Flame-retardant epoxy resin composition, prepreg, fiber-reinforced composite material, method for producing fiber-reinforced composite material, and method for producing flame-retardant epoxy resin composition

Abstract

The present invention relates to a flame-retardant epoxy resin composition containing an epoxy resin structure (in either reacted or unreacted form) and an organic phosphinic acid structure, and to a prepreg and a fiber-reinforced composite material prepared using the epoxy resin composition. More specifically, an epoxy resin composition is provided that contains a combination of a specific type of epoxy resin and a curing agent that provides sufficient flame retardancy when cured at 163°C for 15 minutes. The epoxy resin system is also suitable for preparing fiber-reinforced composite materials that provide sufficient flame retardancy for various applications.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application No. 62 / 923,223, filed October 18, 2019, and U.S. Provisional Application No. 63 / 082,281, filed September 23, 2020, the disclosures of each of which are incorporated herein by reference in their entirety for all purposes.

[0002] The present invention relates to thermosetting epoxy resin compositions, prepregs, and fiber-reinforced composites that provide excellent flame retardancy and are suitable for use in modern rapid cure heating systems. [Background technology]

[0003] Fiber-reinforced plastic (FRP) materials (sometimes called fiber-reinforced composite materials), which contain reinforcing fibers and a matrix resin, are lighter than other conventional materials yet have excellent mechanical properties such as stiffness and strength. Therefore, they are used in a variety of applications, such as aircraft, spacecraft, automobiles, railroad vehicles, ships, sporting goods, and computers, and demand for them continues to increase over time. In industrial applications, improving flame retardancy while keeping raw material production costs and mechanical and thermal performance relatively low is becoming an increasingly common requirement.

[0004] Halogen flame retardants have traditionally been used to impart flame retardancy to a variety of materials, including fiber-reinforced plastics (FRP). Examples of halogen flame retardants include halogenated epoxy resins containing halogens such as bromine and chlorine, such as tetrabrominated bisphenol A. However, halogen flame retardants are strongly avoided due to their potential for emitting toxic gases, such as hydrogen halides and organic halides, during the combustion process. As a result, alternative flame retardant methods, including the addition of red phosphorus or phosphate ester compounds to matrix resins, have become mainstream.

[0005] However, the method of adding red phosphorus or a phosphate ester compound to a matrix resin has the following problems: 1) a decrease in mechanical strength, 2) low storage stability, 3) the red phosphorus or phosphate ester compound gradually permeates into the environment over a long period of time, and 4) red phosphorus and phosphate ester compounds are easily hydrolyzed, making them difficult to use in printed circuit boards, electronic materials, and other applications that require insulation and water resistance.

[0006] A common additional halogen-free flame retardant method for resins is the addition of inorganic flame retardants such as metal hydroxides. However, adding a large amount of inorganic flame retardant results in a decrease in the mechanical strength of the cured resin. This decrease in the mechanical strength of the cured resin also causes a decrease in the mechanical strength of the fiber-reinforced composite material. It is difficult to achieve sufficient flame retardancy with an amount of inorganic flame retardant added that is sufficient to maintain the mechanical strength required for the fiber-reinforced composite material.

[0007] The present invention has been made in view of the above, and it is an object (among other things) of providing an epoxy resin composition that, when combined with a reinforcing material and cured, can produce a composite material having excellent flame retardancy that does not contain halogen-based flame retardants, red phosphorus, or phosphate esters, and does not rely on the addition of inorganic flame retardants such as metal hydroxides. Further objects include, but are not limited to, a prepreg in which a matrix of reinforcing fibers is impregnated with the flame-retardant epoxy resin composition, and a fiber-reinforced composite material obtained using the prepreg. Summary of the Invention [Problem to be solved by the invention]

[0008]

[0013] After extensive research, the present inventors have discovered that by blending a specific amount of a specific phosphorus-containing chemical with a specific type of epoxy resin, excellent flame retardancy can be imparted to the epoxy resin composition. The resulting flame-retardant epoxy resin composition also maintains the mechanical and heat resistance properties of a similar resin composition that does not contain such phosphorus-containing chemical, provided that the blending is adjusted to maintain the crosslink density of the cured material. That is, the present invention includes, but is not limited to, the following embodiments. [Means for solving the problem]

[0009] (1) A flame-retardant epoxy resin composition for fiber-reinforced composite materials, comprising component [A], component [B], and component [C], the flame retardant epoxy resin composition has (or consists essentially of, or consists of) a phosphorus content of at least 0.5 wt. %, based on the total weight of the flame retardant epoxy resin composition; component [A] is comprised of (or consists essentially of, or consists of) at least one low-THR multifunctional epoxy resin having a total heat release (THR) value of 23 kJ / g or less, the total amount of the low-THR multifunctional epoxy resin being at least 15 PHR or at least 10 wt. % of the total weight of the flame retardant epoxy resin composition; Component [B] consists of (or consists essentially of, or consists of) at least one organic phosphinic acid; and Component [C] is a flame-retardant epoxy resin composition for fiber-reinforced composite materials, which is composed of (or consists essentially of, or consists of) at least one curing agent.

[0010] In one embodiment of the flame retardant composition, the at least one organophosphinic acid is represented by Formula (I):

[0011] [ka]

[0012] (In the formula, R 1 and R 2are independently selected from alkyl groups having 1 to 10 carbon atoms and aryl groups having 6 to 10 carbon atoms. In one embodiment, the R of formula (I) 1 and R 2 are each ethyl groups.

[0013] In one embodiment, at least a portion of component [B] is pre-reacted with at least a portion of the low THR multifunctional epoxy resin. In another embodiment, component [B] is not pre-reacted with the low THR multifunctional epoxy resin.

[0014] (2) A flame-retardant epoxy resin composition for fiber-reinforced composite materials, comprising: component [C]; (i) Component [A-1] (ii) component [A-1] and component [A], (iii) component [A] and component [E], (iv) Component [A-1] and Component [E], or (v) Component [A-1], Component [A], and Component [E] and an epoxy component selected from the flame retardant epoxy resin composition has (or consists essentially of, or consists of) a phosphorus content of at least 0.5 wt. %, based on the total weight of the flame retardant epoxy resin composition; component [A] comprises at least one low-THR multifunctional epoxy resin having a total heat release (THR) value of 23 kJ / g or less, and the total amount of the low-THR multifunctional epoxy resin comprising component [A] and / or component [A-1] is at least 15 PHR or at least 10 wt% of the total weight of the flame-retardant epoxy resin composition; Component [A-1] is comprised of at least one low THR multifunctional epoxy resin containing at least one residue of at least one organic phosphinic acid; Component [E] is comprised of at least one epoxy resin other than at least one low THR multifunctional epoxy resin containing at least one residue of at least one organic phosphinic acid; and Component [C] is composed of at least one curing agent, Flame-retardant epoxy resin composition for fiber-reinforced composite materials.

[0015] Therefore, (2) in a specific embodiment of the present invention includes a flame-retardant epoxy resin composition for a fiber-reinforced composite material further containing an epoxy resin other than component [A], component [A-1], and component [E].

[0016] In one embodiment of the flame retardant composition, at least one residue of the at least one organophosphinic acid is represented by formula (II):

[0017] [ka]

[0018] (Wherein, R in formula (II) 1 and R 2 are independently selected from alkyl groups having 1 to 10 carbon atoms and aryl groups having 6 to 10 carbon atoms. Corresponds to.

[0019] The flame-retardant epoxy resin composition of embodiment (1) may further comprise at least one multifunctional epoxy resin other than the low THR multifunctional epoxy resin having a total heat release (THR) value of 23 kJ / g or less.

[0020] In one embodiment, component [E] is a compound of formula (III):

[0021] [ka]

[0022] (Wherein, R in formula (III) 1 and R 2 are independently selected from an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms, and R in formula (III) 3 is a group in which at least one epoxy group has reacted to form a substituent -OP(=O)R1 R 2 is a residue of a multifunctional epoxy resin into which at least one epoxy resin corresponding to formula (III) has at least one unreacted epoxy group. In one embodiment, the epoxy resin comprises at least one epoxy resin corresponding to R in formula (III): 3 is the residue of at least one tetraglycidyldiaminodiphenylmethane.

[0023] The flame-retardant epoxy resin composition of embodiment (2) may further comprise at least one multifunctional epoxy resin other than a low-THR multifunctional epoxy resin, which has a total heat release (THR) value of 23 kJ / g or less and is other than an epoxy resin containing a residue of at least one organic phosphinic acid.

[0024] In another aspect of the flame retardant composition, as disclosed hereinabove, all low THR multifunctional epoxy resins comprise at least 15 PHR or at least 10 wt% of the total weight of the flame retardant epoxy resin composition. In one embodiment, the flame retardant epoxy resin composition may comprise from 15 PHR to 85 PHR of at least one low THR epoxy resin.

[0025] In one aspect of the flame retardant composition, as disclosed hereinabove, the low THR epoxy resin is comprised of at least one glycidylamine-type epoxy resin. In one embodiment, the low THR epoxy resin is comprised of at least one tetraglycidyldiaminodiphenylmethane. In another embodiment, the low THR epoxy resin is a glycidylamine-type epoxy resin.

[0026] In another aspect of the flame retardant composition, as disclosed hereinabove, the epoxy resin composition further comprises at least one accelerator. In one embodiment, the at least one accelerator comprises at least one aromatic urea. The at least one aromatic urea may be present in the epoxy resin composition in a total amount ranging from 0.5 to 7 PHR. In another embodiment, the at least one curing agent comprises at least one dicyandiamide. The at least one dicyandiamide may be present in the epoxy resin composition in a total amount ranging from 3 to 7 PHR.

[0027] In another aspect of the flame retardant composition, as disclosed hereinabove, the epoxy resin composition further comprises at least one thermoplastic resin. In one embodiment, the at least one thermoplastic resin comprises at least one polyvinyl formal. In another embodiment, the at least one thermoplastic resin comprises at least one polyethersulfone.

[0028] In one embodiment of the flame retardant composition, R in formula (I) as disclosed hereinabove 1 and R 2 are each ethyl groups.

[0029] In one aspect, the prepreg comprises a reinforcing fiber matrix impregnated with the flame-retardant epoxy resin composition according to embodiment (1), embodiment (2), or both embodiment (1) and embodiment (2). (For example, the flame-retardant epoxy resin composition may comprise both at least one organophosphinic acid as in embodiment (1) and at least one epoxy resin containing at least one residue of the at least one organophosphinic acid as in embodiment (2).) In one embodiment, the fiber-reinforced composite material is obtained by curing the prepreg. In another embodiment, a method for producing a fiber-reinforced composite material comprises curing the prepreg at a temperature of 120°C to 200°C.

