KR20210141764A - Epoxy resin composition for carbon-fiber-reinforced composite material, resin sheet, prepreg, carbon-fiber-reinforced composite material - Google Patents

Abstract

(식 중, (a) (b)의 비율은 (a)/(b)=1∼3이다. G는 글리시딜기를 나타낸다. n은 반복수이며, 0∼5이다.)The present invention, when used as an epoxy resin composition of a carbon fiber reinforced composite material, a carbon fiber reinforced composite material that can provide a carbon fiber reinforced composite material exhibiting high heat resistance, dimensional stability, and high toughness and rigidity as a cured product An object of the present invention is to provide an epoxy resin composition and an excellent prepreg, a resin sheet, and a carbon fiber reinforced composite material using the resin composition. The epoxy resin composition for carbon fiber reinforced composite materials of the present invention contains an epoxy resin represented by the following general formula (1) and a curing agent as essential components.

(Wherein, the ratio of (a) to (b) is (a)/(b) = 1 to 3. G represents a glycidyl group. n is the number of repetitions and is 0 to 5.)

Description

EPOXY RESIN COMPOSITION FOR CARBON-FIBER-REINFORCED COMPOSITE MATERIAL, RESIN SHEET, PREPREG, CARBON-FIBER-REINFORCED COMPOSITE MATERIAL}

The present invention relates to an epoxy resin composition suitable for a carbon fiber reinforced composite material, a resin sheet using the same, a prepreg, and a carbon fiber reinforced composite material obtained by curing the same.

By curing the epoxy resin with various curing agents, it is generally a cured product with excellent mechanical properties, water resistance, chemical resistance, heat resistance, and electrical properties, and is used in a wide range of fields such as adhesives, paints, laminates, molding materials, and casting materials. have. Among these, especially in the field of fiber-reinforced composite materials, properties such as weight reduction and high strength can be imparted by impregnating and curing the reinforcing fibers with an epoxy resin and a curing agent as a matrix resin, so aircraft structural members, windmill blades, and automobile exterior panels and computer applications such as IC trays and notebook housings, and the like, and the demand thereof is increasing year by year.

In recent years, as described above, the range of application of carbon fiber reinforced composite material (CFRP) has increased, and is used in molded articles of various shapes. In this case, it is necessary to form these complex shapes by bonding a single substrate or a plurality of substrates.

It is assumed that such a molded article is used under a severe temperature environment such as a car or an airplane, and the deformation due to the amount of linear expansion with the carbon fiber is likely to occur greatly depending on the thickness or shape of the CFRP. Specifically, for example, the amount of linear expansion is different between a thick part and a thin part, and since they are mutually attracted, internal stress tends to be concentrated. This originates, and problems, such as a crack and peeling with carbon fiber, arise.

In addition, in general, reinforcing fiber plastics such as CFRP have a large difference in the coefficient of linear expansion between the fiber and the resin of the cured matrix.

Accordingly, in order to have as little change in the linear expansion of the resin itself as possible and to withstand this stress, a matrix resin having high strength and toughness is required.

Conventionally, a phenol novolak resin having a biphenyl skeleton, a phenol novolak type epoxy resin obtained by epoxidizing it, and an epoxy resin composition for sealing electronic parts containing a curing agent as essential components are known (for example, Patent Document 1) . However, in Patent Document 1, although it is described that the epoxy composition for sealing electronic components is excellent in heat resistance and flame retardancy, there is no description at all about a specific resin composition for reducing linear expansion characteristics, and the usefulness of the carbon fiber reinforced composite material is also described. not listed

Japanese Patent Laid-Open No. 2013-43958

In view of the problems of the prior art, the present invention provides a carbon fiber reinforced composite material that exhibits high heat resistance, dimensional stability, and high toughness and rigidity as a cured product when used as an epoxy resin composition of a carbon fiber reinforced composite material An object of the present invention is to provide an epoxy resin composition for carbon fiber reinforced composite materials that can be made, and excellent prepregs, resin sheets, and carbon fiber reinforced composite materials using this resin composition.

