, stannic chloride, stannous chloride hydrate, stannous chloride dihydrate, aluminum nitrate hydrate, aluminum nitrate nonahydrate, triphenylphosphine oxide complex, montmorillonite, chemically modified montmorillonite, 4,4'-(l,3-phenylenedioxy)dianiline, 4,4'-(l,4-phenylenedioxy)dianiline, bis(4-(4-aminophenoxy)phenyl]sulfone, 4,4'-(4,4'-isopropylidenediphenyl-l,l'-diyldioxy)dianiline,                            4,4'-(l,3- phenylenediisopropylidene)dianiline, 4,4'-(l,4-phenylenediisopropylidene)dianiline, 4,4'-(l,r-biphenyl-4,4'-diyldioxy)dianiline, 4,4'-methylenedianiline, 4,4'-sulphonyldianiline, 4,4'-methylene-bis(2-methylaniline), 3,3'-methylenedianiline, 3,d'methylenedianiline, 4,4'-oxydianiline, 4,4'-(isopropylidene)dianiline, 4,4'-(hexafluoroisopropylidene)dianiline,            4,4'-(hexafluoroisopropylidene)bis(p- phenyleneoxy)dianiline, 4,4'-diaminobenzophenone, the compounds 4,4-(1,4-phenylenebis(oxy))bis(3-(trifluoromethyl)aniline) Chemical Formula: C2oH14F6N202 Molecular Weight: 428.33 4,4'-(((perfluoropropane-2,2-diyl)bis(4,1-phenylene))bis(oxy))dianiline Chemical Formula: C27H2oF6N202 Molecular Weight: 518.46 4,4'-(perfluoropropane-2,2-diyl)dianiline Chemical Formula: C15H12F6N2 Molecular Weight: 334.27 2,2'Bis(trifluoromethyl)benzidine Chemical Formula: C14H10F6N2 Molecular Weight: 320.24 4,4'-(perfluoropropane-2,2-diyl)diphenol Chemical Formula: C15H10F6O2 Molecular Weight: 336.23 and mixtures thereof.

[0044] The curing agent may be present in the polymerizable thermosetting composition in an amount of at least about 0.5% by weight, or at least about 1% by weight, or at least about 2% by weight, or at least about 5% by weight, or at least about 10% by weight, at least about 15% by weight or even at least about 20% by weight, based on the total weight of the polymerizable thermosetting composition.

[0045] In other embodiments, the curing agent may be present in an amount of less than about 40% by weight, or less than about 35% by weight, or less than about 30% by weight, or less than about 25% by weight, based on the total weight of the polymerizable thermosetting composition. In still other embodiments, the curing agent may be present in an amount of between about 0.25% by weight to about 45% by weight, or between about 1% by weight to about 40% by weight, based on the total weight of the polymerizable thermosetting composition.

[0046] The polymerizable thermosetting composition may be prepared by mixing the monofunctional benzoxazine compound(s) with the monofunctional phthalonitrile compound(s) at a temperature below the melting point (for example, but without limitation, at a temperature 35 to 40°C or more below the melting point of the components) by using customary devices, such as a stirred vessel, stirring rod, ball mill, sample mixer, static mixer or ribbon blended to form the thermosetting composition.

[0047] Alternatively, the polymerizable thermosetting composition may be prepared by first dissolving the monofunctional benzoxazine compound(s) in a solvent with or without heat to make a solution of monofunctional benzoxazine compound(s) in solvent, then dissolving the phthalonitrile compound(s) in a solvent with or without heat to make a solution of monofunctional phthalonitrile compound(s) in solvent, and then mixing the solutions of monofunctional benzoxazine compound(s) and monofunctional phthalonitrile compound(s) together in a stirred vessel for a period of time and evaporating the solvent with or without the aid of a vacuum pump or customary device for removal of lower boiling point solvent from higher boiling point resin(s).

[0048] The polymerizable thermosetting composition may then be cured to form the thermoset polymer. The expression “cured” as used herein, denotes the conversion of the above thermosetting composition into an insoluble and infusible crosslinked product, with simultaneous shaping to give a shaped article such as a molding, pressing or laminate or to give a two-dimensional structure such as a coating, enamel, or adhesive bond. Typical curing processes include ambient temperature cure to elevated temperature cure using thermal, radiation or any combination of energy sources. Typical curing temperatures may range from between about 50°C to about 500°C, such as between about 75°C to about 375°C or between about 80°C to about 300°C for a time sufficient to at least partially or substantially or fully cure the composition such as, for example, 3 to 20 hours, or from about 5 to 15 hours, or from about 6 to about 15 hours, or from about 7 to about 12 hours, or from about 8 to about 10 hours.

