JP2003073456A - Epoxy resin composition and prepreg using the same composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition, very stable at a room temperature, and to give a cured material capable of mold-releasing by a low- temperature primary curing and having a high heat-resistance by a secondary curing, and to provide a prepreg impregnated this epoxy resin composition in a fiber material for reinforcing. SOLUTION: The epoxy resin composition is composed of a component (a): an epoxy resin having epoxy resins with three or more functionalities, a component (b): a heat-curable latent curing agent to be activated at 100 deg.C or below, a component (c): an aromatic amine-based curing material, and a component (d): an aromatic urea compound, and the prepreg impregnated the epoxy resin composition in the fiber material for rein forcing, is provided.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Fiber-reinforced composite materials are used in a wide range of applications from sports / 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 method of using a molding die.

For example, is it applied by impregnating a reinforcing fiber material such as cloth with a resin while adhering to it, or by adhering a so-called prepreg in which a reinforcing fiber material is impregnated with resin in advance along a molding tool? The above procedure is repeated and then cured, and then the mold is released from the mold to obtain a molded product, the so-called hand lay-up method, in which a reinforcing fiber material such as cloth is set in the mold, and then a resin is injected into it. Resin transfer molding method to obtain a molded product by demolding, and after injecting a molding raw material in which a reinforcing fiber material cut into short fibers is mixed with a resin into a molding die, and then curing it, There is a molding compound method or the like in which a molded product is obtained by demolding.

There are various types of molding dies used in such a molding method, such as metal, resin, wood, etc. Although the metal molding dies have excellent heat resistance and durability, Since it takes time and labor to manufacture the molding die, it is expensive, and the resin molding die and the wooden molding die are
Although it is inferior in heat resistance and durability, it has the advantage of being inexpensively available.

In order to meet various needs in recent years, the production of a small amount of various types of molded products has been increased, and the number of cases of using a resin-made mold which can be obtained at low cost has been increased, and A wooden mold may be used for molding a large molded product such as a ship.

In the molding method using these resin molds and wooden molds, as described above, since the resin or wooden molds themselves do not have sufficient heat resistance, they cannot be molded at high temperatures. There is a problem that a molded product having high heat resistance cannot be molded.

Therefore, as a method of obtaining a molded product made of a fiber-reinforced composite material having high heat resistance by using a resin or wood mold having low heat resistance, a mold having low heat resistance is used. After making the primary cured product that can be demolded by performing the primary curing at a relatively low temperature of ℃ or less, the primary cured product is demolded from the mold with low heat resistance, and then the primary cured product is placed in a high temperature atmosphere. By leaving the cured product to be secondarily cured, a method for obtaining a molded product with high heat resistance has been proposed,
For example, it has been attempted to mold a large-sized molded product that requires high heat resistance for aerospace applications.

[0008] By the way, when the molding method applying the curing means consisting of the primary curing and the secondary curing is applied to the molding means using the prepreg, the prepreg is 80
Curable at a relatively low temperature of ℃ or less for a short period of time so that it can be released from the mold, secondary curing at a high temperature makes it a highly heat-resistant cured product, and the stability of the prepreg itself at room temperature It must be excellent and easy to handle.

Under such circumstances, resin compositions which are relatively stable at room temperature and harden at a relatively low temperature of 70 to 100 ° C. have been disclosed in many technical documents including JP-A No. 11-302412. Is disclosed in.

However, all of the resin compositions disclosed herein are cured at low temperatures and become primary cured products having excellent mechanical properties, but even if they are subsequently subjected to secondary curing at high temperatures, they are sufficient. It does not become a cured product with excellent heat resistance.

On the other hand, the conventional resin composition which becomes a cured product having good heat resistance has a problem that it takes a long time to be removably cured by primary curing at a relatively low temperature of 80 ° C. or lower.

[0012]

Therefore, the problem to be solved by the present invention is to provide a cured product which has good stability at room temperature and can be demolded by primary curing at a relatively low temperature of 80 ° C. or lower. It is an epoxy resin composition that does not take a long time to form a cured product with high heat resistance due to secondary curing, and the prepreg impregnated with the epoxy resin composition has good handleability. An object of the present invention is to provide an epoxy resin composition having certain properties and a prepreg in which a reinforcing fiber material is impregnated with the epoxy resin composition.

[0013]

The above problems can be solved by the epoxy resin composition of the present invention having the constitution described below and a prepreg using the epoxy resin composition. That is, the epoxy resin composition of the present invention comprises an epoxy resin composition containing the following components (a) to (d). Component (a) ... Epoxy resin containing trifunctional or higher functional epoxy resin Component (b) ... Heat-curable latent curing agent that is activated at 100 ° C. or lower Component (c) ... Aromatic amine curing agent Component (d) ... Aromatic urea compound

In the epoxy resin composition of the present invention having the above-mentioned constitution, the component (a) contains 40 or more trifunctional or more functional epoxy resins.
It is preferably an epoxy resin containing at least mass%.

Further, in the epoxy resin composition of the present invention having the above-mentioned constitution, the component (a) is preferably an epoxy resin containing an epoxy resin having a nitrogen atom in the molecule, and has a nitrogen atom in the molecule. As an epoxy resin,
An epoxy resin containing tetraglycidyl diaminophenylmethane and an epoxy resin containing triglycidyl aminophenol are preferable.

Further, in the epoxy resin composition of the present invention having the above-mentioned constitution, the component (a) is preferably an epoxy resin containing a novolac type epoxy resin, and the novolac type epoxy resin is a cresol novolac type epoxy resin. A novolac type epoxy resin represented by the following [Chemical formula 3] and a novolac type epoxy resin represented by the following [Chemical formula 4] are preferable.

[0017]

[Chemical 3] [In the formula, n represents a number of 0 or more]

[0018]

[Chemical 4] [In the formula, n represents a number of 0 or more]

The component (b) of the epoxy resin composition of the present invention having the above-mentioned constitution is preferably a latent curing agent containing an imidazole catalyst, and the latent curing agent containing this imidazole catalyst. Is preferably a microcapsule type latent curing agent.

Further, in the epoxy resin composition of the present invention having the above-mentioned constitution, the mixing ratio of the component (a) and the component (b) is
When the amount of the component (a) is 100 parts by mass, the amount of the component (b) is preferably 3 to 40 parts by mass.

In the epoxy resin composition of the present invention having the above-mentioned constitution, the number of moles of the epoxy groups of the epoxy resin of the component (a) and the number of moles of active hydrogen of the aromatic amine curing agent of the component (c) are adjusted. The ratio is preferably 1 / 0.1 to 1 / 0.7.