As a result of intensive research on the above subject, the present inventors have found that an epoxy resin composition containing a phenol novolac-type epoxy resin having a specific structure and a curing agent provides a cured resin product having excellent high heat resistance and low linear expansion properties For fiber-reinforced composite materials An excellent thing as an epoxy resin composition was found and came to complete this invention.

That is, the present invention

(1) an epoxy resin composition for carbon fiber reinforced composite materials comprising an epoxy resin represented by the following general formula (1) and a curing agent as essential components;

(Wherein, the ratio of (a) to (b) is (a)/(b) = 1 to 3. G represents a glycidyl group. n is the number of repeats and is 0 to 5.)

(2) the epoxy resin composition for carbon fiber reinforced composite materials according to the preceding (1), wherein the curing agent is an amine curing agent;

(3) the epoxy resin composition for carbon fiber reinforced composite materials according to the preceding paragraph (1) or (2) further comprising another epoxy resin;

(4) a resin sheet using the epoxy resin composition for carbon fiber reinforced composite materials according to any one of (1) to (3) above;

(5) A prepreg formed by impregnating carbon fiber with the epoxy resin composition for carbon fiber reinforced composite material according to any one of the preceding paragraphs (1) to (3), or the resin sheet according to the preceding paragraph (4);

(6) a carbon fiber reinforced composite material obtained by curing the prepreg according to the preceding paragraph (5);

is to provide

According to the present invention, an epoxy resin composition for carbon fiber-reinforced composite materials in which the cured product exhibits a low coefficient of linear expansion (excellent dimensional stability), high heat resistance and high toughness and rigidity, a resin sheet, prepreg, and carbon fiber-reinforced composite material using the same can provide

1 is a TMA chart of the carbon fiber reinforced composite material obtained in Example 5;
2 is a TMA chart of the carbon fiber reinforced composite material obtained in Comparative Example 3.

The epoxy resin composition for carbon fiber reinforced composite materials of the present invention will be described.

The epoxy resin composition for carbon fiber-reinforced composite materials of the present invention (hereinafter referred to as "the epoxy resin composition of the present invention") contains the epoxy resin represented by the following general formula (1) as an essential component.

(Wherein, the ratio of (a) to (b) is (a)/(b) = 1 to 3. G represents a glycidyl group. n is the number of repeats and is 0 to 5.)

The epoxy resin represented by the said General formula (1) used in this invention is Unexamined-Japanese-Patent No. 2011-252037, Unexamined-Japanese-Patent No. 2008-156553, Unexamined-Japanese-Patent No. 2013-043958, International publication. Although it can synthesize|combine by the method described in WO2012/053522 and WO2007/007827, if it has the structure of the said Formula (1), you may use the thing of any method.

However, in this invention, the thing of (a)/(b)=1 - 3 is used especially in the ratio of said Formula (a) and said Formula (b). When there are many structures of (a), heat resistance will become high, but not only will the water absorption property worsen by that much, but will also become soft and hard. Therefore, it is set as the polyfunctionalization ratio within the above-mentioned range.

As for the softening point (circular ball method) of the epoxy resin to be used, 50-150 degreeC is preferable, More preferably, it is 52-100 degreeC, Especially preferably, it is 52-95 degreeC. At 50 degrees C or less, the stickiness is severe and handling is difficult, and a subject may arise in productivity. Moreover, in the case of 150 degreeC or more, it is a temperature close to a shaping|molding temperature, and since there exists a possibility that the fluidity|liquidity at the time of shaping|molding may not be ensured, it is unpreferable.

It is preferable that the epoxy equivalent of the epoxy resin to be used is 180-350 g/eq. It is especially preferable that it is 190-300 g/eq. When an epoxy equivalent is less than 180 g/eq., since there are too many functional groups, in the hardened|cured material after hardening, water absorption may become high or it may become easy to become brittle. When the epoxy equivalent exceeds 350 g/eq., it is not preferable because the softening point becomes very large, or it is considered that the epoxidation does not proceed clearly, and there is a possibility that the amount of chlorine may become very large.