[0030] In another aspect, a fiber-reinforced composite material comprises a cured epoxy resin obtained by curing a mixture comprised of the flame-retardant epoxy resin composition as disclosed hereinabove, and reinforcing fibers. [Brief explanation of the drawings]

[0031] [Figure 1] FIG. 1 shows the test setup for the neat resin flammability test inspired by the SFI 56.1 specification, as further described in the Examples. DETAILED DESCRIPTION OF THE INVENTION

[0032] As used herein, the terms "approximately," "about," and "substantially" refer to an amount close to the stated amount that still performs the desired function or achieves the desired result. For example, the terms "approximately," "about," and "substantially" can refer to an amount that is less than 10%, less than 5%, less than 1%, less than 0.1%, and less than 0.01% of the stated amount.

[0033] As used herein, the term "room temperature" has its ordinary meaning known to those of ordinary skill in the art and can include temperatures within the range of about 15°C to 43°C.

[0034] According to the present disclosure, a flame-retardant epoxy resin composition for fiber-reinforced composite materials comprises component [A], component [B], and component [C], and the flame-retardant epoxy resin composition has a phosphorus content of at least 0.5 wt. % based on the total weight of the flame-retardant epoxy resin composition. Component [A] comprises at least one low-THR multifunctional epoxy resin having a total heat release (THR) value of 23 kJ / g or less, and the total amount of the low-THR multifunctional epoxy resin is at least 15 PHR or at least 10 wt. % of the total weight of the flame-retardant epoxy resin composition. Component [B] comprises at least one organic phosphinic acid, and component [C] comprises at least one curing agent. In one embodiment, at least a portion of component [B] is pre-reacted with at least a portion of the low-THR multifunctional epoxy resin of component [A]. In another embodiment, component [B] is not pre-reacted with the low-THR multifunctional epoxy resin of component [A].

[0035] In one embodiment of the flame-retardant epoxy resin composition, the composition comprises component [C] and an epoxy component, wherein the epoxy component comprises one or more of component [A], component [A-1], and component [E]. Component [E] must be present together with either component [A] or component [A-1], and the epoxy component must comprise at least one of component [A-1] and component [E]. Component [A-1] is comprised of at least one low-THR multifunctional epoxy resin containing at least one residue of at least one organic phosphinic acid. Component [E] is comprised of at least one epoxy resin other than at least one low-THR multifunctional epoxy resin containing at least one residue of at least one organic phosphinic acid. In one embodiment, the flame-retardant epoxy resin composition comprises component [C] and component [A-1]. In another embodiment, the flame-retardant epoxy resin composition comprises component [A-1] and component [A]. In yet another embodiment, the flame-retardant epoxy resin composition comprises component [A] and component [E]. In one embodiment, the flame-retardant epoxy resin composition includes component [A-1] and component [E]. In yet another embodiment, the flame-retardant epoxy resin composition includes component [A-1], component [A], and component [E]. The flame-retardant epoxy resin composition may also include an epoxy resin other than component [A], component [A-1], and component [E]. In various embodiments, as disclosed hereinabove, the flame-retardant epoxy resin composition has a phosphorus content of at least 0.5 wt % based on the total weight of the flame-retardant epoxy resin composition. In some embodiments, the total amount of the low THR multifunctional epoxy resin, including component [A] and / or component [A-1], is at least 15 PHR or at least 10 wt % of the total weight of the flame-retardant epoxy resin composition.

[0036] In various embodiments, the flame retardant epoxy resin compositions of the present disclosure maintain the mechanical and heat resistance properties of similar epoxy resin-based flame retardant compositions that do not contain such phosphorus-containing chemicals, but are formulated to maintain the crosslink density of the cured epoxy resin composition.

[0037] In one embodiment, the flame retardant epoxy resin composition is completely free or substantially free of halogen substitution products, epoxy resins having a fluorene backbone, and halogenated epoxy resins. In another embodiment, the flame retardant composition may include one or more of halogen substitution products, epoxy resins having a fluorene backbone, and halogenated epoxy resins in an amount appropriate to improve the flame retardancy of the composite.

[0038] Ingredients [B] In one embodiment of the flame-retardant epoxy resin composition, component [B] consists of, consists essentially of, or consists of at least one organic phosphinic acid. The organic phosphinic acid used in the present invention is not particularly limited. Organic phosphinic acids are compounds containing at least one >P(=O)OH functional group, in which the phosphorus atom is further substituted with two organic groups (e.g., alkyl and / or aryl groups) that may be the same or different, with a carbon atom in each organic group directly bonded to the phosphorus atom. Organic phosphinic acids have the general formula R2PO2H, in which the two hydrogen atoms directly bonded to the phosphorus in the phosphinic acid (PO2H3) are replaced with the organic group R. The organic group R may be a hydrocarbon group, but in certain embodiments, it may contain one or more types of atoms in addition to carbon and hydrogen atoms, such as N, O, or halogens. For example, the organic group may be substituted with a hydroxyl or carboxylic acid group. However, in preferred embodiments, the organic phosphinic acid is halogen-free. Dialkylphosphinic acids, diarylphosphinic acids and alkylarylphosphinic acids, and combinations thereof, are all suitable for use in the present invention.

[0039] According to certain embodiments, the flame retardant epoxy resin composition comprises a compound represented by formula (I):

[0040] [ka]

[0041] (In the formula, R 1and R 2 are independently selected from an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms). 1 and R 2 are identical to each other. 1 and R 2 are different from each other. The alkyl groups can be linear, branched, and / or alicyclic. Suitable alkyl groups having 1 to 10 carbon atoms include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, isooctyl, and cyclohexyl. Suitable aryl groups having 6 to 10 carbon atoms include, but are not limited to, phenyl, tolyl, and naphthyl.

[0042] Examples of suitable organic phosphinic acids include, but are not limited to, dimethylphosphinic acid, methylethylphosphinic acid, diethylphosphinic acid, dipropylphosphinic acid, ethylphenylphosphinic acid, di(isooctyl)phosphinic acid, diphenylphosphinic acid, methylbenzylphosphinic acid, naphthylmethylphosphinic acid, methylphenylphosphinic acid, and combinations thereof. Diethylphosphinic acid is particularly preferred for use in the present invention.

[0043] The flame-retardant epoxy resin composition may contain an amount of organophosphinic acid in its unreacted form as shown in Formula (I) or its reacted form as shown in Formulas (II) and (III), or a mixture of the unreacted and reacted forms, such that the total phosphorus content is at least 0.5 wt.% of the total weight of the flame-retardant epoxy resin composition. When the amount of phosphorus is at least 0.5 wt.%, the epoxy resin composition, when cured, will pass most flame retardancy tests at the specified thickness. In other embodiments, the phosphorus content may exceed 1.5% to provide the cured epoxy resin composition with a sufficient level of flame retardancy to pass most test specifications, even with very thin test specimens. Typically, epoxy resin compositions need not contain more than 5 wt.% phosphorus to achieve satisfactory flame retardancy for most purposes and end uses. Furthermore, increasing the phosphorus content without appropriate adjustments in crosslink density may reduce the mechanical performance of the cured epoxy resin composition. In certain embodiments, all or nearly all of the phosphorus content in the flame retardant epoxy resin composition is attributable to one or more organophosphinic acids and / or organophosphinic acid-modified epoxy resins described herein, although other types of phosphorus-containing compounds may also be present in addition to the organophosphinic acids and / or organophosphinic acid-modified epoxy resins. According to certain embodiments, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% or 100% of the phosphorus content of the flame retardant epoxy resin composition is provided by the organophosphinic acids and / or organophosphinic acid-modified epoxy resins.

[0044] <Epoxy resin>: Component [A] and other epoxy resins (other than component [A], component [A-1], and component [E]) In one embodiment of the flame-retardant epoxy resin composition, component [A] consists essentially of, or consists of, at least one low-THR multifunctional epoxy resin having a total heat release (THR) value of 23 kJ / g or less, and the total amount of the low-THR multifunctional epoxy resin is at least 15 PHR or at least 10 wt% of the total weight of the flame-retardant epoxy resin composition. In one embodiment, the flame-retardant epoxy resin composition may further comprise at least one multifunctional epoxy resin other than the low-THR multifunctional epoxy resin having a total heat release (THR) value of 23 kJ / g or less of component [A]. In yet another embodiment, the flame-retardant epoxy resin composition may comprise an epoxy resin other than component [A], component [A-1], and component [E].

[0045] In one embodiment, the low THR epoxy resin comprises at least one glycidylamine-type epoxy resin. As used herein, a glycidylamine-type epoxy resin is an epoxy resin having at least one glycidylamino group and / or diglycidylamino group. Examples of suitable glycidylamine-type epoxy resins include tetraglycidyldiaminodiphenylmethane, glycidyl compounds of xylenediamine, triglycidylaminophenols (such as triglycidyl-p-aminophenol and triglycidyl-m-aminophenol), tetraglycidyldiaminodiphenyl sulfone, tetraglycidyldiaminodiphenyl ether, tetraglycidylbisaminomethylcyclohexanone, diglycidyltoluidine, diglycidylaniline, diglycidylmethoxyaniline, diglycidyldimethylaniline, diglycidyltrifluoromethylaniline, and diglycidyl-p-phenoxyaniline.

[0046] Suitable epoxy resins include amines (e.g., diamines and compounds containing at least one amine group and at least one hydroxyl group, such as tetraglycidyldiaminodiphenylmethane, tetraglycidyldiaminodiphenyl ether, tetraglycidyldiaminodiphenyl sulfone, tetraglycidyldiaminodiphenylamide, triglycidyl-p-aminophenol, triglycidyl-m-aminophenol, triglycidylaminocresol, and tetraglycidylxylylenediamine, as well as epoxy resins prepared using halogen-substituted products, alkynol-substituted products, hydrogenated products thereof, and the like. Resins), phenols (e.g., bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol S-type epoxy resins, bisphenol R-type epoxy resins, phenol novolac epoxy resins, cresol novolac epoxy resins, resorcinol epoxy resins, and triphenylmethane epoxy resins), naphthalene epoxy resins, dicyclopentadiene epoxy resins, epoxy resins having a biphenyl skeleton, isocyanate-modified epoxy resins, epoxy resins having a fluorene skeleton, and compounds having a carbon-carbon double bond (e.g., alicyclic epoxy resins). The epoxy resins are not limited to the above examples. Halogenated epoxy resins prepared by halogenating these epoxy resins can also be used. Furthermore, mixtures of two or more of these epoxy resins, and compounds having one epoxy group or monoepoxy compounds such as glycidyl aniline, glycidyl toluidine, or other glycidyl amines (particularly glycidyl aromatic amines), can be used to formulate flame-retardant epoxy resin compositions. However, when preparing a prepreg or a fiber-reinforced composite material using a flame-retardant epoxy resin composition, it is usually desirable to limit the amount of monofunctional epoxy resin to, for example, 20 or less, 15 or less, 10 or less, or 5 or less PHR of monofunctional epoxy resin.

