Benzoxazine resin composition, prepreg, and fiber-reinforced composite material

Abstract

A curable benzoxazine resin composition for fiber-reinforced composite materials is provided, containing at least components [A], [B], and [C]. Component [A] includes at least one polyfunctional benzoxazine resin having a non-hydrocarbon linking group, such as carbonyl, oxygen, sulfur, sulfone, or sulfoxide, between aromatic moieties. Component [B] includes at least one polyfunctional benzoxazine resin having a direct bond or a hydrocarbon linking group between aromatic moieties. Component [C] includes at least one cycloaliphatic epoxy resin containing at least two epoxy groups that are part of an alicyclic ring. The curable benzoxazine resin composition is useful for molding fiber-reinforced composite materials. More specifically, the curable benzoxazine resin composition, when heated, provides a cured material that enables fiber-reinforced composite materials to have excellent performance under extreme conditions, such as high temperatures and high compressive loads.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 62 / 909,385, filed October 2, 2019, and U.S. Provisional Patent Application No. 63 / 064,154, filed August 11, 2020, the entire contents of both of which are incorporated by reference herein in their entireties for all purposes.

[0002] The present invention relates to benzoxazine resin compositions, prepregs, and fiber-reinforced composite materials, such as carbon fiber-reinforced composite materials. More specifically, the present disclosure provides benzoxazine resin compositions for use in fiber-reinforced composite materials that have excellent performance under extreme use environments, such as high temperature and high compressive loads. [Background technology]

[0003] Fiber-reinforced composite materials, which contain reinforcing fibers and a matrix resin, are widely used in sports, aerospace, and general industrial applications because they are lightweight and have very good mechanical properties.

[0004] Methods for producing fiber-reinforced composite materials include a method in which uncured matrix resin is injected into reinforcing fibers to form a sheet-like prepreg intermediate, which is then cured, and a resin transfer molding method in which liquid resin is flowed into reinforcing fibers placed in a mold to produce an intermediate, which is then cured. In the method using prepregs, fiber-reinforced composite materials are usually obtained by stacking multiple prepreg sheets and then autoclaving them. The matrix resin used in prepregs is generally a thermosetting resin from the viewpoint of productivity.

[0005] Phenol resin, melamine resin, bismaleimide resin, unsaturated polyester resin, epoxy resin, etc. have been used as thermosetting resins. However, from the viewpoint of improving elastic modulus and heat resistance, research has been conducted in recent years on the use of benzoxazine resin as a matrix resin for fiber-reinforced composite materials, as disclosed in International Publication No. 2003018674.

[0006] However, most multifunctional benzoxazine resins have melting points near or above room temperature and high viscosities. These properties cause benzoxazine resins to have the disadvantages of poor tack and drape when used as a matrix material for prepregs in combination with reinforcing fibers. As disclosed in US Patent Application Publication No. 20150141583, multifunctional glycidyl-type epoxy resins that are liquid at 40°C or less have been effectively used as reactive diluents for benzoxazines. These epoxies are effective reactive diluents for benzoxazines because they are effective in reducing the viscosity of benzoxazine resins, can easily dissolve thermoplastic compounds, and increase the crosslink density of the cured matrix, thereby improving the glass transition temperature compared to undiluted benzoxazine resins. As disclosed in U.S. Patent Application Publication No. 20150376406, the inclusion of an alicyclic epoxy resin in a resin composition can reduce viscosity, reduce water absorption, reduce UV degradation, and increase glass transition temperature compared to benzoxazine resin compositions containing glycidyl-type epoxy resins.

[0007] Without being bound by any particular theory, it is generally accepted that brittle materials, i.e., materials with low toughness and elongation, suffer from reduced tensile strength when used in fiber reinforced composites. Therefore, it is preferred to add a thermoplastic compound to the benzoxazine resin composition to improve the tensile strength and fracture toughness in composite applications. Since the addition of the thermoplastic compound also increases the viscosity of the benzoxazine resin when the thermoplastic compound is completely dissolved (the ideal case for improving the above-mentioned properties), it is essential to add a reactive diluent to the formulation to reduce the viscosity of the benzoxazine resin. Generally, the viscosity of the benzoxazine resin composition should be 1-50,000 poise when the temperature is 25°C-100°C. If the benzoxazine resin composition is intended for use in a hot melt process with prepregs, the viscosity should be 10-10,000 poise when the temperature is 60°C-100°C. Generally, the elastic modulus of the matrix material in fiber reinforced composites for structural applications should be as high as possible. For aerospace applications, the flexural modulus of the matrix material should be at least 3.0 GPa at 25° C. and 50% relative humidity, as measured according to ASTM D790.

[0008] In general, there is a trade-off between glass transition temperature and modulus of elasticity. Increasing the ratio of cycloaliphatic epoxy to benzoxazine increases the glass transition temperature of the resin after curing, but decreases the modulus of elasticity. Alternatively, a different benzoxazine can be used to achieve a high glass transition temperature, but with a corresponding decrease in modulus of elasticity. Thus, there is a need for new compositions in which the resin cured product has both a high glass transition temperature and also a high modulus of elasticity. Summary of the Invention [Problem to be solved by the invention]

[0009] In order to solve the above problems, the inventors have discovered that by using a blend of multifunctional benzoxazines, at least one of which contains a non-hydrocarbon linking group (i.e., a linking group containing at least one heteroatom, in particular a linking group containing at least one oxygen atom and / or at least one sulfur atom, which may be in the form of an ether linking group, a sulfide linking group, a ketone linking group, a sulfone linking group, or a sulfoxide linking group), and at least one of which contains a direct bond or a hydrocarbon linking group (i.e., a linking group containing carbon atoms and hydrogen atoms but no heteroatoms) as a linking group, and at least one cycloaliphatic epoxy, both a high glass transition temperature and a high modulus in the cured matrix, and a low viscosity at room temperature in the uncured state, are achieved. The present invention thus provides a benzoxazine resin composition that can be cured to form a cured article with excellent heat resistance, thereby overcoming the shortcomings of the resin compositions known in the prior art as mentioned above. [Means for solving the problem]

[0010] The present invention relates to a benzoxazine resin composition for a fiber-reinforced composite material, comprising component [A], component [B], and component [C], a) Component [A] comprises at least one benzoxazine of formula (IA):

[0011] [ka]

[0012] wherein Z is selected from C=O, CH2OC(=O), O, S, S=O, or O=S=O; each R is independently hydrogen, C1-C 20 Alkyl group, allyl group, or C6-C 14 aryl group, each R is independently selected from hydrogen, C1-C 20 Alkyl group, allyl group, or C6-C 14 aryl groups; b) Component [B] comprises at least one benzoxazine of formula (IA′) and / or formula (IB′):

[0013] [ka]

[0014] In the formula, n is 0 or 1; when n=1, Z′ is a substituted or unsubstituted C1-C 20 Alkyl group, substituted or unsubstituted divalent C6-C 20 Aryl group or substituted or unsubstituted divalent C2-C 20 heteroaryl groups; when n=0, the benzyl groups of the benzoxazine moieties may be fused or linked by a direct bond between the two benzoxazine moieties;

[0015] [ka]

[0016] In the formula, L is CH2, C(CH3)2, CH(CH3), dicyclopentadiene, Ar, and Ar-Y-Ar. of divalent hydrocarbon linking groups, and Y is selected from a direct bond, C(R2)(R3), C(R2)(Ar), a divalent heterocycle, [C(R2)(R3)]x-Ar-[C(R4)(R5)] y 、S , SO2, and O, Ar is an aryl group, and R2, R3, R4, and R5 are independently selected from H, C1-C8 alkyl, and halogenated alkyl; c) The component [C] comprises at least one cycloaliphatic epoxy resin represented by formula (II):

[0017] [ka]

[0018] wherein m=0 or 1; R6 and R7 are the same or different; It is either a part of a cyclopentane ring, a part of a cyclohexane ring, or a part of a norbornane ring,Each of the substituted or unsubstituted C1-C alkyl groups forms at least one aliphatic ring together with the carbon atom of the epoxy group. 20 an aliphatic moiety, m is 0 or 1; when m=1, X is a single bond, O, S, C.H. 2 , C.H. 2 CH 2 , C.H. 2 CH 2 CH 2 , C.H. 2 CH(CH 3 ), C(CH 3 ) 2 , C.H. 2 OCH 2 , C(=O), CH 2 Either OC(=O) For m=0, X is absent (i.e., not present), and any one of a dicyclopentadiene type diepoxide, a tricyclopentadiene type diepoxide, a tetrahydroindene type diepoxide, a tetracyclotetradecadiene type diepoxide, and a pentacyclopentadecadiene type diepoxide is formed. ; d) Components [A] and [B] are present in a mass ratio [A] / [B] of 1 / 2 to 5 / 1, including the boundary values, and components [A], [B], and [C] are present in a mass ratio [C] / ([A]+[B]) of 1 / 9 to 2 / 3, including the boundary values; The present invention relates to a curable benzoxazine resin composition. Includes:

[0019] In one embodiment, component [C] comprises at least one cycloaliphatic epoxy resin represented by formula (II), wherein R6 and R7 are each independently a part of a cyclopentane ring, a part of a cyclohexane ring, or a part of a norbornane ring.