Further, in the epoxy resin composition of the present invention having the above-mentioned constitution, the mixing ratio of the component (a) and the component (d) is such that the component (d) is 100 parts by mass. Two
It is preferably from 10 to 10 parts by mass.

Further, the epoxy resin composition of the present invention having the above-mentioned constitution has a viscosity at 60 ° C. of 10 to 700 Pa · se.
It is preferably c.

Further, the epoxy resin composition of the present invention having the above-mentioned constitution preferably satisfies the following (1) to (3). (1) The viscosity increase rate (fold) when left for 3 weeks at 25 ° C. after preparation is not more than twice the viscosity immediately after preparation. (2) The degree of cure of the cured product obtained by primary curing within 80 hours at a temperature of 80 ° C. or lower is 70% or higher. (3) The glass transition temperature of the cured product obtained by the secondary curing at 130 ° C or higher subsequent to the primary curing is 150 ° C or higher.

The prepreg of the present invention is obtained by impregnating the reinforcing fiber material with the epoxy resin composition of the present invention having the above constitution.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin containing a trifunctional or higher functional epoxy resin, which is the component (a) in the epoxy resin composition of the present invention, may include a trifunctional or higher functional epoxy resin. It is not particularly limited.
Examples of the trifunctional or higher functional epoxy resin include novolac type epoxy resins such as phenol novolac type and cresol novolac type, and aminoglycidyl type epoxy resins.

The heat-curable latent curing agent which is the component (b) and which is activated at a temperature of 100 ° C. or lower has a curing ability at a temperature of 100 ° C. or lower and also has a heating latent reactivity, that is, a latent ability. To do. By activating the curing agent which constitutes the component (b) at 100 ° C. or lower, primary curing at a low temperature and in a relatively short time provides a demoldable cured product. Further, since the curing agent which constitutes the component (b) has latent reactivity, the stability of the epoxy resin composition at room temperature becomes excellent.

Whether or not the curing agent has a curing ability at 100 ° C. or lower is determined as follows. That is,
An epoxy resin composition obtained by uniformly mixing 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 at 10 ° C. by DSC.
The heat generated when curing was measured under the heating rate condition of 1 / min, and when the temperature on the DSC chart was away from the baseline and the temperature at which the heat of curing started was 100 ° C or lower, the curing agent was cured at 100 ° C or lower. Judge as having ability.

Further, the fact that the curing agent is latently reactive, that is, latent means that it hardly reacts near room temperature, and the confirmation of the potential of the curing agent that it hardly reacts near room temperature is as follows. Do as you would. That is, an epoxy resin composition obtained by uniformly mixing 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,
It can be said that the curing agent is latent when the viscosity when left at 30 ° C. for 3 weeks is not more than twice the viscosity before left. The above-mentioned epoxy resin composition 3
A curing agent having a viscosity of 1.5 times or less of the viscosity before standing at 0 ° C. for 3 weeks has excellent latent reactivity, and contains the component (b). It is more preferable as a latent curing agent.

The curing agent which constitutes the component (c) improves the heat resistance of the cured product obtained by the secondary curing,
The aromatic amine curing agent is not particularly limited as long as it is an aromatic amine curing agent, but an aromatic amine curing agent containing a sulfur atom in the molecule is particularly preferable. This is because the aromatic amine-based curing agent that constitutes the component (c) has a sulfur atom in the molecule, and thus the epoxy resin composition containing this is cured by primary curing at low temperature and in a relatively short time. This is because a cured product having higher heat resistance can be obtained by the secondary curing. Examples of the aromatic amine curing agent having a sulfur atom in the molecule include diaminodiphenyl sulfone and methylthiotoluenediamine.

The aromatic urea compound as the component (d) improves the curability by primary curing at a relatively low temperature without impairing the stability of the epoxy resin composition of the present invention at room temperature. Have the function to As the aromatic urea compound forming the component (d), those represented by the following [Chemical Formula 5] are particularly suitable, and for example, phenyldimethylurea, dichlorophenyldimethylurea and the like are used.

[0032]

[Chemical 5] [In the formula, X ₁ and X ₂ represent hydrogen or chlorine, and X ₁ and X ₂ may be the same or different]

Further, the epoxy resin constituting the component (a) preferably contains 40% by mass or more of a trifunctional or more functional epoxy resin. That is, when 40% by mass or more of the total amount of the epoxy resin constituting the component (a) is a trifunctional or higher functional epoxy resin, the cured product obtained by the secondary curing has more excellent heat resistance, and the component ( By making 60% by mass or more of the epoxy resin constituting a) a trifunctional or more functional epoxy resin, the heat resistance of the cured product obtained by the secondary curing becomes further excellent.

The epoxy resin as the component (a) is
It is preferable to contain an epoxy resin having a nitrogen atom in the molecule. That is, by using an epoxy resin containing an epoxy resin having a nitrogen atom in the molecule as the epoxy resin forming the component (a), a curing that can be more reliably released from the mold by primary curing at a low temperature and in a short time. It is more preferable that 20% by mass or more of the epoxy resin as the component (a) is an epoxy resin having a nitrogen atom in the molecule. Examples of the epoxy resin having a nitrogen atom in the molecule include tetraglycidyl diaminophenylmethane, aminophenol type epoxy resin, aminocresol type epoxy resin and the like.

Furthermore, it is preferable that the epoxy resin as the component (a) contains at least one kind of novolac type epoxy resin. That is, by using the epoxy resin containing the novolac type epoxy resin as the epoxy resin as the component (a), a secondary cured product having more excellent heat resistance can be obtained. As the novolac type epoxy resin, at least one of cresol novolac type epoxy resin, novolac type epoxy resin represented by the following [Chemical formula 6], and novolac type epoxy resin represented by the following [Chemical formula 7] is used. As a result, a secondary cured product having higher heat resistance can be obtained.

[0036]

[Chemical 6]

[0037]

[Chemical 7]

When a latent curing agent containing an imidazole-based catalyst is used as the heat-curable latent curing agent which is the component (b) and is activated at 100 ° C. or lower, primary curing at low temperature and in a short time is performed. The resulting cured product can be more reliably demolded, and the secondary curing provides a cured product having more excellent heat resistance. When the latent curing agent containing the imidazole-based catalyst is a microcapsule type latent curing agent, the epoxy resin composition is more excellent in stability at room temperature. Examples of the latent curing agent containing an imidazole catalyst include Shikoku Kasei Co., Ltd.
Cureduct P-0505, Curesol 2E4 manufactured by the company
MZ-CNS, C11Z-CNS, C11Z-A, etc. are mentioned. As a microcapsule type latent curing agent containing an imidazole-based catalyst, for example, Asahi Chiba Co., Ltd.
Examples include Novacure HX3721, HX3722 and the like.