[0049] In addition, curing may occur in one or more curing stages. For example, the polymerizable thermosetting composition may be subjected to an initial cure at a temperature ranging from between about 50°C to about 500°C, such as between about 75°C to about 375°C or between about 80°C to about 300°C for a time sufficient to at least partially cure the composition such as, for example, a time ranging from 3 to 10 hours, and then post-cured at a temperature below 300 °C, or at or below 280 °C and even at or below 260 °C for a time sufficient to substantially or fully cure the composition such as, for example, a time ranging from 2 to 4 hours. The polymerizable thermosetting composition may have a viscosity at 75°C of less than 3000 centipoise, or less than 1000 centipoise, or less than 500 centipoise, or less than 175 centipoises prior to being cured.

[0050] According to one embodiment, the polymerizable thermosetting composition of the present disclosure may further comprise additives in addition to the monofunctional benzoxazine(s) or multifunctional phthalonitile(s) and any one or more of the curing agents and optional additives to form another thermosetting composition. The additives may include, but are not limited to, fillers, for example, carbon nanotubes, clays, carbon nanofibers, metal oxides, zinc oxides, diatomaceous earth, barium sulfate, talc, silica, calcium carbonate, calcium fluoride and combinations thereof, colorants, anti-oxidant stabilizers, thermal degradation stabilizers, light stabilizers, flow agents, bodying agents, flatting agents, binders, blowing agents, fungicides, bactericides, surfactants, plasticizers, rubber tougheners, and other additives known to those skilled in the art. These additives, if present, are added in an amount effective for their intended purpose.

[0051] As described above, the polymerizable thermosetting composition may be prepared by mixing in any order the monofunctional benzoxazine compound(s) and the monofunctional phthalonitrile compound(s), as well as optional curing agent(s) and additive(s) using customary devices, such as a stirred vessel, stirring rod, ball mill, sample mixer, static mixer or ribbon blended to form the thermosetting composition. The thermosetting composition may then be cured as described above to form the thermoset polymer.

[0102] In still another embodiment, there is provided a thermoset polymer obtained by contacting any suitable substrate with any one of the polymerizable thermosetting compositions described above and subjecting the substrate / polymerizable thermosetting composition to thermal, radiation or a combination of energy sources to cure the substrate / polymerizable thermosetting composition. In one embodiment, the polymerizable thermosetting compositions of the present disclosure may be used to bond one or more substrates together by contacting one or more surfaces of like or dissimilar substrates that are to be bonded with the polymerizable thermosetting composition under conditions sufficient to cure the polymerizable thermosetting composition.

[0103] In an alternative embodiment, by curing the polymerizable thermosetting compositions of the present disclosure, a composite article may be obtained by techniques well known in the industry, for example, pultrusion, infusion, molding, encapsulating or coating. Thus, the polymerizable thermosetting composition of the present disclosure may be used in methods for manufacturing composite articles, such as castings, prepregs, bonding sheets, laminates and metal-foil clad laminates.

[0104] The properties of the composite articles can be tailored for certain applications by the addition of reinforcement fibers. Examples of reinforcement fibers include glass, quartz, carbon, alumina, ceramic, metallic, aramid, natural fibers (e.g. flax, jute, sisal, hemp), paper, acrylic and polyethylene fibers and mixtures thereof. The reinforcement fibers may be in any of various modes, for example, as a strand or roving formed by paralleling continuous fibers or discontinuous fibers (short fibers) in one direction, cloth such as woven fabric or mat, braids, unidirectional, bi-directional, random, pseudo-isotropic or three-dimensionally dispersed mat-like material, heterogeneous lattice or mesh material, and three-dimensional material such as triaxially woven fabric.

[0105] Thus, in another embodiment, there is provided a process for producing a composite article including the steps of contacting a layer of reinforcement fibers with the polymerizable thermosetting composition to coat and / or impregnate the reinforcement fibers; and curing the coated and / or impregnated reinforcement fibers to produce the composite article.

[0106] Coating and / or impregnation may be affected by either a wet method or hot melt method. In the wet method, the thermosetting composition is first dissolved in a solvent to lower viscosity, after which coating and / or impregnation of the reinforcement fibers is effected and the solvent evaporated off using an oven or the like.

[0107] In the hot melt method, coating and / or impregnation may be effected by directly coating and / or impregnating the reinforcement fibers with the polymerizable thermosetting composition, which may have been heated to reduce its viscosity, or alternatively, a coated film of the polymerizable thermosetting composition may first be produced on release paper or the like, and the film placed on one or both sides of the reinforcement fibers and heat and pressure applied to effect coating and / or impregnation.

