JP2024002608A - Epoxy resin composition, and prepreg and structure using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition which achieves both weight reduction and good mechanical strength at higher levels than conventional ones.

SOLUTION: An epoxy resin composition of the present invention contains an epoxy resin and a phenol compound having a fluorene skeleton represented by the following formula (1). (In the formula (1), R₁ and R₂ each independently represent a C4-12 saturated hydrocarbon group; X₁ and X₂ each independently represent an optionally substituted aromatic group; and n and m each independently represent an integer of 0-2.)

SELECTED DRAWING: None

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to an epoxy resin composition, and prepregs and structures using the same.

Conventionally, by curing epoxy resin with various curing agents, it becomes a cured product with excellent mechanical properties, water resistance, chemical resistance, heat resistance, electrical properties, etc., and is used for structures, adhesives, paints, laminates, etc. It is used in a wide range of fields such as molding materials. Among these, it is known that mechanical strength can be improved by making the epoxy resin polyfunctional. For example, Patent Document 1 describes a naphthol structure that may have a substituent on the aromatic ring and a number of carbon atoms as the substituent on the aromatic ring, in order to obtain an epoxy resin composition with excellent mechanical properties. A polyfunctional epoxy resin obtained from a polyfunctional phenol resin characterized in that a catechol structure having 4 to 8 alkyl groups is bonded via a methylene group which may have a substituent. It is disclosed that it can be obtained.

JP2021-66832A

BACKGROUND ART In recent years, from the viewpoint of energy efficiency, there has been an active effort to reduce the weight of parts of transportation machines and the like by replacing them with metals. Thermosetting resins such as epoxy resins are attracting attention as metal substitute parts because they are lighter than metals and have excellent mechanical properties, heat resistance, etc.
However, in the conventional technique as disclosed in Patent Document 1, although the mechanical properties are improved, it is not sufficient to reduce the weight of the epoxy resin composition itself.

Therefore, the present inventor focused on the development of a new epoxy resin composition that can achieve weight reduction while maintaining mechanical properties. As a result, by using an epoxy resin and a phenol compound having a specific fluorene skeleton, it is possible to reduce the weight while maintaining the good mechanical strength obtained by an epoxy resin composition using a conventionally known phenolic curing agent. They discovered this and completed the present invention.

According to the present invention, the following epoxy resin composition and prepregs and structures using the same are provided.

（式（１）中、Ｒ_１、Ｒ_２は各々独立して炭素数４～１２の飽和炭化水素基を表す。Ｘ_１、Ｘ_２は各々独立して置換基を有していてもよい芳香族基を表し、ｎ、ｍは各々独立して０～２の整数を表す。）
［２］ ［１］に記載のエポキシ樹脂組成物であって、
エポキシ樹脂組成物中のエポキシ基数（ＥＰ）とフェノール性水酸基数（ＯＨ）との当量比（ＥＰ／ＯＨ）が、０．９以上１．５以下である、エポキシ樹脂組成物。
［３］ ［１］または［２］に記載のエポキシ樹脂組成物であって、
前記エポキシ樹脂の含有量が、当該樹脂組成物全量に対して、１質量％以上５０質量％以下である、エポキシ樹脂組成物。
［４］ ［１］乃至［３］いずれか一つに記載のエポキシ樹脂組成物であって、
前記エポキシ樹脂が、多官能エポキシ樹脂を含む、エポキシ樹脂組成物。
［５］ ［１］乃至［４］いずれか一つに記載のエポキシ樹脂組成物であって、
さらに硬化促進剤を含む、エポキシ樹脂組成物。
［６］ ［１］乃至［５］いずれか一つに記載のエポキシ樹脂組成物であって、
当該フェノール化合物の融点が３０～２００℃である、エポキシ樹脂組成物。
［７］ ［１］乃至［６］いずれか一つに記載のエポキシ樹脂組成物を基材に含浸させてなる、プリプレグ。
［８］ ［１］乃至［６］いずれか一つに記載のエポキシ樹脂組成物の硬化物を備える、構造体。 [1] An epoxy resin composition containing an epoxy resin and a phenol compound having a fluorene skeleton represented by the following formula (1).