Subsequently, in the epoxy resin composition of the present invention, when the amount of the epoxy resin constituting the component (a) is 100 parts by mass, a heat-curing type latent component which is activated at 100 ° C. or lower constituting the component (b) is used. If the amount of the functional curing agent is less than 3 parts by mass, the primary curing may be insufficient at a low temperature of 80 ° C. or less, and if it exceeds 40 parts by mass, the glass transition temperature and high temperature of the secondary cured product The rigidity may be lowered, and the stability of the epoxy resin composition at room temperature may be lowered. Therefore, when the epoxy resin forming the component (a) is 100 parts by mass, the heat-curable latent curing agent which is activated at 100 ° C. or lower forming the component (b) is 3 to 40 parts by mass. It is preferable that the amount is 3 to 20 parts by mass. As the heat-curable latent curing agent, when using a paste-like mixture in which the latent curing agent is mixed with a low-viscosity epoxy resin in advance, the mass of the curing agent containing only the active ingredient is Of course.

In the epoxy resin composition of the present invention, the ratio of the number of moles of the epoxy group of the epoxy resin of the component (a) to the number of moles of active hydrogen of the aromatic amine curing agent of the component (c) is When the number of moles of active hydrogen of the aromatic amine-based curing agent is less than 0.1 with respect to the number of moles 1 of the epoxy group of the epoxy resin, the glass transition temperature and / or high temperature of the cured product obtained by secondary curing The rigidity tends to be low,
On the other hand, when it exceeds 0.7, unreacted amine residues in the cured product obtained by the secondary curing increase, the rigidity at the glass transition temperature and the high temperature is low, the hygroscopicity increases, or the curing is brittle. It becomes a thing. For this reason, the ratio of the number of moles of epoxy groups of the epoxy resin of component (a) to the number of moles of active hydrogen of the aromatic amine curing agent of component (c) is 1/0.
It is preferably in the range of 1 to 1 / 0.7,
More preferably, it is within the range of 0.2 to 1 / 0.6.

Further, in the epoxy resin composition of the present invention, when the amount of the epoxy resin as the component (a) is 100 parts by mass, the amount of the aromatic urea compound as the component (d) is 2%.
When it is less than 10 parts by mass, the curability of the epoxy resin composition at low temperatures is deteriorated, which is not preferable, and when it exceeds 10 parts by mass, the rigidity of the secondary cured product at the glass transition temperature and / or high temperature becomes low. In addition, the stability of the epoxy resin composition at room temperature may decrease, which is not preferable. Therefore, when the amount of the epoxy resin forming the component (a) is 100 parts by mass, the amount of the aromatic urea compound forming the component (d) is preferably 2 to 10 parts by mass, and 4 to 7 parts by mass. Is more preferable.

When the viscosity at 60 ° C. of the epoxy resin composition of the present invention is lower than 10 Pa · sec, the prepreg using the epoxy resin composition becomes too tacky and sticky.
On the other hand, if it exceeds 700 Pa · sec, the drape property of the prepreg becomes poor and it becomes too hard. For this, 6
The viscosity at 0 ° C. is preferably 10 to 700 Pa · sec, and more preferably 30 to 500 Pa · sec. The viscosity of the epoxy resin composition at 60 ° C. is the viscosity η of the epoxy resin composition immediately after preparation at 60 ° C.
i is a value measured with a parallel plate at a frequency of 10 radians / second by a DSR-200 manufactured by Rheometric or an apparatus having equivalent performance.

Further, in the epoxy resin composition of the present invention, the viscosity increase rate (twice) when left at 25 ° C. for 3 weeks after the resin composition is prepared is not more than twice the viscosity immediately after preparation. When the viscosity increase rate (fold) is 2 times or less, the epoxy resin composition becomes a resin composition having excellent stability at room temperature. When the rate of increase in viscosity (fold) when left at 25 ° C. for 3 weeks is 1.5 times or less, the epoxy resin composition is a resin composition having more excellent stability at room temperature, The working life becomes longer, which is more preferable.

The rate of viscosity increase (times) of the epoxy resin composition is measured by the following method. That is,
The viscosity η0 of the epoxy resin composition immediately after preparation at 40 ° C
Was measured with a parallel plate at a frequency of 10 radians / second using a DSR-200 manufactured by Rheometric Co. or an apparatus having equivalent performance, and 3 in a thermostat at 25 ° C.
The viscosity η1 at 40 ° C. of the epoxy resin composition after being allowed to stand for a week is measured in the same manner as described above, and the viscosity increase rate (times) is obtained from η0 / η1.

The epoxy resin composition of the present invention is subjected to differential scanning with respect to the curing exotherm (E0) of the resin composition immediately after preparation and the residual curing exotherm (E1) of the cured product obtained by primary curing of the resin composition. Curing degree measured by a calorimeter (DSC) and calculated by Curing degree (%) = {(E0-E1) × 100 / E0} is 70% or more. It is preferable in that the product can be obtained.

Further, the epoxy resin composition of the present invention is preferably a cured product having a high degree of heat resistance by secondary curing, that is, a cured product obtained by primary curing followed by secondary curing at 130 ° C. or higher. Has a glass transition temperature of 150
It is preferable that the epoxy resin composition has a glass transition temperature of 180 ° C or higher, which is obtained by secondary curing at 150 ° C or higher (for example, 200 ° C). It becomes a cured product with high heat resistance. The curing time for secondary curing is 10
It is preferably within the period of time, more preferably within 5 hours.

The glass transition temperature of the cured product is measured by the following method. That is, RDA-made by Rheometric Co.
Using a viscoelasticity measuring device having 700 or equivalent performance, the storage elastic modulus (G ′) when the temperature of the cured product for measurement is raised stepwise is measured at each temperature. The temperature is raised at 5 ° C./step, and in each step, the temperature is stabilized and held at that temperature for 1 minute, and then measured at a frequency of 10 radians / second. As shown in [Fig. 1], the logarithmic value of the storage elastic modulus (G ') against temperature was plotted, and the temperature at the intersection of each tangent of the glass elastic region and the transition region of the obtained G'curve was calculated. The glass transition temperature.

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

Further, in order to improve the toughness of the obtained cured product, a fine particle or short fiber thermoplastic resin or a rubber component may be added. For example, polyamide, polyimide, polyurethane, polyether sulfone or the like may be added. Plastic resin,
Examples thereof include rubber components such as acrylic rubber, butadiene rubber, and butyl rubber, and molecular terminal modified products thereof. Further, for the purpose of improving the rigidity of the obtained cured product, it is possible to add fine particles of an inorganic component such as talc, metal such as silica and steel.