The amount of chlorine in the epoxy resin used in the present invention is preferably 200 to 1500 ppm in total chlorine (hydrolysis method), particularly preferably 200 to 900 ppm. From the standards of JPCA, it is desired not to exceed 900 ppm even in simple epoxy. In addition, if there is a large amount of chlorine, it is not preferable because there is a possibility that the electrical reliability is affected that much. When the content is less than 200 ppm, it is not preferable because an excessive refining process is required and there is a tendency that a problem arises in productivity.

Moreover, the melt viscosity in 150 degreeC of the epoxy resin used in this invention becomes like this. Preferably it is 0.05-5 Pa.s. Especially preferably, it is 0.05-2.0 Pa*s. When a viscosity is high, a subject arises in fluidity|liquidity, and there exists a possibility that a problem may arise in the flow property at the time of press and embedding property. When it is less than 0.05 Pa·s, heat resistance may be insufficient because the molecular weight is too small.

The ratio of (a) and (b) in the formula (1) is (a)/(b) = 1 to 3. That is, more than half of it is characterized in that it is a glycidyl ether group having a resorcin structure. This ratio is important for precipitation of crystals and improvement of heat resistance, and (a)/(b) preferably exceeds 1. In addition, when (a)/(b) is 3 or less, the absorption rate and toughness can be improved by limiting the amount of the glycidyl ether having a resorcin structure.

In said formula (1), n is a repeating unit, and it is 0-5. When n does not exceed 5, the flow property and fluidity|liquidity at the time of setting it as a prepreg or a resin sheet are controlled. When this exceeds 5, a subject arises not only in fluidity|liquidity but solubility with respect to a solvent.

For the epoxy resin used in the present invention, solubility in a solvent becomes important. When a biphenyl aralkyl type epoxy resin having the same skeleton is used together, these resins also need solubility in solvents such as methyl ethyl ketone, toluene, and propylene glycol monomethyl ether.

In particular, solubility in methyl ethyl ketone is important, and it is required that crystals do not precipitate for 2 months or more at 5°C and room temperature. Although it is concerned also with the ratio of (a)/(b) mentioned above, since it will become easy to produce a crystal|crystallization when the value of (a) is large, it becomes important that (a)/(b) is 1 or more.

Examples of the curing agent that can be used in the epoxy resin composition of the present invention include an amine curing agent, an acid anhydride curing agent, an amide curing agent, and a phenol curing agent. Among them, the amine-based curing agent is preferable because it can achieve both low linear expansion of the epoxy resin composition and heat resistance of the cured resin in a good balance.

As an amine curing agent preferably contained in the present invention, diaminodiphenylmethane, diaminodiphenylsulfone, isophoronediamine, naphthalenediamine, aniline novolac, orthoethylaniline novolac, or aniline by reaction of xylylene chloride The obtained aniline resin, aniline and substituted biphenyls (4,4'-bis(chloromethyl)-1,1'-biphenyl and 4,4'-bis(methoxymethyl)-1,1'-biphenyl, etc.) ), or by polycondensation of substituted phenyls (1,4-bis(chloromethyl)benzene, 1,4-bis(methoxymethyl)benzene, 1,4-bis(hydroxymethyl)benzene, etc.) Although aniline resin etc. are mentioned, It is not limited to these.

In particular, from the viewpoint of toughness and heat resistance, aromatic amine compounds are preferable, and among them, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, aniline novolac, orthoethylaniline novolac, aniline Aniline resin obtained by reaction of xylylene chloride with aniline and substituted biphenyls (4,4'-bis(chloromethyl)-1,1'-biphenyl and 4,4'-bis(methoxymethyl)) -1,1'-biphenyl, etc.), or substituted phenyls (1,4-bis(chloromethyl)benzene, 1,4-bis(methoxymethyl)benzene, and 1,4-bis(hydroxymethyl)benzene The aniline resin obtained by polycondensation such as etc.) has high strength against sagging and stress, can improve the elastic modulus at high temperature from its crosslinking density, and is preferable from the viewpoint of improving the strength as a CFRP, and It is preferable from the point of heat resistance.

In addition, examples of curing agents that may be contained are given.

