WO2018131580A1 - Epoxy resin composition, epoxy resin cured product, prepreg, fiber-reinforced composite material, block copolymer and method for producing same - Google Patents

Abstract

A purpose of the present invention is to provide an epoxy resin composition which stably forms a fine phase separation structure in accordance with a molding condition width, and which stably provides an epoxy resin cured product that has excellent heat resistance, elastic modulus and toughness. Another purpose of the present invention is to provide a fiber-reinforced composite material which has excellent adhesiveness. Another purpose of the present invention is to provide a novel block copolymer which has excellent heat resistance and toughness and a method for producing this block copolymer. In order to achieve the above-described purposes, the present invention has the configuration described below. Specifically, an epoxy resin composition which contains at least the constituent elements [A]-[D] described below, while containing 16-50% by mass of the constituent element [B] relative to the total 100% by mass of the epoxy resin composition. [A] an epoxy resin [B] a thermoplastic resin which contains 80% by mole or more of a specific constituent unit in the constituent element [B], and which is soluble in an epoxy resin [C] a block copolymer which is composed of a block [c1] and a block [c2], and which satisfies a specific condition [D] an epoxy resin curing agent

Description

Epoxy resin composition, cured epoxy resin, prepreg, fiber reinforced composite material, block copolymer and method for producing the same

The present invention relates to a fiber reinforced composite material suitable for aerospace use, a prepreg suitably used for obtaining the same, and an epoxy resin composition and a cured epoxy resin suitably used as a matrix resin thereof. Further, the present invention relates to a block copolymer suitable for the matrix resin reinforcing material, electronic material, paint, adhesive and the like.

In recent years, fiber reinforced composite materials using reinforcing fibers such as carbon fibers and aramid fibers have utilized high specific strength and specific elastic modulus to make structural materials such as aircraft and automobiles, tennis rackets, golf shafts, fishing rods, etc. It has been used for sports and general industrial applications.

The fiber-reinforced composite material is produced by using a prepreg which is a sheet-like intermediate material in which reinforcing fibers are impregnated with an uncured matrix resin. A resin transfer molding method or the like is used in which a liquid resin is poured into the arranged reinforcing fibers and the resin is heated and cured. Among these production methods, the method using a prepreg has an advantage that it is easy to obtain a high-performance fiber-reinforced composite material because the orientation of the reinforcing fibers can be strictly controlled and the design flexibility of the laminated structure is high. As the matrix resin used in this prepreg, thermosetting resin is mainly used from the viewpoint of productivity such as heat resistance and processability. Among them, the adhesiveness and dimensional stability between the resin and the reinforcing fiber, and obtained are obtained. Epoxy resins have been suitably used from the viewpoint of mechanical properties such as strength and rigidity of the composite material. However, the epoxy resin has a higher elastic modulus than the thermoplastic resin, but is inferior in toughness, so that the interlaminar toughness and impact resistance of the fiber-reinforced composite material may be insufficient. In addition, there is a problem that defects such as cracks and cracks are likely to occur not only when the fiber reinforced composite material is used but also in a processing process that is exposed to a high temperature environment such as painting or baking.

For such problems, it is considered important and effective to improve the toughness of the matrix resin, and modification of the epoxy resin has been attempted. For example, a technique has been proposed in which a thermoplastic resin or a rubber component having excellent toughness is blended and phase-separated from the epoxy resin to increase the toughness. Specifically, a large amount of a thermoplastic resin that easily induces phase separation from the epoxy resin is blended to form a micron-sized continuous phase, and that phase is responsible for energy absorption, greatly improving the toughness of the epoxy resin. A method is disclosed (Patent Document 1). As another method, there is disclosed a method for improving the toughness of an epoxy resin by forming a submicron rubber phase in the course of curing the epoxy resin by adding a block copolymer made of an acrylic polymer. (Patent Document 2). In addition, a method is disclosed in which a thermoplastic resin and a rubber component are blended in the same composition, and the rubber phase is dispersed in a continuous phase derived from a micron-sized thermoplastic resin to achieve high toughness. (Patent Document 3). Furthermore, in recent years, a method for improving toughness while maintaining heat resistance has been disclosed by designing a block copolymer made of an aromatic polymer (Patent Document 4).