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

The fiber material for reinforcement when molding the fiber-reinforced composite material is not particularly limited, and for example, general fiber-reinforced composite materials such as carbon fiber, glass fiber, high-strength organic fiber, metal fiber, inorganic fiber and the like. All of the materials used as the reinforcing fiber material can be used. Also, there is no particular limitation on the form of the reinforcing fiber material, for example, a unidirectional material,
A cloth, a mat, or a tow composed of several thousand filaments or more may be used.

The epoxy resin composition of the present invention can also be used as a sheet-like adhesive by forming it into a film to suppress the resin flow or by impregnating it with glass cloth or the like.

Further, the epoxy resin composition of the present invention can be used as a weight-reducing auxiliary material by adding a microballoon or a foaming agent as an additive thereto.

Furthermore, since the prepreg impregnated with the epoxy resin composition of the present invention can be cured at a low temperature of 80 ° C. or lower, the thermoplastic resin or the rubber component, etc. can be selectively added near the surface of the prepreg. By disposing a tough material, when enhancing the toughness between layers of the obtained laminated cured product, even if a thermoplastic resin having a low melting point is disposed,
It can be molded while maintaining its shape. For this reason, morphology control is easy, and a high toughness material such as a thermoplastic resin or a rubber component can be arranged between the layers as designed, and interlayer toughness as designed can be obtained. In addition,
The form of the high toughness material such as the thermoplastic resin or rubber component to be arranged between the layers at this time is not particularly limited, but particles, long fibers or fibrous single fibers are selected between the layers. It is particularly preferable because it is possible to dispose a highly tough material.

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, an epoxy capable of dissolving these solid components is first prepared. It is preferable to use it by uniformly dissolving it in the resin.

When the component (b) is in the form of powder, the epoxy resin component constituting the component (a) is added to the component (b) when the component (b) is in the form of powder. By using a relatively low-viscosity epoxy resin or the like in the form of a paste and then adding the paste, it is possible to prevent secondary aggregation of the powdery component (b) and to disperse it uniformly. it can. Further, when the component (b) is in a solid state, it is preferable to grind it into a powder state and then add it in a paste form with a low-viscosity epoxy resin or the like. In addition, when the component (b) is a microcapsule type latent curing agent, stirring with a strong shear exerts an adverse effect on the capsule and impairs the stability at room temperature. Therefore,
As the microcapsule type latent curing agent, it is preferable to use a master batch type latent curing agent which has been mixed in advance with a low-viscosity epoxy resin.

The aromatic amine-based curing agent which constitutes the component (c) is used when the component (c) is not dissolved by the primary curing, that is, the melting point of the component (c) is higher than the primary curing temperature or the component (c) has a higher melting point. When the dissolution temperature in the epoxy resin is higher than the primary curing temperature, it is preferable to add it by dissolving it in the epoxy resin as the component (a) in advance. Further, in the case of a powdery form in which the component (c) is dissolved by the primary curing, the component (a)
Secondary agglomeration of the powdery component (c) can be prevented by adding it after forming a paste with a relatively low-viscosity epoxy resin or the like, and can be dispersed uniformly.

Further, when the component (c) is in a solid state which is dissolved by the primary curing, it is pulverized into a powder,
It is preferable to add it 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 uniformly at any stage.

The aromatic urea compound which constitutes the component (d) is made into a paste by the epoxy resin or the like having a relatively low viscosity in the component (a) and then added, so that the powder of the component (d) is added. Secondary aggregation can be prevented and the particles can be uniformly dispersed.

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 which constitutes the component (b), the epoxy resin composition is It is preferably prepared at 60 ° C. or lower. 55
The stability of the epoxy resin composition is further improved if it is prepared at a temperature of not higher than ° C.

As a method of preparing a prepreg using the epoxy resin composition of the present invention, a hot melt method is preferable. When applying the epoxy resin composition to the release step paper when obtaining the filmed epoxy resin composition used for the preparation of the prepreg by the hot melt method,
60 ℃ to stabilize the life of the prepreg prepared
The coating is preferably performed below, and more preferably 55 ° C. or less.

[Reference Example] Reference Examples 1 to 4 In order to confirm whether each of the curing agents shown in [Table 1] is activated at 100 ° C. or lower, a liquid bisphenol A type epoxy having an epoxy equivalent of 189 is used. Resin (manufactured by Japan Epoxy Resin Co., Ltd .: Epicoat 828) 100 parts by mass and each curing agent 20
The epoxy resin composition obtained by uniformly mixing
The heat generation at the time of curing at C at a temperature rising rate of 10 ° C./min was measured, and the activation temperature was confirmed on the DSC chart by the temperature at which the curing heat generation starts apart from the baseline.

Further, each of the above epoxy resin compositions was treated at 30 ° C.
Whether the curing agent is latent or not is measured by measuring the viscosity when left for 3 weeks in a room temperature, and whether or not the rate of increase in viscosity (twice) with respect to the viscosity before standing is 2 times or less. It was confirmed.

The respective results are shown in [Table 1]. In addition,
The epoxy resin and the curing agent are indicated by the following abbreviations. Ep828: Bisphenol A type epoxy resin "Epicoat 82" which is liquid, manufactured by Japan Epoxy Resins Co., Ltd.
8 ", epoxy equivalent: 189 HX3722: manufactured by Asahi Ciba," Nova Cure HX372 "
2 "P0505:" Cure Duct P-0 "manufactured by Shikoku Kasei Kogyo Co., Ltd.
505 ”FXE1000: FXE1000: Fuji Chemical Co., Ltd.,“ Fujicure FXE-1000 ”PN23: Ajinomoto Co.,“ Amicure PN-23 ”

[0065]

[Table 1]

Reference Examples 5 to 7 The temperatures at which each curing agent shown in [Table 2] is activated and the latent potential of the curing agent were confirmed in the same manner as in Reference Example 1 above. The respective results are shown in [Table 2]. The curing agent is indicated by the following abbreviations. 2MZ: 2-methylimidazole “2M” manufactured by Shikoku Kasei
Z "BF3MEA: boron trifluoride monomethylamine complex" BF3MEA "Dicy: manufactured by Japan Epoxy Resins Co., Ltd., dicyandiamide" Dicy7 "

[0067]

[Table 2]

[0068]

EXAMPLES Hereinafter, the concrete constitution of the epoxy resin composition of the present invention and the prepreg using the epoxy resin composition will be described based on Examples while comparing with Comparative Examples. The components used in the epoxy resin compositions of Examples and Comparative Examples are as shown by the following abbreviations.