Examples of the acid anhydride curing agent include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride and methylhexahydrophthalic anhydride. can be heard

As an amide type hardening|curing agent, the polyamide resin synthesize|combined from dicyandiamide, or the dimer of linolenic acid, and ethylenediamine, etc. are mentioned.

Examples of the phenolic curing agent include polyhydric phenols (bisphenol A, bisphenol F, bisphenol S, fluorene bisphenol, terpene diphenol, 4,4'-dihydroxybiphenyl, 2,2'-dihydroxybiphenyl, 3,3 ',5,5'-tetramethyl-(1,1'-biphenyl)-4,4'-diol, hydroquinone, resorcin, naphthalenediol, tris-(4-hydroxyphenyl)methane and 1,1 ,2,2-tetrakis(4-hydroxyphenyl)ethane, etc.); Phenols (for example, phenol, alkyl-substituted phenol, naphthol, alkyl-substituted naphthol, dihydroxybenzene, dihydroxynaphthalene, etc.) and aldehydes (formaldehyde, acetaldehyde, benzaldehyde, p-hydroxybenzaldehyde, o-hydroxy phenol resins obtained by condensation of hydroxybenzaldehyde and furfural), ketones (such as p-hydroxyacetophenone and o-hydroxyacetophenone), or dienes (such as dicyclopentadiene and tricyclopentadiene); The phenols and substituted biphenyls (4,4'-bis(chloromethyl)-1,1'-biphenyl and 4,4'-bis(methoxymethyl)-1,1'-biphenyl, etc.); Or a phenol resin obtained by polycondensation of substituted phenyls (1,4-bis(chloromethyl)benzene, 1,4-bis(methoxymethyl)benzene, 1,4-bis(hydroxymethyl)benzene, etc.) ; modified products of the phenols and/or the phenol resins; Halogenated phenols, such as tetrabromobisphenol A and a brominated phenol resin, are mentioned.

Examples of other imidazole curing agents include BF ₃ -amine complexes and guanidine derivatives.

In the epoxy resin composition of the present invention, the amount of the curing agent to be used is preferably 0.7 to 1.2 equivalents with respect to 1 equivalent of the epoxy groups of the epoxy resin. When the amount is less than 0.7 equivalent to 1 equivalent of the epoxy group, or when it exceeds 1.2 equivalent, curing may be incomplete and good curing properties may not be obtained.

Moreover, in the epoxy resin composition of this invention, you may mix|blend a hardening accelerator as needed. The gelation time can also be adjusted by using a hardening accelerator. Examples of the curing accelerator that can be used include imidazoles such as 2-methylimidazole, 2-ethylimidazole and 2-ethyl-4-methylimidazole, 2-(dimethylaminomethyl)phenol, 1,8- tertiary amines such as diaza-bicyclo[5.4.0]undecene-7, phosphines such as triphenylphosphine, and metal compounds such as tin octylate. The curing accelerator is used as needed in an amount of 0.01 to 5.0 parts by weight based on 100 parts by weight of the epoxy resin.

The epoxy resin composition of this invention WHEREIN: The epoxy resin represented by the said General formula (1) may mix|blend another epoxy resin individually, and may use it together in 2 or more types. Specific examples of other epoxy resins that can be used in combination with the epoxy resin of the general formula (1) include phenols (phenol, alkyl substituted phenol, aromatic substituted phenol, naphthol, alkyl substituted naphthol, dihydroxybenzene, alkyl substituted dihydroxybenzene, Dihydroxynaphthalene, etc.) and various aldehydes (formaldehyde, acetaldehyde, alkylaldehyde, benzaldehyde, alkyl-substituted benzaldehyde, hydroxybenzaldehyde, naphthoaldehyde, glutaraldehyde, phthalaldehyde, crotonaldehyde, cinnamaldehyde, etc.) , phenols and various diene compounds (dicyclopentadiene, terpenes, vinylcyclohexene, norbornadiene, vinylnorbornene, tetrahydroindene, divinylbenzene, divinylbiphenyl, diisopropenylbiphenyl, butadiene , isoprene, etc.), polycondensates of phenols and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, benzophenone, etc.), phenols and substituted biphenyls (4,4'-bis (chloromethyl) -1,1'-biphenyl and 4,4'-bis(methoxymethyl)-1,1'-biphenyl, etc.), or substituted phenyls (1,4-bis(chloromethyl)benzene, 1,4 -Phenolic resins obtained by polycondensation of bis(methoxymethyl)benzene and 1,4-bis(hydroxymethyl)benzene, etc.), polycondensates of bisphenols and various aldehydes, glycidylated alcohols, etc. Diyl ether epoxy resins, alicyclic epoxy resins such as 4-vinyl-1-cyclohexene diepoxide and 3,4-epoxycyclohexylmethyl-3,4'-epoxycyclohexanecarboxylate, tetraglycidyl Examples of diaminodiphenylmethane (TGDDM), triglycidyl-p-aminophenol, etc. are glycidylamine-based epoxy resins and glycidyl ester-based epoxy resins. is not limited to

