Prepreg

Abstract

The present invention addresses the problem of providing a prepreg that yields a carbon fiber composite material that has exceptional tensile strength, heat resistance, and impact resistance and is suitable as a structural material of an aircraft body, wherein the resin composition used in the prepreg furthermore has exceptional viscosity stability.　A prepreg containing a resin composition that contains carbon fibers and at least the constituent elements [A]–[D] indicated below, wherein: the epoxy resin of constituent element [A] contains [A1] and [A2]; [A1] has an epoxy equivalent of 200-265 g / eq (inclusive), the [A1] content of constituent element [A] being 5–45 parts by mass (inclusive); the [A2] content is 55–95 parts by mass (inclusive); [A2] includes at least [A2-1] and [A2-2]; the ratio [A2-1] / [A2-2] is 0.7–4.0 (inclusive) by mass; and the viscosity increase rate when the resin composition is held for two hours at 80°C is 20% or less. Constituent element [A] is an epoxy resin including [A1] and [A2], constituent element [A1] is a dicyclopentadiene epoxy resin, constituent element [A2] is an epoxy resin containing [A2-1] and [A2-2], constituent element [A2-1] is a tetrafunctional liquid epoxy resin, constituent element [A2-2] is a bifunctional liquid epoxy resin, constituent element [B] is a diaminodiphenyl sulfone, constituent element [C] is a polyether sulfone, and constituent element [D] is aspherical polymer particles.

Description

[Technical field]

[0001] The present invention relates to a prepreg for producing a carbon fiber composite material excellent in tensile strength, heat resistance and impact resistance, and further relates to a prepreg in which the resin composition used therefor has excellent viscosity stability. [Background technology]

[0002] Traditionally, fiber-reinforced composite materials consisting of reinforcing fibers and matrix resins have been applied to many fields such as aerospace, automobiles, railway vehicles, ships, civil engineering and construction, and sporting goods because they are lightweight and have excellent mechanical properties such as strength and rigidity, heat resistance, and corrosion resistance. In particular, fiber-reinforced composite materials using continuous reinforcing fibers are used in applications that require high heat resistance. Carbon fibers with excellent specific strength and specific elastic modulus are used as the reinforcing fibers, and thermosetting resins, especially epoxy resins with good adhesion to carbon fibers, heat resistance, elastic modulus, and small cure shrinkage, are often used as the matrix resin. In recent years, as the use of carbon fiber reinforced composite materials (hereinafter abbreviated as CFRP) increases, the required properties are becoming stricter.

[0003] In particular, when applied to aerospace applications and structural materials for vehicles, etc., it is required that physical properties are sufficiently maintained even under high temperature conditions. In order to exhibit physical properties even under high temperature conditions, it is necessary to improve the heat resistance of the epoxy resin, which is the matrix resin, and to improve the heat resistance of the epoxy resin, it is necessary to increase the crosslink density.

[0004] On the other hand, increasing the crosslink density tends to decrease the elongation of the epoxy resin. It is known that in CFRP, if the tensile breaking elongation of the matrix resin decreases, the tensile strength utilization rate of the matrix resin decreases, and the excellent specific strength of CFRP may not be fully utilized. For these reasons, various epoxy resin modification technologies have been proposed to achieve both the heat resistance and strength of CFRP.

[0005] As a method for reducing the crosslink density of an epoxy resin and improving its heat resistance, it is considered to introduce a rigid structure that reduces the degree of freedom of the molecular chain in the main chain of the epoxy resin, and it is effective to use a compound having an aromatic rigid skeleton. For example, Patent Document 1 proposes a resin composition that combines an epoxy resin having a naphthalene skeleton as a rigid skeleton, but it is a resin composition for electronic substrates, and the mechanical properties, moist heat resistance, etc. are not designed for structural materials. In addition, Patent Document 2 uses a bisnaphthalene type epoxy resin with three or more functionalities for structural materials, but the reduction in crosslink density is insufficient. On the other hand, Patent Document 3 describes the use of an epoxy resin having a dicyclopentadiene skeleton, but there is a problem of low heat resistance. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2009-263550 A [Patent Document 2] JP 2014-145017 A [Patent Document 3] JP 2010-202727 A Summary of the Invention [Problem to be solved by the invention]

[0007] In view of the above background art, the present invention provides a prepreg which provides a carbon fiber composite material excellent in tensile strength, heat resistance and impact resistance and which is suitable as a structural material for aircraft bodies, and which further provides a prepreg which provides excellent viscosity stability of a resin composition used therein. [Means for solving the problem]

[0008] The present invention employs the following means to solve the above problems. That is, in a prepreg containing carbon fibers and a resin composition containing at least the following components [A] to [D], the epoxy resin of the component [A] contains [A1] and [A2], the [A1] has an epoxy equivalent of 200 g / eq or more and 265 g / eq or less, the content of the [A1] is 5 parts by mass or more and 45 parts by mass or less, the content of the [A2] is 55 parts by mass or more and 95 parts by mass or less, the [A2] contains at least [A2-1] and [A2-2], the mass ratio [A2-1] / [A2-2] is 0.7 or more and 4.0 or less, and the viscosity increase rate of the resin composition when kept at 80° C. for 2 hours is 20% or less. [A]: Epoxy resin containing [A1] and [A2] [A1]: Dicyclopentadiene type epoxy resin [A2]: Epoxy resin containing [A2-1] and [A2-2] [A2-1]: 4-functional liquid epoxy resin [A2-2]: Bifunctional liquid epoxy resin [B]: Diaminodiphenylsulfone [C]: Polyethersulfone [D]: Spherical polymer particles Alternatively, a prepreg obtained by impregnating the following component [E] with a resin composition containing the components [A] to [D-2], wherein, per 100 parts by mass of the component [A], the prepreg contains 45 parts by mass or more and 80 parts by mass or less of [A1] dicyclopentadiene-type epoxy resin having an epoxy equivalent of 200 g / eq or more and 265 g / eq or less, and 10 parts by mass or more and 40 parts by mass or less of [A2-1] tetrafunctional liquid epoxy resin. [A] Epoxy resin [B] Diaminodiphenylsulfone [C] Polyethersulfone [D-2] Thermoplastic resin particles [E] Carbon fiber Alternatively, it is a prepreg comprising carbon fiber and at least the following components [A] to [D], wherein the epoxy resin of the component [A] contains, relative to 100 parts by mass of the total amount of the epoxy resins blended, 2 parts by mass or more and 15 parts by mass or less of [A1], 45 parts by mass or more and 65 parts by mass or less of [A2-1], 15 parts by mass or more and 35 parts by mass or less of [A3], and 0 parts by mass or more and 35 parts by mass or less of [A4], and the epoxy equivalent of [A1] is 200 g / eq or more and 265 g / eq or less. [A]: Epoxy resin containing [A1], [A2-1], [A3], and [A4] [A1]: Dicyclopentadiene type epoxy resin [A2-1]: 4-functional liquid epoxy resin [A3]: Bifunctional glycidylaniline type epoxy resin [A4]: Epoxy resin other than [A1], [A2-1], and [A3] [B]: Diaminodiphenylsulfone [C]: Polyethersulfone [D]: Spherical polymer particles Effect of the Invention

[0009] According to the present invention, it is possible to provide a prepreg that is an intermediate substrate for obtaining a CFRP having excellent tensile strength, heat resistance, and impact resistance, and further to provide a prepreg that has excellent viscosity stability of the resin composition during the manufacturing process of the prepreg and excellent automatic lamination properties of a prepreg tape made of the prepreg. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will now be described in further detail.

[0011] The present invention discloses three types of prepregs that utilize dicyclopentadiene-type epoxy resins. The first prepreg is a prepreg that contains carbon fiber and a resin composition that contains at least the following components [A] to [D], wherein the epoxy resin of the component [A] contains [A1] and [A2], the [A1] has an epoxy equivalent of 200 g / eq or more and 265 g / eq or less and its content is 5 parts by mass or more and 45 parts by mass or less, the [A2] content is 55 parts by mass or more and 95 parts by mass or less, the [A2] contains at least [A2-1] and [A2-2], the mass ratio [A2-1] / [A2-2] is 0.7 or more and 4.0 or less, and the viscosity increase rate when the resin composition is kept at 80° C. for 2 hours is 20% or less. [A]: Epoxy resin containing [A1] and [A2] [A1]: Dicyclopentadiene type epoxy resin [A2]: Epoxy resin containing [A2-1] and [A2-2] [A2-1]: 4-functional liquid epoxy resin [A2-2]: Bifunctional liquid epoxy resin [B]: Diaminodiphenylsulfone [C]: Polyethersulfone [D]: spherical polymer particles.

[0012] Hereinafter, a resin composition containing at least the components [A] to [D] may be simply referred to as a "resin composition".

[0013] The component [A] in the present invention is an epoxy resin, which is the basis of the mechanical properties of CFRP and the handleability of prepreg. The epoxy resin in the present invention means a compound having one or more epoxy groups in one molecule.

[0014] The dicyclopentadiene-type epoxy resin, which is the component [A1] used in the present invention, refers to an epoxy resin having a dicyclopentadiene skeleton represented by the following structural formula (1), either alone or in admixture.

[0015] [ka]

[0016] In the structural formula (1) contained in the dicyclopentadiene-type epoxy resin of the component [A1], n is not particularly limited as long as it has the epoxy equivalent described below, but it is preferable to use one in which n is an integer of 1 to 6. In addition, n may contain 0 as an impurity.

[0017] By using a dicyclopentadiene-type epoxy resin having an epoxy equivalent of 200 g / eq or more and 265 g / eq or less as the component [A1] used in the present invention, it is possible to reduce the crosslink density of the cured resin composition while achieving high heat resistance. This is believed to be due to the rigidity of the dicyclopentadiene skeleton.

[0018] In the present invention, when the content of the dicyclopentadiene type epoxy resin, which is the component [A1], is 5 parts by mass or more and 45 parts by mass or less in 100 parts by mass of the epoxy resin, which is the component [A], mechanical properties such as tensile strength can be improved. The upper limit of the content of the dicyclopentadiene type epoxy resin, which is the component [A1], is more preferably 45 parts by mass or less in 100 parts by mass of the epoxy resin, which is the component [A].