[0020] In one embodiment, the curable benzoxazine resin composition further comprises a component [D], which comprises a thermoplastic compound comprising one or more repeating units. In one embodiment, the thermoplastic compound is a polyethersulfone or a polyimide resin. In another embodiment, the thermoplastic compound is a polyimide resin having a backbone further comprising phenyltrimethylindane units or phenylindane units.

[0021] In one embodiment of the curable benzoxazine resin composition, component [A] includes two or more multifunctional benzoxazines that differ in at least one of Z, R, or R1. In another embodiment, component [B] includes two or more multifunctional benzoxazines that differ in at least one of Z', L, R, or R1.

[0022] In one embodiment, the cured benzoxazine resin composition has a glass transition temperature, as determined by the G' onset method, of at least 215°C and a flexural modulus at 25°C of at least 4.3 GPa.

[0023] In one embodiment, component [A] comprises at least one benzoxazine of formula (IA) where Z is S.

[0024] In one embodiment, component [A] comprises at least one benzoxazine of formula (IV), (V), (VI), (VII), or (VIII) disclosed below. In another embodiment, component [B] comprises at least one benzoxazine of formula (IX), (X), (XI), (XII), (XIII), or (XIV) disclosed below.

[0025] In another embodiment of the invention, component [A] comprises at least one benzoxazine of formula (V) and component [B] comprises at least one benzoxazine of formula (IX) or formula (XI).

[0026] [ka]

[0027] [ka]

[0028] [ka]

[0029] In one aspect of the invention, there is provided herein a prepreg comprising a reinforcing fiber matrix impregnated with a curable benzoxazine resin composition according to any of the above-mentioned embodiments. In another aspect of the invention, a fiber reinforced composite is obtained by curing such a prepreg. In yet another aspect, a laminate is formed from a plurality of such prepregs. A further embodiment of the invention provides a fiber reinforced composite comprising a cured resin obtained by curing a mixture comprising a benzoxazine resin composition according to any of the above-mentioned embodiments and fibers, the fibers may be made from, for example, carbon, glass, ceramic, polymer, or natural materials. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] All publications, patents, and patent applications cited herein are hereby incorporated by reference in their entirety for all purposes.

[0031] The articles "a" and "an" are used herein to mean one or more (i.e., at least one) of the grammatical object of the article. For example, "polymeric resin" means one polymeric resin or two or more polymeric resins. Any range cited herein is inclusive. The terms "substantially" and "about" are used throughout this specification to describe and account for small variations. For example, they can mean that an amount or quantity varies from a stated value within ±5%.

[0032] References throughout this specification to "one embodiment" or "one embodiment" mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. Thus, the appearances of the phrase "in one embodiment" or "in one embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0033] Unless otherwise specified, "room temperature" as used herein means a temperature of 25°C.

[0034] As used herein, viscosity is the complex viscoelastic coefficient n measured using a dynamic viscoelasticity measuring device (ARES, manufactured by TA Instruments) and a circular parallel plate having a diameter of 40 mm, at a frequency of 10 rad / s and a gap length of 0.6 mm while the temperature is constantly increased at a rate of 2° C. / min. * means...

[0035] As used herein, the term PHR means "parts per hundred parts resin" and takes into account only the reactive portions of the resin formulation (i.e., the components of the resin formulation that undergo a chemical reaction when the resin formulation is cured, such as benzoxazine and epoxy resins).

[0036] As used herein, the term "fiber reinforced composite material" is used interchangeably with the terms "fiber reinforced composite," "fiber reinforced polymer material," "fiber reinforced polymer," "fiber reinforced plastic material," "fiber reinforced plastic," and "carbon fiber reinforced polymer."

[0037] According to the present disclosure, it is possible to obtain a benzoxazine resin composition having excellent heat resistance (when cured) and excellent processability, as well as excellent mechanical properties related to elastic modulus when cured. Furthermore, by using the benzoxazine resin composition of the present disclosure, a fiber-reinforced composite material having a very excellent elastic modulus and glass transition temperature can be obtained by curing the benzoxazine resin composition, and such a fiber-reinforced composite material exhibits excellent mechanical properties when used in combination with reinforcing fibers.

[0038] The benzoxazine resin compositions, prepregs, and fiber reinforced composite materials of the present disclosure are described in detail below.

[0039] As a result of extensive research conducted in light of the problems mentioned above, the present inventors have discovered that the above-mentioned problems can be solved in fiber reinforced composite applications by using a benzoxazine resin composition formed by mixing at least component [A] comprising at least one multifunctional benzoxazine having a non-hydrocarbon linking group, at least component [B] comprising at least one multifunctional benzoxazine having a hydrocarbon linking group, and at least component [C] comprising at least one cycloaliphatic epoxy resin having certain structural features and mixed in a specific ratio.

[0040] As used herein, the term "polyfunctional benzoxazine" refers to a benzoxazine compound having at least two oxazine rings attached to a benzene ring in the molecule, i.e., at least difunctional. Difunctional and trifunctional benzoxazine resins, and combinations thereof, are particularly useful in embodiments of the present invention.

[0041] According to certain embodiments, each of component [A] and component [B] comprises, consists essentially of, or consists of at least one multifunctional benzoxazine resin containing two or more structural units represented by the following general formula (III):

[0042] [ka]

[0043] In formula (III), R8 can represent a linear alkyl group having 1 to 12 carbon atoms, a cyclic alkyl group having 3 to 8 carbon atoms, hydrogen, a phenyl group, or a linear alkyl group having 1 to 12 carbon atoms or a phenyl group substituted with a halogen.

[0044] In the structural unit represented by the above general formula (III), non-limiting examples of R8 include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, cyclopentyl, cyclohexyl, phenyl, o-methylphenyl, m-methylphenyl, p-methylphenyl, o-ethylphenyl, m-ethylphenyl, p-ethylphenyl, ot-butylphenyl, mt-butylphenyl, pt-butylphenyl, o-chlorophenyl, o-bromophenyl, dicyclopentadiene, or benzofuranone.Among these, it is preferable to use methyl, ethyl, propyl, phenyl, or o-methylphenyl, because the presence of such groups contributes to advantageous handling properties.

[0045] The structural units represented by structural formula (III) in component [A] are linked via a non-hydrocarbon divalent linking group such as C=O, CH2OC(=O), S, SO2, SO, or O. Suitable non-hydrocarbon divalent linking groups may be characterized by containing at least one heteroatom selected from oxygen and sulfur. Such a divalent non-hydrocarbon linking group may be bonded to a carbon atom in a benzene ring of one structural unit of formula (III) and to a carbon atom in a benzene ring of another structural unit of formula (III).

[0046] The structural units of structural formula (III) in component [B] may be linked directly (e.g., by a single bond connecting the benzene rings) or through a hydrocarbon linking group, in particular through a divalent hydrocarbon linking group such as CH2, C(CH3)2, CH(CH3), or dicyclopentadiene, or may be condensed with a benzyl group of the benzoxazine moiety. Such a divalent non-hydrocarbon linking group may be bonded to a carbon atom in the benzene ring of one structural unit of formula (III) and to a carbon atom in the benzene ring of another structural unit of formula (III). The structural units of structural formula (III) may also be linked through a nitrogen atom (involving an R8 substituent) of such structural units by a divalent linking group, corresponding to the general formula NLN, where L is a divalent linking group and each N is part of an oxazine ring. For example, such a linker group may be Ar-CH2-Ar, where Ar is an aryl group. Other suitable linking groups include Ar, Ar-S-Ar, and Ar-O-Ar.