When using together with another epoxy resin, 30 weight% or more is preferable, and, as for the ratio which occupies in all the epoxy resins of the epoxy resin of the said General formula (1), 40 weight% or more is especially preferable. When the proportion of the epoxy resin of the general formula (1) is less than 30% by weight, physical properties such as high heat resistance, dimensional stability, toughness, and water resistance may not be obtained.

Moreover, a well-known additive can be mix|blended with the epoxy resin composition of this invention as needed. Specific examples of additives that can be used include polybutadiene and its modified products, modified products of acrylonitrile copolymers, polyphenylene ethers, polystyrenes, polyethylenes, polyimides, fluororesins, maleimide compounds, cyanate ester compounds, Silicone gel, silicone oil, and inorganic fillers such as silica, alumina, calcium carbonate, quartz powder, aluminum powder, graphite, talc, clay, iron oxide, titanium oxide, aluminum nitride, asbestos, mica, glass powder, silane coupling agent, etc. Coloring agents, such as a surface treatment agent of a filler, a mold release agent, carbon black, phthalocyanine blue, and phthalocyanine green are mentioned.

Moreover, a well-known maleimide type compound can be mix|blended with the epoxy resin composition of this invention as needed. Specific examples of the maleimide compound that can be used include 4,4'-diphenylmethanebismaleidide, polyphenylmethanemaleimide, m-phenylenemismaleimide, and 2,2'-bis[4-(4-maleimide). Phenoxy) phenyl] propane, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethanebismaleidide, 4-methyl-1,3-phenylenebismaleimide, 4, 4'-diphenyletherbismaleimide, 4,4'-diphenylsulfonebismaleimide, 1,3-bis(3-maleimidephenoxy)benzene, 1,3-bis(4-maleimidephenoxy) Benzene etc. are mentioned, However, It is not limited to these. These may be used independently and may use 2 or more types together. When blending the maleimide-based compound, a curing accelerator is blended as necessary. However, the curing accelerator and radical polymerization initiators such as organic oxides and azo compounds can be used.

An organic solvent can be added to the epoxy resin composition of the present invention to obtain a varnish-shaped composition (hereinafter, simply referred to as varnish). Examples of the solvent used include amides such as γ-butyrolactone, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and N,N-dimethylimidazolidinone. solvents, sulfones such as tetramethylene sulfone, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monomethyl ether monoacetate, and ether type such as propylene glycol monobutyl ether. and ketone solvents such as solvents, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone and cyclohexanone, and aromatic solvents such as toluene and xylene. The solvent can be used in the range where the solid content concentration excluding the solvent in the obtained varnish is usually 10 to 80% by weight, preferably 20 to 70% by weight.

The resin sheet, prepreg, and carbon fiber reinforced composite material of the present invention will be described.

The epoxy resin composition of this invention may be apply|coated to the single side|surface or both surfaces of a support base material, and you may use it as a resin sheet. As a coating method, for example, a molding method, a method of extruding a resin from a nozzle or a die by a pump or extruder, and adjusting the thickness with a blade, a method of calendering with a roll to label the thickness, spraying using a spray, etc. how to do it, etc. In addition, in the process of forming a layer, you may perform heating in the temperature range which can avoid thermal decomposition of an epoxy resin composition. Moreover, you may perform a rolling process, a grinding process, etc. as needed. Examples of the supporting substrate include porous substrates made of paper, cloth, nonwoven fabric, etc., plastic films or sheets such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, nets, foams, metal foils, and laminates thereof. Suitable thin leaf bodies etc. are mentioned, However, It is not limited to these. The thickness in particular of a support base material is not restrict|limited, It determines suitably according to a use.