[0019] When the content of the dicyclopentadiene type epoxy resin as the component [A1] is 25 parts by mass or more, the tensile strength of the obtained CFRP is improved and the mode I interlaminar toughness (G IC), impact resistance, and heat resistance can be balanced, which is preferable. In addition, by setting the epoxy equivalent of the dicyclopentadiene-type epoxy resin as the component [A1] to 265 g / eq or less, the compatibility with the component [C] polyethersulfone (hereinafter abbreviated as PES) used in combination is improved, and the content of the dicyclopentadiene-type epoxy resin as the component [A1] can be easily increased, which is advantageous for improving the mechanical properties as described above. The epoxy equivalent of the dicyclopentadiene-type epoxy resin is preferably 253 g / eq or less. On the other hand, by setting the epoxy equivalent of the dicyclopentadiene-type epoxy resin as the component [A1] to 200 g / eq or more, the heat resistance of the cured product can be improved.

[0020] Commercially available dicyclopentadiene-type epoxy resins, which are the component [A1] in the present invention, include "EPICLON" HP-7200L (epoxy equivalent: 245 g / eq to 252 g / eq, softening point: 50 to 60° C.), "EPICLON" HP-7200 (epoxy equivalent: 254 g / eq to 264 g / eq, softening point: 56 to 58° C.) (both manufactured by DIC Corporation), XD-10 Examples of such epoxy resins include XD-1000-L (epoxy equivalent 240 g / eq to 255 g / eq, softening point 60 to 70° C.), XD-1000-2L (epoxy equivalent 235 g / eq to 250 g / eq, softening point 53 to 63° C.) (all manufactured by Nippon Kayaku Co., Ltd.), and “Tactix” 556 (epoxy equivalent 215 g / eq to 235 g / eq, softening point 79° C.) (manufactured by Huntsman).

[0021] The component [A2] used in the present invention contains a tetrafunctional liquid epoxy resin [A2-1] and a difunctional liquid epoxy resin [A2-2]. When the content of [A2] is 55 parts by mass or more and 95 parts by mass or less in 100 parts by mass of the epoxy resin of the component [A], a balance can be achieved between the mechanical properties of the CFRP obtained by molding the prepreg of the present invention and the handleability of the prepreg.

[0022] [A2-1] A tetrafunctional liquid epoxy resin is one that contains four or more epoxy groups in one epoxy resin molecule and is liquid at 23°C, and is typically a glycidylamine type epoxy resin. For example, tetraglycidyldiaminodiphenylmethane and its halogen-substituted, alkyl-substituted, aralkyl-substituted, and hydrogenated products can be used. Examples of commercially available products include "Sumiepoxy" ELM434 (manufactured by Sumitomo Chemical Co., Ltd.), "Araldite" MY720, "Araldite" MY721, "Araldite" MY9512, "Araldite" MY9663 (all manufactured by Huntsman Advanced Materials Co., Ltd.), and "Epotohto" YH-434 (manufactured by Tohto Kasei Co., Ltd.).

[0023] [A2-2] The bifunctional liquid epoxy resin is an epoxy resin that contains two epoxy groups in the molecule and is liquid at 23° C., and examples of such resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, and glycidylaniline type epoxy resins. Commercially available glycidylaniline type epoxy resins include GAN (N,N-diglycidylaniline) (manufactured by Nippon Kayaku Co., Ltd.), GOT (N,N-diglycidyl-o-toluidine) (manufactured by Nippon Kayaku Co., Ltd.), and the like.

[0024] As for the mass ratio of [A2-1] and [A2-2], when [A2-1] / [A2-2] is 0.7 or more and 4.0 or less, the heat resistance of the CFRP and mechanical properties such as tensile strength can be balanced. When heat resistance is important, [A2-1] / [A2-2] is preferably 2.0 or more and 4.0 or less, and when tensile strength is important, [A2-1] / [A2-2] is more preferably 0.7 or more and less than 2.0. In addition, when [A2-1] / [A2-2] is 0.7 or more and less than 2.0, the storage modulus G' of the resin composition at room temperature can be reduced, so that it is more preferable from the viewpoint of easily improving the shape conformability at room temperature of the obtained prepreg, that is, the softness. In particular, the use of a glycidyl aniline type epoxy resin is preferable because it improves the softness of the prepreg at room temperature while also improving the tensile strength of the resulting CFRP. In this case, it is also preferable to set [A2-1] / [A2-2] to 2.0 or more, which makes it possible to simultaneously improve the heat resistance.

[0025] Of course, in the epoxy resin composition of the present invention, the epoxy resin which is the component [A] may contain epoxy resins other than the components [A1] and [A2].

[0026] Diaminodiphenylsulfone (hereinafter abbreviated as DDS) is used as the component [B] used in the present invention. DDS is used as a curing agent for the epoxy resin of the component [A]. Examples of DDS include 4,4'-diaminodiphenylsulfone (4,4'-DDS) and 3,3'-diaminodiphenylsulfone (3,3'-DDS). 4,4'-DDS has a lower reaction activity than 3,3'-DDS, so it can improve the stability of the resin composition during the prepreg production process. On the other hand, 3,3'-DDS can improve the elastic modulus of the cured product, and can improve the elastic modulus and compressive strength of CFRP.

[0027] In the present invention, the content of DDS, which is the component [B], is determined based on the total active hydrogen number (H B ) to the total number of epoxy groups (E) in the component [A] epoxy resin, so-called H B / E. H B If / E is 0.7 or more, a sufficient degree of curing can be obtained, and the heat resistance of the cured product can be improved, which is preferable. B If / E is 1.3 or less, the unreacted portion of the curing agent can be reduced, and the heat resistance can be improved, which is preferable. For example, take an epoxy resin [A] containing 40 parts by mass of HP-7200L as the component [A1], 30 parts by mass of ELM434 as the component [A2], and 30 parts by mass of EPICLON830 as an epoxy resin other than the components [A1] and [A2], and explain it as an example. B When / E=0.7, the glass transition temperature of the cured resin is about 185°C, and H B When / E=1.0, the glass transition temperature is about 190°C, and H B When the DDS content is H B When / E=0.6, the resin cured product is brittle and a uniform resin plate cannot be obtained. B When / E=1.4, the glass transition temperature is less than 170° C., and the heat resistance is low.

[0028] In the present invention, a curing agent other than DDS may be used. For example, a hydrazide-based curing agent can be exemplified as a secondary curing agent that shortens the curing time of the resin composition, and among them, isophthalic dihydrazide (hereinafter abbreviated as IDH) is preferable because it has an appropriate reaction initiation temperature in the molding process of prepregs for structural materials. IDH initiates reaction with epoxy groups at a lower temperature than DDS, so it is possible to shorten the curing time and increase the efficiency of CFRP production. Here, the content of IDH is determined by the total number of active hydrogens in the IDH (H F ) to the total number of epoxy groups (E) in the component [A] epoxy resin, so-called H F / E. H F It is preferable that / E is 0.05 or more since the effect of shortening the curing time can be obtained. FA ratio / E of 0.3 or less is preferable since it is possible to balance the effect of shortening the curing time and heat resistance. The addition of IDH can also shorten the time until the resin composition gels during the curing process. Therefore, the addition of IDH can control the resin flow during curing and improve the quality of the obtained CFRP. An example of a commercially available hydrazide curing agent is IDH-S (manufactured by Otsuka Chemical Co., Ltd.).

[0029] In the present invention, a curing accelerator may be contained within a range that does not impair the heat resistance and thermal stability of the resin composition. Examples of the curing accelerator include tertiary amines, Lewis acid complexes, onium salts, imidazole compounds, urea compounds, hydrazide compounds, and sulfonium salts. The content of the curing accelerator needs to be appropriately adjusted depending on the type used, but is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, relative to 100 parts by mass of the total epoxy resin. When the curing accelerator is contained within this range, it is preferable because temperature unevenness is less likely to occur when molding CFRP.

[0030] The component [C] used in the present invention is polyethersulfone (hereinafter, sometimes referred to as PES). PES has an ether bond and a sulfone bond in the main chain, and is effective in controlling the tackiness of the prepreg, controlling the fluidity of the matrix resin when the prepreg is heat-cured, and preventing the heat resistance and elastic modulus of the obtained CFRP from being impaired, and improving the tensile strength, impact resistance, and mode I interlaminar toughness (G IC) is contained for the purpose of imparting a certain degree of mechanical properties such as tensile strength, mode I interlaminar toughness, and impact resistance of the CFRP obtained by molding the prepreg of the present invention. When the weight average molecular weight of PES is 10,000 g / mol or more, it is preferable because it can improve the mechanical properties such as tensile strength, mode I interlaminar toughness, and impact resistance of the CFRP obtained by molding the prepreg of the present invention. The weight average molecular weight here is measured by gel permeation chromatography (hereinafter abbreviated as GPC) and is the weight average molecular weight converted into polystyrene. On the other hand, when the weight average molecular weight of PES is 30,000 g / mol or less, it is preferable because it can improve the compatibility of PES with the dicyclopentadiene type epoxy resin, which is an important component of the present invention, and improve the process stability in the production of the resin composition, the formation of a resin film, and the formation of a prepreg. In addition, by making the weight average molecular weight 30,000 g / mol or less, it is possible to increase the contents of dicyclopentadiene type epoxy resin and PES. The compatibility of PES with epoxy resin means that a homogeneous phase is formed by mixing PES with epoxy resin and heating and stirring it. Forming a homogeneous phase means that no phase separation is visible to the naked eye. In addition, improved compatibility also suppresses the formation of a phase-separated structure between epoxy resin and PES during the curing process, resulting in CFRP of consistent quality regardless of the curing conditions. Furthermore, the range of possible curing conditions is broadened, and structural differences between parts can be suppressed even when molding thick objects, improving quality stability.

[0031] The content of PES is preferably 2 parts by mass or more relative to 100 parts by mass of the epoxy resin, which is the component [A], since it can improve the mechanical properties such as tensile strength, impact resistance, and mode I interlaminar toughness of the CFRP. On the other hand, it is preferable to set the content of PES to 18 parts by mass or less, since it can suppress the epoxy resin composition from becoming highly viscous, and it can improve the process stability in the production of the resin composition, the resin film formation, and the prepreg formation. It is also preferable in terms of the handling properties of the prepreg, such as tackiness. In addition, if the content of PES is 2 parts by mass or more and 18 parts by mass or less, the higher the content within that range, the more excellent the tensile strength, impact resistance, and mode I interlaminar toughness of the CFRP will be.

