JP2006131920A - Epoxy resin composition and prepreg made with the epoxy resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide epoxy resin compositions which are stable at a room temperature, give releasable cured products by primary curing at a low temperature, and give cured products with high heat resistance by secondary curing, as well as to provide prepregs comprising reinforcing fiber materials impregnated with the epoxy resin compositions. <P>SOLUTION: The epoxy resin compositions comprise (a): a certain epoxy resin, (b): a latent curing agent with curing power at 100°C or below, and (c): an aromatic amine-based curing agent and/or an alicyclic amine-based curing agent, which are curable in two stages. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an epoxy resin composition and a prepreg using the epoxy resin composition, particularly suitable for application as a matrix resin for fiber-reinforced composite materials.

  Fiber reinforced composite materials are used in a wide range from sports and leisure related applications to transportation applications such as aircraft and industrial applications. As a general molding method of this fiber-reinforced composite material, there is a molding method using a mold.

  For example, a reinforcing fiber material such as cloth is attached to the mold while impregnating the resin, or a so-called prepreg in which the reinforcing fiber material is pre-impregnated with the resin is attached to the mold, and this is repeated. And then cured, and then removed from the mold, a hand lay-up method in which a molded product is obtained. After setting a reinforcing fiber material such as a cloth on the mold, a resin is injected into the mold and cured, and then removed. Resin transfer molding method to obtain a molded product by molding, after injecting a molding raw material mixed with a resin of reinforcing fiber material cut into short fibers into a molding die, this is cured and then demolded to obtain a molded product There are molding compound methods.

  Molds used in such a molding method include, for example, various materials such as metal, resin, and wood, and metal molds are excellent in heat resistance and durability. It requires labor and labor, and is expensive. Resin molds and wooden molds are inferior in heat resistance and durability, but have the advantage of being available at low cost.

  In order to respond to the various needs in recent years, there are many cases where resin molds that can be obtained at low cost are used because of the increasing production of small-quantity and various types of molded products. A wooden mold may be used to form a large fiber-reinforced composite material.

  Molding methods using these resin molds and wooden molds cannot be molded at high temperatures because the resin and wooden molds themselves are not sufficiently heat resistant. There is a problem that it cannot be applied to the molding of high moldings.

  Therefore, as a method of obtaining a molded product made of a fiber-reinforced composite material having high heat resistance using a low heat resistant mold such as resin or wood, using a mold having low heat resistance, After performing primary curing at a relatively low temperature, a demoldable primary cured molded product is obtained, and then the primary cured molded product is demolded from the mold having low heat resistance, followed by the primary curing in a high temperature atmosphere. There has been proposed a method for obtaining a molded product made of a fiber-reinforced composite material having high heat resistance by allowing the molded product to stand for secondary curing, for example, a large-scale product that requires heat resistance for aviation, space use, etc. Attempts have been made to form molded articles.

  By the way, when the molding method using the prepreg and applying the curing means including the primary curing and the secondary curing described above is performed, the prepreg is removed by a short-time curing at a relatively low temperature of 100 ° C. or less. It is necessary to be moldable, to be a highly heat-resistant cured product by subsequent secondary curing at a high temperature, and to have excellent stability at room temperature and good handleability of the prepreg itself. It is.

  Under such circumstances, a resin composition that is relatively stable at room temperature and is cured at a relatively low temperature of 70 to 100 ° C. has been disclosed in many technical literatures including, for example, JP-A No. 11-302212. All of these resin compositions are cured at a low temperature and become a primary cured product having excellent mechanical properties, but have sufficient heat resistance even by subsequent secondary curing at a high temperature. I don't want to.

  On the other hand, a conventional resin composition that becomes a cured product having good heat resistance has a problem that it takes a long time to be cured so as to be demoldable by primary curing at a relatively low temperature of 100 ° C. or lower.

Japanese Patent Application Laid-Open No. 11-302412

  Therefore, the problem to be solved by the present invention is that it does not take a long time to obtain a cured product that can be removed by primary curing at a relatively low temperature of 100 ° C. or lower, and high heat resistance is achieved by secondary curing. Epoxy resin composition that becomes a cured product of the epoxy resin, and has excellent properties such as good stability at room temperature and good handleability of a prepreg impregnated with a reinforcing fiber material. The object is to provide a resin composition and a prepreg obtained by impregnating a reinforcing fiber material with the epoxy resin composition.

  The said subject can be solved by the epoxy resin composition of this invention which has the structure described below.

  That is, the epoxy resin composition of the present invention comprises the following components (a), (b) and (c), and consists of an epoxy resin composition which can be cured in two stages.

  (A): Epoxy resin containing at least one of the novolak-type epoxy resin of the following formula (1), the novolak-type epoxy resin of the following formula (2), and tetraglycidyldiaminodiphenylmethane

［式中、ｎは０以上の数を表す］

[Wherein n represents a number of 0 or more]

［式中、ｎは０以上の数を表す］

[Wherein n represents a number of 0 or more]

(B): Latent curing agent having curing ability at 100 ° C. or less (c): Aromatic amine-based curing agent and / or alicyclic amine-based curing agent

  In the epoxy resin composition of the present invention having the above-described configuration, when the mixing ratio of the component (a), the component (b), and the component (c) is 100 parts by mass of the component (a), the component ( It is preferable that b) is 3-40 mass parts and a component (c) is 10-40 mass parts.

  The epoxy resin as the component (a) is preferably an epoxy resin mainly composed of a trifunctional or higher functional epoxy resin.

  The latent curing agent as component (b) is preferably an amine adduct type curing agent, and the latent curing agent constituting component (b) is preferably a microcapsule type curing agent.

  The aromatic amine curing agent and / or the alicyclic amine curing agent as the component (c) is preferably diaminodiphenyl sulfone and / or diaminodiphenylmethane.

  Moreover, it is preferable that the epoxy resin composition of this invention contains the hardening accelerator as a component (d) further.

  Furthermore, the epoxy resin composition of the present invention is such that when the epoxy resin composition is prepared and left to stand at 25 ° C. for 3 weeks, the viscosity is not more than twice the viscosity immediately after preparation of the resin composition. preferable.

  Furthermore, in the epoxy resin composition of the present invention, the degree of cure of a cured product obtained by primary curing within 10 hours at a temperature of 100 ° C. or less is 70% or more, or the JIS-K- of the cured product. It is preferable that the tensile shear strength (adhesive strength) according to 6848 and JIS-K-6850 is 10 MPa or more.

  The prepreg of the present invention is formed by impregnating a reinforcing fiber material with the epoxy resin composition having the above-described configuration.