[0047] In one embodiment, the flame-retardant epoxy resin composition is completely free or substantially free of halogen substitution products, epoxy resins having a fluorene backbone, and halogenated epoxy resins. In another embodiment, the epoxy resin may contain one or more of the halogen substitution products, epoxy resins having a fluorene backbone, and halogenated epoxy resins in an amount suitable to improve the flame retardancy of the material.

[0048] Examples of commercially available tetraglycidyldiaminodiphenylmethane resins include "SUMI-EPOXY (registered trademark)" ELM434 (manufactured by Sumitomo Chemical Co., Ltd.), YH434L (manufactured by Nippon Steel Chemical Co., Ltd.), "jER (registered trademark)" 604 (manufactured by Mitsubishi Chemical Corporation), and "ARALDITE (registered trademark)" MY720, MY721, MY9655, and MY9655T (manufactured by Huntsman Advanced Materials).

[0049] An example of commercially available tetraglycidyldiaminodiphenyl sulfone is TG3DAS (Konishi Chemical Industry Co., Ltd.).

[0050] Examples of commercially available triglycidylaminophenol or triglycidylaminocresol resins include "SUMI-EPOXY (registered trademark)" ELM100 (manufactured by Sumitomo Chemical Co., Ltd.), "ARALDITE (registered trademark)" MY0500, MY0510, MY0600, and MY0610 (manufactured by Huntsman Advanced Materials), and "jER (registered trademark)" 630 (manufactured by Mitsubishi Chemical Corporation).

[0051] Examples of commercially available tetraglycidylxylylenediamine and its hydrogenated products include TETRAD-X and TETRAD-C (manufactured by Mitsubishi Gas Chemical Company, Inc.).

[0052] Commercially available bisphenol A epoxy resins include, for example, jER® 825, jER® 828, jER® 834, jER® 1001, jER® 1002, jER® 1003, jER® 1003F, jER® 1004, jER® 1004AF, jER® 1005F, jER® 1006FS, jER® 1007, jER® 1009, and jER® 1010 (manufactured by Mitsubishi Chemical Corporation). Commercially available brominated bisphenol A epoxy resins include jER (registered trademark) 505, jER (registered trademark) 5050, jER (registered trademark) 5051, jER (registered trademark) 5054, and jER (registered trademark) 5057 (manufactured by Mitsubishi Chemical Corporation). Commercially available hydrogenated bisphenol A epoxy resins include ST5080, ST4000D, ST4100D, and ST5100 (manufactured by Nippon Steel Chemical Co., Ltd.).

[0053] Examples of commercially available bisphenol F epoxy resins include jER (registered trademark) 806, jER (registered trademark) 807, jER (registered trademark) 4002P, jER (registered trademark) 4004P, jER (registered trademark) 4007P, jER (registered trademark) 4009P, and jER (registered trademark) 4010P (manufactured by Mitsubishi Chemical Corporation), as well as Epototo (registered trademark) YDF2001 and Epototo (registered trademark) YDF2004 (manufactured by Nippon Steel Chemical Co., Ltd.). Examples of commercially available tetramethylbisphenol F epoxy resins include YSLV-80XY (manufactured by Nippon Steel Chemical Co., Ltd.).

[0054] An example of a commercially available bisphenol S type epoxy resin is "EPICLON (registered trademark)" EXA-154 (manufactured by DIC Corporation).

[0055] Examples of commercially available phenol novolac epoxy resins include jER (registered trademark) 152 and jER (registered trademark) 154 (manufactured by Mitsubishi Chemical Corporation), Araldite (registered trademark) EPN1138 (manufactured by Huntsman Advanced Materials), and EPICLON (registered trademark) N-740, N-770, and N-775 (manufactured by DIC Corporation).

[0056] Commercially available cresol novolac epoxy resins include, for example, "EPICLON (registered trademark)" N-660, N-665, N-670, N-673, and N-695 (manufactured by DIC Corporation), and EOCN-1020, EOCN-102S, and EOCN-104S (manufactured by Nippon Kayaku Co., Ltd.).

[0057] An example of a commercially available resorcinol-type epoxy resin is "Denacol (registered trademark)" EX-201 (manufactured by Nagase ChemteX Corporation).

[0058] Examples of commercially available naphthalene epoxy resins include "EPICLON (registered trademark)" HP-4032, HP-4032D, HP-4700, HP-4710, HP-4770, EXA-4701, EXA-4750, and EXA-7240 (manufactured by DIC Corporation).

[0059] Examples of commercially available triphenylmethane epoxy resins include "jER (registered trademark)" 1032S50 (manufactured by Mitsubishi Chemical Corporation), "Tactix (registered trademark)" 742 (manufactured by Huntsman Advanced Material), and EPPN-501H (manufactured by Nippon Kayaku Co., Ltd.).

[0060] Examples of commercially available dicyclopentadiene-type epoxy resins include "EPICLON (registered trademark)" HP-7200, HP-7200L, HP-7200H, and HP-7200HH (manufactured by DIC Corporation), "Tactix (registered trademark)" 558 (manufactured by Huntsman Advanced Material), and XD-1000-1L and XD-1000-2L (manufactured by Nippon Kayaku Co., Ltd.).

[0061] Commercially available epoxy resins having a biphenyl skeleton include, for example, "jER (registered trademark)" YX4000H, YX4000, and YL6616 (manufactured by Mitsubishi Chemical Corporation), and NC-3000 (manufactured by Nippon Kayaku Co., Ltd.).

[0062] Examples of commercially available isocyanate-modified epoxy resins include AER4152 (manufactured by Asahi Kasei Epoxy Corporation) and ACR1348 (manufactured by ADEKA Corporation), which have an oxazolidone ring.

[0063] Commercially available epoxy resins having a fluorene skeleton include, for example, OGSOL PG-100, CG-200, and EG-200 (manufactured by Osaka Gas Chemicals Co., Ltd.), and LME10169 (manufactured by Huntsman Advanced Material).

[0064] An example of commercially available glycidyl aniline is GAN (manufactured by Nippon Kayaku Co., Ltd.).

[0065] An example of a commercially available product of glycidyl toluidine is GOT (manufactured by Nippon Kayaku Co., Ltd.).

[0066] The epoxy resin component of the flame-retardant epoxy resin composition may comprise an organic phosphinic acid or may be based on the modification of triglycidylaminophenol, triglycidylaminocresol, tetraglycidylamine, phenol novolac-type epoxy resin, cresol-novolac-type epoxy resin, resorcinol-type epoxy resin, naphthalene-type epoxy resin, dicyclopentadiene-type epoxy resin, epoxy resin having a biphenyl skeleton, isocyanate-modified epoxy resin, alicyclic epoxy resin, triphenylmethane-type epoxy resin, and epoxy resin having a fluorene skeleton with an organic phosphinic acid, each of which helps to impart high heat resistance to the cured epoxy resin composition.

[0067] The epoxy resin component may also contain or be based on triglycidyl aminophenol, triglycidyl aminocresol, tetraglycidylamine, naphthalene epoxy resins, epoxy resins having a biphenyl backbone, isocyanate-modified epoxy resins, cycloaliphatic epoxy resins, triphenylmethane epoxy resins, and epoxy resins having a fluorene backbone, each of which can help contribute to both high heat resistance and mechanical properties of the epoxy resin composition once cured.

[0068] In certain embodiments of the present invention, when the flame-retardant epoxy resin composition cures, the burn time of the cured resin is less than 10 seconds, in other embodiments, 5 seconds or less, and in still other embodiments, 3 seconds or less, as determined by a flammability test modified from the SFI 56.1 flammability test specification for application to neat resin specimens. When the burn time is less than 10 seconds, good correlation with flammability test parameters for fiber-reinforced composites can be more easily seen (as described in more detail in the Examples section).

[0069] In certain embodiments of the present invention, when the flame retardant epoxy resin composition is cured, the burn length of the cured resin is 0.7 inches or less, in other embodiments 0.5 inches or less, and in still other embodiments 0.3 inches or less, as determined by a flammability test modified from the SFI 56.1 flammability test specification for application to neat resin specimens. When the burn time is less than 10 seconds, good correlation with flammability test parameters for fiber reinforced composites can be more easily seen (as described in more detail in the Examples section).

[0070] The epoxy resin component may also contain or be based on triglycidyl aminophenol, triglycidyl aminocresol, and tetraglycidyl amine, which can each help contribute (upon cure) to high heat resistance, mechanical properties, and provide surface quality fiber reinforced composites composed of the epoxy resin composition and reinforcing fibers.

[0071] In one embodiment, the first bisphenol-type epoxy resin may be contained in the flame-retardant epoxy resin composition without any particular limitation, as long as it is an epoxidized bisphenol.

[0072] Surprisingly, when cured epoxy resin compositions are tested for flammability, it has been found that those containing at least one epoxy resin having a THR of 23 kJ / g or less have superior flammability resistance when the amount of this type of epoxy resin is at least 15 PHR (i.e., the epoxy resin composition included at least 15 parts by weight of low THR epoxy resin per 100 parts by weight of total epoxy resin) or at least 10% of the total weight of the flame-retardant epoxy resin composition, compared to the flammability resistance of similar compositions that do not contain less than 15 PHR or less than 10% by weight of a total of low THR epoxy resins. According to certain embodiments, the epoxy resin composition contains at least 15 PHR and at least 10% by weight of a low THR epoxy resin (either a single low THR epoxy resin or a combination or two or more low THR epoxy resins).

[0073] Without being bound by theory, it is believed that the lower heat release of the epoxy resin reduces the ability of flames to propagate across parts made from the epoxy resin composition, allowing the phosphorus from the organophosphinic acid or organophosphinic acid-modified epoxy resin the opportunity to react with atmospheric oxygen to produce both a crosslinked char layer and a water barrier to extinguish the flame. This allows test specimens to pass flammability tests with a lower percentage of total phosphorus content compared to conventional flame-retardant epoxy resin compositions based on phosphorus-containing compounds. The lower the phosphorus content in a flame-retardant epoxy resin composition, the more freedom there is in tailoring the formulation to achieve different properties, such as better toughness, a higher Tg, and a higher modulus.

[0074] According to other embodiments, the flame retardant epoxy resin composition may be comprised of a total of at least 15%, at least 20%, at least 25%, or at least 30% low THR epoxy resins, based on the total weight of the flame retardant epoxy resin composition.