[0032] Commercially available PES products, which are the component [C] in the present invention, include "Virantage" VW-10700RFP (weight average molecular weight: 21,000 g / mol) and "Virantage" VW-10200RFP (weight average molecular weight: 46,500 g / mol) (both manufactured by Solvay Advanced Polymers, Ltd.), and "Sumikaexcel" PES5003P (manufactured by Sumitomo Chemical Co., Ltd.) which has a weight average molecular weight similar to that of "Virantage" VW-10200RFP.

[0033] The component [D] of the present invention is a spherical polymer particle. By containing the spherical polymer particle, when the CFRP is made, the impact resistance can be improved in particular. The polymer used for the spherical polymer particle used in the present invention is not particularly limited as long as the effect of the present invention can be obtained, but considering that it gives stable adhesive strength and impact resistance when made into a CFRP for structural materials, further ensures resistance to moist heat and chemicals, and also applies a general prepreg molding method (which may be as high as about 180°C), polyamide, polyethersulfone, polyetherimide, polyamideimide, polyimide, and polyphenylene ether are preferred. Among polyamides, polyamide 12, polyamide 11, polyamide 6, polyamide 66, and polyamide 6 / 12 copolymers, such as semi-IPN (polymer interpenetrating network structure) polyamides (semi-IPN polyamides) exemplified in Example 1 of JP-A-1-104624, are more preferred.

[0034] By making the polymer particles spherical, it is possible to obtain a CFRP with high impact resistance. In the present invention, the term "spherical" means that the sphericity, as defined below, is in the range of 90 to 100. The sphericity is determined by observing 30 particles randomly from a scanning electron microscope photograph, and using their short diameter and long diameter according to the following formula.

[0035]

number

[0036] In addition, S: sphericity, a: major axis, b: minor axis, and n: number of measurements (30). Commercially available spherical polymer particles include polyamide-based SP-500 and SP-10 (manufactured by Toray Industries, Inc.), polymethyl methacrylate-based MBX series such as MBX-12 and SSX series such as SSX-115 (manufactured by Sekisui Chemical Co., Ltd.), polystyrene-based SBX series such as SBX-12 (manufactured by Sekisui Chemical Co., Ltd.), and copolymers thereof such as MSX and SMX (manufactured by Sekisui Chemical Co., Ltd.), polyurethane-based Dimic Beads CM series, cellulose acetate-based BELLOCEA (manufactured by Daicel Corporation), and phenolic resin-based Marilyn (manufactured by Gun-ei Chemical Co., Ltd.). Further examples of spherical particles made of polyamide and its copolymers include polyamide-based particles described in Example 1 of JP-A-1-104624 and polyamide-based particles described in WO2018 / 207728 pamphlet. In addition, examples of the polyethersulfone-based spherical particles include those described in JP 2017-197665 A. Among them, the polyamide-based particles described in Example 1 of JP 1-104624 A are excellent in wet heat resistance, chemical resistance, etc., and are also excellent in the impact resistance development effect when made into CFRP, and are more preferable. The particle size of the spherical polymer particles is preferably 5 μm or more and 45 μm or less in terms of the mode diameter determined by the light scattering method. By setting it in this range, stable impact resistance can be imparted when made into CFRP. The particle size measurement can be performed by applying the light scattering method, for example, using Partica LA-950V2 manufactured by Horiba Ltd. or MT3300II manufactured by Microtrack Co., Ltd.

[0037] The resin composition of the present invention has a viscosity increase rate of 20% or less when kept at 80°C for 2 hours, and therefore has excellent viscosity stability in the prepreg production process, particularly in the process of forming the resin composition into a film, and has excellent unit weight stability, uniformity, and process stability of the resin composition film. It is more preferable that the viscosity increase rate is 10% or less. In order to reduce the viscosity increase rate when kept at 80°C for 2 hours, it is preferable to reduce the reactivity of the resin composition at 80°C, and from this point of view, it is preferable to use 4,4'-DDS as the curing agent rather than 3,3'-DDS. Also, from this point of view, in the epoxy resin used in the present invention, the epoxy resin to be combined with the dicyclopentadiene type epoxy resin and the tetrafunctional type epoxy resin is selected as a bifunctional liquid epoxy resin rather than a highly reactive triglycidylaminophenol type epoxy resin, and it is particularly preferable to use a bisphenol type epoxy resin.

[0038] The second prepreg of the present invention is a prepreg obtained by impregnating the following component [E] with a resin composition containing the components [A] to [D-2], and the prepreg contains, per 100 parts by mass of the component [A], 45 parts by mass or more and 80 parts by mass or less of [A1] dicyclopentadiene-type epoxy resin having an epoxy equivalent of 200 g / eq or more and 265 g / eq or less, and 10 parts by mass or more and 40 parts by mass or less of [A2-1] tetrafunctional liquid epoxy resin. [A] Epoxy resin [B] Diaminodiphenylsulfone [C] Polyethersulfone [D-2] Thermoplastic resin particles [E] Carbon fiber The second prepreg of the present invention is a prepreg obtained by impregnating the following component [E] with an epoxy resin composition containing the components [A] to [D-2], and the prepreg contains, per 100 parts by mass of the component [A], 45 parts by mass or more and 80 parts by mass or less of [A1] dicyclopentadiene-type epoxy resin having an epoxy equivalent of 200 g / eq or more and 265 g / eq or less, and 10 parts by mass or more and 40 parts by mass or less of [A2-1] tetrafunctional liquid epoxy resin. [A] Epoxy resin [B] Diaminodiphenylsulfone [C] Polyethersulfone [D-2] Thermoplastic resin particles [E] Carbon fiber It is preferable that:

[0039] The second prepreg is characterized by the fact that it contains a large amount of dicyclopentadiene-type epoxy resin, between 45 and 80 parts by mass. This makes it possible to improve the mechanical properties in a low-temperature environment, such as the tensile strength at -60°C. When the content of dicyclopentadiene-type epoxy resin is between 45 and 60 parts by mass, the tensile strength and mode I interlaminar toughness (G IC ) and heat resistance can be balanced, which is preferable. From this viewpoint, the content of the dicyclopentadiene type epoxy resin is also preferably 22 mass% or more and 55 mass% or less with respect to the total mass of the resin composition. The epoxy equivalent of the dicyclopentadiene type epoxy resin can be set in the same manner as in the first invention.

[0040] The component [A2-1] used in the second prepreg is a tetrafunctional liquid epoxy resin, which is the same as the [A2-1] in the first prepreg. The content is 10 to 40 parts by mass, preferably 10 to 30 parts by mass, per 100 parts by mass of the epoxy resin in the component [A]. By setting the content of the component [A2-1] in this range, the heat resistance and tensile strength of the obtained CFRP can be well balanced.

[0041] In the resin composition used for the second prepreg, the epoxy resin of component [A] can contain an epoxy resin other than the components [A1] and [A2-1]. Such an epoxy resin is not particularly limited, and examples of the epoxy resin that can be used include bisphenol A type epoxy resin, bisphenol F type epoxy resin, aminophenol type epoxy resin, and glycidyl aniline type epoxy resin.

[0042] The other components [B] and [C] of the second prepreg are the same as those of the first prepreg. By blending the thermoplastic resin particles of the component [D-2], when the CFRP is made, the interlaminar toughness of mode II in particular can be improved, and the impact resistance can be improved. The thermoplastic resin used for the thermoplastic resin particles used in the present invention is not particularly limited as long as the effects of the present invention can be obtained, but it is preferable that the resin maintains its shape in the resin composition from the viewpoint of providing stable adhesive strength and impact resistance when made into a CFRP. Among them, polyamide, polyetherimide, polyamideimide, and polyphenylene ether are preferable. Among polyamides, polyamide 12, polyamide 11, polyamide 6, polyamide 66, polyamide 6 / 12 copolymer, polyamide (semi-IPN polyamide) formed in a semi-IPN (polymer interpenetrating network structure) in an epoxy compound described in Example 1 of JP-A-1-104624 can be preferably used. The shape of the thermoplastic resin particles may be spherical or non-spherical, or may be porous, but a spherical shape is preferred because it does not reduce the flow characteristics of the resin, has excellent viscoelasticity, has no starting point of stress concentration, and provides high impact resistance. In particular, when using spherical polymer particles, the same as the first prepreg can be used. Although not spherical, "Orgasol (registered trademark)" 1002D, 2001UD, 2001EXD, 2002D, 3202D, 3501D, 3502D (all manufactured by Arkema Co., Ltd.), "Grilamid (registered trademark)" TR90 (manufactured by Ms. Welke Co., Ltd.), "TROGAMID (registered trademark)" CX7323, CX9701, CX9704, (manufactured by Degussa Co., Ltd.), etc. can be used. These thermoplastic resin particles may be used alone or in combination. Commercially available polyetherimide products include "Ultem (registered trademark)" 1000, "Ultem (registered trademark)" 1010, and "Ultem (registered trademark)" 1040 (all manufactured by Solvay Advanced Polymers, Inc.).

[0043] The CFRP obtained by molding the second prepreg has excellent tensile strength properties, heat resistance, and mode I interlaminar toughness at room temperature and in low temperature environments.

[0044] Such tensile strength characteristics can be evaluated by 0° tensile strength measurement. As described in JIS K7017 (1999), the 0° of CFRP is defined as the axial direction of the fiber direction of a unidirectional fiber-reinforced composite material, the 0° axis, and the 90° direction perpendicular to the axis. In accordance with the JIS K7073 (1988) standard, a 0° tensile test is performed at two measurement temperatures, room temperature (23°C) and low temperature (-60°C), and the strength retention, which is the ratio of the tensile strength in a low-temperature environment to that in a room-temperature environment, is calculated from the following formula. Strength retention (%) = tensile strength (low temperature environment) / tensile strength (room temperature environment) x 100.

[0045] The strength retention of the tensile strength of the CFRP obtained from the second prepreg is preferably 90% or more and 110% or less, and more preferably 95% or more and 110% or less. By setting the strength retention in this range, the difference between the strength in a low-temperature (-60°C) environment in which an aircraft body is used and the strength at around room temperature is small, and the mechanical properties at low temperatures are excellent.