(In formula (1), R ₁ and R ₂ each independently represent a saturated hydrocarbon group having 4 to 12 carbon atoms. X ₁ and X ₂ each independently represent an aromatic group that may have a substituent. represents a group group, and n and m each independently represent an integer of 0 to 2.)
[2] The epoxy resin composition according to [1],
An epoxy resin composition in which the equivalent ratio (EP/OH) between the number of epoxy groups (EP) and the number of phenolic hydroxyl groups (OH) in the epoxy resin composition is 0.9 or more and 1.5 or less.
[3] The epoxy resin composition according to [1] or [2],
An epoxy resin composition in which the content of the epoxy resin is 1% by mass or more and 50% by mass or less based on the total amount of the resin composition.
[4] The epoxy resin composition according to any one of [1] to [3],
An epoxy resin composition, wherein the epoxy resin includes a polyfunctional epoxy resin.
[5] The epoxy resin composition according to any one of [1] to [4],
An epoxy resin composition further comprising a curing accelerator.
[6] The epoxy resin composition according to any one of [1] to [5],
An epoxy resin composition in which the phenol compound has a melting point of 30 to 200°C.
[7] A prepreg obtained by impregnating a base material with the epoxy resin composition according to any one of [1] to [6].
[8] A structure comprising a cured product of the epoxy resin composition according to any one of [1] to [6].

According to the present invention, it is possible to provide an epoxy resin composition that can realize weight reduction while maintaining good mechanical strength.

FIG. 2 is a diagram showing the results of ¹ H-NMR measurement of the phenol compound (A) of Example.

Embodiments of the present invention will be described in detail below.

In the present specification, the notation "a to b" in the description of numerical ranges represents a range from a to b, unless otherwise specified. For example, "1 to 5% by mass" means "1 to 5% by mass".

<Epoxy resin composition>
The epoxy resin composition of this embodiment (hereinafter also referred to as "resin composition") comprises an epoxy resin and a phenol compound having a fluorene skeleton represented by the following formula (1) (hereinafter also referred to as "phenol compound (A)"). ).

（式（１）中、Ｒ_１、Ｒ_２は各々独立して炭素数４～１２の飽和炭化水素基を表す。Ｘ_１、Ｘ_２は各々独立して置換基を有していてもよい芳香族基を表し、ｎ、ｍは各々独立して０～２の整数を表す。）

(In formula (1), R ₁ and R ₂ each independently represent a saturated hydrocarbon group having 4 to 12 carbon atoms. X ₁ and X ₂ each independently represent an aromatic group that may have a substituent. represents a group group, and n and m each independently represent an integer of 0 to 2.)

In this embodiment, since the phenol compound (A) has a fluorene skeleton represented by formula (1), the cured product of the resin composition of this embodiment can be made lightweight while maintaining good strength. can. Although the details of this are not clear, the multiple aromatic groups provide rigidity and mechanical strength, while the increased bulk provides low specific gravity, while the saturated hydrocarbon group with a relatively large number of carbon atoms provides toughness. It is speculated that it will be possible to reduce the weight while doing so.

The components contained in the resin composition of this embodiment will be explained below.

[Phenol compound (A)]
The phenol compound (A) has a fluorene skeleton represented by the above formula (1).
In formula (1), examples of the aromatic group include a phenyl group, a biphenyl group, a naphthyl group, an anthracene group, etc., and among them, a phenyl group and a biphenyl group are preferable. That is, it is preferable that a plurality of phenyl groups are covalently bonded through a single bond.

Further, in formula (1), R ₁ and R ₂ are each independently a saturated hydrocarbon group having 4 to 12 carbon atoms, preferably a saturated hydrocarbon group having 6 to 11 carbon atoms, and more preferably a saturated hydrocarbon group having 6 to 11 carbon atoms. It is a saturated hydrocarbon group of number 8 to 10. Further, each of the saturated hydrocarbon groups R ₁ and R ₂ is either straight chain or branched, and from the viewpoint of facilitating weight reduction, both are preferably straight chain.