  The epoxy resin composition of the present invention is excellent in curability at a low temperature of 100 ° C. or lower, and also excellent in stability at room temperature, and by secondarily curing a cured product that has been primarily cured at a low temperature at a high temperature. The cured product has excellent heat resistance. Moreover, since the prepreg of the present invention is obtained by impregnating a reinforcing fiber material with the epoxy resin composition having the above-mentioned characteristics, it has a long working life and good handleability, and at a low temperature of 100 ° C. or less. The cured product is cured in a short time to a demoldable hardness by primary curing, and has excellent heat resistance by subsequent secondary curing at high temperature.

  As the epoxy resin constituting the component (a) in the epoxy resin composition of the present invention, the heat resistance of a cured product obtained by secondary curing is superior by using a resin mainly composed of a tri- or higher functional epoxy resin. It becomes a thing.

  If the content of the tri- or higher functional epoxy resin in the epoxy resin constituting the component (a) is less than 40% by mass, the cured product obtained by secondary curing may not have sufficient heat resistance. For this reason, as an epoxy resin which has a trifunctional or higher functional epoxy resin as a main component, it is preferable that 40 mass% or more in the epoxy resin constituting the component (a) is a trifunctional or higher functional epoxy resin. It is more preferable that 60% by mass or more in the epoxy resin forming the above is a trifunctional or higher functional epoxy resin.

  Examples of the tri- or higher functional epoxy resin include tetraglycidyl diaminodiphenylmethane, aminophenol type epoxy resin, aminocresol type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, and the following formulas (3) and (4) The epoxy resin etc. which are represented are mentioned.

［式中、ｎは０以上の数を表す］

[Wherein n represents a number of 0 or more]

［式中、ｎは０以上の数を表す］

[Wherein n represents a number of 0 or more]

  As the trifunctional or higher functional epoxy resin, a novolac type epoxy resin represented by the formula (3) and / or an epoxy resin containing tetraglycidyldiaminodiphenylmethane is particularly suitable.

  Examples of other epoxy resins other than the tri- or higher functional epoxy resin in the epoxy resin constituting the component (a) include, for example, bisphenol type epoxy resins, hydrogenated bisphenol type epoxy resins, biphenol type epoxy resins, naphthalenediol type epoxy resins, etc. In order to provide a high degree of heat resistance to the cured product obtained by secondary curing, an epoxy resin having a relatively rigid skeleton structure such as a biphenol type epoxy resin or a naphthalene diol type epoxy resin is used. Is preferred.

In addition, when a pre-reacted product of, for example, bisphenol S-type epoxy resin or aromatic diamine and bisphenol-type epoxy resin having an SO ₂ structure is used, it has relatively high heat resistance due to secondary curing and is excellent in toughness. It becomes a hardened product.

  Furthermore, when an epoxy resin having an oxazolidone ring represented by the following formula (5) is used, an epoxy resin composition having good adhesion to the reinforcing fiber material is obtained, so that the fiber-reinforced composite material having excellent mechanical properties is obtained. Become.

［式中、Ｒは水素原子又はアルキル基を表す］

[Wherein R represents a hydrogen atom or an alkyl group]

  In addition, when the epoxy resin having an oxazolidone ring is an epoxy resin composed of a unit represented by the following formula (6), an adhesive resin with a reinforcing fiber material has an even better epoxy resin composition. It becomes a fiber reinforced composite material having excellent mechanical properties.

［式中、Ｒはそれぞれ独立して水素原子又はアルキル基を表し、Ｒ_１〜Ｒ_８はそれぞれ独立してハロゲン原子、水素原子、または炭素数１〜４のアルキル基を表し、Ｒ_９は下記式（７）又は（８）の基を表す］

[Wherein, R independently represents a hydrogen atom or an alkyl group, R _{1 to} R ₈ each independently represents a halogen atom, a hydrogen atom, or an alkyl group having 1 to 4 carbon atoms, and R ₉ represents Represents a group of formula (7) or (8)]

［式中、Ｒ’_１〜Ｒ’_４は、それぞれ独立して水素原子又は炭素数１〜４のアルキル基を表す］

[Wherein, R ′ _{1 to} R ′ ₄ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms]

［式中、Ｒ’_１〜Ｒ’_８は、それぞれ独立して水素原子又は炭素数１〜４のアルキル基を表し、Ｒ’_９は単結合、−ＣＨ_２−、−Ｃ（ＣＨ_３）_２−，−ＳＯ_２−、−ＳＯ−、−Ｓ−又は−Ｏ−を表す］

[Wherein, R ′ _{1 to} R ′ ₈ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ′ ₉ represents a single bond, —CH ₂ —, —C (CH ₃ ) _{2. -, - SO 2 -, -} SO -, - representing the S- or -O-]

  Examples of the epoxy resin having an oxazolidone ring represented by the formula (5) include Araldite XAC4151 and XAC4152 manufactured by Asahi Ciba.

  Next, the curing agent constituting the component (b) is a latent curing agent having a curing ability at 100 ° C. or less. That is, the curing agent constituting the component (b) has a curing ability at 100 ° C. or less and has a latent heat reactivity, that is, a latent property.

  Whether or not the curing agent has a curing ability at 100 ° C. or less is determined as follows. That is, an epoxy resin composition in which 100 parts by mass of a liquid bisphenol A type epoxy resin having an epoxy equivalent of 184 to 194 (for example, Epicoat 828 manufactured by Japan Epoxy Resin Co., Ltd.) and 20 parts by mass of a curing agent are uniformly mixed is 10 by DSC. The curing agent is measured at a temperature increase rate of ℃ / min. When the temperature at which the curing exotherm starts is 100 ° C. or less, the curing agent is less than 100 ° C. Judged as having curing ability. Use of a curing agent having a temperature at which curing exotherm begins at 90 ° C. or lower is preferable because an epoxy resin composition having good reactivity at 90 ° C. or lower is obtained.

  Secondly, the fact that the curing agent is heat latent reactivity, that is, latent, means that it hardly reacts near room temperature. Confirmation of the potential of the curing agent that hardly reacts near room temperature is performed as follows. That is, an epoxy resin composition in which 100 parts by mass of a liquid bisphenol A type epoxy resin having an epoxy equivalent of 184 to 194 (for example, Epicoat 828 manufactured by Japan Epoxy Resin Co., Ltd.) and 20 parts by mass of a curing agent were uniformly mixed at 30 ° C. It can be said that the curing agent is latent when the viscosity when left for 3 weeks is within 2 times the viscosity before standing. The curing agent such that the viscosity when the epoxy resin composition is allowed to stand at 30 ° C. for 3 weeks is within 1.5 times the viscosity before being left has excellent latent reactivity, preferable.