[0046] Such mode I interlaminar toughness (G IC ) can be calculated according to JIS K7086 (1993), and G IC is 350 J / m 2 This is preferable because it broadens the range of structural members of aircraft and the like that can be applied. The third prepreg of the present invention is characterized by using a dicyclopentadiene type epoxy resin [A1] and a bifunctional glycidylaniline type epoxy resin [A3] in combination. The dicyclopentadiene type epoxy resin can be the same as that used in the first and second prepregs. As described above, the dicyclopentadiene type epoxy resin is advantageous in improving the tensile strength of CFRP, but on the other hand, it is often a so-called solid epoxy resin with a softening point of 50°C or more, and there are cases where there are limitations in the viscoelasticity control of the resin composition or prepreg near room temperature. More specifically, in the automatic lamination process using prepreg tape, which has become popular in recent years as described later, if the storage modulus (G') of the resin composition is too high, splice failure of the prepreg tape, transport failure of the prepreg tape in the yarn path inside the automatic lamination machine, tape splice coming off, and lamination failure may occur easily, but the G' of the resin composition near room temperature is likely to be high with a solid epoxy resin. For this reason, even if the amount of dicyclopentadiene-type epoxy resin is reduced, a bifunctional glycidylaniline-type epoxy resin is used in combination to maintain high tensile strength of CFRP. Furthermore, bifunctional glycidylaniline-type epoxy resins are often liquid at around room temperature, and are suitable for controlling viscoelasticity at around room temperature. Examples of commercially available bifunctional glycidylaniline-type epoxy resins include GAN (N,N-diglycidylaniline) (manufactured by Nippon Kayaku Co., Ltd.) and GOT (N,N-diglycidyl-o-toluidine) (manufactured by Nippon Kayaku Co., Ltd.).

[0047] A combination of 2 parts by mass or more and 15 parts by mass or less of dicyclopentadiene type epoxy resin and 15 parts by mass or more and 35 parts by mass or less of bifunctional glycidylaniline type epoxy resin can achieve both sufficient CFRP strength and viscoelasticity adjustment near room temperature. A combination of 5 parts by mass or more and 10 parts by mass or less of dicyclopentadiene type epoxy resin is preferable because it is easy to balance the reduction in G' near room temperature of the resin composition and the CFRP strength. In addition, a combination of 20 parts by mass or more of bifunctional glycidylaniline type epoxy resin is preferable because it is easy to improve the CFRP tensile strength. The preferred mass parts of each epoxy resin may be set with the total mass parts of the epoxy resin, which is the first resin composition and the second resin composition, taken as 100.

[0048] [A2-1] is a tetrafunctional liquid epoxy resin, and is the same as [A2-1] for the first and second prepregs. If the content is 45 parts by mass or more and 65 parts by mass or less, a CFRP with a good balance between heat resistance and tensile strength can be obtained. It is more preferable that the content of the tetrafunctional liquid epoxy resin is 50 parts by mass or more and 60 parts by mass or less.

[0049] The third prepreg may also contain an epoxy resin [A4] other than [A1], [A2-1], and [A3]. By appropriately selecting [A4], the viscoelasticity of the resin composition can be adjusted, and the processability in the manufacturing process of the resin composition and prepreg and the molding process of the prepreg can be maintained good. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, aminophenol type epoxy resin, etc. can be used as [A4]. The content is 0 parts by mass or more and 35 parts by mass or less.

[0050] The other components [B], [C], and [D] of the third prepreg are similar to those of the first and second prepregs.

[0051] Other features of the invention are described below.

[0052] Examples of carbon fibers include acrylic, pitch and rayon carbon fibers, and acrylic carbon fibers having high tensile strength are particularly preferred.

[0053] Such acrylic carbon fibers can be produced, for example, through the following process. A spinning dope containing polyacrylonitrile obtained from a monomer mainly composed of acrylonitrile is spun by a wet spinning method, a dry-wet spinning method, a dry spinning method, or a melt spinning method. The solidified yarn after spinning is made into a precursor through a spinning process, and then a carbon fiber can be obtained through processes such as flame retardation and carbonization.

[0054] The form and arrangement of the carbon fibers in the prepreg of the present invention are not limited, and for example, continuous fibers aligned in one direction, single tows, woven fabrics such as plain weave, satin weave, and twill weave, knits, nonwoven fabrics, mats, braids, and other fiber structures can be used. Among these, it is preferable to use the carbon fibers aligned in one direction or in the form of woven fabrics such as plain weave, satin weave, and twill weave, and it is preferable that a layer is formed from such carbon fibers. Here, continuous fibers refer to fibers having an average length of 10 mm or more.

[0055] It is also possible to use two or more types of carbon fiber, or to combine carbon fiber with other reinforcing fibers selected from glass fiber, aramid fiber, boron fiber, PBO fiber, high-strength polyethylene fiber, alumina fiber, silicon carbide fiber, and the like.

[0056] The carbon fiber used in the present invention preferably has a tensile modulus in the range of 200 to 440 GPa. This range is preferable because it provides CFRP with a high level of balance between rigidity and strength. The more preferable modulus is in the range of 230 to 400 GPa, and even more preferably in the range of 250 to 370 GPa.

[0057] The tensile elongation of the carbon fiber is preferably in the range of 0.8 to 3.0%. If the tensile elongation of the carbon fiber is low, sufficient tensile strength and impact resistance may not be exhibited when the carbon fiber is made into CFRP. Furthermore, if the tensile elongation exceeds 3.0%, the tensile modulus of the carbon fiber tends to decrease. The tensile elongation of the carbon fiber is more preferably in the range of 1.0 to 2.5%, and further preferably in the range of 1.2 to 2.3%.

[0058] Here, the tensile modulus and tensile elongation of the carbon fiber are values ​​measured in accordance with JIS R7601 (2006).

[0059] The carbon fiber used in the present invention preferably has a filament number in one fiber bundle in the range of 1,000 to 50,000. If the filament number is less than 2,500, the fiber arrangement tends to be meandering, which may cause a decrease in strength, and the filament number is more preferably in the range of 2,500 to 40,000, which is particularly suitable for aerospace applications.

[0060] Commercially available carbon fibers include "TORAYCA" (registered trademark) T800S-24K, "TORAYCA" (registered trademark) T800G-24K, "TORAYCA" (registered trademark) T1100G-24K, "TORAYCA" (registered trademark) Cloth CO6343 (carbon fiber: T300-3K), and "TORAYCA" (registered trademark) Cloth CK6244C (carbon fiber: T700S-12K).

[0061] The resin composition used in the prepreg of the present invention may contain a coupling agent, or inorganic fillers such as silica gel, carbon black, clay, carbon nanotubes, carbon particles, and metal powder, and flame retardants such as red phosphorus and phosphate ester, within a range that does not impair the effects of the present invention. In particular, the inclusion of conductive particles such as carbon particles dramatically improves the conductivity of CFRP, which is preferable in terms of lightning resistance and the like in aircraft applications. From this perspective, the conductivity of CFRP is preferably 300 Ωcm or less, more preferably 35 Ωcm or less, and even more preferably 20 Ωcm or less, as the volume resistivity in the thickness direction. When conductive particles are used, for example, a method of containing conductive particles as shown in the pamphlet of International Publication No. 2012 / 124450 can be used. In addition, the particle size of carbon particles can be measured by applying a light scattering method, for example, using Partica LA-950V2 manufactured by Horiba Ltd. or MT3300II manufactured by Microtrack Inc.

[0062] The heat resistance of the CFRP used in the prepreg of the present invention depends on the glass transition temperature of the resin composition cured product obtained by curing the resin composition. In order to obtain a CFRP with excellent heat resistance, the glass transition temperature of the resin composition cured product when cured at 180 ° C for 120 minutes is preferably 180 ° C or higher, more preferably 185 ° C or higher. By making the glass transition temperature of the resin composition cured product 180 ° C or higher, the mechanical properties of the CFRP under high temperature and high humidity conditions are excellent. Here, the glass transition temperature is the temperature at the inflection point of the storage modulus G' obtained by measuring a cured resin composition plate cut to a specified size at a heating rate of 5 ° C / min and a frequency of 1 Hz using a dynamic viscoelasticity measuring device (ARES G2, manufactured by TA Instruments). More specifically, the temperature value at the intersection of the tangent in the glass state and the tangent in the transition state in the storage modulus G' curve is the glass transition temperature.

[0063] The curability of the resin composition of the present invention affects the curing time when CFRP is heated and cured to form it. Reducing the curing time contributes to reducing the cost of forming CFRP. The gel time is an index for evaluating the curability of a resin composition. Here, the gel time is measured using a dynamic viscoelasticity measuring device (ARES G2, manufactured by TA Instruments) with a parallel plate of 40 mm in diameter, an angular frequency of 3.14 rad / s, a measurement temperature of 50°C, and a temperature rise to 180°C at 1.5°C / min, and after reaching 180°C, the temperature is maintained at 180°C and measured, and the time is measured to obtain the intersection of G' and G'', which are obtained by measuring the time.

[0064] The prepreg of the present invention can be manufactured by various known methods. For example, a hot melt method can be mentioned in which an epoxy resin film is layered on the surface of a carbon fiber sheet in which carbon fiber bundles are arranged in a sheet shape, and pressure / heat impregnation is performed. In such a method, an epoxy resin composition is applied to a release paper using a reverse roll coater or a knife coater to prepare an epoxy resin composition film, and then this epoxy resin composition film is layered on both sides of the carbon fiber, and the carbon fiber bundle is impregnated by heating and pressurization. Furthermore, the resin composition to be impregnated in the inner layer of the prepreg and the resin composition to be present in the surface layer of the prepreg can be different. In this case, a multi-stage impregnation method can be used in which a resin composition film made of each resin composition is prepared, and each is layered on a carbon fiber sheet and impregnated. There is no limit to the number of stages in the multi-stage impregnation method, but it is common to use two stages.

[0065] The prepreg of the present invention has a carbon fiber content per unit area of ​​70 to 2,000 g / m 2 It is preferable that the amount of carbon fiber is 70 g / m 2 If the carbon fiber content is less than 2,000 g / m, the number of layers must be increased to obtain the desired thickness during CFRP molding, which can make the work complicated. 2 If the temperature exceeds this range, the drapeability of the prepreg tends to deteriorate.

[0066] The carbon fiber mass ratio in the prepreg is preferably from 50% by mass to 80% by mass, since this makes it possible to achieve both the light weight of the CFRP and the reduction in voids due to molding.