The melting point of the phenol compound (A) of this embodiment is preferably 30 to 200°C, more preferably 80 to 190°C, and even more preferably 130 to 180°C.

Next, a method for producing the phenol compound (A) will be explained.
The phenol compound (A) is obtained by reacting a phenol (p) and a fluorene (f) in the presence of a basic catalyst (b). In the phenols (p) and the fluorenes (f), a boronic acid is bonded to one of the aromatic rings, and a halogen is bonded to the other aromatic ring.

Phenols (p) include phenol; cresols such as o-cresol, m-cresol, and p-cresol; ethylphenols such as o-ethylphenol, m-ethylphenol, and p-ethylphenol; isopropylphenol, butylphenol; , p-tert-butylphenol and other butylphenols; p-tert-amylphenol, p-octylphenol, p-nonylphenol, p-cumylphenol and other alkylphenols; fluorophenol, chlorophenol, bromophenol, iodophenol and other halogens substituted monohydric phenols such as p-phenylphenol, aminophenol, nitrophenol, dinitrophenol, and trinitrophenol; monohydric phenols such as 1-naphthol and 2-naphthol; and resorcinol, alkylresorcinol, Examples include polyhydric phenols such as pyrogallol, catechol, alkylcatechol, hydroquinone, alkylhydroquinone, phloroglucin, bisphenol A, bisphenol F, bisphenol S, and dihydroxynaphthalene, among which boronic acid is bonded on the aromatic ring, Alternatively, one in which a halogen is bonded to an aromatic ring is used. Furthermore, the phenols (p) can be used alone or in combination of two or more.

More specifically, those having structures shown in the following formulas (a-1) to (a-3) can be mentioned.

Examples of the fluorenes (f) include alkyl-substituted fluorenes having 4 to 12 carbon atoms. For example, 9,9-dibutylfluorene, 9,9-dipentylfluorene, 9,9-hexylfluorene, 9,9-diheptylfluorene, 9,9-dioctylfluorene, 9,9-dinonylfluorene, 9,9- Examples include didecylfluorene, 9,9-diundecylfluorene, 9,9-didodecylfluorene, and derivatives thereof, among which boronic acid is bonded to the aromatic ring, or halogen is bonded to the aromatic ring. is used.

Furthermore, specific examples of fluorenes (f) having a halogen bonded to them include those represented by the following formula (2).

（式（２）中、Ｒ_５、Ｒ_６は各々独立して炭素数４～１２の飽和炭化水素基を表す。Ｙ_１、Ｙ_２は各々独立して臭素、ヨウ素、塩素、またはフッ素のいずれかのハロゲン原子を示す。）

(In formula (2), R ₅ and R ₆ each independently represent a saturated hydrocarbon group having 4 to 12 carbon atoms. Y ₁ and Y ₂ each independently represent bromine, iodine, chlorine, or fluorine. )

Examples of the basic catalyst (b) include hydroxides of alkali metals or alkaline earth metals such as sodium hydroxide, potassium hydroxide, and calcium hydroxide; carbonates such as sodium carbonate, calcium carbonate, and potassium carbonate; lime; Oxides such as; sulfites such as sodium sulfite; phosphates such as sodium phosphate; amines such as ammonia, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, hexamethylenetetramine, pyridine, etc. .

Furthermore, a palladium catalyst may be used as a catalyst for advancing the coupling reaction. Examples of the palladium catalyst include tetrakis(triphenylphosphine)palladium (Pd(PPh ₃ ) ₄ ), palladium on carbon, and the like.
Moreover, when using a mixed solvent of water and an organic solvent, a phase transfer catalyst may be further used for the purpose of promoting the reaction between two phases. Examples of the phase transfer catalyst include tetrabutylammonium chloride and tetrabutylammonium bromide.