Japanese Patent Laid-Open No. 61-228016 International Publication No. 2006/075153 Japanese Patent Laid-Open No. 7-278212 International Publication No. 2013/017843

When the thermoplastic resin is phase-separated as in Patent Document 1, it leads to improvement in toughness and impact resistance, but causes a decrease in heat resistance, a decrease in adhesive strength with the base material, and a change in phase separation structure depending on molding conditions. There was a case. The method of Patent Document 2 also has a large thickening effect on the epoxy resin, which may deteriorate the processability, and may cause a decrease in elastic modulus resulting from the blending of the rubber component. In some cases, a sufficient balance could not be obtained. Further, when the rubber component is blended in this way, it is not the rubber phase but the epoxy resin phase that is responsible for energy absorption. Therefore, if the plastic deformation ability of the epoxy resin phase is low, the effect of improving toughness tends to be insufficient. It was. Even in the method of Patent Document 3, there is a tendency that it is difficult to stabilize the phase structure due to a decrease in heat resistance or molding conditions, or that the phase separation interface is complex and the adhesion at the phase separation interface tends to be insufficient. Even in the method of Patent Document 4, since it is an epoxy resin phase composed only of an epoxy resin, it is generally brittle and the effect of improving toughness tends to be insufficient.

As described above, a resin composition that has sufficient heat resistance and elastic modulus and stably expresses high toughness has not been obtained, and various properties such as insufficient adhesiveness when used as a fiber-reinforced composite material. Was not enough. In addition, when trying to apply to large structural members such as aircraft main wing structure and wind turbine blades, the phase separation structure fluctuates due to the temperature unevenness in the furnace and the difference of thermal history in the thickness direction of the material. Therefore, there has been a strong demand for materials that exhibit stable characteristics with low dependence on molding conditions.

Accordingly, an object of the present invention is to provide an epoxy resin composition that stably gives an epoxy resin cured product having small heat-resistance, elastic modulus, and toughness, and a prepreg and a fiber-reinforced composite, which have a small variation in phase separation structure depending on molding conditions. It is providing the fiber reinforced composite material excellent in adhesiveness by using a material and this epoxy resin composition.

The application of block copolymers is not limited to the field of fiber reinforced composite materials, but is also progressing in a wide range of fields such as electronic materials, paints, and adhesives. By incorporating various blocks, toughness and crack resistance Improvements are being considered. Furthermore, in recent years, a block copolymer having high heat resistance has been demanded, and as such a material, a material in which an aromatic polymer is introduced has been attracting attention. However, incorporating a low-polarity elastomer block capable of microphase separation into an aromatic polymer has difficulty in synthesis, and cannot exhibit sufficient characteristics.

Therefore, a second object of the present invention is to provide a novel block copolymer excellent in heat resistance and toughness and a method for producing the same.

The present invention has one of the following configurations to achieve the above object.

The epoxy resin composition of the present invention includes at least the following components [A] to [D], and includes an epoxy resin containing 16 to 50% by mass of the component [B] with respect to 100% by mass of the total amount of the epoxy resin composition. It is a composition.
[A] Epoxy resin [B] Thermoplastic resin containing 80 mol% or more of the structural unit represented by formula (1) and capable of being dissolved in the epoxy resin

[C] A block copolymer consisting of block [c1] and block [c2] that satisfies all of the following conditions (i) to (iii) (i) The block [c1] is a structural unit represented by the above formula (1). (Ii) Block [c2] containing 80 mol% or more has a solubility parameter (SP value) of 10 (cal / cm ³ ) ^1/2 or less. (Iii) Block [c1] and block [c2] are ether bonds. [D] Epoxy Resin Curing Agent Connected The prepreg of the present invention is a prepreg obtained by impregnating reinforcing fibers with the epoxy resin composition.

The cured epoxy resin of the present invention is a cured epoxy resin obtained by curing the epoxy resin composition.

Furthermore, the first aspect of the fiber reinforced composite material of the present invention is a fiber reinforced composite material obtained by curing the prepreg.