[0067] There is no particular limit to the width of the prepreg, and it may be a wide width of about several tens of centimeters to 2 m, or a tape-like width of several mm to several tens of mm, and the width can be selected according to the application. In recent years, in order to make the lamination process of the prepreg more efficient, devices called ATL (Automated Tape Laying) and AFP (Automated Fiber Placement) that automatically laminate narrow-width prepregs and prepreg tapes have become widely used, and it is also preferable to set the width to match this. In ATL, narrow-width prepregs with widths of about 7.5 cm, about 15 cm, and about 30 cm are often used, and in AFP, prepreg tapes of about 3 mm to about 25 mm are often used. There is no particular limit to the method of obtaining a prepreg of a desired width, and a method of slitting a wide-width prepreg of about 1 m to 2 m into a narrow width can be used. In addition, in order to simplify or omit the slitting process, a prepreg tape such as a towpreg can also be manufactured so that it has the desired width from the beginning.

[0068] When the prepreg tape is conveyed in a slit processing device or an AFP device, it may pass through a place where the prepreg tape is greatly bent, such as on a small diameter roll or at a folded-back part of the prepreg tape. If the prepreg tape is hard at this time, the shape tracking of the prepreg tape at the above-mentioned greatly bent part may be poor, and the prepreg tape may deviate from the desired conveying path or break at the splice part. Here, splicing refers to joining multiple prepreg tapes together in the longitudinal direction by pressure bonding or the like. For this reason, it is preferable to soften the prepreg. In order to soften the prepreg, it is possible to adjust the elastic modulus and fiber diameter of the carbon fiber used, or a sizing agent, but there may be a limit to the adjustment range from the viewpoint of ensuring the mechanical properties of CFRP and suppressing the fluff of the carbon fiber. In addition, the thinner the prepreg thickness, the better the apparent softness of the prepreg, but there may also be a limit to the adjustment range from the viewpoint of the lamination efficiency of the prepreg. For this reason, it is preferable to reduce the rigidity of the resin composition that is the matrix resin. In this case, it is preferable that the resin composition impregnated in the prepreg inner layer portion and the resin composition present in the prepreg surface layer have different viscoelastic properties, and the resin composition impregnated in the prepreg inner layer portion is defined as the first resin composition, and the resin composition present in the prepreg surface layer is defined as the second resin composition. The viscoelastic properties of the first resin composition are as follows: storage modulus G' measured at 23°C and 77 rad / s is 1×10 4 Pa or more, 2×10 6 A range of 0.1 Pa or less is preferable because it effectively softens the prepreg, improves the transportability of the prepreg tape, and suppresses breakage at the splice portion. In addition, by setting the range, it is possible to suppress deformation of the prepreg tape during slitting, and it is also possible to obtain a prepreg tape with good width accuracy. As a method for obtaining a prepreg having such a configuration, for example, the multi-stage impregnation method described above can be used.

[0069] In the present invention, a dicyclopentadiene type epoxy resin is used, which is often solid at room temperature, and this may cause the G' of the resin composition at room temperature to be excessively high, resulting in hardening of the prepreg. For this reason, in the first prepreg, the component [A2] to be combined with the dicyclopentadiene type epoxy resin is liquid epoxy resin [A2-1], [A2-2], and the mass ratio is designed to control the G' of the resin composition at room temperature and the hardness of the prepreg. In the third prepreg, the content of the dicyclopentadiene type epoxy resin is reduced, but a bifunctional glycidylaniline type epoxy resin that is liquid near room temperature and can improve the CFRP tensile strength is also used in combination to control the G' of the resin composition at room temperature and the hardness of the prepreg.

[0070] In recent years, the use of AFP has expanded rapidly, particularly in aircraft structural material applications, and it has become extremely important to feed back the corresponding transportability of prepreg tapes into the design of prepregs and resin compositions. The prepreg tape of the present invention is excellent not only in the transportability described above, but also in width precision, and can be suitably used for AFP.

[0071] The CFRP obtained from the prepreg of the present invention can be produced, for example, by a so-called hot and pressure molding method in which the above-mentioned prepreg of the present invention is laminated in a predetermined shape and pressurized and heated to form a shape and cure the resin. As the hot and pressure molding method, press molding, autoclave molding, bagging molding, wrapping tape method, internal pressure molding, etc. can be used.

[0072] When the prepreg of the present invention is used, the CFRP is usually molded at a temperature in the range of 150° C. to 220° C. By setting the molding temperature in this range, sufficient curing properties can be obtained.

[0073] The pressure at which CFRP is molded by autoclave molding varies depending on the thickness of the prepreg, the volumetric content of the carbon fibers, etc., but is usually in the range of 0.1 to 1 MPa. By keeping the molding pressure within this range, it is possible to obtain CFRP that is free of defects such as voids and has little dimensional variation such as warping.

[0074] The CFRP obtained by molding the prepreg of the present invention has excellent tensile strength properties, heat resistance, and mode I interlaminar toughness at room temperature and in low temperature environments.

[0075] Such tensile strength characteristics can be evaluated by 0° tensile strength measurement. As described in JIS K7017 (1999), the 0° tensile strength of CFRP is defined as follows: the fiber direction of a unidirectional fiber-reinforced composite material is the axial direction, this direction is defined as the 0° axis, and the direction perpendicular to the axis is defined as 90°. A 0° tensile test is performed at room temperature (23°C) in accordance with the standard of JIS K7073 (1988). The 0° tensile strength of CFRP is preferably 2,850 MPa or more, more preferably 2,950 MPa or more, and even more preferably 3,050 MPa or more.

[0076] Such mode I interlaminar toughness (G IC ) can be calculated according to JIS K7086 (1993), and G IC is 250 J / m 2 If the thickness is more than 100 mm, the range of applicable structural members of aircraft and the like is wide, which is preferable. IC is preferably 280 J / m 2 More preferably, 300 J / m 2 That's all.

[0077] Impact resistance can be evaluated by compressive strength after impact (hereinafter abbreviated as CAI). The CAI of the CFRP obtained by the present invention is preferably 230 MPa or more, more preferably 280 MPa or more, after applying an impact energy of 6.7 J per mm of thickness of the test piece according to JIS K 7089 (1996). If the CAI is in this range, it is preferable because the range of applicable structural members for aircraft and the like is wide.

[0078] A prepreg tape containing the prepreg of the present invention, and a carbon fiber composite material obtained by molding the prepreg of the present invention or the prepreg tape of the present invention can also be preferably used for structural members of aircraft, for example. EXAMPLES

[0079] The present invention will be described in detail below with reference to examples. However, the scope of the present invention is not limited to these examples. The unit "parts" in the composition ratio means parts by mass unless otherwise noted. Furthermore, the measurements of various characteristics (physical properties) were performed in an environment with a temperature of 23°C and a relative humidity of 50% unless otherwise noted.

[0080] <Raw materials used in the Examples, Reference Examples, and Comparative Examples> (1) Component [A1] Dicyclopentadiene type epoxy resin "EPICLON" HP-7200L (DIC Corporation, epoxy equivalent: 246g / eq) ·XD-1000-2L (manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 240g / eq) ·“EPICLON” HP-7200 (manufactured by DIC Corporation, epoxy equivalent 260g / eq). "EPICLON (registered trademark)" HP-7200H (dicyclopentadiene type epoxy resin, manufactured by DIC Corporation, epoxy equivalent weight 278 g / eq, used for comparative examples) "EPICLON" HP-7200HHH (dicyclopentadiene type epoxy resin, manufactured by DIC Corporation, epoxy equivalent 280 g / eq, used as a comparative example).

[0081] (2) Component [A2-1] Tetrafunctional liquid epoxy resin "Sumiepoxy" ELM434 (tetraglycidyldiaminodiphenylmethane, manufactured by Sumitomo Chemical Co., Ltd., epoxy equivalent 120g / eq).

[0082] (3) Component [A2-2] Bifunctional liquid epoxy resin "EPICLON" 830 (bisphenol F type epoxy resin, manufactured by DIC Corporation, epoxy equivalent 171g / eq) "jER (registered trademark)" 825 (bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 170g / eq).

[0083] (4) Component [A3] Bifunctional glycidylaniline type epoxy resin GOT (glycidylaniline type epoxy resin (N,N-diglycidyl-o-toluidine), manufactured by Nippon Kayaku Co., Ltd.).

[0084] (5) Component [A4] Epoxy resin other than [A1], [A2-1], and [A3] "Araldite" MY0510 (triglycidylaminophenol type epoxy resin, manufactured by Huntsman Advanced Materials, Inc., epoxy equivalent 101g / eq). "EPICLON®" HP-4770 (naphthalene type epoxy resin, manufactured by DIC Corporation, epoxy equivalent 204g / eq).

[0085] (6) Component [B] DDS · Seikacure-S (4,4'-DDS, manufactured by Seika Co., Ltd., active hydrogen equivalent 62g / eq) · 3,3'-DAS (3,3'-DDS, manufactured by Mitsui Chemicals Fine Co., Ltd., active hydrogen equivalent 62g / eq).

[0086] (7) Component [C] PES "Virantage" (registered trademark) VW-10700RFP (PES, Solvay Advanced Polymers, weight average molecular weight 21,000 g / mol) · “Virantage” (registered trademark) VW-10200RFP (PES, manufactured by Solvay Advanced Polymers Co., Ltd., weight average molecular weight 46,500 g / mol).

[0087] (8) Components [D] spherical polymer particles and [D-2] thermoplastic resin particles Polyamide particles 1: Epoxy-modified polyamide particles were obtained in the same manner as the epoxy-modified polyamide particles used in the examples (e.g., Examples 1 and 2) of WO 2012 / 124450 (mode diameter 14 μm, sphericity 97). The particle diameter was measured using a Microtrac MT3300II (light source 780 nm-3 mW, wet cell (medium: water)). Polyamide particles 2: Polyamide 6 particles (mode diameter 15 μm, sphericity 96) obtained by the following method. The particle diameter was measured in the same manner as for polyamide particles 1.