Furthermore, although water is generally used as a reaction solvent, organic solvents may also be used.
Examples of the organic solvent include alcohols, ethers, ketones, aromatics, dimethyl sulfoxide (DMSO), and N,N-dimethylformamide (DMF).
Specific examples of alcohols include methanol, ethanol, propyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, glycerin, and the like. Specific examples of ethers include cyclic ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, and 4-methyltetrahydropyran. Specific examples of ketones include acetone, methyl ethyl ketone, and the like. Specific examples of aromatics include toluene, xylene, and the like.
These may be used alone or in combination of two or more. Among these, mixed solvents of water, alcohols, and ethers are preferred.

Phenols (p) and fluorenes (f) are preferably used in a molar ratio (p/f) of 1.5 to 3. Further, the basic catalyst (b) and the phenol (p) are preferably prepared so that the molar ratio (b/p) is 1.5 to 3. By reacting phenols (p) and fluorenes (f) at 80 to 110°C for 12 to 36 hours, a phenol compound (A) having a fluorene skeleton represented by formula (1) is obtained.
Further, these steps are preferably performed under an inert gas atmosphere.

[Epoxy resin]
For the epoxy resin of this embodiment, monomers, oligomers, and polymers in general having two or more epoxy groups in one molecule can be used, and the molecular weight and molecular structure thereof are not particularly limited. In this embodiment, the epoxy resins include, for example, biphenyl type epoxy resin; bisphenol type epoxy resin such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, and tetramethylbisphenol F type epoxy resin; stilbene type epoxy resin; and phenol novolac type epoxy resin. resin, novolak type epoxy resin such as cresol novolac type epoxy resin; polyfunctional epoxy resin such as trisphenol type epoxy resin, which is exemplified by triphenolmethane type epoxy resin, alkyl-modified triphenolmethane type epoxy resin, etc.; having a phenylene skeleton Aralkyl-type epoxy resins such as phenol aralkyl-type epoxy resins, phenol-aralkyl-type epoxy resins having a biphenylene skeleton, and biphenylaralkyl-type epoxy resins; dihydroxynaphthalene-type epoxy resins, epoxy resins obtained by glycidyl etherification of dihydroxynaphthalene dimers, etc. From the group consisting of naphthol-type epoxy resins; triazine nucleus-containing epoxy resins such as triglycidyl isocyanurate and monoallyl diglycidyl isocyanurate; bridged cyclic hydrocarbon compound-modified phenol-type epoxy resins such as dicyclopentadiene-modified phenol-type epoxy resins; Contains one or more selected types. Among these, bisphenol type epoxy resins such as biphenyl type epoxy resin, aralkyl type epoxy resin, biphenyl type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, and tetramethylbisphenol F type epoxy resin, and stilbene type epoxy resin It is preferable that the resin has crystallinity.
In this embodiment, from the viewpoint of improving moldability, heat resistance, etc., it is more preferable to include a polyfunctional epoxy resin such as an aralkyl epoxy resin, a bisphenol epoxy resin, or a trisphenol epoxy resin.

The equivalent ratio (EP/OH) between the number of epoxy groups (EP) and the number of phenolic hydroxyl groups (OH) in the epoxy resin composition of this embodiment is preferably 0.9 or more and 1.5 or less, and 1. More preferably, it is 0 to 1.3.
Thereby, the mechanical strength of the cured product can be effectively improved.

The resin composition of this embodiment may further contain the following components.

[Curing accelerator]
The resin composition of this embodiment can further contain a curing accelerator.
The curing accelerator may be any one that promotes the crosslinking reaction between the epoxy resin and the phenol compound (A), and those used in general resin compositions can be used.