[0108] According to another aspect, there is provided a process for producing a composite article in a RTM system. The process includes the steps of a) introducing a fiber preform comprising reinforcement fibers into a mold; b) injecting the polymerizable thermosetting composition into the mold, c) allowing the polymerizable thermosetting composition to impregnate the fiber preform; and d) heating the resin impregnated preform for a period of time to produce an at least partially cured solid article; and optionally e) subjecting the partially cured solid article to additional heat.

[0109] In still another embodiment, there is provided a process for forming a composite article in a VaRTM system. The process includes the steps of a) introducing a fiber preform comprising reinforcement fibers into a mold; b) injecting the polymerizable thermosetting composition into the mold; c) reducing the pressure within the mold; d) maintaining the mold at about the reduced pressure; e) allowing the polymerizable thermosetting composition to impregnate the fiber preform; f) heating the resin impregnated preform to produce an at least partially cured solid article; and optionally g) subjecting the at least partially cured solid article to additional heat.

[0110] Besides RTM and VaRTM systems, the polymerizable thermosetting composition may be used in other methods and systems for producing composite articles including hot-pressing of prepregs, sheet molding compound, molding, casting, pultrusion and filament winding.

[0111] In another embodiment, the polymerizable thermosetting composition, upon curing, provides a thermoset polymer with excellent well-balanced physical, mechanical and thermal properties. The properties of the polymerizable thermoset polymer that are well-balanced in accordance with the present disclosure may include: a Tg of greater than about 250°C, or greater than about 270°C, or greater than about 290°C; and, a char yield of at least 60%, or at least 65%, or at least 70% at 800°C under nitrogen.

[0112] The polymerizable thermosetting composition and composite articles of the present disclosure may be used in various applications, for example, in aerospace applications, where they may be employed as aircraft primary structural materials (main wings, tail wing, floor beam, etc.), secondary structural materials (flap, aileron, cowl, fairing, interior trim, etc.), rocket motor cases, structural materials for artificial satellites or other moving bodies such as cars, boats and railway carriages, in drive shafts, fuel cells, plate springs, wind turbine blades, pressure vessels, fly-wheels, papermaking rollers and civil engineering and building materials (roofing materials, cables, reinforcing bars, retrofitting materials). Examples:

[0052] Chemicals analysis methods such as NMR, FTIR, LC-MS, GPC, and HPLC were run by analytical service group inside Huntsman Corporation; DSC, DMA and TGA were run on TA instruments, such as DSCQ2000, DSC 2500, DMA 800, TGA 5000, SDT650, viscosities were run on Brookfield CAP+ 2000. Table 1: Composition Characteristics. Example 1 (33c) 2 (44a) 3 (44b) 4 (48a) 5 (50a) 6 (50b) 7 (48b) 8 (46b) 9 (49b) phenol     3- aminophenyl acetylene benzoxazine (VI) 2 1 1 3 2.25 2 2 2 1 Allylphenol benzoxazine (III) 1 .75 1 1 Allylphenol phthalonitrile (II) 3 0.66 4.62 4.62 4.62 2 P- aminophenol phthalonitrile (IV) 0.66 0.33 2.38 2.38 2.38 1 Eugenol phthalonitrile (I) 1.33 2 Propargyl phthalonitrile (V) 1 2 Viscosity (75 °C; cP) 149 1140 265 282 83 120 1275 <50 solid Tonset (°C) 205 163 183 193 205 173 177 214 201 OH (J / g) 342 642 348 394 289 407 514 1146 846 TGA Char Yield (1000 °C) 69.9 73.3 73.8 74.9 75.2 74.5 74.1 75.3 74.1 DMA Tg Onset(°C) 343 338 337 329 339 342 325 344 N / A Examples 1-9 typically display tje beneficial liquid processing attributes characterized by low viscosity at 75 °C, low onset temperatures less than 225 °C, enthalpies typically lower than 600 J / g while the cured thermosetting composition demonstrates high thermomechanical performance characterized by char yield @ 1000 °C under N2 atmosphere of > 65% wt. Table 2: Comparative Examples. Comparative examples with single unsaturated resins are shown below; demonstrating various aspects of either beneficial liquid processing or high thermomechanical performance, but not all aspects as with examples 1-9. Comparative Examples CE1 CE2 CE3 CE4 CE5 phenol      3-aminophenyl acetylene benzoxazine 5 Allylphenol benzoxazine 5 allylphenol phthalonitrile 5 p-aminophenol phthalonitrile 5 Eugenol phthalonitrile 5 Viscosity (75 °C; cP) 132 <20 31.3 Solid (MP 133C) Solid (mp 100C) Tonset (°C) 233 255 329 305 230 CH (J / g) 798 339 591 207 315 TGA Char Yield (J000 °C) 52.5 N / A 74.1 72.2 72.9 DMA TgOnset(°C) 330 N / A 346 265 259 Table 3: Catalyst Effect Example 4(48a) 10(26a) ll(48d) 12(37) 13 14(13) 15(10) phenol            3- aminophenyl acetylene benzoxazine 3 3 3 3 2.25 2.25 2 Allylphenol benzoxazine .75 .75 1 Allylphenol phthalonitrile 4.62 4.62 4.62 4.62 4.62 4.62 4.62 p-aminophenol phthalonitrile 2.38 2.38 2.38 2.38 2.38 2.38 2.38 2-Phenylimidazole 5% Aradur DT 300 5% 5% 5% Aradur DT 310 0.7% Viscosity (75 °C; cP) 282 644 255 1226 83 641 548 Tonset (°C) 193 150 169 182 205 143 189 CH (J / g) 394 432 243 283 289 418 257 TGA Char Yield (1000 °C) 74.9 75.3 74.7 75.2 75.2 74.0 73.2 DMA TgOnset(°C) 329 276 285 309 339 306 271 Table 3 provides data on examples 10-15 showing the effect of catalyst on the resin composition. It is noted that a catalyst will generally lower the onset temperature of the uncured resin while still maintaining a high char yield. Table 4: Mechanical Properties Example Flex Strength (ksi) Flex Modulus (ksi) Tensile Strength (ksi) Tensile Modulus (ksi) 2(78) 21.42 ± 1.98 774.81 ± 7.97 8.58 ±0.71 711.79 ± 38.37 4(24) 20.38 ± 1.17 721.05 ± 12.17 7.50 ±0.77 556.97 ± 17.40 13 (13) 20.30 ± 0.83 703.79 ± 10.28 8.88 ± 1.07 609.55 ± 48.71 14(10) 23.25 ± 0.60 691.76 ± 10.67 9.80 ±0.57 590.31 ± 18.79 Table 4 shows various resin compositions consisting of monofunctional benzoxazine resin(s) and monofunctional phthalonitrile resin(s) demonstrating beneficial mechanical performance as noted by both high flexural strength and high moduli.