[0075] According to other embodiments, the flame-retardant epoxy resin composition may be comprised of a total of at least 20 PHR, at least 25 PHR, at least 30 PHR, or at least 35 PHR of low-THR epoxy resins. All of the epoxy resins present in the flame-retardant epoxy resin composition may be low-THR epoxy resins (i.e., the amount of low-THR epoxy resins may be 100 PHR). In other embodiments, one or more high-THR epoxy resins (i.e., epoxy resins having a total heat release (THR) value greater than 23 kJ / g, referred to herein as "high-THR epoxy resins") may be present in combination with the low-THR epoxy resins. For example, the flame-retardant epoxy resin composition may be comprised of 15 PHR to 85 PHR of at least one low-THR epoxy resin, with the remainder of the epoxy resins being one or more high-THR epoxy resins (i.e., the flame-retardant epoxy resin composition may include 15 PHR to 85 PHR of high-THR epoxy resins).

[0076] In the present invention, the epoxy resin having a total heat release (THR) of 23 kJ / g or less is not particularly limited and can be any one of multifunctional epoxy resins as long as the above THR characteristics are met. The epoxy resin having a total heat release (THR) of 23 kJ / g or less can be selected from any one of the above epoxy resins as long as it has a THR of 23 kJ / g or less and a functionality (number of epoxy groups per molecule) of at least 2. Such epoxy resins are referred to herein as "low THR epoxy resins." The THR is determined by curing each epoxy resin in combination with diaminodiphenyl sulfone mixed in a 1:1 EEW (Epoxy Equivalent Weight) to AEW (Amine Equivalent Weight) ratio. The cured test specimens are then machined to a size of 100 mm x 100 mm x 3 mm and tested for a heat release rate (HRR according to ISO 5660-1) of 50 kW / m. 2 The test is performed via a cone calorimeter with the external heat flux set to . The THR is calculated by integrating the HRR data over time.

[0077] Examples of epoxy resins having a THR of 23 kJ / g or less include, but are not limited to, tetraglycidyldiaminodiphenylmethane, triglycidyl-p-aminophenol, and mono- or bisnaphthalene epoxy resins having a functionality of at least 2.

[0078] According to another embodiment, the THR is preferably 22 kJ / g or less, more preferably 21.4 kJ / g or less, and the lower limit of the THR is preferably 15 kJ / g or more, more preferably 17 kJ / g or more, particularly preferably 19 kJ / g or more, and even more particularly preferably 19.3 kJ / g or more.

[0079] According to another embodiment, the flame-retardant epoxy resin composition has a viscosity of 1.0×10 at 40° C. 2 ~1.0×10 5 The viscosity at 40°C is preferably 1.0 x 10 poise.2 By setting the viscosity at 40°C to 1.0 × 10 poise or more, a prepreg with appropriate cohesiveness can be obtained. 5 By setting the viscosity to 1.0×10 poise or less, it is possible to impart appropriate drapeability and tackiness when laminating prepregs. The viscosity at 40°C is 1.0×10 3 ~5.0×10 4 More preferably in the poise range, 5.0 x 10 3 ~2.0×10 4 It is particularly preferred that the range is 7.0 x 10 poise. 3 ~1.0×10 4 It is more particularly preferred to be in the poise range.

[0080] According to another embodiment, the minimum viscosity of the flame-retardant epoxy resin composition is preferably 0.1 to 200 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 become too high, which may result in the resin leaking out of the prepreg during prepreg curing. Furthermore, the desired resin fraction may not be achieved in the resulting fiber-reinforced composite material, the fluidity of the matrix resin in the prepreg may become insufficient, the prepreg consolidation process may end earlier than usual, and many voids may occur in the resulting fiber-reinforced composite material. If the minimum viscosity is too high, the fluidity of the matrix resin in the prepreg may decrease, the prepreg consolidation process may end earlier than usual, and many voids may occur in the resulting fiber-reinforced composite material.

[0081] Here, the viscosity at 40°C and the minimum viscosity are determined by the following method. Specifically, measurements are taken using a 40 mm diameter parallel plate rheometer (ARES, manufactured by TA Instruments) with a gap of 0.6 mm. A torsional displacement of 10 rad / s is applied. The temperature is increased from 40°C to 180°C at a rate of 2°C / min until the minimum viscosity of the resin is determined.

[0082] Adducts of organic phosphinic acids with epoxy resins Here, component [A-1] refers to an adduct of an organic phosphinic acid and a low-THR multifunctional epoxy resin. In particular, component [A-1] refers to a low-THR multifunctional epoxy resin containing at least one residue of at least one organic phosphinic acid, including any of the residues of the organic phosphinic acids described above. As used herein, component [E] refers to an adduct of an organic phosphinic acid and an epoxy resin other than at least one low-THR multifunctional epoxy resin. In particular, component [E] refers to an epoxy resin other than at least one low-THR multifunctional epoxy resin, containing at least one residue of at least one organic phosphinic acid (including any of the residues of the organic phosphinic acids described above).

[0083] In a particular embodiment of the present invention, the flame-retardant epoxy resin composition contains component [E] which comprises, consists essentially of, or consists of component [C] and one or more of component [A-1] or component [E], such that component [E] must be present together with either component [A] or component [A-1].

[0084] Such residues correspond to the organic phosphinic acid that has reacted with the epoxy resin and thus become incorporated into the epoxy resin. Such epoxy resins further contain at least one epoxy group and can be considered organic phosphinic acid-modified epoxy resins or adducts of organic phosphinic acid and multifunctional epoxy resins. Epoxy resins useful as component [E] or component [A-1] of the present invention can be obtained by reacting an organic phosphinic acid with a multifunctional epoxy resin other than a low-THR multifunctional epoxy resin, respectively, with the stoichiometry controlled so that one or more epoxy groups of the multifunctional epoxy resin remain unreacted. During such a reaction, the acidic group of the organic phosphinic acid can ring-open the epoxy group of the starting multifunctional epoxy resin.

[0085] For example, at least one residue of the at least one organophosphinic acid may be represented by formula (II):

[0086] [ka]

[0087] (Wherein, R in formula (II) 1 and R 2 are independently selected from alkyl groups having 1 to 10 carbon atoms and aryl groups having 6 to 10 carbon atoms. It can correspond to.

[0088] In certain embodiments of the present invention, component [E] or component [A-1] is a compound represented by formula (III):

[0089] [ka]

[0090] (Wherein, R in formula (III) 1 and R 2 are independently selected from an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms, and R in formula (III) 3 is a group in which at least one epoxy group has reacted to form a substituent -OP(=O)R 1 R 2 is a residue of a multifunctional epoxy resin into which at least one epoxy resin corresponding to formula (III) has at least one unreacted epoxy group. The epoxy resin may include at least one epoxy resin corresponding to:

[0091] Thus, in certain embodiments of the present invention, any one of the multifunctional epoxy resin structures present in the flame retardant epoxy resin composition contains at least one organophosphinic acid residue, one or more of the reactive sites of the multifunctional epoxy resin (e.g., the site where the epoxy group was originally located) is occupied by the structure of formula (II), and at least one epoxy group of the starting multifunctional epoxy resin remains unreacted and therefore free to react when the flame retardant epoxy resin composition is cured.

[0092] As an illustrative and non-limiting example, a multifunctional epoxy resin that is a diglycidyl ether of bisphenol A can be reacted with one equivalent of diethylphosphinic acid to provide an organophosphinic acid-modified epoxy resin useful as (or in) component [E] of the present invention.

[0093] (CH3CH2)2P(=O)OH+GE-Ar-C(CH3)2-Ar-GE→(CH3CH2)2P(=O)OCH2CH(OH)CH2-Ar-C(CH3)2-Ar-GE wherein Ar=arylene and GE=glycidyl ether. Any suitable arylene ring may be used, such as a benzene ring.

[0094] Similarly, a low THR multifunctional epoxy resin can be reacted with one equivalent of diethylphosphinic acid to provide an organophosphinic acid-modified low THR multifunctional epoxy resin useful as (or in) component [A-1] of the present invention.

[0095] In certain embodiments, at least one epoxy resin containing at least one residue of at least one organic phosphinic acid may be preformed prior to formulating the flame-retardant epoxy resin composition by conducting an initial reaction between the one or more organic phosphinic acids and one or more multifunctional epoxy resins. Such pre-reaction may be carried out, for example, by combining these components to form a mixture and heating the mixture at a temperature and for a time effective to achieve the desired degree of reaction between the organic phosphinic acid and the multifunctional epoxy resin. Such heating may be carried out while stirring or otherwise agitating the mixture. Suitable reaction temperatures may include, for example, temperatures from 50°C to 150°C. Suitable reaction times may include, for example, reaction times from 0.1 to 5 hours. Depending on the stoichiometry selected, a portion of the multifunctional epoxy resin may remain unreacted, and the resulting reaction product, which is then used in the flame-retardant epoxy resin composition, is a mixture of an organic phosphinic acid-modified epoxy resin and a multifunctional epoxy resin that does not contain organic phosphinic acid residues.

[0096] Alternatively, the organic phosphinic acid and the multifunctional epoxy resin may undergo reaction in the presence of one or more additional components of the flame retardant epoxy resin composition after the flame retardant epoxy resin composition has been partially or fully formulated (e.g., either before or during curing of the flame retardant epoxy resin composition).

[0097] The above-described embodiment (at least one epoxy resin containing at least one residue of at least one organic phosphinic acid is present in the flame-retardant epoxy resin composition) allows for the preparation of specific types of flame-retardant epoxy resin compositions by controlling the reaction of different amounts of organic phosphinic acid with specific epoxy resins. By selecting the type of epoxy resin, it is possible to tailor different formulations for toughness, glass transition temperature (Tg), and modulus. For example, a multifunctional epoxy resin with a functionality of 4 can be reacted with organic phosphinic acid at organic phosphinic acid to epoxy equivalent ratios of 1:4, 2:4, and 3:4.

[0098] In certain embodiments of the present invention, when the flame-retardant epoxy resin composition contains component [A-1] or component [E], the multifunctional epoxy resin has a functionality of at least 3 or more (i.e., three or more epoxy groups per molecule). When the multifunctional epoxy resin has a functionality of 3 or more, it allows at least two of the epoxy groups to self-polymerize with each other or with at least one curing agent (after reaction with the organic phosphinic acid), enabling good crosslink density. In other embodiments of the present invention, the multifunctional epoxy resin has a functionality of 4 or more, which can provide the advantage of increasing crosslink density and improving properties such as Tg. In yet another embodiment of the present invention, the multifunctional epoxy resin is a glycidylamine epoxy resin. In yet another embodiment of the present invention, the multifunctional epoxy resin is tetraglycidyldiaminodiphenylmethane. When the multifunctional epoxy resin is tetraglycidyldiaminodiphenylmethane, the epoxy resin composition can maintain a high Tg upon curing.

[0099] In some embodiments, when the flame retardant epoxy resin composition is cured, the glass transition temperature of the cured resin, as determined by the G' onset method (described in more detail in the Examples), is at least 100°C, in other embodiments at least 110°C, in still other embodiments at least 125°C, and in yet further embodiments at least 140°C. When the flame retardant epoxy resin has a Tg greater than 100°C, the cured fiber reinforced composite part can withstand deformation at higher temperatures and can have a higher use temperature to extend its applications.