In this embodiment, the curing accelerator is a phosphorus atom-containing compound such as an organic phosphine, a tetra-substituted phosphonium compound, a phosphobetaine compound, an adduct of a phosphine compound and a quinone compound, an adduct of a phosphonium compound and a silane compound; , 8-diazabicyclo[5.4.0]undecene-7, benzyldimethylamine, 2-methylimidazole, etc., among nitrogen atom-containing compounds such as amidines, tertiary amines, and quaternary salts of the above-mentioned amidines and amines. One type or two or more types can be included. Among these, it is more preferable to include a phosphorus atom-containing compound from the viewpoint of improving curability. In addition, from the viewpoint of improving the balance between moldability and curability, it is desirable to have latent properties such as tetra-substituted phosphonium compounds, phosphobetaine compounds, adducts of phosphine compounds and quinone compounds, and adducts of phosphonium compounds and silane compounds. It is more preferable to include something.

Examples of organic phosphines that can be used in the resin composition of the present embodiment include primary phosphines such as ethylphosphine and phenylphosphine; secondary phosphines such as dimethylphosphine and diphenylphosphine; trimethylphosphine, triethylphosphine, tributylphosphine, and trimethylphosphine; Examples include tertiary phosphines such as phenylphosphine.

The content of the curing accelerator is preferably 0.01 to 10% by mass, more preferably 0.1 to 5% by mass, and 0.5 to 2% by mass based on the total amount of the resin composition. It is even more preferable that there be.

[Curing agent]
The resin composition of this embodiment may further include a curing agent. Examples of the curing agent include phenolic curing agents other than the above-mentioned phenolic compound (A), amines, polyoxystyrenes such as polyparaoxystyrene, alicyclics such as hexahydrophthalic anhydride (HHPA), and methyltetrahydrophthalic anhydride (MTHPA). acid anhydrides, including aromatic acid anhydrides such as trimellitic anhydride (TMA), pyromellitic anhydride (PMDA), and benzophenone tetracarboxylic acid (BTDA); Examples include isocyanate compounds such as polymercaptan compounds, isocyanate prepolymers, and blocked isocyanates, and organic acids such as carboxylic acid-containing polyester resins.

Specifically, the phenolic curing agent includes novolak type phenolic resins such as phenol novolak resin, cresol novolak resin, naphthol novolak resin, aminotriazine novolak resin, novolak resin, and trisphenylmethane type phenol novolac resin; terpene-modified phenolic resin , modified phenolic resins such as dicyclopentadiene-modified phenolic resins; phenol aralkyl resins having a phenylene skeleton and/or biphenylene skeleton; aralkyl type resins such as naphthol aralkyl resins having a phenylene skeleton and/or biphenylene skeleton; bisphenol A, bisphenol F, etc. bisphenol compounds; one or more selected from resol type phenol resins and the like. Further, from the viewpoint of curability, it is preferable that the hydroxyl equivalent of the phenolic resin curing agent is, for example, 90 g/eq or more and 250 g/eq or less.

The content of the curing agent is preferably 1 to 40 parts by weight, more preferably 10 to 30 parts by weight, based on 100 parts by weight of the epoxy resin.

[Reinforced fiber]
The resin composition of this embodiment may also contain reinforcing fibers. In this embodiment, reinforcing fibers are used to increase mechanical strength and heat resistance.
Examples of reinforcing fibers include metal fibers, carbon fibers, glass fibers, ceramic fibers, polyamide fibers, aramid fibers, polyimide fibers, polyvinyl alcohol fibers, polyester fibers, acrylic fibers, polyparaphenylenebenzoxazole fibers, polyethylene fibers, and polypropylene fibers. , polyacrylonitrile fiber, and ethylene vinyl alcohol fiber. Among these, carbon fibers and glass fibers are preferred because they are effective in improving the strength of molded products.
Furthermore, the reinforcing fibers may be surface-treated.

Further, the content of the reinforcing fibers is adjusted appropriately depending on the use, but for example, the content of the reinforcing fibers is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, and still more preferably 30% by mass, based on the total amount of the resin composition. ~65% by mass. By setting the reinforcing fiber content to the above lower limit or more, mechanical strength and heat resistance can be improved. On the other hand, by setting the content of reinforcing fibers to the above upper limit or less, weight reduction can be achieved and moldability can be maintained favorably.