(1) Trifunctional or higher functional epoxy resin Ep604: tetraglycidyl diaminodiphenylmethane "Epicoat 60" manufactured by Japan Epoxy Resins Co., Ltd.
4 ", epoxy equivalent: 120 ELM434: manufactured by Sumitomo Chemical Co., Ltd., tetraglycidyl diaminodiphenylmethane" ELM434 ", epoxy equivalent:
120 Ep1032: manufactured by Japan Epoxy Resins Co., Ltd. [Chemical Formula 3]
Special novolac type epoxy resin “Epicoat 1032S50” corresponding to n> 0, epoxy equivalent: 16
9 Ep157: EP157S65: manufactured by Japan Epoxy Resin Co., Ltd., a special novolac type epoxy resin “Epicoat 157S65” corresponding to n> 0 in [Chemical formula 4] epoxy equivalent: 210 ELM100: Sumitomo Chemical Co., Ltd., aminophenol type epoxy resin “Sumi-” Epoxy ELM-100 "Epoxy equivalent: 107 N740: Dainippon Ink and Chemicals, Inc., phenol novolac type epoxy resin" Epiclon N-740 "Epoxy equivalent: 180 N673: Dainippon Ink and Chemicals, cresol novolac type epoxy resin" Epiclon N " -673 "epoxy equivalent: 212

(2) Epoxy resin other than trifunctional or higher functional epoxy resin Ep828: Bisphenol A type epoxy resin "Epicoat 828" manufactured by Japan Epoxy Resin Co., Ltd.
Epoxy equivalent: 189 YD128: liquid bisphenol A type epoxy resin "YD-128" manufactured by Tohto Kasei Co., Ltd. Epoxy equivalent: 18
9 Ep1001: Semi-solid bisphenol A type epoxy resin "Epicoat 1" manufactured by Japan Epoxy Resins Co., Ltd.
001 "epoxy equivalent: 475

(3) Heat-curable latent curing agent HX3722 which is activated at 100 ° C. or lower: "Novacure HX372" manufactured by Asahi Ciba Co., Ltd.
2 "P0505:" Cure Duct P-0 "manufactured by Shikoku Kasei Kogyo Co., Ltd.
505 ”FXE1000:“ Fujicure FX ”manufactured by Fuji Kasei Co., Ltd.
E-1000 "PN23:" Amicure PN-23 "manufactured by Ajinomoto Co., Inc.

(4) Aromatic amine-based curing agent having a sulfur atom in the molecule DDS: diaminodiphenyl sulfone "SEIKACURE S" amine equivalent, manufactured by Wakayama Seika Co., Ltd .: 62

(5) Aromatic urea compound PDMU: phenyl dimethyl urea "Omicure 94" manufactured by BTR Japan Co., Ltd. DCMU: dichlorophenyl dimethyl urea "DCMU 99" manufactured by Hodogaya Chemical Co., Ltd.

(6) Other components PES: Sumitomo Chemical Co., Ltd., polyether sulfone "Sumika Excel PES 3600P" Aerosil 300: Nippon Aerosil Co., Ltd. "Aerosil 300" 2MZ: Shikoku Kasei Co., Ltd. 2-methylimidazole "2M"
Z ”BF3MEA: boron trifluoride monomethylamine complex“ BF3MEA ”Dicy: manufactured by Japan Epoxy Resins, dicyandiamide“ Dicy7 ”diethylenetriamine: manufactured by Wako Pure Chemical Industries, Ltd., aliphatic amine“ diethylenetriamine ”amine equivalent: 20.6

Examples 1 to 23 Epoxy resin compositions having the composition components described in respective predetermined columns of [Table 3], [Table 4], [Table 5] and [Table 6] below were obtained. The numbers in the table are parts by mass of the blended components. Further, the column of "(a) epoxy group / (c) active hydrogen (molar ratio)" in the table indicates the number of moles of the epoxy group of the epoxy resin constituting the component (a) in each epoxy resin composition and the component ( It is the ratio with the number of moles of active hydrogen of the aromatic amine-based curing agent that constitutes c).

The procedure for compounding each component is as follows. First, the epoxy resin forming the component (a) was heated to 150 ° C. and uniformly mixed. When other components such as a thermoplastic resin and an inorganic substance are contained in the blended component, this component (a)
Other ingredients were added at the time of heating and mixing to dissolve or disperse. Then, the above component (a) or component (a)
Each epoxy resin composition is prepared by cooling a mixture of the above-mentioned and other components to 50 to 60 ° C., adding the component (b), the component (c) and the component (d) to the mixture and mixing them uniformly. did.

The viscosity of each obtained epoxy resin composition at 60 ° C. was measured. Further, the stability of each epoxy resin composition was evaluated by the ratio of viscosity increase (viscosity increase rate) when left at 25 ° C. for 3 weeks. The results are also shown in [Table 3], [Table 4], [Table 5] and [Table 6].

After heating each of the epoxy resin compositions to 60 ° C. for defoaming, the epoxy resin compositions were sandwiched between release-treated glass plates, heated from room temperature to 80 ° C. over 1 hour, and then heated to 80 ° C., 5
It was subjected to primary curing for 7 hours or at 80 ° C. to obtain a primary cured product composed of a molded plate having a thickness of 2 mm.

The residual calorific value (E1) of the primary cured product and the curing calorific value (E0) of the resin immediately after resin preparation were measured by a differential operation calorimeter (DSC), and the degree of cure (%) by the primary curing was It was determined according to the calculation formula of {(E0)-(E1)} × 100 / E0. The results are also shown in [Table 3], [Table 4], [Table 5] and [Table 6].

Regarding the releasability of the primary cured product when demolded, it could be demolded without any problems ... ◎, demoldable: ◯, bending or cracking occurred Could not be removed from the mold well ... ..., shown in [Table 3], [Table 4], [Table 5] and [Table 6] by x.

Subsequently, the demolded primary cured product obtained by primary curing at 80 ° C. for 5 hours was left standing in a hot air oven in a free-standing state, heated to 200 ° C. over 150 minutes, and then heated to 200 ° C. It was subjected to secondary curing at 4 ° C. for 4 hours. Regarding Example 10, the primary cured product obtained by primary curing at 80 ° C. for 7 hours was subjected to secondary curing under the same conditions.

The glass transition temperature (° C.) of each secondary cured product is
[Table 3], [Table 4], along with the value of G ′ at 150 ° C.
It is also described in [Table 5] and [Table 6]. The value of G ′ at 150 ° C. is a measure of the physical properties at high temperature of the composite material using this epoxy resin composition.