  In addition, the viscosity of the epoxy resin composition containing the said hardening | curing agent is measured as follows. That is, using a DRM-200 manufactured by Rheometrics Co., Ltd. or a measuring instrument having equivalent performance, using two disk plates with a diameter of 25 mm under a condition of a shear rate of 10 radians / second, with a disk plate interval of 0.5 mm Measure the isothermal viscosity at 30 ° C. and capture the data 10 minutes after the start of measurement. The viscosity of the epoxy resin composition for measurement is measured by this method before and after being left to stand at 30 ° C. for 3 weeks, and the presence or absence of latent reactivity is determined.

  The curing agent as the component (b) is not particularly limited as long as it has a curing ability at 100 ° C. or less as described above, and has heat latent reactivity. By using a curing agent, the epoxy resin composition of the present invention can be excellent in the balance between curability at 90 ° C. or lower and stability near room temperature. Examples of the curing agent as the component (b) having a curing ability at 100 ° C. or less and a latent property at room temperature include NovaCure HX3721 and HX3722 manufactured by Asahi Ciba.

  Furthermore, an epoxy resin composition using an amine adduct type curing agent as the curing agent constituting the component (b) has a curing ability at 90 ° C. or less and has a good stability near room temperature. Furthermore, it is more preferable. As this amine adduct type curing agent, Fuji Chemical FXE1000 FXE1030, Ajinomoto PN-23, ACR Hardener H-3615, H-4070, H-3293, H-3366, H-3849, H-3670, cure duct P-0505 manufactured by Shikoku Kasei Kogyo Co., Ltd. and the like.

  The blending amount of the latent curing agent constituting the component (b) is such that the blending amount of the latent curing agent constituting the component (b) is 3 parts by mass when the epoxy resin constituting the component (a) is 100 parts by mass. If the amount is too small, primary curing at a low temperature of 100 ° C. or less often becomes insufficient, and if it exceeds 40 parts by mass, the stability of the resin composition at room temperature may be reduced. A range of 40 parts by weight is preferred. In addition, when using the paste-form hardening | curing agent which mixed the hardening | curing agent with low-viscosity epoxy resin etc. beforehand, it is needless to say that it is the mass of the hardening | curing agent only of an active ingredient.

  The epoxy resin composition of the present invention is cured in a primary curing step at a relatively low temperature and in a relatively short time, so that it can be removed by the action of the curing agent constituting the component (b). The cured product has a high degree of heat resistance in which a crosslinked structure is completed by the action of the aromatic amine-based curing agent and / or the alicyclic amine-based curing agent forming the component (c) by subsequent high-temperature secondary curing. That is, a cured product having a high glass transition temperature and excellent rigidity at high temperatures.

  Of the aromatic amine-based curing agents and / or alicyclic amine-based curing agents that constitute component (c), aromatic polyamines are preferred, such as xylenediamine, diaminodiphenylmethane, and diaminodiphenyl. Examples include sulfone, phenylenediamine, and dimethylthiotoluenediamine. Diaminodiphenylmethane and diaminodiphenylsulfone are preferable, and 3,3′-diaminodiphenylsulfone and 4,4′-diaminodiphenylsulfone are preferable as diaminodiphenylsulfone. Can be mentioned.

  The alicyclic amine-based curing agent is preferably an alicyclic polyamine, such as mensendiamine, isophoronediamine, bis (4-amino-3-methylcyclohexyl) methane, bis (4-aminocyclohexyl) methane, Bis (aminomethyl) cyclohexane is mentioned.

  The compounding amount of the aromatic amine-based curing agent and / or the alicyclic amine-based curing agent forming the component (c) is the component (c) when the epoxy resin forming the component (a) is 100 parts by mass. If the curing agent is less than 10 parts by mass, the glass transition temperature and / or high-temperature rigidity of the cured product obtained by secondary curing tends to be low, and if it exceeds 40 parts by mass, the cured product obtained by secondary curing. Since the amount of unreacted amine residues increases and the hygroscopicity increases or becomes brittle, the amount is preferably in the range of 10 to 40 parts by mass.

  The epoxy resin composition of the present invention may further contain a curing accelerator as a component (d) for accelerating curing when obtaining a primary cured product, for example, a urea compound, a cyano compound, a dihydrazide compound. A curing accelerator composed of an acid anhydride or the like can be blended as the component (d).

  Epoxy resin composition excellent in curability of primary curing at a relatively low temperature without impairing the stability at room temperature of the resin composition by using a urea compound as a curing accelerator to be component (d). It can be a thing. As a urea compound mix | blended as a hardening accelerator which makes a component (d), an aromatic urea compound is especially preferable, and the compound represented by following formula (9) is more preferable.

［式中、Ｘ_１、Ｘ_２は水素又は塩素を表し、Ｘ_１とＸ_２は同一であっても相異なっていてもよい］

_Wherein, X 1, _{X 2} represents hydrogen or chlorine, _{X 1} and _{X 2} may be different from each be the same]

  In the epoxy resin composition of the present invention, the viscosity when the epoxy resin composition is prepared and left at 25 ° C. for 3 weeks is not more than twice the viscosity immediately after preparation of the resin composition, that is, at room temperature. It is preferable to be cured so as to be demoldable by primary curing within 100 hours or less and within 10 hours, and to be demoldable by primary curing within 100 hours or less within 5 hours. In some cases, it is more preferable in terms of a molding cycle, and it is even more preferable if it is cured so as to be demoldable by primary curing at 90 ° C. or less within 5 hours.

  In addition, when the epoxy resin composition is prepared and left to stand at 25 ° C. for 3 weeks, the viscosity of the epoxy resin composition is not more than 1.5 times the viscosity immediately after the preparation of the resin composition, the working life of the epoxy resin composition is It becomes longer and more preferable.

  The viscosity of the epoxy resin composition is measured by the following method. That is, the viscosity ηi at 40 ° C. of the epoxy resin composition immediately after preparation was measured on a parallel plate at a frequency of 10 radians / second using a DSR-200 manufactured by Rheometric Co., Ltd. or an apparatus having equivalent performance, and then the epoxy resin composition was measured. After leaving the resin composition in a 25 ° C. incubator for 3 weeks, the viscosity η at 40 ° C. is measured in the same manner as described above, and the viscosity increase ratio is determined by η / ηi.