[Curing aid]
The resin composition of this embodiment may also contain a curing aid.
Examples of the curing aid include curing aids known in the field of resin compositions. Examples include alkaline earth metal oxides or hydroxides such as magnesium oxide, calcium hydroxide, and barium hydroxide; and aromatic carboxylic acids such as salicylic acid and benzoic acid.

[Inorganic filler]
The resin composition of this embodiment can use an inorganic filler. The inorganic filler can impart mechanical properties, dimensional stability, etc. to the resin composition.
The inorganic filler is not particularly limited, but one or more types selected from clay, calcium carbonate, talc, aluminum hydroxide, etc. can be used. Among them, it is more preferable to use clay in consideration of the performance required of the resin composition (mechanical properties, electrical properties, flame retardance, dimensional stability, water resistance, etc.).
Note that some inorganic fillers such as aluminum hydroxide also have an effect as a flame retardant aid.

The content of the above-mentioned inorganic filler is appropriately adjusted depending on the application, but for example, it is preferably 1 to 10% by mass, more preferably 2 to 5% by mass based on the entire resin composition. . By setting the content of the inorganic filler to the above-mentioned lower limit or more, good mechanical properties and heat resistance can be maintained, and by setting the content of the inorganic filler to the above-mentioned upper limit or less, the processability of the resin composition can be improved.

[Elastomer]
For the resin composition of this embodiment, an elastomer can be used. Elastomers can maintain dimensional stability and increase the toughness of molded products.
Examples of the elastomer include acrylonitrile butadiene rubber, isoprene, styrene butadiene rubber, and ethylene propylene rubber. Among these, acrylonitrilyl butadiene rubber is preferred.
The content of the above-mentioned elastomer is appropriately adjusted depending on the application, but for example, it is preferably 1 to 10% by mass, more preferably 2 to 5% by mass, based on the entire resin composition. By setting the content of the elastomer to the above-mentioned lower limit or more, good mechanical properties can be maintained, and by setting the content of the elastomer to below the above-mentioned upper limit, the processability of the resin composition can be improved.

[Other ingredients]
The resin composition of the present embodiment may contain other components other than those described above, as long as the effects of the invention are not impaired. Examples of other components include additives such as thermosetting resins and thermoplastic resins other than those mentioned above, curing agents, mold release agents, pigments, flame retardants, adhesion improvers, and coupling agents.
When the resin composition of this embodiment contains these other components, it may contain only one type, or may contain two or more types.

Examples of the thermoplastic resin include resins having a triazine ring such as urea resin and melamine resin, bismaleimide resins, silicone resins, and resins having a benzoxazine ring.

Examples of the above mold release agent include fatty acids such as stearic acid, fatty acid salts such as calcium stearate and zinc stearate, fatty acid amides, and polyethylene.
When a mold release agent is used, its content is, for example, 0.1 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the epoxy resin.

Examples of the above pigments include carbon black. In addition, various coloring pigments can also be used to obtain molded products of desired colors.
When a pigment is used, its content is, for example, 0.1 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the epoxy resin.

Examples of the above-mentioned coupling agents include epoxy silane coupling agents, cationic silane coupling agents, silane coupling agents such as aminosilane coupling agents, titanate coupling agents, and silicone oil type coupling agents. . One type of coupling agent may be used alone, or two or more types may be used in combination. In this embodiment, a silane coupling agent is preferably used. It is believed that the use of a coupling agent improves the compatibility between the inorganic filler and other components, and improves the mechanical properties and heat resistance of the resin composition.

The resin composition of this embodiment may contain a solvent (organic solvent, etc.). However, from the viewpoint of ease of distribution and handling as a resin composition, suppression of VOC generation in the working environment, etc., it is preferable that the resin composition of the present embodiment does not substantially contain a solvent (organic solvent, etc.).

[Glass-transition temperature]
The glass transition temperature of the cured product of the resin composition of this embodiment is preferably 80 to 180°C, more preferably 90 to 150°C, even more preferably 100 to 125°C. Thereby, thermal properties can be improved while maintaining good moldability.