[0083]

[Table 3]

[0084]

[Table 4]

[0085]

[Table 5]

[0086]

[Table 6]

Comparative Example 1 An epoxy resin composition having the composition components described in the predetermined columns of [Table 7] below was cooled to 70 ° C. immediately after PES was dissolved in ELM434 at 150 ° C., and YD128 and Dicy were added thereto. And PN23 were uniformly mixed with a three-roll mill, and the mixture was uniformly mixed.

The stability of the obtained epoxy resin composition was
It was evaluated by the rate of increase in viscosity (viscosity increase rate) when left at 25 ° C. for 3 weeks. The results are also shown in [Table 7].

The above epoxy resin composition was heated to 60 ° C. to defoam, and then sandwiched between release-treated glass plates,
The temperature was raised from room temperature to 80 ° C. over 1 hour and subjected to primary curing at 80 ° C. for 5 hours or at 80 ° C. for 7 hours to obtain a primary cured product composed of a molded plate having a thickness of 2 mm.

The residual calorific value (E1) of this primary cured product and the curing calorific value (E0) of the resin immediately after resin preparation were measured by a differential operation calorimeter (DSC), and the degree of curing (%) by primary curing was It was determined according to the calculation formula of {(E0)-(E1)} × 100 / E0. The results are also shown in [Table 7].

Regarding the releasability of this primary cured product when demolded, it could be demolded without any problems ... ◎, demoldable: ◯, bending or cracking occurred It was not possible to remove the mold well ...

Then, the demolded primary cured product obtained by primary curing at 80 ° C. for 5 hours was left standing in a hot air oven in a free-standing state, heated to 200 ° C. over 150 minutes, and then heated to 200 ° C. It was subjected to secondary curing at 4 ° C. for 4 hours. The glass transition temperature (° C.) of this secondary cured product is shown in [Table 7] together with the value of G ′ at 150 ° C. The secondary cured product of this epoxy resin composition did not have sufficient heat resistance.

Comparative Example 2 Ep604, Ep828, and N67 were used to prepare an epoxy resin composition having the composition components shown in the predetermined columns of [Table 7] below.
3 was uniformly mixed at 120 ° C, then cooled to 70 ° C, and P
Prepared by adding DMU, DDS and Dicy, dispersing and mixing.

With respect to the obtained epoxy resin composition, the stability of the epoxy resin composition, the degree of curing of the cured product by the primary curing at 80 ° C. and the demolding property were evaluated in the same manner as in Comparative Example 1 above. The results are also shown in [Table 7]. The epoxy resin composition was not sufficiently cured even by primary curing at 80 ° C. for 7 hours, and did not become a demoldable cured product.

Comparative Example 3 Ep604, Ep828, and N67 were used to prepare an epoxy resin composition having the composition components shown in the predetermined columns of [Table 7] below.
3 was uniformly mixed at 120 ° C, then cooled to 70 ° C, and P
Prepared by adding DMU, DDS and BF3MEA, dispersing and mixing.

With respect to the obtained epoxy resin composition, the stability of the epoxy resin composition, the degree of curing of the cured product by the primary curing at 80 ° C. and the demolding property were evaluated in the same manner as in Comparative Example 1. The results are also shown in [Table 7]. The epoxy resin composition was not sufficiently cured even by primary curing at 80 ° C. for 7 hours, and did not become a demoldable cured product.

Comparative Example 4 Ep604, Ep828 and N67 were used to prepare an epoxy resin composition having the composition components described in the predetermined columns of [Table 7] below.
3 was mixed uniformly at 120 ℃, then cooled to 70 ℃, 2
Prepared by adding MZ, DDS and PDMU, dispersing and mixing.

Evaluation of the obtained epoxy resin composition was carried out in the same manner as in Comparative Example 1 above. The results are also shown in [Table 7]. The epoxy resin composition is 2
When left at 5 ° C. for 3 weeks, it had already gelled and had poor stability at room temperature.

[0099]

[Table 7]

Comparative Example 5 Ep604, Ep828 and N67 were used to prepare an epoxy resin composition having the composition components described in the predetermined columns of [Table 8] below.
3 was mixed uniformly at 120 ℃, then cooled to 70 ℃, H
Prepared by adding X3722, diethylenetriamine and PDMU, dispersing and mixing.

The obtained epoxy resin composition was evaluated in the same manner as in Comparative Example 1 above. The results are also shown in [Table 8]. The epoxy resin composition is 2
When left at 5 ° C. for 3 weeks, it had already gelled and had poor stability at room temperature. Further, the secondary cured product did not have sufficient heat resistance.

Comparative Example 6 Ep604, Ep828 and N67 were used to prepare an epoxy resin composition having the composition components described in the predetermined columns of [Table 8] below.
3 was mixed uniformly at 120 ℃, then cooled to 70 ℃, H
Prepared by adding X3722 and DDS, dispersing and mixing.

With respect to the obtained epoxy resin composition, the stability of the epoxy resin composition, the degree of cure of the cured product obtained by the primary curing at 80 ° C. and the demolding property were evaluated in the same manner as in Comparative Example 1. The results are also shown in [Table 8]. The epoxy resin composition was not sufficiently cured even by primary curing at 80 ° C. for 7 hours, and did not become a demoldable cured product.

Comparative Example 7 Ep828 and Ep1001 were used as epoxy resin compositions having the composition components shown in the predetermined columns of [Table 8] below.
Mix evenly at 0 ° C, then cool to 60 ° C and mix with HX372.
2. Prepared by adding and mixing DDS and PDMU.

The obtained epoxy resin composition was evaluated in the same manner as in Comparative Example 1. The results are shown in [Table 8].
Also described in. The secondary cured product of this epoxy resin composition did not have sufficient heat resistance.

[0106]

[Table 8]

Example 24 The epoxy resin composition described in Example 1 was heated at 60 ° C. and uniformly coated on a release process paper to give a basis weight of 80 g / m ^2.
The resin film of was produced.

Next, carbon fiber "TR50S-12L" manufactured by Mitsubishi Rayon Co., Ltd. was aligned on one side in one direction so that the weight per unit area of the carbon fiber was 150 g / m ² , and then heated and pressed. By doing so, a unidirectional prepreg obtained by impregnating carbon fiber with the epoxy resin composition was obtained. This prepreg had good tack and drape.

Further, when the prepreg was left to stand at 25 ° C. for 3 weeks, the change in tack and drape of the prepreg was evaluated by touch, and it was found that there was little change in tack and drape even after being left for 3 weeks. , Had a good life.