[0088] With reference to WO 2018 / 207728, 200 g of ε-caprolactam (manufactured by Toray Industries, Inc.), 800 g of polyethylene glycol (Wako Pure Chemical Industries, Ltd., grade 1 polyethylene glycol 20,000, weight average molecular weight 18,600) as a second component polymer, and 1,000 g of water were added to an autoclave equipped with a 3 L helical ribbon type stirring blade to form a uniform solution, which was then sealed and purged with nitrogen. The stirring speed was then set to 100 rpm, and the temperature was raised to 240°C. During this process, the pressure of the system was 10 kg / cm 2 After reaching 10kg / cm 2 The steam pressure was controlled to maintain a constant pressure of 0.2 kg / cm after the temperature reached 240°C. 2 The pressure was released at a rate of 1.5 liters per minute. The temperature was then maintained for 1 hour while nitrogen was flowing to complete the polymerization, and the mixture was discharged into a 2,000 g water bath to obtain a slurry. After dissolving the dissolved material, filtration was performed, and 2,000 g of water was added to the filtered material and washed at 80°C. The slurry was then filtered again to remove the aggregates passed through a 200 μm sieve, and the isolated filtered material was dried at 80°C for 12 hours to produce 140 g of polyamide 6 powder. The melting point of the obtained powder was 218°C, the same as polyamide 6, and the crystallization temperature was 170°C. Potato-shaped polyamide particles: “Orgasol” 1002D (manufactured by Arkema Co., Ltd., sphericity 68).

[0089] (9) Component [E] Carbon fiber "TORAYCA" (registered trademark) T800G-24K-31E (manufactured by Toray Industries, Inc., carbon fiber with 24,000 filaments, tensile strength of 5.9 GPa, tensile modulus of elasticity of 294 GPa, and tensile elongation of 2.0%). "TORAYCA" (registered trademark) T800S-24K-10E (manufactured by Toray Industries, Inc., carbon fiber with 24,000 filaments, tensile strength of 5.9 GPa, tensile modulus of elasticity of 294 GPa, and tensile elongation of 2.0%).

[0090] (10) Secondary curing agent (isophthalic dihydrazide) IDH-S (Otsuka Chemical Co., Ltd., active hydrogen equivalent: 48g / eq).

[0091] (11) Conductive particles "Mitsubishi" conductive carbon black #3230B (primary particle diameter 23 nm (arithmetic mean diameter obtained by observing carbon black particles under an electron microscope), manufactured by Mitsubishi Chemical Corporation) Carbon particles "Nikabeads" ICB2020 (average particle size: 20 μm, manufactured by Nippon Carbon Co., Ltd.).

[0092] <Various evaluation methods> (12) Preparation of resin composition The epoxy resin (component A) and the PES (component C) were mixed and heated to 150°C or higher, and stirred for 1 hour to dissolve the component C, obtaining a transparent viscous liquid. After the liquid was cooled while being mixed, the DDS (component B) was added and further mixed to obtain a first resin composition.

[0093] In addition, the epoxy resin [A] and the PES [C] were kneaded, heated to 150°C or higher, and stirred for 1 hour to dissolve the component [C] and obtain a transparent viscous liquid. After lowering the temperature of this liquid while kneading, the component [D] was added and kneaded, and then the component [B] was added and kneaded to obtain a second resin composition. In addition, when IDH and conductive particles were included, both the first resin composition and the second resin composition were added at the same time as the component [B].

[0094] The compositional ratios of the resin compositions in each of the Examples and Comparative Examples are as shown in Tables 1 to 7.

[0095] (13) Measurement of viscosity increase rate of resin composition The viscosity increase rate of the resin composition was measured using a dynamic viscoelasticity device ARES-G2 (manufactured by TA Instruments). Flat parallel plates with a diameter of 40 mm were used for the upper and lower measuring jigs, and the resin composition was set so that the distance between the upper and lower jigs was 1 mm, and then the measurement was performed at an angular frequency of 3.14 rad / s. Viscosity η when held at 80°C for 1 minute * 1. Viscosity η when held at 80℃ for 2 hours * 120 The viscosity increase rate was then calculated as follows: Viscosity increase rate (%) = (1 - η * 120 / η * 1) x 100%.

[0096] (14) Measurement of G' of resin composition The G' (storage modulus) of the resin composition was measured using a dynamic viscoelasticity device ARES-G2 (manufactured by TA Instruments). Flat parallel plates with a diameter of 8 mm were used for the upper and lower measuring jigs, and the resin composition was set so that the distance between the upper and lower jigs was 0.5 mm. Then, a temperature rise measurement was performed at a strain rate of 77 rad / s and a temperature rise rate of 2.0°C / min. G' at 23°C was read from the G' curve obtained by the temperature rise measurement.

[0097] (15) Gel time measurement of resin composition The gel time of the resin composition was measured using a dynamic viscoelasticity measuring device ARES-G2 (manufactured by TA Instruments).

[0098] Flat parallel plates with a diameter of 40 mm were used for the upper and lower measuring jigs, and the resin composition was set so that the distance between the upper and lower jigs was 1 mm. The strain rate was 3.14 rad / s, and the measurement temperature was raised from 50°C to 180°C at a rate of 1.5°C / min. After reaching 180°C, the temperature was maintained at 180°C and measurements were taken to determine the time when the intersection of G' and G'' was obtained.

[0099] (16) Measurement of glass transition temperature of cured resin composition The resin composition was poured into a mold, then heated in a hot air dryer from 30°C at a rate of 1.5°C / min, heat-cured at 180°C for 2 hours, and then cooled to 30°C at a rate of 2.5°C / min to produce a 2 mm-thick cured resin plate.

[0100] A test piece measuring 12.7 mm in width and 55 mm in length was cut out from the prepared resin-cured plate, and the glass transition temperature was determined by the DMA method in accordance with SACMA SRM18R-94.

[0101] The glass transition temperature was determined as the intersection temperature between the tangent line in the glassy state and the tangent line in the transition state in the storage modulus G' curve. The temperature was measured at a heating rate of 5.0°C / min and a frequency of 1 Hz.

[0102] (17) Preparation of prepreg In this example, the prepreg was produced using a two-stage impregnation method as follows. The first resin composition or the second resin composition produced in (12) above was uniformly applied onto a release paper coated with silicone to produce a first resin film and a second resin film, respectively. Carbon fibers uniformly aligned in one direction were sandwiched between two first resin films, and heated and pressed using a press roll to obtain a first prepreg in which the carbon fibers were impregnated with the first resin composition (resin content: 20% by mass). After the first prepreg was impregnated with the first resin composition, both release papers were peeled off. Next, the first prepreg was sandwiched between second resin films, and heated and pressed using a press roll to obtain a prepreg in which the first prepreg was impregnated with the second resin composition (resin content: 34% by mass).

[0103] (18) CFRP 0° tensile strength measurement The unidirectional prepreg was cut to a specified size, and four sheets were laminated in one direction. The laminate was then vacuum-bagged and heated in an autoclave at a temperature of 180°C and a pressure of 6 kg / cm. 2The laminate was then cured for 2 hours. This unidirectional reinforcement was cut to a width of 12.7 mm and a length of 230 mm, and glass fiber reinforced plastic tabs measuring 1.2 mm and 50 mm in length were attached to both ends to obtain test pieces. This test piece was subjected to a 0° tensile test in accordance with the JIS K7073 (1988) standard using an Instron universal testing machine. Measurements were performed at room temperature (23°C) and, in some cases, at a low temperature (-60°C). The strength retention, which is the ratio of the tensile strength in a low temperature environment to that in a room temperature environment, was calculated from the following formula. Strength retention (%) = tensile strength (low temperature environment) / tensile strength (room temperature environment) x 100.

[0104] (19) Mode I Interlaminar Toughness (G IC ) Preparation of composite test plates and G IC measurement According to JIS K7086 (1993), the following operations (a) to (e) are performed to obtain G IC Test composite plates were prepared.

[0105] (a) The unidirectional prepreg prepared in (17) is laminated with the same fiber direction and a carbon fiber mass of 268 g / m 2 For 12 plies, carbon fiber mass 194g / m 2 In the case of , 20 plies were laminated. However, the central plane of the laminate (carbon fiber mass 268g / m 2 In the case of the 6th and 7th plies, the carbon fiber mass is 194g / m 2 In the case of the 10th and 11th plies, a 40 mm wide fluororesin film was sandwiched perpendicular to the fiber arrangement direction between the 10th and 11th plies.

[0106] (b) The laminated prepreg is vacuum-bagged and then autoclaved at a temperature of 180°C and a pressure of 6 kg / cm 2 The mixture was cured for 2 hours to obtain a laminate.

[0107] (c) The unidirectional CFRP obtained in (b) was cut to a width of 20 mm and a length of 195 mm. The fiber direction was cut parallel to the length of the specimen.

[0108] (d) A pin load block (length 25 mm, made of aluminum) described in JIS K7086 (1993) was attached to the end of the test piece (the side sandwiching the fluororesin film).

[0109] (e) To make it easier to observe the crack propagation, both sides of the test specimen were painted with white paint.

[0110] (f) Using the prepared test piece, G IC The measurements were performed using an Instron universal testing machine (manufactured by Instron) in accordance with JIS K7086 (1993) Appendix 1. The crosshead speed was 0.5 mm / min until the crack had grown to 20 mm, and 1 mm / min after that. The test was performed until the crack had grown to 100 mm, and the G was calculated from the area of ​​the load-displacement curve obtained during the test. IC was calculated.

[0111] (20) Compressive after impact (CAI) measurements in CFRP Unidirectional prepreg with carbon fiber mass of 268g / m 2 In the case of [+45° / 0° / -45° / 90°]2s configuration, 16 plies are layered quasi-isotropically, and the carbon fiber mass is 194g / m 2 In the case of , 24 plies were laminated pseudo-isotropically in a [+45° / 0° / -45° / 90°] 3s configuration, and then autoclaved at 180°C for 2 hours at a pressure of 6kg / cm 2 CFRP was produced by molding at a temperature rise rate of 1.5°C / min. A sample of 150 mm length x 100 mm width was cut out from this CFRP, and a falling weight impact of 6.7 J / mm was applied to the center of the sample in accordance with SACMA SRM 2R-94 to determine the compressive strength after impact.

[0112] (21) Conductivity measurement in the thickness direction of CFRP Unidirectional prepreg with carbon fiber mass of 268g / m 2 In the case of [+45° / 0° / -45° / 90°]2s configuration, 16 ply laminated quasi-isotropically, carbon fiber mass 194g / m 2In the case of , 24 plies were laminated pseudo-isotropically in a [+45° / 0° / -45° / 90°] 3s configuration, and then autoclaved at 180°C for 2 hours at a pressure of 6kg / cm 2 The CFRP was produced by molding at a temperature rise rate of 1.5°C / min. A sample of 40 mm length x 40 mm width was cut out from the obtained CFRP, and the resin layers on both surfaces were polished and removed. Then, conductive paste N-2057 (manufactured by Shoei Chemical Industry Co., Ltd.) was applied to both sides to a thickness of about 70 μm using a bar coater, and cured for 30 minutes in a hot air oven adjusted to a temperature of 180°C to obtain a sample for conductivity evaluation. The resistance in the thickness direction of the obtained sample was measured by the four-terminal method using an R6581 digital multimeter manufactured by Advantest Corporation. The measurement was performed six times, and the average value was taken as the volume resistivity (Ωcm) in the thickness direction of the CFRP. Examples 1 to 17, Reference Example 1, and Comparative Examples 1 to 7 relate to the first prepreg.