[0100] In some embodiments, when the flame retardant epoxy resin composition is cured to provide a cured resin having a flexural modulus, the flexural modulus of the cured matrix at 25° C. is at least 3.0 GPa, in other embodiments at least 3.4 GPa, and in still other embodiments at least 3.8 GPa. When the flame retardant resin has a modulus greater than 3.0 GPa at 25° C., the fiber reinforced composite parts have high compressive strength, further expanding the material for more structural applications.

[0101] In the present invention, the type of epoxy resin is not particularly limited as long as it does not impair the effects of the present invention. Difunctional or higher functional epoxy resins and mixtures thereof can be used as the epoxy resin. The flame-retardant epoxy resin composition can also contain at least a certain amount of monofunctional epoxy resin in addition to one or more polyfunctional epoxy resins (i.e., epoxy resins containing two or more reactive epoxy groups in one molecule).

[0102] In embodiments in which the epoxy resin composition comprises component [A-1], i.e., at least one low-THR multifunctional epoxy resin containing at least one residue of at least one organic phosphinic acid (organophosphinic acid-modified epoxy resin), such organic phosphinic acid-modified low-THR epoxy resin may be the only epoxy resin present in the epoxy resin composition. However, the epoxy resin composition may also comprise one or more additional epoxy resins that are not organic phosphinic acid-modified epoxy resins (i.e., epoxy resins that do not contain organic phosphinic acid residues), such as component [A] or epoxies other than component [A], component [A-1], and component [E].

[0103] In embodiments in which the epoxy resin composition includes component [E], i.e., at least one epoxy resin containing at least one residue of at least one organic phosphinic acid (organophosphinic acid-modified epoxy resin), such organic phosphinic acid-modified epoxy resin must be present together with component [A] and / or component [A-1]. Furthermore, the epoxy resin composition may also include one or more additional epoxy resins that are not organic phosphinic acid-modified epoxy resins (i.e., epoxy resins that do not contain organic phosphinic acid residues).

[0104] Component [C]: Hardener In a specific embodiment of the present invention, dicyandiamide is used as a curing agent. When dicyandiamide is used as a curing agent, the storage stability of the uncured epoxy resin composition is high and the heat resistance of the cured epoxy resin composition is high.

[0105] The amount of dicyandiamide may range from 3 to 7 PHR per 100 PHR of total epoxy resin (where "PHR" stands for parts per hundred parts of resin, meaning that the dicyandiamide is present in the flame-retardant epoxy resin composition in an amount of 3 to 7 parts by weight per 100 parts by weight of total epoxy resin). When the amount of dicyandiamide is at least 3 PHR, the cured epoxy resin composition may have high heat resistance. When the amount of dicyandiamide is 7 PHR or less, the cured epoxy resin composition may have high elongation.

[0106] Commercially available dicyandiamide products include, for example, DICY-7 and DICY-15 (manufactured by Mitsubishi Chemical Corporation) and Dyhard (registered trademark) 100S (manufactured by AlzChem Trostberg).

[0107] In other embodiments of the present invention, a curing agent other than dicyandiamide may be included or added as long as it does not impair the effects of the present invention. Examples of suitable curing agents include, but are not limited to, polyamides, amidoamines (e.g., aromatic amidoamines such as aminobenzamide, aminobenzanilide, and aminobenzenesulfonamide), aromatic diamines (e.g., diaminodiphenylmethane, diaminodiphenylsulfone [DDS]), aminobenzoates (e.g., trimethylene glycol di-p-aminobenzoate and neopentyl glycol di-p-aminobenzoate), aliphatic amines (e.g., triethylenetetramine, isophoronediamine), and fatty acids. Examples of the curing agent include cyclic amines (e.g., isophoronediamine), imidazole derivatives, guanidines such as tetramethylguanidine, carboxylic anhydrides (e.g., methylhexahydrophthalic anhydride), carboxylic hydrazides (e.g., adipic hydrazide), phenol novolac resins and cresol novolac resins, carboxylic amides, polyphenol compounds, polysulfides and mercaptans, and Lewis acids and Lewis bases (e.g., boron trifluoride ethylamine, tris-(diethylaminomethyl)phenol). At least one curing agent selected from these curing agents may be used, or two or more of these curing agents may be combined, or dicyandiamide may be used in combination with one or more of these curing agents.

[0108] accelerator In certain embodiments of the present invention, at least one aromatic urea is used as an accelerator for the reaction between the epoxy resin and the curing agent and / or the self-polymerization of the epoxy resin. In some embodiments, a combination of aromatic ureas may be used. The use of at least one aromatic urea as an accelerator provides the epoxy resin composition with high storage stability and high heat resistance for the cured epoxy resin composition.

[0109] The amount of the at least one aromatic urea may be in the range of 0.5 to 7 PHR per 100 PHR of total epoxy resin (i.e., from 0.5 parts by weight of aromatic urea per 100 parts by weight of total epoxy resin to 7 parts by weight of aromatic urea per 100 parts by weight of total epoxy resin). When the amount of the at least one aromatic urea is at least 0.5 PHR, the cured epoxy resin composition can have high heat resistance. When the amount of aromatic urea is 7 PHR or less, the epoxy resin composition has high storage stability.

[0110] Examples of suitable aromatic urea include N,N-dimethyl-N'-(3,4-dichlorophenyl)urea, toluenebis(dimethylurea), 4,4'-methylenebis(phenyldimethylurea), and 3-phenyl-1,1-dimethylurea, and combinations thereof. Commercially available aromatic urea includes, for example, DCMU99 (manufactured by Hodogaya Chemical Co., Ltd.), Omicure® U-24, U-24M, U-52, U-52M, and 94 (manufactured by Huntsman Advanced Materials). Among these, aromatic urea having multiple urea groups may be used to promote rapid curing.

[0111] In another embodiment of the present invention, any accelerator other than or in addition to aromatic urea may be added as long as it does not impair the effects of the present invention. Examples of such accelerators include, but are not limited to, sulfonic acid compounds, boron trifluoride piperidine, pt-butylcatechol, sulfonic acid compounds (e.g., ethyl p-toluenesulfonate or methyl p-toluenesulfonate), tertiary amines and their salts, imidazoles and their salts, phosphorus curing accelerators, metal carboxylic acids, and Lewis acids and Bronsted acids and their salts.

[0112] Commercially available imidazole compounds or derivatives thereof include, for example, Curezol (registered trademark) 2MZ, 2PZ, and 2E4MZ (manufactured by Shikoku Chemical Industry Co., Ltd.) Examples of Lewis acid catalysts include boron trifluoride piperidine complex, boron trifluoride monoethylamine complex, boron trifluoride triethanolamine complex, boron trichloride octylamine complex, and complexes of boron trihalides with bases such as methyl p-toluenesulfonate, ethyl p-toluenesulfonate, and isopropyl p-toluenesulfonate.

[0113] thermoplastic resin In certain embodiments of the present invention, any thermoplastic resin (i.e., a polymer or resin that is essentially thermoplastic) may be included in the flame-retardant epoxy resin composition as long as it does not impair the effects of the present invention. Examples of suitable thermoplastic resins include thermoplastic resins that are soluble in epoxy resins and thermoplastic resins that are insoluble in epoxy resins and may be in the form of particles (i.e., thermoplastic particles). Other types of organic particles, such as rubber particles (including crosslinked rubber particles), may also be included in the flame-retardant epoxy resin composition.

[0114] As the thermoplastic resin soluble in epoxy resin, a thermoplastic resin having a hydrogen-bonding functional group, which is expected to have the effect of improving the adhesion between the epoxy resin composition and the reinforcing fiber, can be used. Examples of the thermoplastic resin having a hydrogen-bonding functional group soluble in epoxy resin include a thermoplastic resin having an alcoholic hydroxyl group, a thermoplastic resin having an amide bond, and a thermoplastic resin having a sulfonyl group.

[0115] Examples of thermoplastic resins having hydroxyl groups include polyvinyl acetal resins such as polyvinyl formal and polyvinyl butyral, polyvinyl alcohol, and phenoxy resin. Examples of thermoplastic resins having amide bonds include polyamides, polyimides, and polyvinylpyrrolidones. Examples of thermoplastic resins having sulfonyl groups include polysulfones. Polyamides, polyimides, and polysulfones may have functional groups such as ether bonds and / or carbonyl groups in their main chains. For example, the thermoplastic resin may be polyethersulfone. Polyamides may have a substituent on the nitrogen atom of the amide group.

[0116] Examples of commercially available thermoplastic resins that are soluble in epoxy resins and have hydrogen-bonding functional groups include polyvinyl acetal resins such as "Denkabutyral®" and "Denkaformal®" (manufactured by Denki Kagaku Kogyo Co., Ltd.) and "Vinylec®" (manufactured by JNC Corporation); phenoxy resins such as "UCAR®" PKHP (manufactured by Union Carbide Corporation); polyamide resins such as "Macromelt®" (manufactured by Henkel-Hakusui Corporation) and "Amilan®" CM4000 (manufactured by Toray Industries, Inc.); polyimides such as "Ultem®" (manufactured by General Electric Co., Ltd.) and "Matrimid®" 5218 (manufactured by Ciba Inc.); and polysulfones such as "SUMIKAEXCEL®" (manufactured by Sumitomo Chemical Co., Ltd.) and "UDEL®" (manufactured by Solvay Advanced Polymers Kabushiki Kaisha). and polyvinylpyrrolidone "Luviskol (registered trademark)" (manufactured by BASF Japan Ltd.).

[0117] Other additives Flame-retardant epoxy resin compositions according to certain embodiments of the present invention may contain one or more acrylic resins. Acrylic resins are highly incompatible with epoxy resins, making them suitable for controlling viscoelasticity. Commercially available acrylic resins include the Dianale (registered trademark) BR series (manufactured by Mitsubishi Rayon Co., Ltd.), Matsumoto Microsphere (registered trademark) M, M100, and M500 (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.), and Nanostrength (registered trademark) E40F, M22N, and M52N (manufactured by Arkema K.K.).

[0118] The flame-retardant epoxy resin composition may also contain rubber particles. From the viewpoint of ease of handling, the rubber particles may be crosslinked rubber particles or core-shell rubber particles produced by graft polymerization of a different polymer onto the surface of the crosslinked rubber particles.

[0119] Commercially available crosslinked rubber particles include, for example, FX501P (manufactured by Japan Synthetic Rubber Co., Ltd.), which is made of a crosslinked product of a carboxyl-modified butadiene-acrylonitrile copolymer, the CX-MN series (manufactured by Nippon Shokubai Co., Ltd.), which is made of acrylic rubber microparticles, and the YR-500 series (manufactured by Nippon Steel Chemical Co., Ltd.).