[0047] In one embodiment of the polyfunctional benzoxazine, a bifunctional benzoxazine containing two structural units represented by general formula (III) suitable for use as component [A] of the present invention includes, for example, a benzoxazine represented by the following formula (IA):

[0048] [ka]

[0049] In component [A], Z in formula (IA) is selected from C=O, CH2OC(=O), O, S, S=O, or O=S=O.

[0050] R and R1 in formula (IA) are independently selected from alkyl (e.g., C1-C8 alkyl), cycloalkyl (e.g., C5-C7 cycloalkyl, preferably C6 cycloalkyl), and aryl, where the cycloalkyl and aryl groups may be optionally substituted, for example by C1-C8 alkyl, halogen, and amine groups, and when substituted, one or more substituents (preferably one substituent) may be present on each cycloalkyl and aryl group.

[0051] In one embodiment of the polyfunctional benzoxazine, examples of bifunctional benzoxazines containing two structural units represented by general formula (III) suitable for use as component [B] of the present invention include benzoxazines represented by the following formulae (IA') and (IB').

[0052] [ka]

[0053] [ka]

[0054] In formula (IA'), n is 0 or 1. When n=1, Z' is a direct bond, C(R2)(R3), C(R2)(Ar), a divalent heterocycle (e.g., 3,3-isobenzofuran-1(3h)-one), and [C(R2)(R3)]. x -Ar-[C(R4)(R5)] y When n=0, the benzyl group of the benzoxazine moiety may be fused between the two benzoxazine moieties or may be attached by a direct bond.

[0055] In formula (IB'), L is CH2, C(CH3)2, CH(CH3), dicyclopentadiene, Ar, and Ar-Y-Ar. ofdivalent hydrocarbon linking groups, and Y is selected from a direct bond, C(R2)(R3), C(R2)(Ar), a divalent heterocycle, [C(R2)(R3)]x-Ar-[C(R4)(R5)] y , S, SO2, and O, Ar is an aryl group, and x and y are independently 0 or 1.

[0056] R in formula (IA') is independently hydrogen, C1-C 20 Alkyl group, allyl group, or C6-C 14 aryl group, each R is independently selected from hydrogen, C1-C 20 Alkyl group, allyl group, or C6-C 14 R1 in formula (IB') may be independently selected from the same groups.

[0057] R2, R3, R4, and R5 are independently selected from H, C1-C8 alkyl (preferably C1-C4 alkyl, and preferably methyl), and alkyl halide (wherein halogen is typically chlorine or fluorine), and x and y are independently 0 or 1. When an aryl group is present, the aryl group is preferably phenyl. In one embodiment, the groups attached to the phenyl group may be arranged in the para or meta positions relative to each other.

[0058] The Z' and L groups may be linear or non-linear, typically linear. The L groups are preferably attached to each nitrogen of the benzoxazine moiety as shown in formula (IB'). The Z groups may be attached at either the meta or ortho positions on one or both of the aryl groups of the bifunctional benzoxazine compound. Thus, the Z' groups may be attached to the aryl ring in a para / para, para / meta, para / ortho, meta / meta, or ortho / meta configuration.

[0059] In another embodiment, the bifunctional benzoxazine moiety corresponding to formula (IA) or formula (IA') is selected from compounds where each R is independently selected from aryl, or preferably from compounds where R is phenyl. In one embodiment, the aryl group may be substituted, preferably the substituents are selected from C1-C8 alkyl, preferably there is a single substituent on at least one aryl group. C1-C8 alkyl includes linear and branched alkyl chains. Preferably, each R of formula (IA) or formula (IA') is independently selected from unsubstituted aryl, preferably unsubstituted phenyl.

[0060] The aryl rings in each benzoxazine group of the bifunctional benzoxazine moiety defined herein as formula (IA) or formula (IA') may be independently substituted at any of the three available positions on each ring, and typically any optional substituents are present in the ortho position relative to the attachment position of the Z or Z' group. However, it is preferred that the aryl rings remain unsubstituted.

[0061] Suitable trifunctional benzoxazine resins include compounds that can be prepared by reacting an aromatic triamine with a phenol (monohydric or polyhydric) in the presence of an aldehyde, such as formaldehyde, or a source or equivalent thereof.

[0062] In the present disclosure, it is preferable to use at least one monomer represented by the following structural formulas (IV) to (VIII) as the polyfunctional benzoxazine resin of component [A], and it is preferable to use at least one monomer represented by the following structural formulas (IX) to (XV) as the polyfunctional benzoxazine resin of component [B].

[0063] [ka]

[0064] [ka]

[0065]

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[0074]

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[0075] In certain embodiments of the present invention, each of component [A] and component [B] preferably comprises (or consists of, or consists essentially of) at least one multifunctional benzoxazine, and may be composed of a monomer alone, or may have the form of an oligomer in which multiple molecules are polymerized. In addition, multifunctional benzoxazines having different structures may be used together. In one embodiment, component [A] may contain two or more multifunctional benzoxazines having a non-hydrocarbon linking group, in which the two or more multifunctional benzoxazines are different in at least one of Z, R, or R1, and the different components [A] may be represented as [An], where n is an integer from 2 to 10, and [A1], [A2]... to [An], etc. In another embodiment, component [B] may contain two or more multifunctional benzoxazine moieties, where the two or more multifunctional benzoxazine moieties differ in at least one of Z', L, R, or R1, and the different components [B] may be represented as [Bn], where n is an integer from 2 to 10, [B1], [B2]... through [Bn], etc.

[0076] In another embodiment of the present invention, the mass ratio ([A] / [B]) of component [A] to component [B] is 1 / 2 to 5 / 1, including the boundary value. In one embodiment, the lower limit of the mass ratio ([A] / [B]) of component [A] to component [B] is 1 / 2 or more, preferably 2 / 3 or more, and more preferably 3 / 2 or more. Furthermore, the upper limit of the mass ratio ([A] / [B]) of component [A] to component [B] is 5 / 1 or less, preferably 4 / 1 or less, preferably 3 / 1 or less, and more preferably 5 / 2 or less. Within this range, when blended with an appropriate amount of component [C], the benzoxazine resin composition will simultaneously have a higher Tg and elastic modulus than predicted by the rule of mixtures. In one embodiment, the mass ratio of component [C] to the total amount of component [A] and component [B] ([C] / ([A]+[B])) is 1 / 9 to 2 / 3, including the boundary value (the mass of component [C] to the total mass of component [A] and component [B] is 1 part or more of component [C] per 9 parts of component [A] and component [B] combined, and 2 parts or less of component [C] per 3 parts of component [A] and component [B] combined).

[0077] In various embodiments of the present invention, the curable benzoxazine resin composition comprises component [A] present in an amount of less than 98 PHR and more than 1 PHR, or preferably less than 60 PHR and more than 27 PHR, or more preferably less than 60 PHR and more than 25 PHR, or particularly preferably less than 50 PHR and more than 40 PHR. In another embodiment, component [B] is present in an amount of less than 98 PHR and more than 1 PHR, or preferably less than 50 PHR and more than 15 PHR, or more preferably less than 35 PHR and more than 25 PHR. In some embodiments, component [C] is present in an amount of less than 98 PHR and more than 1 PHR, or preferably less than 40 PHR and more than 10 PHR, or preferably less than 30 PHR and more than 20 PHR. Thus, in such an embodiment, the curable benzoxazine resin composition comprises component [A] of >1 to <98 PHR, component [B] of >1 to <98 PHR, and component [C] of >1 to <98 PHR. In other embodiments, the curable benzoxazine resin composition includes 25-60 PHR of component [A], 15-50 PHR of component [B], and 10-40 PHR of component [C]. In some other embodiments, the curable benzoxazine resin composition includes 40-50 PHR of component [A], 25-35 PHR of component [B], and 20-30 PHR of component [C].

[0078] Fiber reinforced composite materials such as carbon fiber reinforced polymers (CFRP) made with the curable benzoxazine resin compositions according to embodiments of the present invention are particularly suitable for structural aerospace applications with high service temperature requirements.