[form]
Although the resin composition of this embodiment is not particularly limited, it is preferably in the form of powder, granules, tablets, or sheets at 23°C.

<Method for manufacturing resin composition>
The method for producing the resin composition of this embodiment is not particularly limited, and it can be obtained by mixing the above components by a known method. For example, after blending the above ingredients and mixing them uniformly, heat-melting and kneading them using a kneading device such as a roll, a co-kneader, or a twin-screw extruder, or a combination of a roll and other mixing device, and then granulating or pulverizing the ingredients is possible. used.

<Cured product/molded product>
The resin composition of the present embodiment can be made into a cured product by curing, for example, at 160 to 220° C. for 5 to 240 minutes.
Molded products using the resin composition of the present embodiment are not particularly limited, but include, for example, prepregs formed by impregnating a base material with the resin composition, and structures comprising a cured product of the resin composition. .

[specific gravity]
The specific gravity of the cured product of the resin composition of this embodiment (curing conditions: 180° C., 120 minutes) is preferably 1.00 to 1.20, more preferably 1.05 to 1.15.
By setting the specific gravity of the cured product of the resin composition to be equal to or higher than the above lower limit, good strength can be obtained and heat resistance and dimensional stability can be maintained. On the other hand, weight reduction can be achieved by controlling the specific gravity of the cured product of the resin composition to be equal to or less than the above upper limit.

The molded article of this embodiment can be obtained by a known method, but for example, the resin composition of this embodiment is melted or dissolved in a solvent such as ethanol to form a liquid, and reinforcing fibers are immersed therein. The resin composition of the embodiment is impregnated into reinforcing fibers. Thereafter, the resin is dried and heated and pressed into a desired shape, thereby curing the resin and producing a molded product. Although the molding conditions depend on the thickness of the molded article, for example, molding can be carried out at a mold temperature of 170 to 190° C., a molding pressure of 0.01 to 1 MPa, and a curing time of 2 to 10 minutes. Thereafter, additional curing may be performed by further heating.

[Application]
The use of the cured product and molded product is not particularly limited. Examples of applications include various structural members such as automobiles, aircraft, railway vehicles, ships, office equipment, general-purpose machines, household appliances, and electrical equipment. It can also be applied to impregnation applications and binder applications in which various base materials such as organic fibers, metals, and glass are impregnated. Of course, uses other than these are not excluded.

Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and the present invention includes modifications, improvements, etc. within a range that can achieve the purpose of the present invention.

Embodiments of the present invention will be described in detail based on Examples and Comparative Examples. Note that the present invention is not limited to the examples.

(1) Synthesis of phenol compound (A) 4-hydroxyphenylboronic acid (manufactured by Tokyo Kasei Kogyo Co., Ltd.) 19.0 g, 2,7-dibromo-9,9-di-n-octylfluorene (manufactured by Tokyo Kasei Kogyo Co., Ltd.) To 25.3 g of potassium carbonate (manufactured by Tokyo Kasei Kogyo Co., Ltd.), 25.4 g of tetrabutylammonium chloride (manufactured by Tokyo Kasei Kogyo Co., Ltd.), 83.8 g of water, 155.0 g of tetrahydrofuran, and 31.0 g of ethanol were added. Dissolved. To this solution, 2.1 g of tetrakis(triphenylphosphine)palladium (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was added under a nitrogen atmosphere, heated to 90° C. in an oil bath, and reacted for 24 hours. After that, the organic layer is taken out and the organic solvent is removed, and the obtained solid is purified with a silica gel column (solvent: dichloromethane) to produce a phenol compound (A) represented by the following formula (3) (melting point 160 ° C.) 16.8g of was obtained.

(2) Analysis/Measurement ¹ H-NMR was measured for the obtained phenol compound (A) under the following conditions. The results are shown in Figure 1.
< ^1H -NMR measurement conditions>
Equipment: JNM-ECA400 manufactured by JEOL Ltd.
Solvent: DMSO (dimethyl sulfoxide)-d6
Pulse angle: 45°
Sample concentration: 3wt%
Accumulated number of times: 16 times

¹ H-NMR measurement confirmed that the phenol compound (A) had a fluorene structure. Note that a to d in FIG. 1 correspond to the structure expressed by the following formula.