Further, a second aspect of the fiber reinforced composite material of the present invention is a fiber reinforced composite material comprising the cured epoxy resin and reinforced fibers.

The block copolymer of the present invention is a block copolymer composed of a block [c1] and a block [c2] that satisfies all of the following conditions (i) to (iii).
(I) The block [c1] contains 80 mol% or more of the structural unit represented by the formula (1)

(Ii) The block [c2] has a solubility parameter (SP value) of 10 (cal / cm ³ ) ^1/2 or less. (Iii) The block [c1] and the block [c2] are connected by an ether bond.

According to the present invention, an epoxy resin composition that stably forms a fine phase separation structure with a wide range of molding conditions and gives a cured epoxy resin having excellent heat resistance, elastic modulus, and toughness, and a prepreg and fiber reinforcement A composite material is obtained. Furthermore, a fiber-reinforced composite material excellent in adhesiveness can be obtained by forming a fine phase separation structure with the cured epoxy resin.

Furthermore, in addition to the matrix resin reinforcement for fiber reinforced composite materials, block copolymers that give excellent heat resistance and toughness can be obtained with electronic materials, paints, adhesives, and the like.

Hereinafter, the epoxy resin composition, the cured epoxy resin, the prepreg, the fiber reinforced composite material, the block copolymer and the production method thereof according to the present invention will be described in detail.

The epoxy resin composition of the present invention includes an epoxy resin as a constituent element [A], a thermoplastic resin having a predetermined structure as a constituent element [B], a block copolymer that satisfies a predetermined condition as a constituent element [C], and a constituent It is essential to include an epoxy resin curing agent as the element [D].

The component [A] in the present invention is an epoxy resin. Component [A] forms the basis of the mechanical properties and handleability of the cured epoxy resin. The epoxy resin in the present invention means a compound having one or more epoxy molecules in one molecule.

Specific examples of the epoxy resin in the present invention include bisphenol type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, resorcinol type epoxy resin, dicyclopentadiene type epoxy resin, epoxy resin having biphenyl skeleton, urethane and isocyanate. Examples thereof include modified epoxy resins and amine type epoxy resins. These epoxy resins may be added in combination of not only one type but also a plurality of types. Among them, amine type epoxy resins can be suitably used because of their low viscosity and excellent impregnation into reinforcing fibers, and excellent mechanical properties such as heat resistance and elastic modulus when used as fiber reinforced composite materials. According to a more preferable aspect, it is desirable that the component [A] contains an amine type epoxy resin and the content thereof exceeds 50 parts by mass with respect to 100 parts by mass of the total amount of the component [A].

Examples of the amine-type epoxy resin preferably used in the present invention include tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, triglycidylaminocresol, diglycidylaniline, diglycidyltoluidine, tetraglycidylxylylenediamine, and halogens and alkyls thereof. Substituted products, hydrogenated products and the like can be mentioned.

Commercially available products of tetraglycidyldiaminodiphenylmethane include “Sumiepoxy (registered trademark)” ELM434 (manufactured by Sumitomo Chemical Co., Ltd.), YH434L (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), and “jER (registered trademark)” 604 (Mitsubishi Chemical). "Araldide (registered trademark)" MY720, "Araldide (registered trademark)" MY721 (manufactured by Huntsman Advanced Materials), and the like can be used. Commercially available products of triglycidylaminophenol or triglycidylaminocresol include “Sumiepoxy (registered trademark)” ELM100, “Sumiepoxy (registered trademark)” ELM120 (manufactured by Sumitomo Chemical Co., Ltd.), “Araldide (registered trademark)” “MY0500”, “Araldide (registered trademark)” MY0510, “Araldide (registered trademark)” MY0600 (manufactured by Huntsman Advanced Materials), “jER (registered trademark)” 630 (manufactured by Mitsubishi Chemical Corporation), etc. Can be used. Examples of commercially available diglycidyl aniline include GAN (manufactured by Nippon Kayaku Co., Ltd.). As a commercially available product of diglycidyl toluidine, GOT (manufactured by Nippon Kayaku Co., Ltd.) or the like can be used. “TETRAD (registered trademark)”-X, “TETRAD (registered trademark)”-C (above, manufactured by Mitsubishi Gas Chemical Co., Ltd.), etc. are used as commercial products of tetraglycidylxylylenediamine and hydrogenated products thereof. be able to.