  Whether or not the epoxy resin composition is cured so as to be demoldable by primary curing is determined by the following method. That is, the curing heat value (Ei) of the prepared epoxy resin composition and the primary curing heat value (E1) of the epoxy resin composition were measured using a differential scanning calorimeter (DSC), respectively, and the degree of cure ( %) = {(Ei)-(E1)} × 100 / Ei, the degree of cure is 70% or more, or the primary cured product of the epoxy resin composition is JIS-K-6848, JIS-K- It can be said that when the tensile shear strength (adhesive strength) according to 6850 is 10 MPa or more, it is cured so as to be demoldable.

Measurement of the tensile shear strength (adhesion strength) of the primary cured product of the epoxy resin composition according to JIS-K-6848 and JIS-K-6850 was performed on an aluminum plate of 25 × 100 × 1.5 mm (JIS-H-4000). 12.5mm lapping part of A2024P) is polished with sandpaper (# 240), degreased with acetone, and then the epoxy resin composition for measurement is uniformly applied to this lapping part, and then polished in the same manner The sample is prepared by superposing the lap portions of another aluminum plate that has been degreased, fixing it at a pressure of 1 kgf / cm ² , first hardening it, and then gradually cooling it to room temperature.

  Furthermore, the epoxy resin composition of the present invention has a glass transition temperature of 150, which is obtained by subjecting a primary cured product cured at a low temperature of 100 ° C. or lower to a secondary curing at a temperature of 130 ° C. or higher. Those that are at or above ° C are preferred. In particular, an epoxy resin composition in which the glass transition temperature of a cured product obtained by secondary curing at 150 ° C. or higher (for example, 180 ° C.) is 180 ° C. or higher becomes a cured product with more excellent heat resistance. The curing time for secondary curing is not particularly limited, but is preferably within 10 hours, and more preferably within 5 hours.

  The glass transition temperature of the cured product is measured by the following method. That is, when the temperature of the cured product for measurement is raised stepwise by the rheometric RDA-700 or a viscoelasticity measuring device having equivalent performance, the temperature is raised stepwise. Is measured at each temperature. The temperature is raised at 5 ° C./step. In each step, the temperature is maintained for 1 minute after the temperature is stabilized, and then measured at a frequency of 10 radians / second. As shown in FIG. 1, the logarithmic value of the storage elastic modulus (G ′) is plotted against the temperature, and the temperature at the intersection of each tangent of the obtained G ′ curve is defined as the glass transition temperature.

  Additives can be added to the epoxy resin composition of the present invention within a range not departing from the object of the present invention. For example, by dissolving and adding a thermoplastic resin, the tackiness of the resin composition can be suppressed, and the tackiness of the prepreg can be adjusted to an appropriate level, or the change with time of tack can be suppressed. Examples of such thermoplastic resins include phenoxy resin, polyvinyl formal, polyethersulfone, and the like.

  In addition, for the purpose of improving the toughness of the resulting cured product, a fine particle or short fiber thermoplastic resin or rubber component may be added to the epoxy resin composition of the present invention. And thermoplastic resins such as polyurethane and polyethersulfone; rubber components such as acrylic rubber, butadiene rubber and butyl rubber; and molecular end-modified products thereof.

  Furthermore, fine particles of inorganic components such as metals such as talc, silica, and steel can be added to the epoxy resin composition of the present invention for the purpose of improving the rigidity of the resulting cured product.

  The use of the epoxy resin composition of the present invention is not particularly limited. For example, it can be applied as a matrix resin for a fiber reinforced composite material, an adhesive for a structural material, etc. It can be particularly suitably used as a matrix resin.

  The fiber reinforced composite material for molding the fiber reinforced composite material is not particularly limited. For example, carbon fiber, glass fiber, high strength organic fiber, metal fiber, inorganic fiber, etc. Any of those used as the reinforcing fiber material can be used. The form of the reinforcing fiber material is not particularly limited, and for example, a unidirectional material, a cloth, a mat, or a tow composed of thousands or more filaments can be used.

  In the epoxy resin composition of the present invention, those having a viscosity at 60 ° C. of 10 Pa · sec or more, preferably 30 Pa · sec or more and 700 Pa · sec or less, preferably 500 Pa · sec or less are reinforced fiber materials. It is suitable as a matrix resin when making a so-called prepreg impregnated with a matrix resin.

  In other words, when the viscosity of the epoxy resin composition at 60 ° C. is lower than 10 Pa · sec, the tack and stickiness of the prepreg becomes too strong, which is not preferable, and when it exceeds 700 Pa · sec, the drapability of the prepreg is poor and stiff. Pass. The method for measuring the viscosity of the epoxy resin composition at 60 ° C. is the same as the method for measuring the viscosity of the epoxy resin composition described above, except that the measurement temperature is 60 ° C.

  Moreover, the epoxy resin composition of the present invention can be used as a sheet-like adhesive by making it into a film to suppress the resin flow or impregnating it with a glass cloth or the like. Furthermore, the epoxy resin composition of the present invention can be used as a light weight auxiliary material by adding a microballoon or a foaming agent as an additive thereto.

  Furthermore, when a high toughness material such as a thermoplastic resin or a rubber component is selectively disposed near the surface of the prepreg impregnated with the epoxy resin composition of the present invention, the toughness between the layers of the resulting laminated cured product is increased. Can be cured at a low temperature of 100 ° C. or lower, so that even when a low-melting thermoplastic resin is disposed, it can be molded while maintaining its form. For this reason, morphological control is easy, and a high-toughness material such as a thermoplastic resin or a rubber component in a designed amount can be arranged between layers, and a designed interlayer toughness can be obtained. The form of the high toughness material such as the thermoplastic resin or rubber component to be disposed between the layers is not particularly limited, but the ones in the form of particles, long fibers or single fibers are selected between the layers. In particular, a highly tough material can be arranged, which is preferable.

  The method for preparing the epoxy resin composition of the present invention is not particularly limited, but when a solid epoxy resin, a thermoplastic resin, or the like is dissolved and blended, the solid component is first uniformly formed into a soluble epoxy resin. It is preferable to use after dissolving.

  The addition of a latent curing agent having a curing ability at 100 ° C. or less forming component (b) is relatively low in the epoxy resin component forming component (a) when component (b) is in powder form. If the epoxy resin or the like is used to make a paste and then added, secondary agglomeration of the powdery component (b) can be prevented and the powder can be uniformly dispersed. When the component (b) is solid, it is preferably pulverized into a powder and then added as a paste with a low viscosity epoxy resin or the like. In the case where the component (b) is a microcapsule type latent curing agent, stirring with a strong shear stress adversely affects the capsule and impairs stability at room temperature. Therefore, as the microcapsule-type latent curing agent, it is preferable to use a masterbatch type that is uniformly mixed with a low-viscosity epoxy resin in advance.