The prepreg of this invention can be obtained by heat-melting the epoxy resin composition and/or resin sheet of this invention, making it low-viscosity, and impregnating into a fiber base material.

Moreover, the prepreg of this invention can also be obtained by making a fiber base material impregnate a varnish-shaped epoxy resin composition, and heat-drying. After cutting and laminating the prepreg into a desired shape, the carbon fiber reinforced composite material of the present invention can be obtained by heating and curing the epoxy resin composition while applying pressure to the laminate by a press molding method, autoclave molding method, sheet winding molding method, etc. . Moreover, copper foil and an organic film can also be laminated|stacked at the time of lamination|stacking of a prepreg.

In addition, the molding method of the carbon fiber reinforced composite material of the present invention may be obtained by molding by a known method other than the above method. For example, a carbon fiber base material (usually using a carbon fiber fabric) is cut, laminated, and shaped to produce a preform (preform before impregnation with resin), the preform is placed in a mold, the mold is closed, and the resin is injected After impregnating and curing the preform, the resin transfer molding technology (RTM method) can be used to open the mold and take out the molded product.

In addition, a type of RTM method, for example, the VaRTM method, the SCRIMP (Seeman's Composite Resin Infssion Molding Process) method, and the resin supply tank described in Japanese Patent Publication 2005-527410 is exhausted to a pressure lower than atmospheric pressure, and circulation compression is used. In addition, the CAPRI (Controlled Atmospheric Pressesre Resin Infssion) method, which more appropriately controls the resin injection process, in particular the VaRTM method, by controlling the molding pressure of the milled rice can also be used.

In addition, the film stacking method of sandwiching the fiber base with a resin sheet (film), the method of attaching a powder-shaped resin to the reinforcing fiber base to improve impregnation, and the fluidized bed or fluid slurry method in the process of mixing the resin with the fiber base The molding method used (Powder Impregnated Yarn) and the method of mixing resin fibers to the fiber base can also be used.

Examples of the carbon fibers include carbon fibers such as acrylic, pitch, and rayon, and among them, acrylic carbon fibers with high tensile strength are preferably used. You may mix and use 2 or more types of these fibers. The form of the carbon fibers is not particularly limited, and for example, long fibers aligned in one direction, tows, fabrics, mats, knits, braids, short fibers cut to a length of less than 10 mm, and the like are used. Long fibers as used herein refer to short fibers or fiber bundles that are substantially continuous for 10 mm or more. In addition, the short fiber refers to a fiber bundle cut to a length of less than 10 mm. In particular, an arrangement in which fiber bundles are aligned in a single direction is most suitable for applications requiring high specific strength and specific modulus, but a cross (fabric) arrangement for easy handling is also suitable.

(Example)

Hereinafter, the characteristics of the present invention will be described in more detail with reference to Synthesis Examples and Examples. Materials, processing contents, processing procedures, etc. shown below can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

・Epoxy equivalent

It is measured by the method described in JIS K-7236, and the unit is g/eq.

・Softening point

It measures by the method based on JISK-7234, and a unit is °C.

Synthesis Example 1

In a flask equipped with a thermometer, a cooling tube, and a stirrer, 316 parts of phenol and 158 parts of resorcin were put, and the temperature was raised to 100 ° C. Then, 201 parts of 4,4'-bischloromethylbiphenyl were added in portions over 2 hours, and the copper The reaction was further carried out at the temperature for 5 hours. Thereafter, the temperature was raised to 160°C, and all 4,4'-bischloromethylbiphenyl was reacted. In the meantime, the generated HCl was trapped in an alkali and distilled off. After completion of the reaction, unreacted phenol and unreacted resorcin were distilled off under reduced pressure at 180°C using a rotary evaporator to obtain 266 parts of phenol resin (P-1). The obtained phenol resin (P-1) had a hydroxyl equivalent of 137 g/eq., a softening point of 94°C, an ICI viscosity of 470 mPa·s, and a dihydric phenol introduction ratio of 64%.