The component [B] in the present invention is a thermoplastic resin that contains 80 mol% or more of the structural unit represented by the formula (1) (referred to as the main structural unit) with respect to all the structural units and can be dissolved in the epoxy resin. is there. By using such a thermoplastic resin as the constituent element [B], the constituent element [B] can be dissolved in the epoxy resin phase, and an epoxy resin cured product having excellent heat resistance and plastic deformation ability can be obtained. . The constituent element [B] may contain less than 20 mol% of constituent units different from the main constituent unit. Although the structure of such a structural unit is not particularly limited, it is desirable to have a skeleton having high compatibility with epoxy resins and high heat resistance. As such structural units, for example, structural units of polyether ether sulfone, polysulfone, polyether ketone, and polyether imide are preferably used. Furthermore, from the viewpoint of heat resistance, it is preferable that 90% by mole or more of the main structural unit is contained in the component [B], and 100% by mole, that is, the component [B] is polyethersulfone. More preferred.

The component [B] is a thermoplastic resin that can be dissolved in the epoxy resin, and is important for the component [B] to be uniformly dissolved in the epoxy resin phase during the curing process. Here, the thermoplastic resin that can be dissolved in the epoxy resin means that the epoxy resin of the component [A] is 5% by mass with respect to 100% by mass of the total mass of the component [A] and the thermoplastic resin. In addition, when the temperature is raised to 150 ° C., it is kneaded at 200 rpm for 1 hour, and when left at room temperature for 1 hour, it means that the two are uniformly compatible at the molecular level. As a means for confirming whether or not they are uniformly compatible at the molecular level, a phase contrast microscope is used to judge from the presence or absence of an insoluble thermoplastic resin or a phase separation structure having a size of 0.5 μm or more.

As described above, when confirming the dissolved state of the epoxy resin composition, a phase contrast micrograph of a predetermined region is taken. When the thermoplastic resin does not dissolve in the epoxy resin of the component [A], it exists as an insoluble matter without being compatible with the component [A] or has a phase of 0.5 μm or more with the component [A]. Since a continuous structure or a sea-island structure having a separation structure is formed, the measurement is performed as follows.

When the thermoplastic resin forms a continuous structure with the constituent element [A], a straight line having a length of 3 mm (a length of 1 μm on the sample) is randomly drawn on a micrograph taken at a magnification of 200 times. Among these, the number average value of the lengths of the portions passing through the phase mainly composed of the thermoplastic resin is defined as the structure period, that is, the size of the phase separation structure. And when the magnitude | size of this phase-separation structure is less than 0.5 micrometer, let the thermoplastic resin be a thermoplastic resin which can be melt | dissolved in an epoxy resin.

In addition, when the thermoplastic resin is present as an insoluble matter or when forming the sea-island structure with the constituent element [A], an area of 20 mm square on the micrograph taken at a magnification of 200 times (100 μm square area on the sample) ) Select three locations, measure the long diameter of all insoluble matter or island phase existing in those areas, and calculate the number average value of the insoluble matter diameter or island phase diameter (ie, the size of the phase separation structure) Sa)). And when the diameter of this insoluble matter or the magnitude | size of a phase-separation structure is less than 0.5 micrometer, let the thermoplastic resin be a thermoplastic resin which can melt | dissolve in an epoxy resin. In addition, the term “insoluble matter or island phase exists in the region” means that more than half of the area of the insoluble matter or island phase is inside the region.

Further, the weight average molecular weight (Mw) of the component [B] is preferably in the range of 4,000 to 40,000 g / mol, more preferably 4,500 to 25,000 g / mol. If the Mw is lower than 4,000 g / mol, it may be insufficient to increase the plastic deformation capacity. On the other hand, when Mw is higher than 40,000 g / mol, when the thermoplastic resin is dissolved in the epoxy resin, the viscosity of the epoxy resin composition becomes high and kneading is difficult, and prepreg may be difficult. In addition, it becomes difficult for the component [B] to be uniformly compatible with the epoxy resin phase during the curing process, and a phase-separated structure is formed, which may result in a material having a large dependence on molding conditions. Here, Mw refers to the relative molecular weight determined by GPC (Gel Permeation Chromatography) using a polystyrene standard sample.