  The aromatic amine-based curing agent and / or the alicyclic amine-based curing agent constituting the component (c) is, when the component (c) is not dissolved by the primary curing, that is, whether the melting point of the component (c) is higher than the primary curing temperature. Alternatively, when the melting temperature of the component (c) in the epoxy resin is higher than the primary curing temperature, it is preferably dissolved in the epoxy resin of the component (a) in advance. In the case of powder form in which component (c) is dissolved by primary curing, it is made into a powder form by adding it after making it into a paste form with a relatively low viscosity epoxy resin or the like in component (a). Secondary aggregation of the component (c) can be prevented and it can be uniformly dispersed. Furthermore, when the component (c) is in a solid form that dissolves by primary curing, it is preferably pulverized into a powder and then added in a paste form with a low viscosity epoxy resin or the like. When the component (c) is in a liquid state, it is mixed evenly at any stage.

  Since the epoxy resin composition of the present invention has the property of initiating the reaction at a low temperature, after the addition of the latent curing agent constituting the component (b), the epoxy resin composition is stable at room temperature. It is preferable to prepare at 70 ° C. or lower. In addition, if it prepares at 60 degrees C or less, the stability at room temperature of an epoxy resin composition will further improve.

  Moreover, as a method for preparing a prepreg using the epoxy resin composition of the present invention, a hot melt system is preferable. Release process when obtaining a film-formed epoxy resin composition used for preparing a prepreg by a hot melt method When applying an epoxy resin composition to paper, it is applied at 70 ° C. or lower in order to stabilize the life of the prepared prepreg. It is preferable to apply, and it is more preferable to apply at 60 ° C. or less.

  Hereinafter, specific configurations of the epoxy resin composition of the present invention and a prepreg using the epoxy resin composition will be described based on examples and compared with comparative examples. In addition, each component used for the epoxy resin composition of an Example and a comparative example is as showing with the following abbreviation.

(1) Trifunctional or higher functional epoxy resin Ep604: Tetraglycidyldiaminodiphenylmethane “Epicoat 604” manufactured by Japan Epoxy Resin Co., Ltd.
TACTIX 742: manufactured by Dow Chemical Co., Ltd., solid trifunctional epoxy resin “TACTIX 742” corresponding to n = 0 in the formula (1)
Ep1032: manufactured by Japan Epoxy Resin Co., Ltd., special novolac type epoxy resin “Epicoat 1032S50” corresponding to n> 0 in formula (1)
Ep157: EP157S65: manufactured by Japan Epoxy Resin Co., Ltd., special novolac epoxy resin “Epicoat 157S65” corresponding to n> 0 in formula (2)
ELM-100: Aminophenol type epoxy resin “Sumi-Epoxy ELM-100” manufactured by Sumitomo Chemical Co., Ltd.
N-740: Dainippon Ink Chemical Co., Ltd., phenol novolac type epoxy resin “Epicron N-740”
N-670: Dainippon Ink Chemical Co., Ltd., cresol novolac type epoxy resin “Epicron N-670”

(2) Epoxy resins other than tri- or higher functional epoxy resins Ep828: Japan Epoxy Resin Co., Ltd., liquid bisphenol A type epoxy resin “Epicoat 828”
Ep1001: Semi-solid bisphenol A type epoxy resin “Epicoat 1001” manufactured by Japan Epoxy Resin Co., Ltd.
Ep5050: Made by Japan Epoxy Resin, Flame Retardant Epoxy Resin “Epicoat 5050”
XAC4152: Asahi Ciba, modified epoxy resin "Araldite XAC4152"

(3) Latent curing agent having curing ability at 100 ° C. or lower HX3722: “Novacure HX3722” manufactured by Asahi Ciba
FXE1000: manufactured by Fuji Kasei Co., Ltd., “Fujicure FXE-1000”
PN23: “Amicure PN-23” manufactured by Ajinomoto Co., Inc.

(4) Aromatic amine-based or alicyclic amine-based curing agent DDS: manufactured by Wakayama Seika Co., Ltd., diaminodiphenyl sulfone “Seika Cure S”
DDM: manufactured by Hodogaya Chemical Co., Ltd., diaminodiphenylmethane BACHM: manufactured by Shin Nippon Rika Co., Ltd., bis (4-aminocyclohexyl) methane “Wandamine HM”
ET300: manufactured by Ethyl Corporation, dimethylthiotoluenediamine "Etacure 300"

(5) Curing accelerator PDMU: manufactured by BTR Japan, Phenyldimethylurea "Omicure 94"
DCMU: Hodogaya Chemical Co., Ltd., dichlorophenyldimethylurea “DCMU99”

(6) Other components PES: manufactured by Sumitomo Chemical Co., Ltd., polyethersulfone "Sumika Excel PES 3600P"
Aerosil 300: “Aerosil 300” manufactured by Nippon Aerosil Co., Ltd.
BF3MEA: Boron trifluoride monomethylamine complex Dicy: Japan Epoxy Resin, Dicyandiamide “Dicy7”
T # 241: manufactured by Fuji Kasei Co., Ltd., tomide # 241

Examples 1-11
The epoxy resin composition by the composition component described in each predetermined column of the following Table 1 and Table 2 was obtained. In addition, the number in a table | surface shows the mass part of the mix | blended component.

  The blending procedure of each component is as follows. First, the epoxy resin constituting component (a) was heated to 150 ° C. and uniformly mixed. In addition, when there existed other components, such as a thermoplastic resin and an inorganic substance, in a compounding component, the other component was added at the time of heat mixing of this component (a), and it dissolved or disperse | distributed.

  Next, after the component (a) or a mixture of the component (a) and other components is lowered to 130 ° C., an aromatic amine-based curing agent and / or an alicyclic amine-based curing agent forming the component (c) Was added and dissolved uniformly. Immediately after that, it is cooled to 50 to 60 ° C., and when there is a component (b) and a curing accelerator as component (d), this component (d) is added and mixed uniformly. An epoxy resin composition was prepared.

  The stability of each of the obtained epoxy resin compositions was evaluated by the ratio of increase in viscosity (viscosity increase ratio) when left at 25 ° C. for 3 weeks. The results are shown in Table 1 and Table 2.

  Moreover, after heating the obtained epoxy resin composition to 60 degreeC and defoaming, it casts by 2 mm thickness on the glass plate which has performed the mold release process, and also with the glass plate which has performed the same process After sandwiching, the temperature was raised to 100 ° C. over 1 hour, followed by primary curing at 100 ° C. for 4 hours. The degree of cure in this primary curing was determined by the above-described method for measuring the degree of cure using DSC. The obtained results are also shown in Tables 1 and 2. On the other hand, each of the obtained epoxy resin compositions was heated to 100 ° C. over 1 hour, and then subjected to primary curing at 100 ° C. for 4 hours, JIS-K-6848, JIS-K of the primary cured product. The tensile shear strength (adhesion strength) was measured by -K-6850. The obtained results are also shown in Tables 1 and 2.