[0120] Examples of commercially available core-shell rubber particles include "PARALOID (registered trademark)" EXL-2655 (manufactured by Kureha Corporation), which is made of a butadiene-alkylstyrene methacrylate copolymer; "STAFILOID (registered trademark)" AC-3355, TR-2122 (manufactured by Takeda Pharmaceutical Company Limited), which are made of an acrylic acid ester-methacrylic acid ester copolymer; "PARALOID (registered trademark)" EXL-2611, EXL-3387 (manufactured by Rohm & Haas), which are made of a butyl acrylate-methyl methacrylate copolymer; and "KANE ACE (registered trademark)" MX series (manufactured by Kaneka Corporation).

[0121] Examples of thermoplastic resin particles that can be used include polyamide particles and polyimide particles. Polyamide particles are most preferred for significantly increasing the impact resistance of cured epoxy resin compositions due to the excellent toughness they impart to them. Among polyamides, nylon 12, nylon 11, nylon 6, nylon 6 / 12 copolymers, and nylons modified with epoxy compounds to have semi-IPN (interpenetrating polymer networks) structures (semi-IPN nylons) as disclosed in Example 1 of JP-A-1-104624 provide particularly good adhesive strength when combined with epoxy resins. Examples of suitable commercially available polyamide particles include SP-500 (manufactured by Toray Industries, Inc.) and Orgasol® (manufactured by Arkema), Grilamid® TR-55 (manufactured by EMS-Grivory), and Trogamid® CX (manufactured by Evonik Industries AG).

[0122] Additives - Inorganic Particles In certain embodiments of the present invention, any type of inorganic particles can be added as long as the effects of the present invention are not impaired. Examples of suitable inorganic particles include metal oxide particles, metal particles, and mineral particles. Two or more types of these inorganic particles can also be combined. The inorganic particles may be used to improve or impart certain functions to the cured epoxy resin composition. Examples of such functions include surface hardness, blocking resistance, heat resistance, barrier properties, electrical conductivity, antistatic properties, electromagnetic wave absorption, UV shielding, toughness, impact resistance, and / or a low linear thermal expansion coefficient.

[0123] Examples of suitable metal oxides include silicon oxide, titanium oxide, zirconium oxide, zinc oxide, tin oxide, indium oxide, aluminum oxide, antimony oxide, cerium oxide, magnesium oxide, iron oxide, tin-doped indium oxide (ITO), antimony-doped tin oxide, and fluorine-doped tin oxide.

[0124] Examples of suitable metals include gold, silver, copper, aluminum, nickel, iron, zinc, and stainless steel. Examples of suitable minerals include montmorillonite, talc, mica, boehmite, kaolin, smectite, xonotlite, vermiculite, and sericite.

[0125] Examples of other suitable inorganic materials include carbon black, acetylene black, ketjen black, carbon nanotubes, graphene, aluminum hydroxide, magnesium hydroxide, glass beads, glass flakes, and glass balloons.

[0126] Inorganic particles of any suitable size can be used, for example, inorganic particles in the size range of 1 nm to 10 μm. Furthermore, the inorganic particles can have any suitable shape, for example, spherical, needle, plate, balloon, or hollow. The inorganic particles can be used simply as a powder or in a dispersion in a solvent such as a sol or colloid.

[0127] The surfaces of the inorganic particles may be treated with one or more coupling agents to improve dispersibility and interfacial affinity with the epoxy resin.

[0128] In a specific embodiment of the present invention, the epoxy resin composition may contain any other material in addition to or in place of the above-mentioned materials, as long as the effect of the present invention is not impaired. Examples of other materials that can be contained in the epoxy resin composition include, but are not limited to, a mold release agent, a surface treatment agent, a flame retardant (in addition to the organic phosphinic acid or the organic phosphinic acid-modified epoxy resin), an antibacterial agent, a leveling agent, an antifoaming agent, a thixotropic agent, a heat stabilizer, a light stabilizer, an ultraviolet absorber, a pigment, a coupling agent, and a metal alkoxide.

[0129] The components of the epoxy resin composition can be mixed using a kneader, planetary mixer, three-roll mill, twin-screw extruder, or the like. The epoxy resin and optional thermoplastic resin (excluding the curing agent and accelerator) are added to the selected equipment. The mixture is then heated to a temperature in the range of 130 to 180°C while stirring to uniformly dissolve the epoxy resin. The mixture is then cooled to a temperature below 100°C while stirring, and the curing agent and optional accelerator are then added and kneaded to disperse the components. This method can be used to provide an epoxy resin composition with excellent storage stability.

[0130] reinforced fiber There are no particular limitations or restrictions on the type of reinforcing fiber that can be used as long as it does not impair the effects of the present invention. Examples include glass fibers such as S-glass, S-1 glass, S-2 glass, S-3 glass, E-glass, and L-glass; organic fibers such as carbon fiber, graphite fiber, and aramid fiber; metal fibers such as boron fiber and alumina fiber; silicon carbide fiber; tungsten carbide fiber; and natural / bio-fibers. In particular, the use of carbon fiber can provide a cured FRC material that is extremely strong and rigid while also being lightweight. Examples of suitable carbon fibers are those manufactured by Toray Industries, Inc., having a standard modulus of elasticity of about 200 to 280 GPa (TORAYCA® T300, T300J, T400H, T600S, T700S, T700G), an intermediate modulus of elasticity of about 280 to 340 GPa (TORAYCA® T800H, T800S, T1000G, T1100G, M30S, M30G), or a high modulus of elasticity of more than 340 GPa (TORAYCA® M40, M35J, M40J, M46J, M50J, M55J, M60J).

[0131] The form and arrangement of the reinforcing fiber layers used to prepare the fiber-reinforced composite material of the present invention are not particularly limited. Any of the forms and spatial arrangements of reinforcing fibers known in the art can be used, such as long fibers in a certain direction, short fibers in random orientation, single tow, narrow tow, woven fabric, mat, knitted fabric, and braided fabric. As used herein, the term "long fiber" refers to a single fiber or a fiber bundle containing a single fiber that is substantially continuous over 10 mm or more. As used herein, the term "short fiber" refers to a fiber bundle containing fibers cut to a length of less than 10 mm. In particular, for end uses where high specific strength and high specific modulus are desired, a form in which the reinforcing fiber bundles are arranged in one direction is optimal. From the viewpoint of ease of handling, a cloth-like (woven) form is also suitable for the present invention.

[0132] The FRC material of the present invention can be manufactured using methods such as prepreg lamination, resin transfer molding, resin film infusion, hand layup, wet layup, sheet molding compound, filament winding, and pultrusion, although no particular limitations or restrictions apply in this regard.

[0133] Resin transfer molding is a method in which a liquid thermosetting resin composition is directly impregnated into a reinforcing fiber substrate and then cured. Because this method does not involve intermediate products such as prepregs, it has a high potential for reducing molding costs and is advantageously used in the production of structural materials for spacecraft, aircraft, railroad cars, automobiles, ships, etc.

[0134] The prepreg lamination molding method is a method in which a prepreg made by impregnating a reinforcing fiber substrate with a thermosetting resin composition is molded and / or laminated, and heat and pressure are applied to the molded and / or laminated prepreg to cure the resin, thereby obtaining an FRC material.

[0135] The filament winding method involves aligning one to several dozen reinforcing fiber rovings in one direction and winding them around a rotating metal core (mandrel) at a predetermined angle under tension while impregnating them with a thermosetting resin composition. After the roving wrap reaches a predetermined thickness, the roving is cured and then the metal core is removed.

[0136] The pultrusion method involves continuously passing reinforcing fibers through an impregnation tank filled with a liquid thermosetting resin composition, impregnating the fibers with the thermosetting resin composition, and then continuously stretching the impregnated reinforcing fibers using a tensioning machine to form them through a squeeze mold and a heating mold. This method offers the advantage of continuously molding FRC materials, and is therefore used to manufacture FRC materials for fishing rods, rods, pipes, sheets, antennas, architectural structures, and other applications. In particular, prepreg lamination molding may be used to impart excellent rigidity and strength to the resulting FRC material.

[0137] The prepreg may contain an epoxy resin composition and reinforcing fibers. Such a prepreg can be obtained by impregnating a reinforcing fiber substrate with the epoxy resin composition of the present invention. Impregnation methods include a wet method and a hot melt method (dry method).

[0138] The wet method involves first immersing reinforcing fibers in a solution of an epoxy resin composition prepared by dissolving the reinforcing fibers in a solvent such as methyl ethyl ketone or methanol, removing the reinforcing fibers, and then evaporating the solvent using an oven or the like to impregnate the reinforcing fibers. The hot-melt method involves directly impregnating the reinforcing fibers with an epoxy resin composition that has been preheated and fluidized, or by coating the epoxy resin composition used as a resin film on release paper or the like, placing the film on one or both sides of a flat-shaped reinforcing fiber, and applying heat and pressure to impregnate the reinforcing fibers with the resin. The hot-melt method can produce a prepreg that is substantially free of residual solvent.

[0139] Prepreg: 40 to 700 g / m 2 The carbon fiber weight may be between 40 g / m 2 If the carbon fiber weight is less than 700 g / m, the fiber content will be insufficient and the strength of the FRC material may decrease. 2 If the resin content exceeds 20%, the drapeability of the prepreg may be impaired. The prepreg may also have a resin content between 20 and 70% by weight. If the resin content is less than 20% by weight, impregnation may be insufficient, resulting in many voids. If the resin content exceeds 70% by weight, the mechanical properties of the FRC may be reduced.

[0140] Appropriate heat and pressure may be used in a prepreg lamination molding method, press molding method, autoclave molding method, bagging molding method, wrapping tape method, internal pressure molding method, or the like.

[0141] Autoclave molding is a process in which prepregs are layered on a tool plate of a predetermined shape, then covered with a bagging film and cured under heat and pressure while removing air from the laminate. This process allows for precise control of fiber orientation and, due to minimal void content, can produce high-quality molding materials with excellent mechanical properties. The pressure applied during the molding process can be 0.3 to 1.0 MPa, while the molding temperature can be in the range of 90 to 300°C (in one embodiment of the present invention, in the range of 180 to 220°C, e.g., 200 to 220°C).

[0142] The wrapping tape method involves wrapping prepreg around a mandrel or some other core rod to form a tubular FRC material. This method can be used to manufacture golf shafts, fishing rods, and other rod-shaped products. More specifically, this method involves wrapping prepreg around a mandrel and wrapping a wrapping tape made of a thermoplastic resin film over the prepreg under tension to secure the prepreg and apply pressure to the prepreg. After heating in an oven to cure the resin, the core rod is removed to obtain a tubular body. The tension used to wrap the wrapping tape can be 20 to 100 N. The curing temperature can be in the range of 90 to 300°C (in one embodiment of the present invention, in the range of 180 to 220°C, e.g., 200 to 220°C).