Furthermore, it is preferable that the terminal of this component [B] has a functional group which can react with an epoxy resin. The functional group capable of reacting with an epoxy resin means a functional group capable of reacting with an oxirane group of an epoxy molecule or a functional group of an epoxy resin curing agent. For example, a functional group such as an amino group, a hydroxyl group or a carboxyl group can be mentioned, but the functional group is not limited thereto. When this functional group reacts with an epoxy resin or an epoxy resin curing agent, an epoxy resin cured product in which the component [B] is uniformly compatible with the epoxy resin phase is easily obtained, and stable characteristics can be expressed. Among them, the component [B] having a hydroxyl group as a functional group is preferably used because it provides high toughness.

The production method of the component [B] in the present invention is not particularly limited. For example, it is produced by the method described in JP-B-42-7799, JP-B-45-21318, and JP-A-48-19700. According to the literature, aprotic polarities such as N-methylpyrrolidone, DMF, DMSO, sulfolane, etc. in the presence of alkali metal compounds such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, etc. It can be obtained by polycondensing a divalent phenol compound such as 4,4′-dihydroxydiphenylsulfone and a divalent dihalogenodiphenyl compound such as 4,4′-dichlorodiphenylsulfone in a solvent. As another method, first, a high-molecular-weight polyether sulfone obtained by a generally known method, that is, a high-molecular-weight polyether sulfone obtained by polycondensation of a dihydric phenol compound and a dihalogenodiphenyl compound, The method of manufacturing by introduce | transducing a hydroxyphenyl group to the terminal by heating a dihydric phenol compound in an aprotic polar solvent is mentioned.

Commercially available components [B] in the present invention include “Sumika Excel (registered trademark)” PES3600P, “Sumika Excel (registered trademark)” PES5003P, “Sumika Excel (registered trademark)” PES5200P, and “Sumika Excel (registered trademark)”. ) "PES7600P (above, manufactured by Sumitomo Chemical Co., Ltd.)", "Ultrason (registered trademark)" E2020P SR, "Ultrason (registered trademark)" E2021SR (above, manufactured by BASF), "GAFONE (registered trademark)" 3600RP, “GAFONE (registered trademark)” 3000RP, “Virantage (registered trademark)” VW-10700RP (manufactured by Solvay Advanced Polymers) and the like.

The epoxy resin composition of the present invention needs to contain 16 to 50% by mass of component [B], preferably 20 to 45% by mass, with respect to 100% by mass of the total amount of the epoxy resin composition. If it is less than 16% by mass, the epoxy resin phase becomes brittle. Even when the component [C] is introduced into such an epoxy resin phase, energy absorption by plastic deformation is small, and as a result, the effect of improving the toughness of the cured epoxy resin is small. On the other hand, when it exceeds 50 mass%, the viscosity of an epoxy resin composition will rise and the manufacturing process property and handleability of an epoxy resin composition and a prepreg will become inadequate. In addition, the constituent element [B] forms a coarse phase separation structure, or the constituent element [C] becomes secondary agglomerated during resin preparation or molding curing.

The component [C] in the present invention is a block copolymer composed of a block [c1] and a block [c2] that satisfies all of the following conditions (i) to (iii). The block copolymer of the present invention comprises a block [c1] and a block [c2] that satisfy all of the following conditions (i) to (iii).
(I) The block [c1] contains 80 mol% or more of the structural unit represented by the above formula (1). (Ii) The block [c2] has a solubility parameter (SP value) of 10 (cal / cm ³ ) ^1/2 or less. (Iii) The block [c1] and the block [c2] are connected by an ether bond.