[0079] The polyfunctional benzoxazine resin used as component [A] can be obtained from several suppliers, including but not limited to Konishi Chemical Industry Co., Ltd. and Huntsman Advanced Materials. The polyfunctional benzoxazine resin used as component [B] can be obtained from several suppliers, including but not limited to Shikoku Chemical Industry Co., Ltd., Konishi Chemical Industry Co., Ltd., and Huntsman Advanced Materials. Among these suppliers, Shikoku Chemical Industry Co., Ltd. provides bisphenol A aniline type benzoxazine resin, bisphenol A methylamine type benzoxazine resin, and bisphenol F aniline type benzoxazine resin. Instead of using commercially available raw materials, the polyfunctional benzoxazine resin can also be produced by reacting a phenolic compound (e.g., bisphenol A, bisphenol F, bisphenol S, or thiodiphenol), an aldehyde, and an arylamine, as needed. Detailed manufacturing methods can be found in U.S. Pat. Nos. 5,543,516, 4,607,091 (Schreiber), 5,021,484 (Schreiber), and 5,200,452 (Schreiber).

[0080] In the present invention, epoxy resin means an epoxy compound having at least two 1,2-epoxy groups in the molecule, i.e. an epoxy compound that is at least difunctional with respect to the epoxy functionality.

[0081] In particular, the curable benzoxazine resin composition according to an embodiment of the present invention comprises, as component [C], one or more cycloaliphatic epoxy resins containing at least two epoxide groups per molecule, and at least one of the epoxide groups, preferably at least two of the epoxide groups, being part of an alicyclic ring. In certain embodiments of the present invention, component [C] comprises at least one cycloaliphatic epoxy resin represented by formula (II): 20 and X represents a single bond or a divalent moiety. In other embodiments, X is absent in formula (II) and the cycloaliphatic epoxy resin comprises a fused ring system comprising R6 and R7, such as dicyclopentadiene diepoxide.

[0082] [ka]

[0083] wherein m=0 or 1; R6 and R7 are the same or different; It is either a part of a cyclopentane ring, a part of a cyclohexane ring, or a part of a norbornane ring, Each of the substituted or unsubstituted C1-C alkyl groups forms at least one aliphatic ring together with the carbon atom of the epoxy group. 20 an aliphatic moiety, m is 0 or 1; when m=1, X is a single bond, O, S, C.H. 2 , C.H. 2 CH 2 , C.H. 2 CH 2 CH 2 , C.H. 2 CH(CH 3 ), C(CH 3 ) 2 , C.H. 2 OCH 2 , C(=O), CH 2 Either OC(=O) Represents. RR6 and R7 may each independently contain a three carbon chain or a four carbon chain, thereby forming a five or six membered aliphatic ring, respectively. R6 and / or R7 may also have a structure that provides a bicyclic ring, such as a norbornane ring. In other embodiments, when m=0, X is absent (i.e., not present), and any one of a dicyclopentadiene type diepoxide, a tricyclopentadiene type diepoxide, a tetrahydroindene type diepoxide, a tetracyclotetradecadiene type diepoxide, and a pentacyclopentadecadiene type diepoxide is formed. .

[0084] Here, cycloaliphatic epoxy resin means an epoxy resin in which at least two 1,2-epoxycycloalkane structural moieties are present (each such moiety is an aliphatic ring in which two adjacent carbon atoms that are part of the aliphatic ring are also part of an epoxy ring, each bonded to the same oxygen atom). Cycloaliphatic epoxy resins are useful because they can increase the Tg of the cured product and reduce the viscosity of the uncured resin composition. X can be selected from CH2OC(=O), O, S, alkyl (e.g., X=CH2, CH2CH2, CH2CH2CH2, CH2CH(CH3), or C(CH3)2), ether-containing moiety (e.g., X=CHOCH2), carbonyl-containing moiety (e.g., X=C(=O)), oxirane ring-containing moiety (e.g., X=CH-O-CH, where a single bond exists between two carbon atoms to form a three-membered ring containing an oxygen atom and two carbon atoms), or a fused ring system.

[0085] In certain embodiments, when m=0, X in formula (II) is absent, which means that R6 and R7 are part of a fused ring system. Dicyclopentadiene-type diepoxide is an example of an alicyclic epoxy resin in which R6 and R7 are part of a fused ring system. In other embodiments, when m=1, X in formula (II) is a single bond connecting the cyclic group containing R6 and R7.

[0086] The cycloalkane groups present in such cycloaliphatic epoxy resins may be, for example, monocyclic or bicyclic (e.g., norbornane groups). Examples of suitable monocyclic cycloalkane groups include, but are not limited to, cyclopentane groups (where R6 and R7 can be C3H5 groups), cyclohexane groups (where R6 and R7 each can be C4H8 groups), or norbornane groups (where R6 and R7 can be C5H9 groups).

[0087] Such cycloalkane groups may be substituted (e.g., by alkyl groups) or, preferably, unsubstituted. When X is a single bond or a divalent moiety, the epoxy groups on such cyclohexane and cyclopentane rings may be in the 2,3 or 3,4 positions on the ring.

[0088] Specific examples of cycloaliphatic epoxy resins useful as component [C] include, but are not limited to, bis(3,4-epoxycyclohexyl), also known as 3,4,3',4'-diepoxybicyclohexyl, bis[(3,4-epoxycyclohexyl)ether], bis[(3,4-epoxycyclohexyl)oxirane, bis[(3,4-epoxycyclohexyl)methane], 2,2-bis(3,4-epoxycyclohexyl)propane, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and the like, and combinations thereof. In addition, cyclopentane mono- or di-substituted versions of the above-mentioned monomers may be used, including bis(3,4-epoxycyclopentyl), bis(3,4-epoxycyclopentyl)ether, and 3,4-epoxycyclopentyl-3,4-epoxycyclohexyl.

[0089] Examples of cycloaliphatic epoxy resins where m=0, X is zero (i.e., absent), and R6 and R7 are part of a fused ring system include, but are not limited to, dicyclopentadiene-type diepoxides, tricyclopentadiene-type diepoxides, tetrahydroindene-type diepoxides, tetracyclotetradecadiene-type diepoxides, and pentacyclopentadecadiene-type diepoxides.

[0090] Examples of suitable alicyclic epoxy resins include, but are not limited to, the following compounds represented by the following structural formulas (XVI) to (XX) as the epoxy resin of component [C].

[0091] [ka]

[0092] [ka]

[0093] [ka]

[0094] [ka]

[0095] [ka]

[0096] In formula (XIX) and formula (XX), X=a single bond, O, S, CH2, CH2CH2, CH2CH2CH2, CH2CH(CH3), C(CH3)2, CH2OCH2, C(=O), CH2OC(=O), or oxirane, and one or both of the cyclohexane rings in formula (XX) may be replaced with a cyclopentane ring.

[0097] Formula (XIX) shown above is an example of a cycloaliphatic epoxy resin, where R6 and R7 are aliphatic moieties that are part of a bicyclic aliphatic ring.

[0098] Formulae (XVI), (XVII), and (XVIII) are examples of cycloaliphatic epoxy resins where in formula (II), m=0, X is absent, and the cycloaliphatic epoxy resin contains fused aliphatic rings (these compounds also contain bicyclic aliphatic rings).

[0099] Such cycloaliphatic epoxy resins are known in the art and may be prepared using any suitable synthetic method, for example, by epoxidation of cycloaliphatic di- and triolefinic compounds, such as compounds having a 3,3'-dicyclohexenyl backbone. For example, U.S. Patent No. 7,732,627 and U.S. Patent Application Publication Nos. 2004 / 0242839 and 2014 / 0357836 describe methods for obtaining cycloaliphatic epoxy resins useful in the present invention.

[0100] Also suitable for use in component [C] of the present invention are any of the cycloaliphatic epoxy resins disclosed in U.S. Pat. No. 4,607,091, the entire contents of which are incorporated herein by reference in their entirety, and in particular the cycloaliphatic epoxy resins listed in Table 1.

[0101] In one embodiment of the present invention, component [C] may contain two or more cycloaliphatic epoxy resins differing in at least one of X, R6, and R7, in which case the different cycloaliphatic epoxy resins may be represented as [C1], [C2], [C3], etc.