Synthesis Example 2

266 parts of the phenol resin (P-1) obtained in Synthesis Example 1, 719 parts of epichlorohydrin, 72 parts of methanol, and 21 parts of water were added while nitrogen purge was performed in a flask equipped with a stirrer, a reflux cooling tube, and a stirring device, It heated up to 75 degreeC. Subsequently, after adding 83 parts of flake-shaped sodium hydroxide in portions over 90 minutes, reaction was further performed at 75 degreeC for 75 minutes. It washed with water after completion|finish of reaction, and solvent, such as excess epichlorohydrin, was distilled off from the organic layer under reduced pressure at 140 degreeC using the rotary evaporator. 750 parts of methyl isobutyl ketone was added to the residue, it melt|dissolved, and it heated up to 75 degreeC. 52 parts of 30% sodium hydroxide aqueous solution is added under stirring, and after reaction for 1 hour, the organic layer is washed with water until the washing water becomes neutral. From the obtained organic layer, methyl isobutyl ketone, etc. 338 parts of epoxy resins (EP1) were obtained by distilling off the solvent of The epoxy equivalent of the obtained epoxy resin (EP1) was 209 g/eq., the softening point was 71 degreeC, the viscosity in 150 degreeC was 370 mPa*s, and the introduction ratio of a divalent glycidyl-substituted phenyl group was 68%.

Example 1, Comparative Example 1

Using the epoxy resin (EP1) obtained in Synthesis Example 2, and a comparative epoxy resin (EP2 Nippon Kayaku Bisphenol A type epoxy resin RE-310S), 1 equivalent of a curing agent in terms of active hydrogen equivalent to the epoxy resin, further curing 1 phr of the catalyst as an accelerator based on the weight of the epoxy resin is diluted with the same amount of methyl ethyl ketone as the epoxy resin, mixed at room temperature, and then applied to polyimide (Upyrex) using a 100 micron applicator, and then applied at 120 ° C. 5 It dried with a hot air dryer while flowing a minute and nitrogen gas, and each resin sheet was obtained. The resin sheet of the present invention using the epoxy resin (EP1) obtained in Synthesis Example 2 had an average film thickness of 32 µm, and the comparative resin sheet using the comparative epoxy resin was semi-solid, and the film thickness could not be measured. The obtained resin sheet of this invention was soluble in tetrahydrofuran, and it confirmed that it was before hardening.

Examples 2 to 4, Comparative Example 2

21 parts of the epoxy resin (EP1) obtained in Synthesis Example 2 and 18 parts of a comparative epoxy resin (EP2 Nippon Kayaku Bisphenol A type epoxy resin RE-310S) were each used, and the curing agent was 1 in the equivalent of active hydrogen to the epoxy resin. The equivalent was stirred while melting at 140°C in an aluminum cup to make it uniform, and 1 phr of the catalyst serving as a curing accelerator was added with respect to the weight of the epoxy resin, stirred, and cooled. Thereby, a resin plate was obtained.

The obtained resin plate was placed in an oven at 180 ° C with an aluminum cup, and heated at 180 ° C for 10 hours as it was, and a molded article of the epoxy resin composition of the present invention and a comparative molded article (curing agent H-1 in Table 2: Meiwa Kasei Kogyo Co., Ltd.) ) phenol novolak resin) was obtained. A sample for evaluation of 2 mm x 10 mm x 5 mm was cut out from the obtained resin plate, and the properties were measured by the following items and methods. The measurement results are shown in Tables 1 and 2.

·Heat resistance, dimensional stability (change rate of linear expansion): TMA (thermomechanical measuring device TA instrument TMA-Q400EM temperature increase rate 2℃/min)

· Modulus of elasticity (DMA)

Dynamic Viscoelasticity Meter : TA-instRsments, DMA-2980

Measurement temperature range: -30 to 280℃

Temperature increase rate: 2℃/min

Test piece size: 5 mm x 50 mm cut out was used

Tg: The peak point of Tan-δ in the DMA measurement was taken as Tg.