The block copolymer composed of the block [c1] and the block [c2] in the present invention satisfies the conditions (i) to (iii), so that the component [B] has a phase of 16 to 50% by mass in the epoxy resin. Even when melted, the constituent element [C] can be finely dispersed. As a result, the toughness is greatly improved while maintaining the heat resistance and elastic modulus of the cured epoxy resin. Moreover, it is possible to suppress the improvement of the adhesiveness at the interface and the fluctuation of the phase separation structure due to the molding conditions.

As the condition (i) of the block copolymer in the present invention, it is necessary that the structural unit (main structural unit) represented by the formula (1) in the block [c1] is 80 mol% or more with respect to all the structural units. It is. Thereby, compatibility with the component [B] which is compatible with the epoxy resin is increased, which leads to formation of a stable phase separation structure. Note that the block [c1] may contain less than 20 mol% of other structural units, and their configuration is not particularly limited, but the block [c1] as a whole preferably has a skeleton with high heat resistance. For example, structural units of polyether ether sulfone, polysulfone, polyether ketone, and polyether imide are preferably used. Furthermore, from the viewpoint of heat resistance, the main constituent unit is preferably included in the block [c1] in an amount of 90 mol% or more, and more preferably 100 mol%. Here, the block [c1] preferably has the same composition of the constituent unit [B] and the constituent unit from the viewpoint of compatibility.

As the condition (ii) of the block copolymer in the present invention, the SP value of the block [c2] needs to be 10 (cal / cm ³ ) ^1/2 or less. As a result, the block [c2] can form a fine phase in the cured epoxy resin phase and exhibit high toughness while maintaining heat resistance and elastic modulus.

Here, the SP value is a generally known solubility parameter, and is an index of solubility and compatibility. There are a method for calculating the SP value from physical properties such as heat of evaporation and a method for estimating the SP value from the molecular structure. Here, Polym. Eng. Sci. , 14 (2), 147-154 (1974), the SP value calculated from the molecular structure based on the Fedors method is used, and the unit is (cal / cm ³ ) ^1/2 . I will do it.

The block [c2] having an SP value of 10 (cal / cm ³ ) ^1/2 or less in the present invention is not particularly limited in chemical structure or molecular weight, but induces plastic deformation of the epoxy resin phase. The elastomer is preferably capable of causing large energy absorption. Examples of such elastomers include polybutadiene, polyisoprene, poly (2,3-dimethyl-1,3-butadiene), poly (1,3-pentadiene), and poly (2-phenyl-1,3-butadiene). Polyalkylene (meth) acrylate selected from polydiene, polyethyl acrylate, polybutyl acrylate, poly (2-ethylhexyl acrylate), polyhydroxyethyl acrylate and poly (2-ethylhexyl methacrylate) selected from Examples include siloxane and polytetrafluoroethylene. Among these, polysiloxane having a good balance of mechanical properties is preferably used.

In the epoxy resin composition of the present invention, the component [C] is such that the block [c1] is polyethersulfone from the viewpoint of good compatibility with the component [B] and heat resistance, and the block [c2] is tough. From this point of view, a block copolymer which is polysiloxane is preferable.

In the block copolymer of the present invention, the block [c1] is preferably polyethersulfone from the viewpoint of heat resistance, and the block [c2] preferably contains a siloxane bond from the viewpoint of toughness.

As the condition (iii) of the block copolymer in the present invention, it is necessary that the block [c1] and the block [c2] are connected by an ether bond. Furthermore, the block [c1] and the block [c2] are preferably connected by a structure represented by the formula (2) or the formula (3). Thereby, it becomes a chemically stable linear linked structure, and compatibility with the epoxy resin phase is enhanced, and an epoxy resin cured product having excellent solvent resistance and adhesiveness is easily obtained.

The weight average molecular weight (Mw) of the block copolymer in the present invention is preferably in the range of 5,000 to 70,000 g / mol, and more preferably 7,000 to 60,000 g / mol. When Mw is lower than 5,000 g / mol, the effect of improving toughness may be insufficient. On the other hand, if Mw is higher than 70,000 g / mol, heat resistance and elastic modulus may be lowered. In addition, when the block copolymer is dissolved in the epoxy resin composition, the viscosity of the epoxy resin becomes high and kneading is difficult, and prepreg may be difficult.