[0102] In one embodiment, the lower limit of the mass ratio ([C] / ([A]+[B])) of the epoxy component [C] to the total amount of benzoxazine provided by the components [A] and [B] is 1 / 9 or more, preferably 1 / 5 or more, and more preferably 3 / 10 or more. Furthermore, the upper limit of the mass ratio ([C] / ([A]+[B])) of the component [C] to the total amount of benzoxazine provided by the components [A] and [B] is 2 / 3 or less, preferably 1 / 2 or less, and more preferably 2 / 5 or less. Within this range, a curable benzoxazine resin composition having a viscosity range more suitable for the manufacturing process is obtained, and at the same time, suitable adhesion (tack) and deformability (drapeability) are obtained in the prepreg. In addition, since the cured benzoxazine resin composition maintains an excellent elastic modulus and glass transition temperature, when used as a composite material, this material provides excellent mechanical properties at high temperatures. When the blending amount of component [C] is less than 1 / 9 of the blending amount of component [A] and component [B], the viscosity of the benzoxazine resin composition increases, which may impair the manufacturing processability, and the Tg of the material decreases, limiting its use in high-temperature applications. However, when the blending amount of component [C] exceeds 2 / 3, the Tg decreases again. As a result, the mechanical properties tend to be impaired when used as a composite material in a hot environment.

[0103] In a particular embodiment of the present invention, it may be desirable to mix or dissolve at least one thermoplastic compound as component [D] in the above-mentioned benzoxazine resin composition in order to improve the properties of the cured material and to increase the minimum viscosity during curing to improve processability. In general, thermoplastic compounds (polymers) having a bond selected from the group consisting of carbon-carbon bonds, amide bonds, imide bonds, ester bonds, ether bonds, carbonate bonds, urethane bonds, thioether bonds, sulfone bonds, and / or carbonyl bonds in the main chain of the thermoplastic compound (polymer) are preferred. Furthermore, the thermoplastic compound may also have a partially crosslinked structure and may be crystalline or amorphous. In particular, it is suitable or preferred that at least one thermoplastic compound selected from the group consisting of polyamide, polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyester, polyamideimide, polyimide resin (including polyimide resin having a phenyltrimethylindane structure or a phenylindane structure), polyetherimide, polysulfone, polyethersulfone, polyetherketone, polyetheretherketone, polyaramid, polyethernitrile, and polybenzimidazole is mixed or dissolved in the benzoxazine resin composition. In the case of a polyimide resin thermoplastic compound, the backbone of the thermoplastic compound may additionally contain a phenyltrimethylindane unit or a phenylindane unit.

[0104] In a specific embodiment of the present invention, the glass transition temperature (Tg) of component [D] is 150° C. or higher, preferably 170° C. or higher, more preferably 200° C. or higher, and particularly preferably 220° C. or higher, so as to obtain advantageous heat resistance. If the glass transition temperature of the blended component [D] is less than 150° C., the obtained molded article tends to be thermally deformed during use. From the viewpoint of obtaining high heat resistance or high solvent resistance, or from the viewpoint of affinity for the benzoxazine resin composition including solubility and adhesiveness, it is preferable to use polysulfone, polyethersulfone, polyphenylene sulfide, polyimide resin (including polyimide resin having a phenyltrimethylindane structure or a phenylindane structure), or polyetherimide.

[0105] Specific examples of suitable sulfone-based thermoplastic compounds include, but are not limited to, polyethersulfone and polyethersulfone-polyetherethersulfone copolymer oligomers as described in U.S. Patent Application Publication No. 2004 / 044141(A1).Specific examples of suitable imide-based thermoplastic compounds include, but are not limited to, polyimide resins and polyimide-phenyltrimethylindane oligomers as described in U.S. Patent No. 3,856,752.

[0106] As used herein, the term oligomer refers to a relatively low molecular weight polymer formed by the bonding of a finite number of monomer molecules, from about 10 to about 100. In one embodiment, component [D] is an oligomer.

[0107] The molecular weight of component [D] is preferably a weight average molecular weight of 150000 g / mol or less. More preferably, the weight average molecular weight is 7000 to 150000 g / mol. If it is less than 7000 g / mol, the effect of improving the physical properties is slight, and the heat resistance of the benzoxazine resin composition is impaired. If it is more than 150000 g / mol, the affinity with the curable benzoxazine resin composition is poor, and the improvement of the physical properties is not obtained in the curable or cured benzoxazine resin composition or in the carbon fiber reinforced composite material. In addition, when dissolved, even if a small amount is blended, the viscosity becomes too high, and when a prepreg is produced, the tackiness and drapeability are reduced. When component [D] having a weight average molecular weight of 7000 to 150000 g / mol is used, it has the effect of improving the affinity with the benzoxazine resin composition and the effect of improving the physical properties without impairing the heat resistance of the benzoxazine resin composition. Furthermore, when the prepreg is manufactured, suitable tack and drape properties are obtained.

[0108] The average molecular weight referred to in the embodiments of this specification refers to the weight average molecular weight obtained by gel permeation chromatography (hereinafter "GPC"). An example of a method for measuring the number average molecular weight is to use two Shodex 80M (registered trademark) [columns] (Showa Denko) and one Shodex 802 (registered trademark) [column] (Showa Denko), inject 0.3 μL of sample, and convert the retention time of the sample measured at a flow rate of 1 mL / min to molecular weight by using the retention time of a calibration sample made of polystyrene. When multiple peaks are observed in liquid chromatography, the components of interest are separated in advance by liquid chromatography, and then each component is subjected to GPC, followed by conversion to molecular weight.

[0109] Although the benzoxazine resin composition need not contain a thermoplastic compound as component [D], in various embodiments of the present invention, the benzoxazine resin composition includes at least 1 part by weight, at least 5 parts by weight, or at least 10 parts by weight of component [D], i.e., thermoplastic compound per 100 parts by weight of the combined total of components [A], [B], and [C]. For example, the curable benzoxazine resin composition may include 5 to 30 parts by weight of component [D] (thermoplastic compound) per 100 parts by weight of the combined total of components [A], [B], and [C].

[0110] In certain embodiments of the invention, the ratios of components [A], [B], and [C] are varied such that the mass ratio of [A] / [B] is between 1 / 2 and 5 / 1, inclusive, and the mass ratio of [C] / ([A]+[B]) is between 1 / 9 and 2 / 3, inclusive. Surprisingly, it has been found that these ratios produce resins with higher Tg and flexural modulus than would be predicted based on the rule of mixtures, making them particularly well suited for structural aerospace applications. Additionally, these ratios produce resin viscosities that are ideally suited for the production of prepregs and fiber reinforced composites.

[0111] In certain embodiments, the curable benzoxazine resin composition further comprises, consists essentially of, or consists of one or more additional additives. Examples of suitable additional additives include, but are not limited to, toughening agents, catalysts, reinforcing agents, fillers, adhesion promoters, flame retardants, thixotropic agents, and combinations thereof.

[0112] In certain embodiments of the present invention, the curable benzoxazine resin composition preferably has a viscosity of 1.0×10 at 40° C. 2 ~1.0×10 6 It has a viscosity of poise. The viscosity at 40°C is 1.0 x 10 2 By setting the viscosity at 40°C to 1.0×10 or more, it is possible to obtain a prepreg with appropriate adhesiveness. 6By setting the viscosity at 40°C to 1.0×10 or less, it is possible to provide appropriate drapeability and tackiness when laminating prepregs. 3 ~1.0×10 5 In particular, the range of 1.0×10 4 ~1.0×10 5 It is within the poise range.

[0113] In a further specific embodiment, the minimum viscosity of the benzoxazine resin composition is preferably 0.1 to 300 poise, more preferably 0.5 to 100 poise, and particularly preferably 1 to 50 poise. If the minimum viscosity is too low, the fluidity of the matrix resin may be too high, and therefore, the resin may come out of the prepreg when the prepreg is cured. Furthermore, the desired resin fraction may not be realized in the obtained fiber reinforced composite material, the flow of the matrix resin in the prepreg may be insufficient, the solidification process of the prepreg may end too early, and many voids may occur in the obtained fiber reinforced composite material. If the minimum viscosity is too high, the flow of the matrix resin in the prepreg may be low, the solidification process of the prepreg may end too early, and many voids may occur in the obtained fiber reinforced composite material. In this specification, the viscosity at 40°C and the minimum viscosity are specified by the following method. Briefly, measurements were performed using a 40 mm diameter parallel plate rheometer (ARES, TA Instruments) with a gap of 0.6 mm. The torsional displacement was applied at 10 rad / sec. The temperature was ramped from 40° C. to 180° C. at 2° C. / min.

[0114] In another embodiment, when the benzoxazine resin composition is cured, the glass transition temperature of the matrix is ​​preferably at least 200°C, more preferably at least 215°C, and especially preferably at least 230°C, as determined by the G' onset method (described in more detail in the Examples).