Subsequently, the prepregs were aligned in one direction, laminated for 14 plies, and primarily cured by a vacuum bag molding method. The primary curing at this time was performed under the curing conditions of 80 ° C. and 5 hours after the temperature was raised from room temperature to 80 ° C. over 1 hour. The cured product obtained by the primary curing was sufficiently capable of demolding, and cracking did not occur even if the primary cured product after demolding was cut with a diamond wet cutter. or,
The glass transition temperature (° C.) was determined by measuring G ′ of the cured product obtained by this primary curing, and it was 94 ° C.

Further, the demolded cured product obtained by the primary curing was allowed to stand in a hot-air oven in a free-standing state, allowed to stand at 200 ° C. for 3 hours, heated at 200 ° C. for 4 hours, and then heated. Then, it cooled to room temperature over 3 hours, and shape | molded the secondary hardened | cured material.

Ultrasonic flaw detection was carried out on the obtained secondary cured product composed of a molded plate having a thickness of about 2 mm, and it was found that almost no void was generated. Further, a glass transition temperature (° C) was determined by cutting out a test body from this cured product and measuring G ', and it was 188 ° C.

Example 25 Using the epoxy resin composition described in Example 5, a unidirectional prepreg was obtained in the same manner as in Example 24. This prepreg has good tack and drape,
Even after being left at 25 ° C. for 3 weeks, there was little change in tackiness and drapability, and the product had a good life.

Further, when a molded plate made of the primary cured product by the unidirectional prepreg was molded in the same manner as in Example 24, the mold release was sufficiently possible, and the primary cured product after the mold removal was diamond wet. No cracks occurred even when cut with a cutter. Further, the glass transition temperature (° C) was determined by measuring G'of the cured product obtained by the primary curing, and it was 98 ° C.

Subsequently, the primary cured product was treated as in Example 2 above.
Ultrasonic flaw detection of a secondary cured product consisting of a molded plate having a thickness of about 2 mm obtained by subjecting it to secondary curing in the same manner as in 4 revealed that some voids were generated. It was something without. Further, a glass transition temperature (° C) was determined by cutting out a test body from this cured product and measuring G ', which was 202 ° C.

Examples 26 to 30 Epoxy resin compositions having the composition components shown in the predetermined columns of [Table 9] were prepared. The mixing procedure is as follows:
After dissolving p604 and Ep157 at 120 ° C. and cooling to 50 ° C., a mixture of Ep828 of component (a) and PDMU of component (d) uniformly mixed with a three-roll and HX3722 of component (b), and The DDS of the component (c) was blended, and when other components were included, the other components were simultaneously added and mixed uniformly.

The viscosity of each of the obtained epoxy resin compositions at 60 ° C. and the ratio of increase in viscosity when left at 25 ° C. for 3 weeks were measured. The measurement results are also shown in [Table 9].

Further, a reinforcing fiber material prepared by unidirectionally arranging pyrofil carbon fiber TR50S-12L manufactured by Mitsubishi Rayon Co., Ltd. was impregnated with each of the above-mentioned epoxy resin compositions by a hot melt method, and a fiber basis weight of 125 g / m ² A prepreg with a content of 30% by weight was obtained.

The tack of this prepreg was evaluated by touch, and it was found to have a proper tack and was good. Further, even after leaving this prepreg at 25 ° C. for 20 days, it still had an appropriate tack, and it was confirmed that the life of this prepreg was 20 days or more.

Subsequently, 2 m in one direction using the prepreg.
When an m-thick molded plate was molded by primary curing at 80 ° C. for 5 hours, the primary cured product had good demoldability.

Further, the primary cured product after demolding is further added to 200
The Tg of the CFRP panel as the secondary cured product obtained by the secondary curing at 4 ° C. for 4 hours and the elastic modulus retention rate (%) of the CFRP panel at 150 ° C. to 30 ° C. were evaluated. The elastic modulus retention rate (%) of 150 ° C. with respect to 30 ° C. is obtained by measuring the G ′ value at 30 ° C. and the G ′ value at 150 ° C., and the value is “(G ′ at 150 ° C.) × 100 / (30 ° C
G ') in ". Furthermore, the ILSS of the CFRP panel at 150 ° C. was set to ASTM D2344-
When it was measured according to 84, it was confirmed that the mechanical properties at high temperature were excellent. The results are also shown in [Table 9].

[0122]

[Table 9]

Comparative Example 8 After preparing an epoxy resin composition by the composition components described in the predetermined column of [Table 10] below, the epoxy resin composition was used in the same manner as in Example 24 to prepare a prepreg. Preparation and primary curing and secondary curing of the prepreg were performed to obtain a cured product.

Since the component (c) was not mixed in the epoxy resin composition of Comparative Example 8, the Tg of the cured product obtained by the secondary curing was low, and the elastic modulus retention ratio at 150 ° C. to 30 ° C. ( %), The ILPS at 150 ° C. of the CFRP panel, which is a cured product obtained by secondary curing, is also low, and the mechanical properties at high temperatures are low.

Comparative Example 9 A prepreg was prepared in the same manner as in Example 24, except that an epoxy resin composition was prepared by using the compositional components described in the predetermined columns of [Table 10] below, and the epoxy resin composition was used. Then, in the same manner as in Example 26, primary curing with the prepreg was performed to form a primary cured product.

Since the epoxy resin composition according to Comparative Example 9 does not contain the component (b) and contains a curing agent composed of dicyandiamide (Dicy) which is not activated at 100 ° C. or lower, the primary curing is performed. It did not harden so that it could be demolded.

Comparative Example 10 An prepreg was prepared in the same manner as in Example 24 using an epoxy resin composition prepared by using the composition components described in the predetermined column of [Table 10] below. Then, in the same manner as in Example 26, primary curing with the prepreg was performed to form a primary cured product.

The epoxy resin composition of Comparative Example 10 did not contain the component (b) and was not activated at 100 ° C. or lower. Boron trifluoride monomethylamine complex (B
(F3MEA) contains a curing agent,
It did not cure to such an extent that the primary cured product could be released from the mold.

Comparative Example 11 After preparing an epoxy resin composition with the composition components described in the predetermined column of [Table 10] below, the epoxy resin composition was used in the same manner as in Example 24 to prepare a prepreg. Preparation and primary curing and secondary curing of the prepreg were performed to obtain a cured product.

The epoxy resin composition according to Comparative Example 11 did not contain the component (b) and was activated at 100 ° C. or lower, but had no latentity at room temperature. 2-Methylimidazole (2MZ) The epoxy resin composition is remarkably thickened because a curing agent consisting of
It gelled after 3 weeks. Therefore, the life of the prepreg was short, and the tack had completely disappeared after 3 days, and the life had run out.