The block mass fraction of the block [c2] in the block copolymer in the present invention is preferably 0.05 to 0.60, and more preferably 0.15 to 0.50. When the block mass fraction is less than 0.05, the toughness of the cured epoxy resin may be lowered. When the block mass fraction exceeds 0.60, it may be difficult to lower the elastic modulus of the cured epoxy resin and to stabilize the phase separation.

Although there is no restriction | limiting in particular in the manufacturing method of the block copolymer in this invention, Obtaining by the nucleophilic substitution reaction of a phenolic hydroxyl group is preferable from a highly efficient simple method. According to this technique, a thermoplastic resin that can be dissolved in an epoxy resin having a phenolic hydroxyl group at the terminal for a compound having an oxirane group of the epoxy molecule at the terminal and an SP value of 10 (cal / cm ³ ) ^1/2 or less. A block copolymer can be obtained by the nucleophilic substitution reaction. In addition, by heating a phenol compound made of an elastomer having a divalent SP value of 10 (cal / cm ³ ) ^1/2 or less and a thermoplastic resin that can be dissolved in an epoxy resin in an aprotic polar solvent, A block copolymer can also be obtained.

The content of the block copolymer of the component [C] is 2 to 30 masses with respect to 100 parts by mass of the total amount of the epoxy resin of the component [A], from the viewpoint of mechanical properties and compatibility with the composite production process. Parts, preferably 3 to 20 parts by mass. If the content of the component [C] is less than 2 parts by mass, the toughness and plastic deformation ability of the cured epoxy resin may be reduced. When content of component [C] exceeds 30 mass parts, the elasticity modulus of epoxy hardened | cured material may fall remarkably and the adhesiveness of the fiber reinforced composite material obtained may deteriorate.

The component [D] in the present invention is an epoxy resin curing agent. Here, the epoxy resin curing agent is not particularly limited as long as it is a compound having an active group capable of reacting with the oxirane group of the epoxy molecule. For example, dicyandiamide, aromatic polyamine, aminobenzoic acid esters, various acid anhydrides, Phenol novolac resin, cresol novolac resin, polyphenol compound, imidazole derivative, aliphatic amine, tetramethylguanidine, thiourea addition amine, carboxylic acid anhydride such as methylhexahydrophthalic anhydride, carboxylic acid hydrazide, carboxylic acid amide, And Lewis acid complexes such as polymercaptan and boron trifluoride ethylamine complex.

Above all, by using an aromatic polyamine as an epoxy resin curing agent for the component [D], a cured epoxy resin with good heat resistance can be obtained. In particular, diaminodiphenyl sulfone or a derivative thereof, or various isomers thereof are the most suitable epoxy resin curing agents for obtaining a cured epoxy resin with good heat resistance.

Further, by using a combination of dicyandiamide and a urea compound such as 3,4-dichlorophenyl-1,1-dimethylurea or imidazoles as an epoxy resin curing agent, high heat and water resistance can be achieved while curing at a relatively low temperature. can get. Curing the epoxy resin with an acid anhydride gives a cured epoxy resin having a lower water absorption than the amine compound curing. In addition, by using a latent product of these curing agents, for example, a microencapsulated product, the storage stability of the prepreg, in particular, tackiness and draping properties hardly change even when left at room temperature.

The optimum value of the addition amount of the epoxy resin curing agent of the component [D] varies depending on the type of epoxy resin and epoxy resin curing agent. For example, when an aromatic amine curing agent is used, the content is preferably 0.6 to 1.2 times the amount of active hydrogen in the epoxy resin from the viewpoint of heat resistance and mechanical properties. 0.7 to 1.1 times is more preferable. When less than 0.6 times, since the crosslinking density of the cured epoxy resin is not sufficient, the elastic modulus and heat resistance may be insufficient, or the static strength characteristics of the fiber reinforced composite material may be insufficient. When exceeding 1.2 times, the crosslinking density and water absorption rate of the cured epoxy resin are too high, the deformation ability is insufficient, and the impact resistance of the fiber composite material may be inferior.