  Subsequently, after removing the primary cured product obtained when determining the degree of cure of the cured product by the primary curing, leaving it in a free stand state in a hot air oven, and raising the temperature to 180 ° C. over 2 hours , 180 ° C., 4 hours secondary curing. The glass transition temperature (° C.) of the obtained secondary cured product is shown in Table 1 and Table 2 together with the values of G ′ at 150 ° C. and 180 ° C. In addition, the value of G ′ at 150 ° C. and 180 ° C. is a measure of the physical properties at high temperature of the composite material using this epoxy resin composition.

Comparative Example 1
An epoxy resin composition having the composition components described in the predetermined column of Table 3 below was obtained by dissolving and mixing DDS in Ep604 at 130 ° C. and immediately lowering to 70 ° C., followed by dissolving and mixing BF3MEA.

  The obtained epoxy resin composition was stable at room temperature and cured at 180 ° C. for 2 hours to become a cured product having a glass transition temperature (° C.) of 205 ° C., but was subjected to primary curing at 100 ° C. for 10 hours. However, it was poorly cured.

Comparative Example 2
By mixing Ep828 and Ep1001 uniformly at 120 ° C. at a temperature of 120 ° C. and then adding HX3722 and PDMU after mixing the epoxy resin composition having the composition components described in the predetermined column of Table 3 below at 120 ° C. Obtained.

  About the obtained epoxy resin composition, it carried out similarly to having demonstrated in Example 1, the stability of an epoxy resin composition, the hardening degree of the primary hardened | cured material which carried out the primary hardening for 4 hours at 100 degreeC, and primary hardening. The tensile shear strength (adhesive strength) of the product, the glass transition temperature (° C.) of the secondary cured product subjected to secondary curing at 180 ° C. for 4 hours, and the values of G ′ at 150 ° C. and 180 ° C. were measured. The results are also shown in Table 3. In addition, this epoxy resin composition did not have sufficient heat resistance in the cured product after the secondary curing.

Comparative Example 3
The epoxy resin composition having the composition components described in the prescribed column of Table 3 below is mixed with Ep1032, Ep828 and Ep1001 uniformly at 120 ° C, then lowered to 70 ° C, and then PDMU and Dicy are added and dispersed. Obtained by mixing.

  About the obtained epoxy resin composition, it carried out similarly to the comparative example 2, stability of an epoxy resin composition, the hardening degree of a primary cured material, the tensile shear strength (adhesion strength) of a primary cured material, The values of G ′ at glass transition temperature (° C.), 150 ° C. and 180 ° C. were measured. The results are also shown in Table 3. In addition, this epoxy resin composition did not have sufficient heat resistance in the cured product after the secondary curing.

Example 12
The same epoxy resin composition as in Example 2 was prepared. The epoxy resin composition has a viscosity at 60 ° C. of 100 Pa · sec. This epoxy resin composition heated to 60 ° C. was uniformly coated on the release process paper to prepare a resin film having a basis weight of 80 g / m ² .

Next, on the resin film, carbon fibers “TR50S-12L” manufactured by Mitsubishi Rayon Co., Ltd. are aligned in one direction so that the carbon fiber basis weight is 150 g / m ² , and then heated and pressed. A unidirectional prepreg obtained by impregnating carbon fiber with an epoxy resin composition was obtained. This prepreg had good tack and drape.

  Furthermore, after the prepreg was allowed to stand at 25 ° C. for 3 weeks, the prepreg tack and draping property were evaluated by tactile sensation. Had.

  Subsequently, the prepreg was aligned in one direction and 14 ply laminated, and was primarily cured by vacuum bag molding. The primary curing at this time was performed by raising the temperature from room temperature to 100 ° C. over 1 hour and then at 100 ° C. for 4 hours. The molded product obtained by the primary curing was sufficiently demoldable and did not cause cracking even when cut with a diamond wet cutter. G ′ of the molded product by the primary curing was 120 ° C.

  Further, the molded product by the primary curing was left in a hot air oven (free stand) and subjected to secondary curing. The secondary curing was performed according to conditions in which the temperature was raised from room temperature to 180 ° C. over 3 hours, maintained at 180 ° C. for 4 hours, and further cooled to room temperature over 3 hours.

  When ultrasonic inspection was performed on the obtained cured product having a thickness of about 2 mm, it was found that almost no voids were generated. Further, a specimen was cut out from the cured product and the glass transition temperature (° C.) was determined by measuring G ′, which was 199 ° C. Further, the cured product was measured for interlaminar shear strength at room temperature (23 ° C.), 100 ° C., 160 ° C., and 180 ° C. in accordance with ASTM D 2344. The results are shown in Table 4.

Example 13
The same epoxy resin composition as in Example 9 was prepared. The epoxy resin composition has a viscosity at 60 ° C. of 50 Pa · sec. Using this epoxy resin composition, a unidirectional prepreg was obtained in the same manner as in Example 12. This prepreg had good tack and drape properties, and even after being left at 25 ° C. for 3 weeks, there was little change in tack and drape properties, and it had a good life.

  Further, in the same manner as in Example 12, when the primary cured molded plate by the unidirectional prepreg was molded, the molded product obtained by the primary curing was sufficiently demoldable, and a diamond wet cutter was used. Even if it cut | disconnects, it was a thing which does not produce a crack. G ′ of the molded product by the primary curing was 115 ° C.

  Subsequently, the molded product by the primary curing was left in a hot air oven (free stand) and subjected to secondary curing. The secondary curing was performed in the same manner as in Example 12.

  When ultrasonic flaw detection was performed on the obtained cured product having a thickness of about 2 mm, it was found that some voids were generated, but there was no problem. Furthermore, when a glass transition temperature (° C.) was determined by cutting a test body from this cured product and measuring G ′, it was 189 ° C. Moreover, about this hardened | cured material, the interlayer shear strength in room temperature (23 degreeC), 100 degreeC, 160 degreeC, and 180 degreeC was measured based on ASTMD2344. The results are also shown in Table 4.

Example 14
The epoxy resin composition by the composition component described in the predetermined column of the following Table 5 was obtained. When the curing ability of HX3722 as the component (b) was examined, the temperature at which curing exotherm began was 86 ° C., and the curing ability was 100 ° C. or lower. Further, when the stability at room temperature, that is, the latent reactivity, was examined, the thickening ratio was 1.1 times, it was very stable near room temperature, and it had excellent potential.