[0115] According to yet a further embodiment, when the benzoxazine resin composition is cured to provide a cured matrix having a flexural modulus, the flexural modulus of the cured matrix at 25° C. may preferably be at least 4.3 GPa, more preferably at least 4.5 GPa, and especially preferably at least 4.7 GPa.

[0116] Next, a fiber reinforced composite (FRC) material can be obtained by impregnating reinforcing fibers and then curing an embodiment of the benzoxazine resin composition to obtain an FRC material containing an embodiment of the curable benzoxazine resin composition in the form of a cured product as its matrix resin.

[0117] There is no particular restriction or limitation regarding the type of reinforcing fiber used in the present invention, and a wide range of fibers may be used, including, but not limited to, glass fiber, carbon fiber, graphite fiber, aramid fiber, boron fiber, alumina fiber, and silicon carbide fiber. Carbon fibers may provide a particularly lightweight and stiff FRC material. For example, carbon fibers having a tensile modulus of 180-800 GPa may be used. When carbon fibers having a high modulus of 180-800 GPa are combined with the curable benzoxazine resin composition of the present invention, a desirable balance of stiffness, strength, and impact resistance may be achieved in the fiber reinforced composite material.

[0118] There is no particular restriction or limitation on the form of the reinforcing fiber, and various forms of fibers may be used, including, for example, long fibers (unidirectionally stretched), tows, woven fabrics, mats, knits, braids, and short fibers (cut to a length of less than 10 mm). Here, long fibers refer to single fibers or fiber bundles that are substantially continuous over at least 10 mm. On the other hand, short fibers are fiber bundles cut to a length of less than 10 mm. For applications requiring high specific strength and specific modulus, a fiber arrangement in which reinforcing fiber bundles are aligned in the same direction may be suitable.

[0119] Fiber reinforced composite materials according to embodiments of the present invention may be manufactured using methods such as prepreg lamination, resin transfer molding, resin film injection, hand lay-up, sheet molding compound, filament winding, and pultrusion, although no particular limit or restriction is applied in this regard.

[0120] Resin transfer molding is a process in which a reinforcing fiber-based material is directly impregnated with a liquid thermosetting resin composition (such as the benzoxazine resin composition described herein) and cured. This process has great potential for reducing molding costs since no intermediate products such as prepregs are involved, and is advantageously used in the manufacture of structural materials for spacecraft, aircraft, rail vehicles, automobiles, ships, etc.

[0121] The prepreg lamination molding method is a method in which a prepreg produced by impregnating a reinforcing fiber base material with a thermosetting resin composition is molded and / or laminated, and then heat and pressure are applied to the molded and / or laminated prepreg to harden the resin and obtain an FRC material.

[0122] Filament winding is a process in which one to several dozen reinforcing fiber rovings are wrapped around a rotating metal mandrel under tension at a given angle while being stretched together in one direction and impregnated with a thermosetting resin composition. Once the roving wrap reaches a given thickness, it is cured and the metal mandrel may or may not then be removed.

[0123] Pultrusion is a method in which reinforcing fibers are continuously passed through an impregnation tank filled with a liquid thermosetting resin composition to impregnate them with the thermosetting resin composition, and then passed through a squeeze die and a heated die for molding and curing, and continuously stretched using a tensile machine. This method offers the advantage of continuously molding FRC materials, and is therefore used in the manufacture of FRC materials for fishing rods, rods, pipes, sheets, antennas, building structures, etc.

[0124] Among these methods, prepreg lamination may be used to impart exceptional stiffness and strength to the resulting fiber reinforced composite material.

[0125] A prepreg may contain the curable benzoxazine resin composition and reinforcing fiber embodiments of the present invention. Such a prepreg may be obtained by impregnating a reinforcing fiber base material with the curable benzoxazine resin composition according to an embodiment of the present invention. Impregnation methods include a wet method and a hot melt method (dry method).

[0126] The wet method is a method in which the reinforcing fibers are first immersed in a solution of the curable benzoxazine resin composition of the present invention made by dissolving the curable benzoxazine resin composition in a solvent such as methyl ethyl ketone or methanol, removed, and then the solvent is removed, such as by evaporation in an oven, to impregnate the reinforcing fibers with the benzoxazine resin composition.

[0127] The hot melt process can be carried out by directly impregnating the reinforcing fibers with the benzoxazine resin composition that has been pre-fluidized by heating, or by first coating a release paper or the like with the benzoxazine resin composition for use as a resin film, then placing the film on one or both sides of the reinforcing fibers arranged in a flat configuration, followed by application of heat and pressure to impregnate the reinforcing fibers with the resin. The hot melt process can provide a prepreg that has substantially no residual solvent therein.

[0128] The cross-sectional density of the reinforced fibers in the prepreg is 50 to 350 g / m 2 The cross-sectional density may be at least 50 g / m 2 When the cross-sectional density is 350 g / m, the number of prepregs that need to be laminated to ensure a predetermined thickness during molding of the fiber-reinforced composite material can be reduced, and this can simplify the lamination process. 2When the mass fraction of the reinforcing fibers is 90% or less, the drapeability of the prepreg can be good. The mass fraction of the reinforcing fibers of the prepreg can be 50-90% by mass in some embodiments, 60-85% by mass in other embodiments, or 70-80% by mass in still other embodiments. When the mass fraction of the reinforcing fibers is at least 50% by mass, the fiber content is sufficient, which can provide the fiber reinforced composite material with its very good specific strength and specific modulus, as well as the advantage of preventing the FRC material from generating excessive heat during curing. When the mass fraction of the reinforcing fibers is 90% or less by mass, it can be sufficiently impregnated by the resin, and the risk of forming a large amount of voids in the fiber reinforced composite material can be reduced.

[0129] For application of heat and pressure under the prepreg lamination molding method, press molding, autoclave molding, bagging molding, wrapping tape method, internal pressure molding, etc. may be appropriately used.

[0130] Autoclave molding is a method in which prepregs are stacked on a shaped tool plate, then covered with a bagging film, followed by curing by application of heat and pressure while air is pulled out of the stack. It may allow precise control of fiber orientation and may also provide high quality molded materials with very good mechanical properties by minimizing void content. The pressure applied during the molding process may be 0.3-1.0 MPa, while the molding temperature may be in the range of 90-300°C. Due to the exceptionally high Tg of the cured benzoxazine resin composition of the present invention, it may be advantageous to carry out the curing of the prepregs at relatively high temperatures (e.g., temperatures of at least 180°C or at least 200°C). For example, the molding temperature may be 200°C to 275°C. Alternatively, the prepreg may be molded at a somewhat lower temperature (e.g., 90°C-200°C), demolded, and then post-cured at a higher temperature (e.g., 200°C-275°C) after removal from the mold.

[0131] The wrapping tape method is a method in which a prepreg is wrapped around a mandrel or some other core to form a tubular fiber reinforced composite. This method can be used in the manufacture of golf shafts, fishing rods, and other rod-shaped products. More specifically, this method involves wrapping a prepreg around a mandrel and wrapping a wrapping tape made of a thermoplastic film over the prepreg under tension in order to fix the prepreg and apply pressure to it. After curing of the resin by heating in an oven, the core is removed to obtain a tubular body. The tension used in wrapping the wrapping tape can be 20-100 N. The molding temperature can be in the range of 80-300°C.

[0132] The internal pressure molding method is a method in which a preform obtained by wrapping a prepreg around a thermoplastic resin tube or some other internal pressure applicator is set inside a metal mold, and then high pressure gas is introduced into the internal pressure applicator to apply pressure, and the metal mold is heated at the same time to mold the prepreg. This method can be used in molding objects with complex shapes such as golf shafts, bats, and tennis or badminton rackets. The pressure applied during the molding process can be 0.1 to 2.0 MPa. The molding temperature can be in the range of room temperature to 300°C, or 180 to 275°C.

[0133] The fiber reinforced composite material produced from the prepreg of the present invention may have a Class A surface, as mentioned above. The term "Class A surface" refers to a surface that exhibits extremely high finish quality characteristics, free of aesthetic defects and imperfections.