[0143] Internal pressure molding is a method in which a preform, formed by wrapping a prepreg around a thermoplastic resin tube or some other internal pressure applying device, is placed in a mold, and high-pressure gas is introduced into the internal pressure applying device to apply pressure while simultaneously heating the mold to mold the prepreg. This method can be used to form 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 between room temperature and 300°C, or in the range of 120 to 180°C (in one embodiment of the present invention, in the range of 180 to 220°C, e.g., 200 to 220°C).

[0144] FRC materials containing the cured epoxy resin composition and reinforcing fibers obtained from the epoxy resin composition of the present invention are advantageously used in general industrial applications and aerospace applications. The FRC materials may also be used in other applications, such as sports applications (e.g., golf shafts, fishing rods, tennis or badminton rackets, hockey sticks, and ski poles) and vehicle structural materials (e.g., automobiles, bicycles, marine and rail vehicles, drive shafts, leaf springs, wind turbine blades, pressure vessels, flywheels, papermaking rollers, roofing materials, cables, and repair / reinforcement materials).

[0145] In certain embodiments of the present invention, the burn time of the flame retardant fiber reinforced composite material is less than 3 seconds, in other embodiments 2 seconds or less, and in still other embodiments 1 second or less, as determined by the SFI 56.1 flammability test standard. If the burn time is less than 3 seconds, as more plies are added to the fiber reinforced composite, the sample can pass multiple flammability test standards.

[0146] In certain embodiments of the present invention, when the flame retardant epoxy resin composition is cured, the burn length of the flame retardant fiber reinforced composite, as determined by SFI 56.1 flammability test standard, is 2.0 inches or less, in other embodiments 1.8 inches or less, and in still other embodiments 1.6 inches or less. If the burn length is 2.0 inches or less, adding more plies to the fiber reinforced composite allows the sample to pass multiple flammability test standards.

[0147] While embodiments have been described herein in a manner that enables a clear and concise specification to be written, it is intended and will be understood that the embodiments can be combined or separated in various ways without departing from the invention. For example, it will be understood that all preferred features described herein are applicable to all aspects of the invention described herein.

[0148] In some embodiments, the invention herein can be construed to exclude any element or process step that does not materially affect the basic and novel characteristics of the composition or process. Further, in some embodiments, the invention can be construed to exclude any element or process step not specified herein.

[0149] Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications in the details can be made without departing from the invention, within the scope and range of equivalents of the claims. [Example]

[0150] Next, embodiments of the present invention will be described in more detail using examples. Measurements of various properties were carried out using the methods described below. These properties were measured under environmental conditions of a temperature of 23°C and a relative humidity of 50%, unless otherwise specified. Prepregs were then produced from the resins of the examples using a hot-melt prepreg method. The components used in the examples and comparative examples are as follows:

[0151] Component [A] <Low THR epoxy resin> Tetraglycidyldiaminodiphenylmethane, "Araldite®" MY9655T (Huntsman Advanced Materials) with an EEW of 117-134 g / eq.

[0152] Triglycidyl p-aminophenol, "Araldite®" MY0510 (Huntsman Advanced Material) with an EEW of 95-107 g / eq.

[0153] Araldite® EPN1138 (Huntsman Advanced Materials), a phenolic novolac epoxy resin with an EEW of 175-182 g / eq and functionality of 3.6.

[0154] Ingredient [A-1] Reaction product of diethylphosphinic acid and Araldite® MY9655T in an equivalent ratio of 1:4, respectively.

[0155] Reaction product of diethylphosphinic acid and Araldite® MY0510 in an equivalent ratio of 1:3, respectively.

[0156] Reaction product of diethylphosphinic acid and Araldite® EPN1138 in an equivalent ratio of 1:3.6, respectively.

[0157] Component [E] Reaction product of diethylphosphinic acid and EPON™ 828 in an equivalent ratio of 1:2, respectively.

[0158] DOPO (dihydro-9-oxa-10-phospha-phenanthrene-10-oxide) modified multifunctional epoxy resin EXA9726 (manufactured by Dainippon Ink and Chemicals, Inc.).

[0159] Epoxy resins other than component [A], component [A-1] and component [E] Epon™ 828 (Hexion, Inc.), a bisphenol A type epoxy resin with an EEW of 185-192 g / eq.

[0160] Epon™ 3002 (Hexion, Inc.), a bisphenol A type epoxy resin with an EEW of 520-590 g / eq.

[0161] Ingredients [B] Diethylphosphinic acid Diphenylphosphinic acid Component [C]: <Hardening agent> Dicyandiamide, "Dyhard®" 100S (AlzChem Trostberg GmbH) with an AEW of 12 g / eq.

[0162] 4,4-Diaminodiphenyl sulfone, "Aradur®" 9664-1 (Huntsman Advanced Materials) <Accelerator> 2,4'-toluenebis(dimethylurea), "Omicure®" U-24M (manufactured by Huntsman Advanced Materials).

[0163] <Thermoplastic resin> Polyvinyl formal, "Vinylec (registered trademark)" K (manufactured by JNC Corporation).

[0164] method The following methods were used to prepare and characterize the epoxy resin compositions, prepregs, and FRC materials of each example.

[0165] (1) Resin mixture All components other than the curing agent and accelerator were dissolved in a mixer in predetermined amounts to prepare a mixture, and then the curing agent was mixed with a predetermined amount of accelerator to obtain an epoxy resin composition.

[0166] (2) Adduct formation The reaction products of diethylphosphinic acid and multifunctional epoxy resins (EPON™ 828, Araldite® MY510, Araldite® MY9655T) were prepared by constantly stirring the epoxy resin and diethylphosphinic acid in a predetermined ratio at a temperature of 100°C for 1 hour.

[0167] (3) Curing profile The resulting cured epoxy resin composition was molded by the following method. After mixing, the epoxy resin composition prepared in (1) was injected into a mold set to a thickness of 2 mm using a 2 mm thick Teflon (registered trademark) spacer. The mixture was then heated from room temperature to 163°C at a rate of 1.7°C / min and held at 163°C for 15 minutes to obtain a 2 mm thick plate of the cured epoxy resin composition.

[0168] (4) Flammability of resin (burning time, burning length, drip) The specimens detailed in the Examples and Comparative Examples were tested for flame retardancy according to a flammability test modified from the SFI 56.1 flammability test specification for application to neat resin specimens. The SFI 56.1 specification is specifically for CFRP testing; the example specimens did not contain fibers when tested, and the test had to be modified.

[0169] The resin flammability test involves high-shear mixing of a degassed epoxy resin composition under vacuum, followed by pouring the epoxy resin composition between two plates using a 2 mm Teflon spacer and curing at a specified temperature for a set time. In the example presented herein, the epoxy resin composition was cured at a temperature of 163°C for 15 minutes and ramped to the temperature at a rate of 10°C / min. The cured resin plate was then demolded and machined into 2" x 3" test specimens. The resin plate was placed in the flammability test chamber as shown in Figure 1. The flame was at least 1550°F, the visible flame was approximately 22 mm high as measured from the burner base, and the faint outer blue cone of the flame was approximately 38 mm high from the burner base. The 3-inch side of the resin plate specimen was centered approximately 19 mm above the burner base. The flame was moved below the resin specimen and held in place for 15 seconds, at which point the flame was removed and the time required for the flame to extinguish was measured. Additionally, any drips of the flaming epoxy resin material were recorded, along with the time that those drips remained ignited. The sighting of a drip was considered an automatic failure of the flammability test. The burn length of the specimen was also recorded. These three values, burn time, burn length, and drip, are used to characterize the flammability of the cured resin specimen. A lower burn time and a lower burn length are desirable qualities for a flame-retardant material.

[0170] (5) THR Total heat release (THR) was measured by curing a combination of one epoxy resin (e.g., tetraglycidyldiaminodiphenylmethane (TGDDM) alone or diglycidyl ether of bisphenol A (DGEBA) alone, not together) with diaminodiphenylsulfone mixed in a 1:1 EEW (epoxy equivalent weight) to AEW (amine equivalent weight) ratio. The cured specimens were then machined into 100 mm x 100 mm x 3 mm samples and tested for a heat release rate (HRR according to ISO 5660-1) of 50 kW / m. 2 The temperature was measured via a cone calorimeter with an external heat flux set at 0.05°C. The THR was calculated by integrating the HRR data over time.

[0171] (6) Glass transition temperature (Tg by DMA torsion) The epoxy resin composition was cured and molded in the following manner. After high-shear mixing by deformation under vacuum, the epoxy resin composition prepared in (1) was injected into a mold set to a thickness of 2 mm using a 2 mm Teflon spacer. The epoxy resin composition was then cured at a set temperature for a set time. In the example presented herein, the resin was cured at a temperature of 163°C for 15 minutes and then ramped up to the above temperature at a rate of 10°C / min.

[0172] Next, using a dynamic viscoelasticity measuring device (ARES manufactured by TA Instruments), the test piece was heated from 50°C to 250°C at a rate of 5°C / min in accordance with SACMA SRM 18R-94, and subjected to Tg measurement in a 1.0 Hz torsion mode.

[0173] Tg was determined by finding the intersection of the tangent to the glass region and the tangent to the transition region from the glass region to the rubber region on the temperature storage modulus curve (also called the G' curve), and the temperature at this intersection was considered to be the glass transition temperature (also called G'Tg).

[0174] However, when the cured product of the cured resin composition had one or more loss modulus (G'') peaks, the Tg was determined using the following method. The height of each peak was calculated by subtracting the peak height (MPa) from the corresponding valley preceding the peak. If the height of any one of these peaks exceeded 15 MPa, the corresponding transition on the G' curve was used to calculate the Tg.

[0175] (7) Resin flexural modulus The flexural properties were measured by the following procedure. A 10 mm x 50 mm test piece was cut from the cured epoxy resin composition obtained according to the process under glass transition temperature (Tg) described above in (6). The test piece was then subjected to a three-point bending test in accordance with ASTM D7264 using an Instron universal testing machine (manufactured by Instron Corporation). The test piece was tested at room temperature to obtain the RTD (Room Temperature Dry) flexural properties of the cured epoxy resin composition.

[0176] The properties of the cured epoxy resin compositions of the examples and comparative examples were evaluated using the following measurement methods.

[0177] (i) Glass transition temperature (Tg) (ii) Flexural modulus (iii) Flammability of the resin (burn length, burn time, drip) (8) Viscosity of uncured resin The uncured resin specimen was placed in a 40 mm diameter parallel plate rheometer (ARES, TA Instruments) with a 0.6 mm gap preheated to 40 °C. A torsional displacement of 10 rad / s was applied. The temperature was increased at 2 °C / min until the minimum viscosity of the resin was determined.