From Table 1, when the epoxy resin composition of the present invention is used, it can be confirmed that the dimensional stability is excellent because the change in linear expansion is small compared to the comparative epoxy resin composition.

From Table 2, it can be confirmed that the epoxy resin composition of the present invention is a material having high heat resistance, low water absorption, and high elastic modulus at high temperature, even compared to other curing agents having the same equivalent active hydrogen equivalent. .

Example 5, Comparative Example 3

6.8 parts of the epoxy resin (EP1) obtained in Synthesis Example 2 and 6.5 parts of a comparative epoxy resin (EP2 Nippon Kayaku Bisphenol A type epoxy resin RE-310S) were used, respectively, and the curing agent was 1 in the equivalent of active hydrogen to the epoxy resin. Using 6.7 parts of methyl ethyl ketone (MEK) as an equivalent and a solvent, it stirred in an aluminum cup, and produced the uniform resin varnish so that resin concentration might be 60 weight%. After impregnating the prepared resin varnish with carbon cloth having a thickness of 150 µm and an areal density of 18 pieces/inch, the solvent was volatilized under the drying conditions of Table 3 to prepare prepregs. Subsequently, the prepreg was pre-cured at 175 ° C. for 10 minutes in a hot plate press by applying a load of 10 kg, followed by post-curing at 160 ° C. for 2 hours and 180 ° C. for 6 hours to obtain a carbon fiber reinforced composite material (CFRP). A 4 mm x 16 mm evaluation sample was cut out from the obtained CFRP, and heat resistance was measured by the following method. Table 3 shows the measurement results.

·Heat resistance, dimensional stability (change rate of linear expansion): TMA (thermomechanical measuring device TA instrument TMA-Q400EM temperature increase rate 2℃/min)

From Table 3, the carbon fiber reinforced composite material (CFRP) prepared by combining the epoxy resin composition of the present invention with carbon fibers has a small change in linear expansion compared to CFRP prepared using the comparative epoxy resin composition, so it has excellent dimensional stability. can be checked

Although this invention was demonstrated in detail with reference to the specific form, it is clear for those skilled in the art that various changes and correction are possible without deviating from the mind and range of this invention.

In addition, this application is based on the Japanese patent application filed on August 1, 2014 (Japanese Patent Application No. 2014-157631) and the Japanese Patent Application filed on January 29, 2015 (Japanese Patent Application No. 2015-14980), the The entirety is incorporated by reference. In addition, all references cited herein are incorporated in their entirety.

The carbon fiber reinforced composite material manufactured using the epoxy resin composition of the present invention is lightweight and has excellent resistance to impact from the outside, so the body, main wing, hind wing, rotor, fairing, cowl, door, seat and aircraft members such as interior materials; Space machine members, such as a motor case and a main wing; satellite members such as spheres and antennas; automotive members such as exterior plates, chassis, aerodynamic members and seats; railroad vehicle members such as spheres and seats; It can be suitably used for many structural materials such as ship members such as hulls and seats.

Claims (5)

An epoxy resin and a curing agent represented by the following general formula (1) as essential components,
The epoxy resin composition for carbon fiber reinforced composite materials, wherein the curing agent is an aniline resin obtained by polycondensation of aniline and substituted biphenyls or substituted phenyls.

(Wherein, the molar ratio of (a) (b) is (a)/(b) = 1 to 3. G represents a glycidyl group. n is the number of repeats and is 0 to 5.) The method of claim 1,
An epoxy resin composition for a carbon fiber reinforced composite material formed by further mixing another epoxy resin. A resin sheet formed by applying the epoxy resin composition for a carbon fiber reinforced composite material according to claim 1 or 2 to a supporting substrate. A prepreg obtained by impregnating carbon fibers with the epoxy resin composition for carbon fiber-reinforced composite materials according to claim 1 or 2, or a resin sheet obtained by applying the epoxy resin composition to a supporting substrate. A carbon fiber reinforced composite material obtained by curing the prepreg according to claim 4.

Images