[0053] Although making and using various embodiments of the present invention have been described in detail above, it should be appreciated that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the invention.

Claims

1. A polymerizable thermosetting composition comprising (i) one or more monofunctional benzoxazine resins with pendant unsaturated functionality, and (ii) one or more monofunctional phthalonitrile resins.

2. The polymerizable thermosetting composition according to claim 1, wherein the one or more monofunctional benzoxazine resins with pendant unsaturated functionality are represented by the following structure:Wherein:Each RI through R9 is independently selected from a hydrogen atom, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, a substituted or unsubstituted C2-C20 heteroaryl group, a substituted or unsubstituted C2-C20 heterocyclic group, or a C3-C8 cycloalkyl group; andat least one of RI through R9 consists of an alkenyl or alkynyl substituted Cl-C20 alkyl group, an alkenyl or alkynyl substituted C6-C20 aryl group, an alkenyl or alkynyl substituted C2-C20 heteroaryl group, an alkenyl or alkynyl substituted C2-C20 heterocyclic group, or an alkenyl or alkynyl substituted C3-C8 cycloalkyl group.

3. The polymerizable thermosetting composition according to claim 1, wherein the monofunctional phthalonitrile resin is one or more compounds represented by the following structure:Wherein:RIO is independently selected from an alkenyl or alkynyl substituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, a substituted or unsubstituted C2-C20 heteroaryl group, a substituted or unsubstituted C2-C20 heterocyclic group, or a substituted or unsubstituted C3-C8 cycloalkyl group.

4. A polymerizable thermosetting composition comprising (i) one or more monofunctional benzoxazine resins with pendant unsaturated functionality, (ii) one or more monofunctional phthalonitrile resins, and (iii) a catalyst.

5. A thermoset polymer obtained by curing the thermosetting composition according to any one of claims 1-4.

6. A thermoset polymer obtained by curing the thermosetting composition according to any one of claims 1-4 with a Tg of 300 °C and char yield at 1000 °C (in N2 atmosphere) of at least 65% wt.

7. A process for forming a fiber-reinforced composite material, comprising: a. Contacting reinforcement fiber with the polymerizable thermosetting composition according to any one of the claims 1-4.b. Curing the polymerizable thermosetting composition in contact with the reinforcement fiber.

8. A fiber-reinforced composite material produced according to the method of claim 7.