  In addition, the compounding procedure of the epoxy resin composition is as follows. First, after adding the component (c) to the component (a) other than Ep828 in the component (a) and dissolving at 100 ° C., the temperature is immediately lowered to 50 ° C., Ep828 And component (b) were added and mixed uniformly. When the stability of this epoxy resin composition was confirmed by the ratio of thickening when left at 25 ° C. for 3 weeks, it was 1.5 times, indicating excellent stability at 25 ° C.

  Next, the epoxy resin composition was subjected to primary curing at 90 ° C. for 2 hours to form a 2 mm thick molded plate.

  The mold could be removed without any problem when it was removed from the mold .... ◎, it was possible to remove the mold ...., it was bent or cracked and could not be removed successfully. It is shown in Table 5 by X.

  Subsequently, the primary cured molded plate was subjected to secondary curing at 200 ° C. for 4 hours. The glass transition temperature (° C.) Tg of the cured plate obtained by the secondary curing was 185 ° C. as determined by a measurement method by G ′ temperature dispersion in RDS-700 manufactured by Rheometrics. The results are summarized in Table 5.

Examples 15-22
The epoxy resin composition by the composition component shown in each predetermined column of Table 5 and Table 6 was obtained.

  The compounding procedure of the epoxy resin composition is that the component (a) has Ep828, that is, Example 15, Example 16, Example 17, Example 20 and Example 22 are the same as the component (a) other than Ep828. After the component (c) was added and dissolved at 100 ° C., the temperature was immediately lowered to 50 ° C., and a mixture in which Ep828 and PDMU as the component (d) were uniformly mixed with three rolls, b) was added and mixed uniformly. Moreover, what does not have Ep828 in a component (a) is as follows. First, Example 18 was prepared by dissolving the total amount of TACTIX 742 in component (a), 30 parts by mass of N-740 and component (c) at 100 ° C., then immediately lowering the temperature to 50 ° C. A mixture in which 3 parts by mass of N-740 and component (d) were uniformly mixed with three rolls and component (b) were added and mixed uniformly.

  Example 19 was prepared by dissolving the total amount of Ep1032, 30 parts by mass of N-670 and component (c) at 100 ° C., and immediately lowering the temperature to 50 ° C., to which 20 parts by mass of N-740 and components A mixture obtained by uniformly mixing (d) with three rolls and component (b) were added and mixed uniformly.

  In Example 21, the total amount of Ep1032, the total amount of XAC4152, 20 parts by mass of Ep604 and component (c) were dissolved at 100 ° C, and the temperature was immediately lowered to 50 ° C, to which 20 parts by mass of Ep604 and components A mixture obtained by uniformly mixing (d) with three rolls and component (b) were added and mixed uniformly.

  The stability of each epoxy resin composition according to the above Examples 15 to 22 was examined by the rate of thickening when left at 25 ° C. for 3 weeks. The results are shown in Tables 5 and 6. Further, the demoldability of the primary cured product of each epoxy resin composition and the Tg of the secondary cured product were evaluated in the same manner as in Example 14. The results are shown in Tables 5 and 6.

Comparative Example 4
The epoxy resin composition by the composition component shown in the predetermined column of Table 7 was obtained. The blending procedure was the same as Example 15 except that HX3722 was not added. An attempt was made to evaluate the demoldability of the primary cured product of the obtained epoxy resin composition in the same manner as in Example 14, but it was not cured by primary curing at 90 ° C. for 2 hours.

Comparative Example 5
The epoxy resin composition by the composition component shown in the predetermined column of Table 7 was obtained. The blending procedure was the same as in Example 15 except that DDS was not added. When the mold release property of the primary cured product of the obtained epoxy resin composition was evaluated in the same manner as in Example 14, the mold release property in the primary cure was good. Furthermore, Tg after secondary curing was measured in the same manner as in Example 14, and it was 134 ° C., which was low.

Comparative Example 6
The epoxy resin composition by the composition component shown in the predetermined column of Table 7 was obtained. The blending procedure was the same as Example 15 except that HX3722 was not added. Dicy was mixed uniformly with three rolls in addition to 20 parts by mass of Ep828 together with PDMU.

  An attempt was made to evaluate the demoldability of the primary cured product of the obtained epoxy resin composition in the same manner as in Example 14. However, the primary curing at 90 ° C. for 2 hours could not be demolded due to insufficient curing.

  Dicy used in this comparative example is an excellent latent curing agent and can be used in general as a curing agent for epoxy resin compositions for prepregs because it can lower the activation temperature when used in combination with a urea compound. However, even if it is a Dicy / PDMU system as in this comparative example, the curing start temperature is 115 ° C., and it does not have curing ability at 100 ° C. or less.

Examples 23-26
The epoxy resin composition by the composition component shown in the predetermined column of Table 8 was obtained. In addition, as for a mixing | blending procedure, what does not mix | blend other components, ie, in Example 23 and Example 24, 100 mass parts of Ep1032 and 30 mass parts Ep604 in a component (a), and a component (c) are set to 100. Immediately after dissolution at 0 ° C., the temperature is lowered to 50 ° C. If there is a component (b) and a curing accelerator as component (d), 20 mass in component (d) and component (a) A mixture obtained by uniformly mixing a part of Ep604 with three rolls was added, and the entire composition was uniformly mixed.

  In Example 25, PES was added to 50 parts by mass of Ep1032 and 30 parts by mass of Ep604 in the component (a), and PES was dissolved at 150 ° C. After addition and dissolution, the subsequent procedure was the same as in Example 23.

  In Example 26, there was no mixture obtained by uniformly mixing Aerosil 300, PDMU, and 20 parts by mass of Ep604 with three rolls, and the other procedures were the same as in Example 23.

  The viscosity at 60 ° C. of the epoxy resin composition, the rate of thickening when left at 25 ° C. for 3 weeks, the flexural modulus of the primary cured product subjected to the primary curing at 90 ° C. for 2 hours, and this primary The cured product was subjected to secondary curing at 200 ° C. for 4 hours, and the Tg of the secondary cured product and the retention rate (%) of the elastic modulus with respect to 30 ° C. at 180 ° C. were measured.

  The glass transition temperature (° C.) Tg was determined from the temperature dispersion of G ′. Further, the elastic modulus retention rate (%) of 180 ° C. with respect to 30 ° C. was determined by measuring the value of G ′ at 30 ° C. and the value of G ′ at 180 ° C., and “(G ′ at 180 ° C.) × 100 / (G ′ at 30 ° C.) ”. The results are also shown in Table 8.