(3) Examples and Comparative Examples The following raw material components were mixed to give the composition (mass%) shown in Table 1, kneaded for 30 seconds on a hot plate at 150°C, taken out, and granulated. Each epoxy resin composition was obtained by pulverization.
[material]
・Epoxy resin 1: 4-(2,3-epoxypropan-1-yloxy)-N,N-bis(2,3-epoxypropan-1-yl)-2-methylaniline (EMA), Osaka Soda Co., Ltd.・Epoxy resin 2: Biphenyl type epoxy resin, YL6677, manufactured by Mitsubishi Chemical Corporation ・Phenol compound 1: Bisphenol F, DIC-BPF, melting point 90°C, manufactured by DIC Corporation ・Phenol compound 2: Formula (3) synthesized above ) Phenol compound (A) represented by
・Curing accelerator: Triphenylphosphine (TPP), manufactured by Tokyo Chemical Industry Co., Ltd.

(4) Evaluation The following evaluations and measurements were performed on each of the obtained epoxy resin composition molded products. The results are shown in Table 1.
・Specific gravity: Each epoxy resin composition was press-cured at 0.1 MPa and 200°C for 5 minutes using a hydraulic press, and the resulting test piece was then post-cured at 180°C for 2 hours, and then cured in water. The specific gravity of each molding material was determined by the substitution method.

- Bending strength and flexural modulus: Each epoxy resin composition was press-cured at 0.1 MPa and 200° C. for 5 minutes using a hydraulic press to create a test piece with a width of 10 mm, a thickness of 1 mm, and a length of 100 mm. Next, the obtained test piece was post-cured at 180°C for 2 hours, and then the bending strength (MPa) and bending elastic modulus (GPa) at 25°C were measured.

- Breaking energy: A curve (stress-strain curve) was created that graphed the relationship between stress and strain during the bending test. Next, using strain as a variable, the integral value of stress from the starting point of the bending test to the breaking point was calculated.

・Glass transition point: Each epoxy resin composition was press-cured at 0.1 MPa and 200°C for 5 minutes using a hydraulic press to create a test piece with a width of 4 mm, a thickness of 0.5 mm, and a length of 50 mm. The obtained test piece was post-cured at 180° C. for 2 hours to prepare a sample. The obtained sample was subjected to tensile mode thermomechanical analysis under the conditions of 0-350°C and a heating rate of 10°C/min, and the glass transition point was determined from the inflection point of the position change graph.

Claims (8)

An epoxy resin composition comprising an epoxy resin and a phenol compound having a fluorene skeleton represented by the following formula (1).

(In formula (1), R ₁ and R ₂ each independently represent a saturated hydrocarbon group having 4 to 12 carbon atoms. X ₁ and X ₂ each independently represent an aromatic group that may have a substituent. represents a group group, and n and m each independently represent an integer of 0 to 2.) The epoxy resin composition according to claim 1,
An epoxy resin composition in which the equivalent ratio (EP/OH) between the number of epoxy groups (EP) and the number of phenolic hydroxyl groups (OH) in the epoxy resin composition is 0.9 or more and 1.5 or less. The epoxy resin composition according to claim 1 or 2,
An epoxy resin composition in which the content of the epoxy resin is 1% by mass or more and 50% by mass or less based on the total amount of the resin composition. The epoxy resin composition according to claim 1 or 2,
An epoxy resin composition, wherein the epoxy resin includes a polyfunctional epoxy resin. The epoxy resin composition according to claim 1 or 2,
An epoxy resin composition further comprising a curing accelerator. The epoxy resin composition according to claim 1 or 2,
An epoxy resin composition in which the phenol compound has a melting point of 30 to 200°C. A prepreg obtained by impregnating a base material with the epoxy resin composition according to claim 1 or 2. A structure comprising a cured product of the epoxy resin composition according to claim 1 or 2.

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