[0134] The fiber-reinforced composite materials containing the cured benzoxazine resin composition and reinforcing fibers obtained from the curable benzoxazine resin composition according to the embodiment of the present invention are advantageously used in sports, general industrial, and aerospace applications.Sports applications in which these materials are advantageously used include golf shafts, fishing rods, tennis or badminton rackets, hockey sticks, and ski poles.General industrial applications in which these materials are advantageously used include structures for vehicles such as automobiles, bicycles, ships, and railroad cars, drive shafts, leaf springs, windmill blades, pressure vessels, flywheels, papermaking rollers, roofing materials, cables, and repair / reinforcement materials.

[0135] Although the embodiments have been described herein in a manner that enables a clear and concise specification to be written, it is contemplated and understood that the embodiments can be variously combined or separated without departing from the invention, and for example, it is understood that all preferred features described herein are applicable to all aspects of the invention described herein.

[0136] In some embodiments, the invention may be construed as excluding any element or process step herein that does not materially affect the basic and novel characteristics of the composition or process. In addition, in some embodiments, the invention may be construed as excluding any element or process step not specified herein.

[0137] Although the invention is illustrated and described herein with reference to specific embodiments, it is not intended that the invention be limited to the details shown, but rather, various modifications may be made thereto within the scope and range of equivalents of the claims without departing from the invention. EXAMPLES

[0138] In the examples of the present invention, the properties were measured according to the methods described below. Details of each example are shown in Tables 1 to 3.

[0139] <Preparation of resin plate> A mixture was prepared by dissolving all the components in the mixture in the prescribed amounts. The benzoxazine resin composition was poured into a mold cavity set to a thickness of 2 mm using a 2 mm thick polytetrafluoroethylene (PTFE) spacer. The benzoxazine resin composition was then cured by heat treatment in an oven to obtain a 2 mm thick cured resin plate.

[0140] <Manufacturing of Fiber Reinforced Composite (FRC) Materials> A prepreg was prepared containing the specified reinforcing fibers impregnated with the specified resin composition. A mixture was first prepared by dissolving all the components in the mixture in the prescribed amounts. It was then coated on release paper using a knife coater to prepare two resin films. The above two sheets of prepared resin film were superimposed on either side of the specified fiber arrangement in the form of a sheet and impregnated with a benzoxazine resin composition using a roller to obtain a carbon fiber basis weight of 190 grams / m2. 2 A prepreg with a resin content of 35% was prepared.

[0141] <Fiber weight> The resin weight per unit area (RAW) was determined by taking the resin in a film form before prepregging, cutting out a 100x100mm square sample, scraping off the resin from the square, and measuring the weight of the resin. The weight per unit area is calculated by doubling this weight and dividing by the area of ​​the square sample. The fiber weight per unit area (FAW) was determined by the same method after prepregging, cutting out a 100x100mm square sample, weighing the prepreg, and subtracting the RAW from this value.

[0142] <Resin content> Resin Content (RC) is the weight percent of resin in the prepreg.

[0143]

number

[0144] <Curing> The resin slabs alone were cured in a convection oven with one of two cure profiles. Curing conditions 1 (1) Increase the temperature from room temperature to 180°C at a rate of 1.5°C / min; (2) 180°C for 2 hours; (3) increasing the temperature from 180°C to 220°C at a rate of 1.5°C / min; (4) 220°C for 2 hours; (5) Decrease the temperature from 220°C to 30°C at a rate of 3°C / min. Curing conditions 2 (1) Increase the temperature from room temperature to 180°C at a rate of 1.5°C / min; (2) 180°C for 2 hours; (3) increasing the temperature from 180°C to 220°C at a rate of 1.5°C / min; (4) 220°C for 6 hours; (5) increasing the temperature from 220°C to 240°C at a rate of 1.5°C / min; (6) 240°C for 6 hours; (5) Decrease the temperature from 240°C to 30°C at a rate of 3°C / min.

[0145] The composites were cured in an autoclave with vacuum applied until the pressure exceeded 20 PSI. 85 PSI was applied during the initial heat up and maintained throughout the cure cycle. The thermal profile was identical to cure condition 1.

[0146] <Viscosity> Uncured resin samples were placed in a 40 mm diameter parallel plate rheometer (ARES, TA Instruments) with a gap of 0.6 mm preheated to 40° C. Torsional displacement was applied at 10 rad / sec. The temperature was increased at 2° C. / min until the viscosity decreased below the detection limit of 1.1 poise or until the minimum viscosity of the resin was identified.

[0147] <Glass Transition Temperature of Cured Benzoxazine Resin Composition> Samples were machined from a 2 mm thick cured resin plate and then measured in torsion mode at 1.0 Hz by heating from 50 °C to 300 °C at a rate of 5 °C / min using a dynamic viscoelasticity measuring device (ARES, manufactured by TA Instruments) in accordance with SACMA SRM 18R-94. The glass transition temperature (Tg) was specified by finding the intersection of the tangent line in the glassy state and the tangent line in the transition state between the glassy state and the rubbery state on the temperature-logarithmic storage modulus curve. The temperature at that intersection was regarded as the glass transition temperature, generally referred to as G’ onset Tg (G’onset Tg).

[0148] <Flexural Test of Cured Benzoxazine Resin Composition> Samples were machined from a 2 mm thick cured resin plate, and the flexural modulus and flexural strength were measured at room temperature in accordance with ASTM D-790.

[0149] <Open-Hole Compressive Strength (OHC) of FRC> In some embodiments, an FRC laminate comprising an epoxy resin composition was fabricated and the open-hole compressive strength (OHC) was tested. The prepreg was cut into samples of 350 mm × 350 mm. Sixteen fabric prepreg samples were laminated to form a laminate with a structure of [+45, 0, -45, 90] 2s and vacuum bagging was performed. The laminate was cured according to the procedure disclosed above to obtain a quasi-isotropic FRC material. This test sample was then subjected to an open-hole compressive strength test using an Instron universal testing machine in accordance with the provisions of ASTM-D6484.

[0150] <Raw Materials> The following commercially available products and chemicals were used to prepare the benzoxazine resin composition.

[0151] Component [A]: Araldite® MT35900 (manufactured by Huntsman Advanced Materials), a thiodiphenol type benzoxazine resin, formula (V) BS-BXZ (Konishi Chemical Industry Co., Ltd.), bisphenol S-aniline type benzoxazine resin, formula (IV) Ingredients [B]: Araldite® MT35600 (manufactured by Huntsman Advanced Materials), a bisphenol A-aniline type benzoxazine resin, of formula (X): Fa (manufactured by Shikoku Chemical Industry Co., Ltd.), bisphenol F-aniline type benzoxazine resin, formula (XI) Pd (manufactured by Shikoku Chemical Industry Co., Ltd.), phenol-diaminodiphenylmethane type benzoxazine resin, formula (XV) Ingredient [C]: Araldite® CY-179 (Huntsman Advanced Materials), 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, formula (XX) where X is CH2OC(=O). CELLOXIDE (registered trademark) 8000 (manufactured by Daicel Corporation), bis(3,4-epoxycyclohexyl), formula (XX) in which X is a direct bond Epocalic™ THI-DE (manufactured by JXTG Nippon Oil & Energy Corporation), tetrahydroindene diepoxide, formula (XX) Epocalic™ DE-102 (manufactured by JXTG Nippon Oil & Energy Corporation), tetracyclotetradecadiene diepoxy, formula (XVI) Epocalic™ DE-103 (manufactured by JXTG Nippon Oil & Energy Corporation), pentacyclopentadecadiene diepoxy, Formula (XVII) Other Ingredients: Epon™ 828 (Hexion Inc.), bisphenol A diglycidyl ether Component [D] Matrimid® 9725 (Huntsman Advanced Materials), polyimide resin, weight average molecular weight 80,000 g / mol; Virantage® VW30500 (Solvay), polyethersulfone, weight average molecular weight 14,000 g / mol The benzoxazine resin compositions shown in Tables 1 and 2 were prepared as follows. A mixture was prepared by dissolving all the components in the prescribed amounts. The benzoxazine resin composition was poured into a mold cavity set to a thickness of 2 mm using a 2 mm thick polytetrafluoroethylene (PTFE) spacer. The benzoxazine resin composition was then cured by heat treatment in an oven according to Curing Condition 1 or Curing Condition 2 to obtain a 2 mm thick cured resin plate. The measured properties of the resin composition alone (in its cured form) are shown in Tables 1 and 2.