[0131]

[Table 10]

Comparative Example 12 After preparing an epoxy resin composition with the composition components described in the predetermined columns of [Table 11] below, using the epoxy resin composition in the same manner as in Example 24, a prepreg was prepared. Preparation and primary curing and secondary curing of the prepreg were performed to obtain a cured product.

Since the epoxy resin composition according to Comparative Example 12 did not contain the component (c) but did contain diethylenetriamine as a curing agent, the Tg of the cured product obtained by the secondary curing was low. , 150 ℃ 30
The elastic modulus retention rate (%) at low temperature is also low. Furthermore, 15 of a CFRP panel made of a cured product obtained by secondary curing
ILSS at 0 ° C is also low, and mechanical properties at high temperature are low.

Further, the viscosity of the epoxy resin composition itself was remarkably increased, and gelation occurred after 3 weeks at 25 ° C. Therefore, the life of the prepreg was short, and the tack had completely disappeared after 7 days, and the life was exhausted.

Comparative Example 13 After preparing an epoxy resin composition by the composition components described in the predetermined column of [Table 11], a prepreg was prepared in the same manner as in Example 24 using the epoxy resin composition,
Further, in the same manner as in Example 26, primary curing with the prepreg was performed to form a primary cured product.

Since the epoxy resin composition of Comparative Example 13 did not contain the component (d), it did not cure to such an extent that the primary cured product could be released from the mold.

Comparative Example 14 Preparation of an epoxy resin composition by the composition components described in the predetermined column of [Table 11], and using the epoxy resin composition in the same manner as in Example 24, preparation of a prepreg,
And performing primary curing and secondary curing of the prepreg,
A cured product was obtained.

Since the epoxy resin composition according to Comparative Example 14 does not contain a trifunctional or higher functional epoxy resin, the cured product obtained by the secondary curing has a low Tg,
Further, the elastic modulus retention rate (%) at 150 ° C. to 30 ° C. is also low. Further, C composed of a cured product obtained by secondary curing
The FRP panel also has a low ILSS at 150 ° C, and the mechanical properties at high temperatures are low.

[0139]

[Table 11]

[0140]

As described above in detail, since the epoxy resin composition of the present invention has excellent stability at room temperature and has curability at low temperature, it can be used at a relatively low temperature. It does not take a long time to make a cured product that can be demolded by primary curing, and has excellent heat resistance by secondary curing at high temperature after demolding a cured product that has been primary cured at low temperature. It becomes a cured product.

Further, since the prepreg of the present invention is obtained by impregnating the reinforcing fiber material with the epoxy resin composition having the above-mentioned various properties, it has a long working life and good handleability, The cured product is cured to a demoldable hardness in a short time by the primary curing at a low temperature, and is then cured at a high temperature to obtain a cured molded article having excellent heat resistance.

[Brief description of drawings]

FIG. 1 is a graph used to obtain Tg of a cured product from the intersection of the tangent line of the cured product in the glass state and the tangent line in the transition region.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4F072 AA04 AA07 AB10 AB22 AD23                       AD27 AD30 AE01 AE02 AF15                       AF28 AF31 AG03 AG20 AG22                       AH04 AH43 AK02 AK05 AK14                       AL01 AL17                 4J036 AF06 AH02 AH07 DC02 DC10                       DC25 DC41 HA07 JA11

Claims (15)

[Claims] 1. An epoxy resin composition comprising the following components (a) to (d). Component (a) ... Epoxy resin containing trifunctional or higher functional epoxy resin Component (b) ... Heat-curable latent curing agent that is activated at 100 ° C. or lower Component (c) ... Aromatic amine curing agent Component (d) ... Aromatic urea compound 2. The epoxy resin composition according to claim 1, wherein the component (a) is an epoxy resin containing 40% by mass or more of a trifunctional or higher functional epoxy resin. 3. The epoxy resin composition according to claim 1 or 2, wherein the component (a) is an epoxy resin containing an epoxy resin having a nitrogen atom in the molecule. 4. The epoxy resin composition according to claim 3, wherein the epoxy resin having a nitrogen atom in the molecule is an epoxy resin containing tetraglycidyldiaminophenylmethane. 5. The epoxy resin composition according to claim 3, wherein the epoxy resin having a nitrogen atom in the molecule is an epoxy resin containing triglycidyl aminophenol. 6. The epoxy resin composition according to any one of claims 1 to 5, wherein the component (a) is an epoxy resin containing a novolac type epoxy resin. 7. The novolac type epoxy resin is at least one of a cresol novolac type epoxy resin, a novolac type epoxy resin represented by the following [Chemical formula 1], and a novolac type epoxy resin represented by the following [Chemical formula 2].
It is a kind, The epoxy resin composition of Claim 6 characterized by the above-mentioned. [Chemical 1] [In the formula, n represents a number of 0 or more] [In the formula, n represents a number of 0 or more] 8. The component (b) is a latent curing agent containing an imidazole-based catalyst, which is characterized in that
The epoxy resin composition according to claim 1. 9. The epoxy resin composition according to claim 8, wherein the latent curing agent containing an imidazole catalyst is a microcapsule type latent curing agent. 10. The compounding ratio of the component (a) and the component (b) is characterized in that the component (b) is 3 to 40 parts by mass when the component (a) is 100 parts by mass. The epoxy resin composition according to any one of claims 1 to 9. 11. The ratio of the number of moles of epoxy groups of the epoxy resin of component (a) to the number of moles of active hydrogen of the aromatic amine curing agent of component (c) is 1 / 0.1 to 1/0. 7. The epoxy resin composition according to any one of claims 1 to 10, which is 7. 12. The compounding ratio of the component (a) and the component (d) is such that the component (d) is 2 to 10 parts by mass when the component (a) is 100 parts by mass. The epoxy resin composition according to any one of claims 1 to 11. 13. The viscosity at 60 ° C. is 10 to 700 Pa.
It is sec, The epoxy resin composition in any one of Claim 1- Claim 12 characterized by the above-mentioned. 14. The epoxy resin composition according to claim 1, which satisfies the following (1) to (3). (1) The viscosity increase rate (fold) when left for 3 weeks at 25 ° C. after preparation is not more than twice the viscosity immediately after preparation. (2) The degree of cure of the cured product obtained by primary curing within 80 hours at a temperature of 80 ° C. or lower is 70% or higher. (3) The glass transition temperature of the cured product obtained by the secondary curing at 130 ° C or higher subsequent to the primary curing is 150 ° C or higher. 15. A prepreg using an epoxy resin composition, characterized in that a reinforcing fiber material is impregnated with the epoxy resin composition according to any one of claims 1 to 14.