[0178] Examples 1 to 16 and Comparative Examples 1 to 6 The various amounts of the components used in each example are listed in Tables 1 to 4. The epoxy resin compositions shown in Tables 1, 2, 3, and 4 were prepared according to the following method: All components except the curing agent and curing accelerator were dissolved in a mixer in the specified amounts to prepare a mixture, and then the curing agent was mixed with the specified amount of accelerator to obtain the epoxy resin composition.

[0179] The prepared epoxy resin compositions were cured by the methods described in the various test descriptions. The results of each test are shown in Tables 1, 2, 3, and 4.

[0180] Examples 1 to 16 in Tables 1, 2 and 3, which are embodiments of the present invention, provided good flammability results.

[0181] Examples 1 to 5 and Comparative Example 1 In Examples 1-5 and Comparative Example 1, the key difference between the compositions of Examples 1-5 and Comparative Example 1 is that Comparative Example 1 lacks phosphorus by 0.5% or more by weight. Comparative Example 1 exhibits long burn times, lengths, and drips, while the Examples have short burn times, lengths, and no drips.

[0182] Example 6 and Comparative Example 2 The key difference between Example 6 and Comparative Example 2 is that Comparative Example 2 lacks a sufficient amount of phosphorus content, and Comparative Example 2 exhibits a long burn time, length, and drip, while Example 6 has a short burn time, length, and no drip.

[0183] Example 7 and Comparative Example 3 In Example 7 and Comparative Example 3, Comparative Example 3 used EXA-9726, which is a DOPO (dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) modified difunctional epoxy resin (i.e., an organic phosphonous acid modified epoxy resin), instead of an organic phosphinic acid modified difunctional epoxy resin as in Example 7. Example 7 maintained a short burn time of 1.8 seconds, while Comparative Example 3 had a significantly longer burn time of 13.5 seconds.

[0184] Example 8 and Comparative Example 4 The key difference between Example 8 and Comparative Example 4 is the phosphorus content of the two systems. Comparative Example 4 did not contain an organic phosphinic acid compound and did not achieve the good flame retardancy shown by Example 8.

[0185] Examples 1, 8-9 and Comparative Examples 5-6 In Examples 1, 8, and 9 and Comparative Examples 5 and 6, the difference is the percentage of the epoxy resin composition that is a low-THR epoxy resin (i.e., an epoxy resin with a THR of 23 kJ / g or less). In the Examples, all blends contain at least 10 wt. % (23 kJ / g or less) low-THR epoxy resin and at least 15 PHR low-THR epoxy resin. When the amount of low-THR epoxy resin used falls below this threshold, an increase in burn time is observed in Comparative Example 5, at 11.2 seconds, longer than the burn times of the Examples of 4, 3.3, and 9.3 seconds, respectively. Additionally, Comparative Example 6 exhibited dripping, a phenomenon seen only in the other Examples with 0 wt. % phosphorus content.

[0186] Examples 8 and 15 The key difference between Examples 8 and 15 is the type of low THR epoxy resin. When a glycidyl amine-type epoxy resin was used as the low THR epoxy resin, a decrease in burning time was observed compared to when a glycidyl amine-type epoxy resin was not used as the low THR epoxy resin.

[0187] [Table 1]

[0188] [Table 2]

[0189] [Table 3]

[0190] [Table 4]

Claims

1. A flame-retardant epoxy resin composition comprising component [A], component [B], and component [C], the flame retardant epoxy resin composition has a phosphorus content of at least 0.5 wt %, based on the total weight of the flame retardant epoxy resin composition; the component [A] is comprised of at least one low THR multifunctional epoxy resin having a total heat release (THR) value of 23 kJ / g or less, the total amount of the low THR multifunctional epoxy resin being at least 15 PHR or at least 10 wt% of the total weight of the flame retardant epoxy resin composition, and the low THR multifunctional epoxy resin is comprised of at least one glycidyl amine type epoxy resin; Component [B] is composed of at least one organic phosphinic acid, and at least a portion of component [B] is pre-reacted with at least a portion of a low THR multifunctional epoxy resin; and The component [C] is a flame-retardant epoxy resin composition comprising at least one curing agent.

2. The at least one organophosphinic acid has formula (I): 【Chemistry 1】 (In the formula, R １ and R ２ are independently selected from an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms.

2. The flame retardant epoxy resin composition of claim 1, comprising at least one organic phosphinic acid corresponding to

3. 10. The flame retardant epoxy resin composition of claim 1, further comprising at least one multifunctional epoxy resin other than a low THR multifunctional epoxy resin having a total heat release (THR) value of 23 kJ / g or less.

4. 2. The flame retardant epoxy resin composition of claim 1, wherein the total amount of the low THR multifunctional epoxy resin is at least 20 PHR or at least 15 wt% of the total weight of the flame retardant epoxy resin composition.

5. 10. The flame retardant epoxy resin composition of claim 1, comprising 15 PHR to 85 PHR of said at least one low THR multifunctional epoxy resin.

6. 10. The flame retardant epoxy resin composition of claim 1, wherein the low THR multifunctional epoxy resin is comprised of at least one tetraglycidyldiaminodiphenylmethane.

7. 2. The flame-retardant epoxy resin composition according to claim 1, wherein the low THR multifunctional epoxy resin is a glycidyl amine type epoxy resin.

8. 10. The flame retardant epoxy resin composition of claim 1, wherein the at least one curing agent comprises at least one dicyandiamide.

9. 10. The flame retardant epoxy resin composition of claim 1, further comprising at least one thermoplastic resin.

10. 10. The flame retardant epoxy resin composition of claim 9, wherein the at least one thermoplastic resin comprises at least one polyvinyl formal.

11. 10. The flame retardant epoxy resin composition of claim 9, wherein the at least one thermoplastic resin comprises at least one polyethersulfone.

12. R in formula (I) １ and R ２ and each represent an ethyl group.

13. A prepreg comprising a reinforcing fiber matrix impregnated with the flame-retardant epoxy resin composition according to any one of claims 1 to 12.

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

15. A fiber-reinforced composite material comprising a cured epoxy resin obtained by curing a mixture comprising the flame-retardant epoxy resin composition according to any one of claims 1 to 12, and reinforcing fibers.

16. A method for producing a fiber-reinforced composite material, comprising curing the prepreg according to claim 13 at a temperature of 120°C to 200°C.

17. A flame-retardant epoxy resin composition comprising component [C] and (i) Component [A-1] (ii) the component [A-1] and the component [A], (iv) the component [A-1] and the component [E], or (v) the component [A-1], the component [A], and the component [E] and an epoxy component selected from the flame retardant epoxy resin composition has a phosphorus content of at least 0.5 wt %, based on the total weight of the flame retardant epoxy resin composition; the component [A] comprises at least one low THR multifunctional epoxy resin having a total heat release (THR) value of 23 kJ / g or less, the total amount of the low THR multifunctional epoxy resins comprising the component [A] and / or the component [A-1] is at least 15 PHR or at least 10 wt % of the total weight of the flame-retardant epoxy resin composition, and the low THR multifunctional epoxy resin is composed of at least one glycidyl amine-type epoxy resin; The component [A-1] is composed of at least one low THR multifunctional epoxy resin containing at least one residue of at least one organic phosphinic acid, said component [E] being comprised of at least one epoxy resin other than said at least one low THR multifunctional epoxy resin containing at least one residue of at least one organic phosphinic acid; and The component [C] is composed of at least one curing agent. Flame-retardant epoxy resin composition.

18. The flame-retardant epoxy resin composition according to claim 17, further comprising an epoxy resin other than the component [A], the component [A-1], and the component [E].

19. The at least one residue of an organophosphinic acid has the formula (II): 【Chemistry 2】 (Wherein, R in formula (II) １ and R ２ are independently selected from an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms.

18. The flame retardant epoxy resin composition of claim 17, which corresponds to

20. The component [E] is represented by formula (III): 【Transformation 3】 (Wherein R in formula (III) １ and R ２ are independently selected from an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms, and R3 in formula (III) is a group in which at least one epoxy group is reacted to form a substituent -O-P(=O)R １ R ２ wherein at least one epoxy resin corresponding to formula (III) has at least one unreacted epoxy group.

18. The flame retardant epoxy resin composition of claim 17, comprising the at least one epoxy resin corresponding to

21. 18. The flame retardant epoxy resin composition of claim 17, wherein the total amount of the low THR multifunctional epoxy resin is at least 20 PHR or at least 15 wt% of the total weight of the flame retardant epoxy resin composition.

22. 18. The flame retardant epoxy resin composition of claim 17, comprising 15 PHR to 85 PHR of said at least one low THR multifunctional epoxy resin.

23. 18. The flame retardant epoxy resin composition of claim 17, wherein the low THR multifunctional epoxy resin is comprised of at least one tetraglycidyldiaminodiphenylmethane.

24. 18. The flame-retardant epoxy resin composition according to claim 17, wherein the low THR multifunctional epoxy resin is a glycidyl amine type epoxy resin.

25. 18. The flame retardant epoxy resin composition of claim 17, wherein the at least one curing agent comprises at least one dicyandiamide.

26. 20. The flame retardant epoxy resin composition of claim 17, further comprising at least one thermoplastic resin.

27. 27. The flame retardant epoxy resin composition of claim 26, wherein the at least one thermoplastic resin comprises at least one polyvinyl formal.

28. 27. The flame retardant epoxy resin composition of claim 26, wherein the at least one thermoplastic resin comprises at least one polyethersulfone.

29. R in formula (II) １ and R ２ and each is an ethyl group.

30. A prepreg comprising a reinforcing fiber matrix impregnated with the flame retardant epoxy resin composition of claim 17.

31. A fiber-reinforced composite material obtained by curing the prepreg according to claim 30.

32. A fiber-reinforced composite material comprising a cured epoxy resin obtained by curing a mixture composed of the flame-retardant epoxy resin composition according to any one of claims 17 to 29, and reinforcing fibers.

33. A method for producing a fiber-reinforced composite material, comprising curing the prepreg according to claim 30 at a temperature of 120°C to 200°C.

34. A method for producing a flame-retardant epoxy resin composition by combining component [A], component [B], and component [C], the flame retardant epoxy resin composition has a phosphorus content of at least 0.5 wt %, based on the total weight of the flame retardant epoxy resin composition; the component [A] is comprised of at least one low THR multifunctional epoxy resin having a total heat release (THR) value of 23 kJ / g or less, the total amount of the low THR multifunctional epoxy resin being at least 15 PHR or at least 10 wt% of the total weight of the flame retardant epoxy resin composition, and the low THR multifunctional epoxy resin is comprised of at least one glycidyl amine type epoxy resin; The component [B] is composed of at least one organic phosphinic acid, The component [C] is composed of at least one curing agent, and 10. A method for making a flame retardant epoxy resin composition, further comprising heating for a time and at a temperature effective to achieve at least partial reaction of said at least one organophosphinic acid with at least one low THR multifunctional epoxy resin.

Images