[0152] Examples 1-4 provide unexpectedly better results than Comparative Examples 1-6 in terms of simultaneously providing the desired glass transition temperature and flexural modulus ranges. This advantage is best seen by comparing Example 1 with Comparative Example 2, which demonstrates that replacing 25 PHR of Fa with MT35900 results in a significant improvement in Tg while maintaining the desired modulus. This advantage is best seen by comparing Example 4 with Comparative Example 5, which demonstrates that replacing 5 PHR of MT35900 with Fa results in a significant improvement in modulus while maintaining the desired Tg. This is surprising given that the Tg of Fa is much lower than MT35900, whether cured as a single component or blended with CY-179.

[0153] Comparison between Example 2, Example 8, Comparative Example 3, and Comparative Example 6 clearly shows that when the ratio of CY-179 to benzoxazine is selected outside the preferred range, the Tg is significantly reduced.

[0154] Examples 1, 2, 3, and 4 highlight the extent to which Tg increases with increasing MT35900 concentration beyond that predicted by the rule of mixtures while still maintaining good flexural modulus.

[0155] Examples 2 and 3 clearly show that a particularly advantageous combination of Tg and modulus can be achieved by blending component [A], component [B], and component [C] in a specific ratio.

[0156] Example 6 clearly shows the advantageous modulus and viscosity due to the addition of component [D] when compared to Example 3. Example 6 also clearly shows the benefits of the addition of component [D] on modulus, Tg, and viscosity when compared to Example 15.

[0157] Example 7 clearly shows the advantageous combination of Tg and modulus when Celloxide 8000 is used as component [C].

[0158] Examples 9, 10, and 11 clearly demonstrate the advantageous Tg and modulus when BS-BXZ benzoxazine of formula (IV) is used as component [A].

[0159] Examples 12, 13, and 14 clearly demonstrate the advantageous Tg and modulus when using component [C] in formula (II) where X is absent and is part of a fused ring system.

[0160] From Comparative Example 7, it is clear that the Tg is low when an epoxy other than component [C] is used.

[0161] Example 16 clearly shows that high Tg and modulus were simultaneously obtained when Pd-type benzoxazine of formula (IB') was used as component [B] in the specified ratio.

[0162] Table 3 illustrates the advantageous Tg and open-hole compressive strength of fiber-reinforced composites obtained by curing prepregs made of benzoxazine resins with specific ratios of component [A], component [B], component [C], and component [D]. Examples 17, 18, and 19 clearly show the advantageous Tg and open-hole compressive strength with different types of carbon fibers and different sizing agents. Example 20 clearly shows the advantageous Tg and open-hole compressive strength when the ratio of component [A] to component [B] is 27 / 8 and the ratio of component [C] to the sum of components [A] and [B] ([C] / ([A]+[B])) is 3 / 7, which is higher than those shown in Examples 17, 18, and 19. Comparative Example 9 clearly shows that the Tg of the fiber-reinforced composite is reduced when the ratio of component [A] to component [B] is outside the specified range.

[0163] [Table 1]

[0164] [Table 2-1]

[0165] [Table 2-2]

[0166] [Table 3]

Claims

1. A curable benzoxazine resin composition comprising at least component [A], component [B], and component [C]: a) The component [A] comprises at least one benzoxazine of formula (IA): 【Chemistry 1】 In the formula, Z is C=O, CH ２ OC(=O), O, S, S=O, or O=S=O, and each R is independently selected from hydrogen, C １ ~C ２０ Alkyl group, allyl group, or C ６ ~C １４ aryl groups, each R １ are independently hydrogen, C １ ~C ２０ Alkyl group, allyl group, or C ６ ~C １４ aryl groups; b) The component [B] comprises at least one benzoxazine of formula (IA′) and / or formula (IB′): 【Chemistry 2】 In the formula, n is 0 or 1; when n=1, Z′ is a substituted or unsubstituted C １ ~C ２０ Alkyl group, substituted or unsubstituted divalent C ６ ~C ２０ An aryl group or a substituted or unsubstituted divalent C ２ ~C ２０ heteroaryl groups; when n=0, the benzyl groups of the benzoxazine moieties are fused or linked by a direct bond between the two benzoxazine moieties; 【Chemistry 3】 L is CH ２ , C(CH ３ ) ２ , CH(CH ３ ), dicyclopentadiene, Ar, and a divalent hydrocarbon linking group of Ar-Y-Ar, where Y is a direct bond, C(R ２ ) (R ３ ), C(R ２ )(Ar), a divalent heterocycle, [C(R ２ ) (R ３ )]x-Ar-[C(R ４ ) (R ５ ) ]y, S, SO ２ , and O, Ar is an aryl group, R ２ , R ３ , R ４ , and R ５ are independently H, C １ ~C ８ alkyl, and alkyl halides; c) The component [C] contains at least one alicyclic epoxy resin represented by formula (II): 【Chemistry 4】 In the formula, m=0 or 1; R ６ and R ７ are the same or different, and are either a part of a cyclopentane ring, a part of a cyclohexane ring, or a part of a norbornane ring, and each of them is a substituted or unsubstituted C which forms at least one aliphatic ring together with the carbon atom of the epoxy group. １ ~C ２０ an aliphatic moiety, m is 0 or 1; when m=1, X represents a single bond, O, S, CH2, CH2CH2, CH2CH2CH2, CH2CH(CH3), C(CH3)2, CH2OCH2, C(=O), or CH2OC(=O); when m=0, X is absent (i.e., not present), forming any of a dicyclopentadiene type diepoxide, a tricyclopentadiene type diepoxide, a tetrahydroindene type diepoxide, a tetracyclotetradecadiene type diepoxide, and a pentacyclopentadecadiene type diepoxide; d) components [A] and [B] are present in a mass ratio [A] / [B] of 1 / 2 to 5 / 1, inclusive, and components [A], [B], and [C] are present in a mass ratio [C] / ([A]+[B]) of 1 / 9 to 2 / 3, inclusive; Curable benzoxazine resin compositions.

2. 2. The curable benzoxazine resin composition of claim 1, further comprising a component [D], said component [D] comprising a thermoplastic compound comprising one or more repeat units.

3. 3. The curable benzoxazine resin composition of claim 2, wherein the thermoplastic compound is a polyethersulfone or a polyimide resin.

4. 4. The curable benzoxazine resin composition of claim 3, wherein the thermoplastic compound is a polyimide resin having a backbone containing additional phenyltrimethylindane units or phenylindane units.

5. The component [A] is Z, R, or R １ 2. The curable benzoxazine resin composition of claim 1, comprising two or more multifunctional benzoxazine moieties, at least one of which is different.

6. The component [B] is Z′, L, R, or R １ 2. The curable benzoxazine resin composition of claim 1, comprising two or more multifunctional benzoxazine moieties, at least one of which is different.

7. 2. The curable benzoxazine resin composition of claim 1, wherein the cured benzoxazine resin composition has a glass transition temperature, as determined by the G' onset method, of at least 215°C while also having a flexural modulus of at least 4.3 GPa.

8. 2. The curable benzoxazine resin composition of claim 1, wherein component [A] comprises at least one benzoxazine of formula (IA) where Z is S.

9. 2. The curable benzoxazine resin composition of claim 1, wherein component [A] comprises at least one benzoxazine represented by formula (IV), formula (V), formula (VI), formula (VII), or formula (VIII). 【Chemistry 5】 【Chemistry 6】 【Chemistry 7】 【Chemistry 8】 【Chemistry 9】

10. 2. The curable benzoxazine resin composition of claim 1, wherein component [B] comprises at least one benzoxazine represented by formula (IX), formula (X), formula (XI), formula (XII), formula (XIII), or formula (XIV). 【Chemistry 10】 【Chemistry 11】 【Chemistry 12】 【Chemistry 13】 【Chemistry 14】 【Chemistry 15】

11. 2. The curable benzoxazine resin composition of claim 1, wherein component [A] comprises at least one benzoxazine represented by formula (V), and component [B] comprises at least one benzoxazine represented by formula (IX) or formula (XI). 【Chemistry 16】 【Chemistry 17】 【Chemistry 18】

12. A prepreg comprising a reinforcing fiber matrix impregnated with the curable benzoxazine resin composition of any one of claims 1 to 11.

13. A fiber-reinforced composite material obtained by curing the prepreg according to claim 12.

14. A fiber reinforced composite material comprising a cured matrix obtained by curing a mixture comprising the curable benzoxazine resin composition according to any one of claims 1 to 11 and reinforcing fibers.

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