Furthermore, each epoxy resin composition was impregnated by a hot melt method into a reinforcing fiber material in which Mitsubishi Rayon Pyrofil carbon fiber TR50S-12L was aligned in one direction, and a fiber basis weight of 125 g / m ² , a resin content of 30 A mass% prepreg was obtained.

  When the tack of this prepreg was evaluated by tactile sensation, it had a suitable tack and was good. Further, even after this prepreg was left at 25 ° C. for 20 days, it had an appropriate tack, and it was confirmed that the prepreg had a life of 20 days or longer.

  Using the prepreg, a molded plate having a thickness of 2 mm in one direction was molded by primary curing at 90 ° C. for 2 hours. The demoldability of this primary cured product was good. Further, the decured primary cured product was further subjected to secondary curing at 200 ° C. for 4 hours, and the ILRP at 150 ° C. was measured in accordance with ASTM D2344-84 for the CFRP panel after the secondary curing. However, it was confirmed that the mechanical properties at high temperatures were excellent. The results are also shown in Table 8.

Comparative Example 7
After obtaining an epoxy resin composition having the composition components shown in the predetermined column of Table 9, using the epoxy resin composition, a prepreg was prepared in the same manner as in Example 23, and a primary cured product was further obtained using the prepreg. Although it tried to shape | mold like Example 23, it did not harden | cure by primary curing.

Comparative Example 8
After obtaining an epoxy resin composition having the composition components shown in the predetermined column of Table 9, using the epoxy resin composition, a prepreg was prepared in the same manner as in Example 23. The next cured product was molded.

  In addition, T # 241 used for the epoxy resin composition of this comparative example is a curing agent having a curing ability at 100 ° C. or less, but has no latent reactivity, and the latent reactivity is evaluated. As a result, it was cured after one day. Therefore, the viscosity of the epoxy resin composition increased rapidly, and was completely cured after 3 weeks at 25 ° C. Therefore, the life of the prepreg was short, and the tack was completely lost after 3 days, and the life was expired.

Comparative Example 9
After obtaining an epoxy resin composition having the composition components shown in the predetermined column of Table 9, using the epoxy resin composition, a prepreg was prepared in the same manner as in Example 23. The next cured product was molded.

  In addition, since the epoxy resin composition of this comparative example does not contain the component (c), the Tg of the molded product by secondary curing is low, and the elastic modulus retention (%) with respect to 30 ° C. at 180 ° C. Low. Furthermore, CFRP obtained by secondary curing cannot measure ILSS at 150 ° C. and has low mechanical properties at high temperatures.

Examples 27-32
The epoxy resin composition by the composition component shown in the predetermined column of Table 10 was obtained. In the preparation of the resin composition, all of the component (a) is uniformly mixed at 100 ° C. or lower, and then the temperature is lowered to 60 ° C., and the component (b), the component (c), and the component (d) In addition, mixing was performed uniformly. FXE1000 has a curing start temperature of 69 ° C., and PN23 has a curing start temperature of 62 ° C. Further, the stability of FXE1000 and PN23 by thickening is 1.2 times that of FXE1000 and 1.2 times that of PN23, respectively, and has excellent latent reactivity.

  The stability of each obtained epoxy resin composition was evaluated by the rate of thickening when left at 25 ° C. for 3 weeks. The results are also shown in Table 10. Further, the obtained epoxy resin composition was subjected to primary curing at 90 ° C. for 2 hours and then demolded, and then subjected to secondary curing at 200 ° C. for 4 hours. Table 10 shows the glass transition temperature (° C.) of the obtained secondary cured product together with the demoldability of the primary cured product.

INDUSTRIAL APPLICABILITY As described in detail above, the epoxy resin composition of the present invention is excellent in curability at a low temperature of 100 ° C. or lower, excellent in stability at room temperature, and primary at low temperature. A cured product having excellent heat resistance is obtained by secondarily curing the cured product at a high temperature. Moreover, since the prepreg of the present invention is obtained by impregnating a reinforcing fiber material with the epoxy resin composition having the above-mentioned characteristics, it has a long working life and good handleability, and at a low temperature of 100 ° C. or less. The cured product is cured in a short time to a demoldable hardness by primary curing, and has excellent heat resistance by subsequent secondary curing at high temperature. Therefore, the present invention is extremely useful industrially.

It is a graph used when calculating | requiring Tg of this hardened | cured material from the intersection of the tangent of the graph in the glass state of hardened | cured material, and the tangent in a transition area | region.

Claims (10)

An epoxy resin composition containing the following components (a), (b) and (c) and capable of two-stage curing.
(A): Epoxy resin containing at least one of the novolak-type epoxy resin of the following formula (1), the novolak-type epoxy resin of the following formula (2), and tetraglycidyldiaminodiphenylmethane

[Wherein n represents a number of 0 or more]

[Wherein n represents a number of 0 or more]
(B): Latent curing agent having curing ability at 100 ° C. or less (c): Aromatic amine-based curing agent and / or alicyclic amine-based curing agent   The blending ratio of the component (a), the component (b), and the component (c) is 3 to 40 parts by mass when the component (a) is 100 parts by mass, and the component (c) The composition according to claim 1, wherein is 10 to 40 parts by mass.   The composition of Claim 1 or 2 whose epoxy resin of a component (a) is an epoxy resin which has a trifunctional or more than trifunctional epoxy resin as a main component.   The composition in any one of Claims 1-3 whose latent hardener which makes a component (b) is an amine adduct type hardener.   The composition according to any one of claims 1 to 4, wherein the latent curing agent constituting the component (b) is a microcapsule type curing agent.   The composition in any one of Claims 1-5 whose aromatic amine type hardening | curing agent as a component (c) is diamino diphenyl sulfone and / or diamino diphenyl methane.   Furthermore, the composition in any one of Claims 1-6 containing a hardening accelerator as a component (d).   The composition according to any one of claims 1 to 7, wherein an epoxy resin composition is prepared, and the viscosity when the epoxy resin composition is allowed to stand at 25 ° C for 3 weeks is not more than twice the viscosity immediately after preparation of the resin composition.   The degree of cure of the cured product obtained by primary curing within 10 hours at a temperature of 100 ° C. or less is 70% or more, or the tensile shear strength of the cured product according to JIS-K-6848 and JIS-K-6850 ( The composition according to any one of claims 1 to 8, wherein the adhesive strength is 10 MPa or more.   A prepreg formed by impregnating a reinforcing fiber material with the epoxy resin composition according to claim 1.

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