[0113] (Examples 1 to 3) A first resin composition was prepared in the composition ratios shown in Table 1 according to (12) above using “EPICLON” HP-7200L (epoxy equivalent: 246 g / eq) as the component [A1], “Sumiepoxy” ELM434 as the component [A2-1], “EPICLON” (registered trademark) 830 as the epoxy resin of the component [A2-2], 4,4′-DDS as the component [B], and “Virantage” VW-10700RFP (weight average molecular weight 21,000 g / mol) as the component [C]. Next, a second resin composition was prepared in the content ratios shown in Table 1 according to (12) above using “EPICLON” (registered trademark) HP-7200L (epoxy equivalent: 246 g / eq) as the component [A1], “Sumiepoxy” ELM434 as the component [A2-1], “EPICLON” 830 as the component [A2-2], 4,4′-DDS as the component [B], “Virantage” VW-10700RFP (weight average molecular weight 21,000 g / mol) as the component [C], and polyamide particles 1 as the component [D].

[0114] Furthermore, a prepreg was produced according to (17) above using "TORAYCA" (registered trademark) T800G-24K-31E as the carbon fiber and the first and second resin compositions prepared above. The carbon fiber mass in the prepreg was 268 g / m 2 It was.

[0115] As shown in Table 1, by optimizing the content of the dicyclopentadiene type epoxy resin, which is the component [A1], and the liquid epoxy resin, which is the component [A2], the 0° tensile strength, G IC We obtained a CFRP with excellent heat resistance and CAI.

[0116] (Comparative Examples 1 to 7, Reference Example 1) A prepreg was prepared in the same manner as in Example 2 using the composition ratio shown in Table 2.

[0117] In Comparative Example 1, the content of the dicyclopentadiene type epoxy resin was low, and therefore the tensile strength of the obtained CFRP was poor.

[0118] In Reference Example 1, the content of the dicyclopentadiene type epoxy resin, which is solid at room temperature, was excessively high from the viewpoint of the first prepreg, while the content of the epoxy resin [A2], which is liquid at room temperature, was excessively low, so that the G' of the resin composition at room temperature was excessively high. Therefore, the obtained prepreg was also hard at room temperature and had poor handleability. The 0° tensile strength at -60°C was 3,160 MPa, and the strength retention at -60°C was 96%.

[0119] In Comparative Example 2, the [A2-1] / [A2-2] ratio was excessively high, and therefore the tensile strength of the obtained CFRP was low.

[0120] In Comparative Example 3, the [A2-1] / [A2-2] ratio was too high, and thus the tensile strength of the obtained CFRP was low, similar to that of Comparative Example 3. Furthermore, the viscosity stability at 80°C was also poor, due to the use of a triglycidylaminophenol type epoxy resin in combination.

[0121] In Comparative Example 4, the [A2-1] / [A2-2] ratio was too low, and therefore the heat resistance was poor.

[0122] In Comparative Example 5, since PES was not contained, the tensile strength of the obtained CFRP was insufficient. In addition, there was a lot of resin flow during the molding process, and the quality of the CFRP was reduced.

[0123] In Comparative Example 6, non-spherical polyamide particles (Orgasol1002D) were used as the polymer particles, and therefore the impact resistance (CAI) of the obtained CFRP was insufficient.

[0124] In Comparative Example 7, the epoxy group equivalent of the dicyclopentadiene type epoxy resin was too high, which resulted in poor compatibility with PES and caused a problem of large basis weight unevenness during production of the resin film.

[0125] (Examples 4 to 9) A prepreg was produced in the same manner as in Example 2 using the composition ratio shown in Table 3.

[0126] In Example 4, since the epoxy group equivalent of the dicyclopentadiene type epoxy resin was large, the compatibility with PES was reduced. Although this was not a problem, there were cases in which the basis weight unevenness became larger when the resin film was produced compared to Example 2.

[0127] In Example 5, since [A2-1] / [A2-2] was high, the heat resistance was improved.

[0128] In Example 6, a glycidylaniline type epoxy resin was used in combination as a bifunctional liquid epoxy resin, and therefore the tensile strength of the obtained CFRP was improved compared to Example 1. Furthermore, since the content of the liquid epoxy resin was high, the room temperature G' of the resin composition was effectively lowered, and the obtained prepreg was soft and had excellent handleability. In this way, by using a glycidylaniline type epoxy resin in combination, it was possible to achieve a high level of balance between the mechanical strength of the CFRP, heat resistance, and the handleability of the prepreg.

[0129] In Example 7, since 3,3'-DDS was used as the DDS, the viscosity stability at 80°C was slightly inferior to that of Example 2, although this was not a problem.

[0130] In Example 8, because a high molecular weight PES was used, the compatibility with the dicyclopentadiene type epoxy resin was reduced. Although this was not a problem, there were cases in which the basis weight unevenness became larger when the resin film was produced compared to Example 2.

[0131] In Example 9, polyamide particles 2 were used as the spherical polymer particles, and the impact resistance (CAI) of the obtained CFRP was good.

[0132] Example 10 A prepreg was produced in the same manner as in Example 2 using the composition ratio shown in Table 4.

[0133] In this example, since IDH was contained, the gelation time was shortened to 84 minutes compared to 101 minutes in Example 2, and the molding time shortening effect was confirmed. Furthermore, the handleability of the obtained prepreg and the mechanical properties of the CFRP were both good.

[0134] Example 11 A prepreg was produced in the same manner as in Example 2 using the composition ratio shown in Table 4.

[0135] In this example, since conductive particles are added, the volume resistivity in the thickness direction of the obtained CFRP is 15 Ωcm, which is 10% lower than that of Example 2. 5 The electrical conductivity was improved compared to Ωcm. This means that if this material is applied to aircraft, it is expected to improve lightning resistance. The handling of the obtained prepreg and the mechanical properties of the CFRP were also good.

[0136] Example 12 A prepreg was produced in the same manner as in Example 2 using the composition ratio shown in Table 4.

[0137] The gelation time of the resin composition obtained in this example was 84 minutes, shorter than the 101 minutes in Example 2, and the molding time shortening effect was confirmed. In addition, the volume resistivity in the thickness direction of the obtained CFRP was 16 Ωcm, which was 10 times that of Example 2. 5 The electrical conductivity was improved compared to Ωcm. The handleability of the obtained prepreg and the mechanical properties of the CFRP were also good.

[0138] Example 13 A resin composition was prepared and a prepreg was obtained in the same manner as in Example 11 except that carbon black was not added, and favorable properties were obtained as in Example 11. In addition, the volume resistivity in the thickness direction of the CFRP was 300 Ωcm.

[0139] Example 14 A resin composition was prepared and a prepreg was obtained in the same manner as in Example 13, except that the carbon fiber was changed to "TORAYCA" (registered trademark) T800S-24K-10E and the amount of carbon particles was changed. The volume resistivity of the CFRP in the thickness direction was 14 Ω cm.

[0140] Example 15 The prepregs obtained in Examples 1 to 14 were slit to a width of 1 inch. There was no problem with the transportability of the prepreg tape after slitting, it showed excellent shape conformability, and there was no breakage at the splice portion.

[0141] Example 16 The prepreg tape obtained in Example 15 was laminated by an automatic laminator, and there was no problem with the conveyability of the prepreg tape, it showed excellent shape conformability, and there was no breakage at the splice portion.

[0142] (Example 17) The prepreg tape obtained in Example 15 was laminated by an automatic laminator and then molded to obtain a CFRP. The CFRP showed excellent mechanical properties almost equivalent to those of Examples 1-14.

[0143] Examples 18 to 32, Reference Example 2, and Comparative Examples 8 to 15 relate to the second prepreg.

[0144] (Example 18) A first resin composition was prepared according to the above (12) using 45 parts of “EPICLON (registered trademark)” HP-7200L (epoxy equivalent: 246 g / eq) as the component [A1], 30 parts of “Sumiepoxy (registered trademark)” ELM434 as the component [A2-1], 25 parts of “EPICLON (registered trademark)” 830 as an epoxy resin other than the components [A1] and [A2-1], 40 parts of 4,4′-DDS as the component [B], and 8 parts of “Virantage (registered trademark)” VW-10700RFP (weight average molecular weight 21,000 g / mol) as the component [C]. Next, a second resin composition was prepared according to the above (12) using 45 parts of “EPICLON (registered trademark)” HP-7200L (epoxy equivalent: 246 g / eq) as the component [A1], 30 parts of “Sumiepoxy (registered trademark)” ELM434 as the component [A2-1], 25 parts of “EPICLON (registered trademark)” 830 as an epoxy resin other than the components [A1] and [A2-1], 40 parts of 4,4′-DDS as the component [B], 8 parts of “Virantage (registered trademark)” VW-10700RFP (weight average molecular weight 21,000 g / mol) as the component [C], and 37 parts of the polyamide particles 1 produced by the method of the above (8) as the component [D-2].

[0145] Furthermore, a prepreg was produced according to (17) above using "TORAYCA (registered trademark)" T800G-24K-31E as the component [E] and the first and second resin compositions prepared above. The carbon fiber mass in the prepreg was 194 g / m 2 It was.

[0146] As shown in Tables 5 and 6, by optimizing the blending amount of dicyclopentadiene type epoxy resin and tetrafunctional liquid epoxy resin, the strength retention rate and G IC As a result, a CFRP with excellent heat resistance was obtained.

[0147] (Examples 19 to 23, 27 to 30, Reference Example 2, and Comparative Examples 8 to 12) The compounding ratios of the resin compositions were according to Tables 5 to 7, and prepregs were produced in the same manner as in Example 18.

[0148] As shown in Tables 5 and 6, in Examples 19 to 23, a dicyclopentadiene type epoxy resin having an epoxy equivalent of 200 g / eq or more and 265 g / eq or less was selected, and the blending amount was adjusted to a preferred range, thereby improving heat resistance, strength retention, and G IC As shown in Examples 19, 20, and 27 to 30, the IDH compounding ratio (H F It was confirmed that the gel time was shortened as the ratio of IDH to the curing time was increased. Examples 19, 20, 29, and 30, in which the IDH content was within the preferred range, exhibited an excellent balance between the effect of shortening the curing time and heat resistance.

[0149] As shown in Table 7, in Reference Example 2 and Comparative Example 8, the blending amount of the dicyclopentadiene type epoxy resin is outside the preferred range of the second prepreg, so that Reference Example 2 has a low strength retention rate and G IC is lower than that of Example 18. In Reference Example 2, the viscosity increase rate of the resin composition when kept at 80° C. for 2 hours was 10% for both the first resin composition and the second resin composition, and G′ at 23° C. and 77 rad / sec was 3.0×10 for the first resin composition. 5 Pa, 3.2 × 10 for the second resin composition 5 In Comparative Example 8, the blend ratio of dicyclopentadiene-type epoxy resin was high, so PES and the epoxy resin were not compatible with each other, and it was not possible to produce a uniform resin cured product or a resin film. In Comparative Example 9, a dicyclopentadiene-type epoxy resin was not used, and other epoxy resins were blended, so the strength retention rate and G ICwas lower than that of Example 18. In Comparative Examples 10 and 11, the epoxy equivalent of the blended dicyclopentadiene-type epoxy resin was larger than the preferred range (the epoxy equivalent of the component [A1] in Comparative Example 10 was 278 g / eq, and the epoxy equivalent of the component [A1] in Comparative Example 11 was 280 g / eq), so that the PES and the epoxy resin were not compatible with each other, and it was not possible to prepare a uniform resin plate or a resin film. In Comparative Example 12, no dicyclopentadiene-type epoxy resin was included, and the blended amount of the tetrafunctional liquid epoxy resin was large, so that the strength retention rate, G IC was lower than that in Example 18.

[0150] (Examples 24 to 26 and Comparative Example 13) The compounding ratio of the epoxy resin composition was according to Tables 5 to 7, and prepregs were prepared in the same manner as in Example 18. The compounding ratio of the epoxy resin was 60 parts of component [A1] "EPICLON (registered trademark)" HP-7200 (epoxy equivalent: 260 g / eq), 25 parts of "Sumiepoxy (registered trademark)" ELM434, and 15 parts of "EPICLON (registered trademark)" 830 to prepare an epoxy resin composition and prepare a prepreg. However, due to the low compatibility between HP-7200 and PES, the quality of the prepreg was not as good as that of Example 18. For this reason, the amount of HP-7200 was reduced to 45 parts, and a prepreg was prepared. (Example 24) In Example 25, a prepreg was produced by changing the PES of the component [C] to 8 parts of "Virantage (registered trademark)" VW-10200RFP (weight average molecular weight 46,500 g / mol) having a large weight average molecular weight. However, the quality of the prepreg was inferior to that of Example 18. Therefore, a prepreg was produced by changing the amount of "Virantage (registered trademark)" VW-10200RFP to 4 parts as described in Example 25 in Table 1. (Example 25) As shown in Tables 5 and 6, in Examples 24 to 26, the heat resistance, strength retention and G IC In particular, in Examples 24 and 25, since the compounding ratio of the tetrafunctional liquid epoxy was high, a CFRP with excellent heat resistance was obtained.

[0151] As shown in Table 7, in Comparative Example 13, the amount of the tetrafunctional liquid epoxy resin mixed was not optimal for the second prepreg, so that Comparative Example 13 had lower heat resistance than Example 18.

[0152] (Examples 27, 28, 30 and Comparative Example 14) The compounding ratios of the epoxy resin compositions were according to Tables 5 to 7, and prepregs were prepared in the same manner as in Example 18.

[0153] As shown in Tables 5 and 6, in Examples 27, 28, and 30, the strength retention and G IC In Example 28, the amount of PES was large, and the strength utilization rate, G IC A CFRP with high performance was obtained.

[0154] As shown in Table 7, Comparative Example 14 had a lower strength retention rate than Example 18 because it did not contain PES.

[0155] (Examples 31 and 32) The compounding ratio of the epoxy resin composition was according to Table 8, and a prepreg was prepared in the same manner as in Example 18. As shown in Table 8, Example 31 contained conductive particles, so the volume resistivity in the thickness direction was 14 Ωcm, whereas Example 32 did not contain conductive particles (volume resistivity 10 5 It showed excellent conductivity against a resistance of 1000Ωcm.

[0156] Examples 6, 33, Reference Example 1, and Comparative Examples 1 and 15 relate to the third prepreg.

[0157] In Reference Example 1 (reprinted in Tables 2 to 9), the amount of dicyclopentadiene-type epoxy resin was large, so that the G' of the resin composition at room temperature was excessively high, which could cause problems with the transportability and lamination properties of the tape depending on the conditions of the automatic lamination process of the prepreg tape.

[0158] On the other hand, in Comparative Example 1 (reprinted in Tables 2 to 9), the amount of dicyclopentadiene-type epoxy resin was small and no difunctional glycidylaniline-type epoxy resin was used in combination, so the 0° tensile strength of the CFRP decreased.

[0159] In Example 6 (reprinted in Tables 3 to 9), the amount of dicyclopentadiene-type epoxy resin was reduced while a bifunctional glycidylaniline-type epoxy resin was used in combination, so that sufficient 0° tensile strength of the CFRP was obtained, and the room temperature G' of the first resin composition was also within a range that provided excellent transportability in the automatic lamination process.

[0160] In addition, "TORAYCA" (registered trademark) T800S-24K-10E was used as the carbon fiber, and the compounding ratio of the resin composition was according to Table 9. A resin composition and a prepreg were prepared in the same manner as in Example 14. The mass of the carbon fiber in the prepreg was 268 g / m 2 (Example 33). In Example 33, a CFRP having good mechanical properties was obtained, and the volume resistivity in the thickness direction was 14 Ωcm, which was good electrical conductivity. Furthermore, the G' of the resin composition at room temperature was also in a range that was excellent in transportability in the automatic lamination process. In addition, the viscosity increase rate of the resin composition when held at 80°C for 2 hours was 10%.

[0161] On the other hand, in Comparative Example 15, a bifunctional glycidylaniline type epoxy resin was used, but no dicyclopentadiene type epoxy resin was blended, and therefore the 0° tensile strength of the CFRP was poor.

[0162] [Table 1]

[0163] [Table 2]

[0164] [Table 3]

[0165]

Table 4

[0166]

Table 5

[0167]

Table 6

[0168]

Table 7

[0169]

Table 8

[0170]

Table 9

Claims

1. A prepreg containing carbon fiber and a resin composition containing at least the following components [A] to [D], wherein the epoxy resin of the component [A] contains [A1] and [A2], the [A1] has an epoxy equivalent of 200 g / eq or more and 265 g / eq or less and is contained in an amount of 5 parts by mass or more and 45 parts by mass or less, the [A2] has an amount of 55 parts by mass or more and 95 parts by mass or less, the [A2] contains at least [A2-1] and [A2-2] and the mass ratio thereof, [A2-1] / [A2-2], is 0.7 or more and 4.0 or less, and the resin composition has a viscosity increase rate of 20% or less when kept at 80° C. for 2 hours. [A]: Epoxy resin containing [A1] and [A2] [A1]: Dicyclopentadiene type epoxy resin [A2]: Epoxy resin containing [A2-1] and [A2-2] [A2-1]: tetrafunctional liquid epoxy resin [A2-2]: Bifunctional liquid epoxy resin [B]: Diaminodiphenyl sulfone [C]: Polyethersulfone [D]: Spherical polymer particles

2. A prepreg obtained by impregnating the following component [E] with a resin composition containing the components [A] to [D-2], wherein the prepreg contains, per 100 parts by mass of the component [A], 45 parts by mass or more and 80 parts by mass or less of [A1] dicyclopentadiene-type epoxy resin having an epoxy equivalent of 200 g / eq or more and 265 g / eq or less, and 10 parts by mass or more and 40 parts by mass or less of [A2-1] tetrafunctional liquid epoxy resin. [A] Epoxy resin [B] Diaminodiphenyl sulfone [C] Polyethersulfone [D-2] Thermoplastic resin particles [E] Carbon fiber

3. A prepreg comprising carbon fiber and at least the following constituent elements [A] to [D], wherein the epoxy resin of the constituent element [A] contains, relative to 100 parts by mass of a total amount of the blended epoxy resins, an [A1] of 2 parts by mass or more and 15 parts by mass or less, an [A2-1] of 45 parts by mass or more and 65 parts by mass or less, an [A3] of 15 parts by mass or more and 35 parts by mass or less, and an [A4] of 0 parts by mass or more and 35 parts by mass or less, and the epoxy equivalent of [A1] is 200 g / eq or more and 265 g / eq or less. [A]: Epoxy resin containing [A1], [A2-1], [A3], and [A4] [A1]: Dicyclopentadiene type epoxy resin [A2-1]: tetrafunctional liquid epoxy resin [A3]: Bifunctional glycidyl aniline type epoxy resin [A4]: Epoxy resin other than [A1], [A2-1], and [A3] [B]: Diaminodiphenyl sulfone [C]: Polyethersulfone [D]: Spherical polymer particles

4. 4. The prepreg according to claim 1, wherein the dicyclopentadiene type epoxy resin has an epoxy equivalent of 253 g / eq or less.

5. The prepreg according to any one of claims 1 to 4, wherein the weight average molecular weight of the component [C] is 10,000 to 30,000 g / mol.

6. The prepreg comprises a first resin composition impregnated in an inner layer of the prepreg and a second resin composition present in a surface layer of the prepreg, and the first resin composition has a storage modulus G' of 1 x 10 measured at 23°C and 77 rad / s. ４ Pa or more, 2×10 ６ The prepreg according to any one of claims 1 to 5, wherein the elastic modulus is 10 Pa or less.

7. Contains isophthalic dihydrazide, and the total active hydrogen number (H Ｆ ) to the total number of all epoxy groups (E) of the component [A], Ｆ / E is 0.05≦H Ｆ The prepreg according to any one of claims 1 to 6, wherein / E≦0.3 or less.

8. The prepreg according to any one of claims 1 to 7, which contains conductive particles.

9. A prepreg tape comprising the prepreg according to any one of claims 1 to 8.

10. A carbon fiber composite material obtained by molding the prepreg according to any one of claims 1 to 8 or the prepreg tape according to claim 9.

Images