Commercially available aromatic polyamine curing agents include Seika Cure S (manufactured by Wakayama Seika Kogyo Co., Ltd.), MDA-220, 3,3′-DAS (manufactured by Mitsui Chemicals, Inc.), “jER Cure (registered) Trademarks) “W (Mitsubishi Chemical Corporation)”, “Lonacure (registered trademark)” M-DEA, “Lonacure (registered trademark)” M-DIPA, “Lonacure (registered trademark)” M-MIPA (above, Lonza ( And Lonzacure (registered trademark) DETDA 80 (manufactured by Lonza).

Also, the epoxy resin and epoxy resin curing agent, or a product obtained by pre-reacting a part of them can be contained in the composition. This method may be effective for viscosity adjustment and storage stability improvement.

The cured epoxy resin of the present invention is obtained by curing the epoxy resin composition of the present invention.

The glass transition temperature of the cured epoxy resin of the present invention is preferably 120 to 250 ° C., more preferably 140 to 210 ° C., from the viewpoint of sufficiently ensuring the heat resistance required for aircraft materials and compressive strength under wet heat. is there. Such a relatively high heat resistance epoxy resin composition and a prepreg using the epoxy resin composition require a relatively high curing temperature. The prepreg currently used for aircraft fuselage structural materials generally has a curing molding temperature in the range of 180 ± 10 ° C. Further, in order to sufficiently develop the strength of the fiber reinforced composite material formed by curing, the prepreg laminate is generally cured and molded under a pressure condition of 1 atm or higher.

In the cured epoxy resin of the present invention, the size of the phase separation structure composed mainly of the component [C] is preferably in the range of 0.01 to 0.5 μm. That is, in the cured epoxy resin of the present invention, the constituent element [A], the constituent element [B], and the constituent element [D] have a homogeneous phase structure or the constituent element [B] as a main component. It is preferable to form a fine phase separation structure of less than 5 μm, and further to form a fine phase separation structure of 0.01 μm to 0.5 μm containing the constituent element [C] as a main component. Among them, the constituent element [A], the constituent element [B], and the constituent element [D] form a uniform phase structure, and a fine phase of 0.01 μm to 0.5 μm mainly containing the constituent element [C]. It is more preferable to form a separation structure because stable characteristics can be obtained. Here, forming a homogeneous phase structure refers to a state in which the component [A], the component [B], and the component [D] are compatible at the molecular level in the cured epoxy resin. When the component [B] or the component [C] forms a phase of less than 0.01 μm, it is difficult to observe with a transmission electron microscope, so that it is regarded as a homogeneous phase structure. In addition, the phase having the constituent element [C] as a main component is the density (content per unit area) of the constituent element [C] among phases forming a phase separation structure such as a continuous structure or a sea-island structure. Represents a larger phase than the other phases. Whether the density of the constituent element [C] is larger than the other phases is determined based on the composition contrast. If it is difficult to determine by composition contrast, it is determined by elemental analysis using an electron microscope.

When the component [B] and the component [C] are phase-separated exceeding 0.5 μm, the elastic modulus and heat resistance may be lowered, and the adhesiveness at the phase-separated interface may be deteriorated. is there. In addition, it may be difficult to stabilize the phase structure depending on the molding conditions.

When the constituent element [C] forms a phase of less than 0.01 μm, or forms a homogeneous phase structure, the energy absorption due to plastic deformation is small, and the effect of improving the toughness of the cured epoxy resin is small. There is a case.

In the present invention, the phase separation structure means that a phase mainly composed of resins having different constituent elements has a size of a phase separation structure of 0.01 μm or more. On the other hand, the state of being uniformly mixed at the molecular level is called a compatible state, and in the present invention, the phase composed mainly of resins having different constituent elements is less than 0.01 μm in size of the phase separation structure. If there is, it shall be regarded as a compatible state.

In the cured epoxy resin of the present invention, the size of the phase separation structure of a phase mainly composed of a certain resin is defined as follows. In addition, since the phase separation structure has a continuous structure and a sea-island structure, each is defined.

In the case of a continuous structure, a straight line having a predetermined length is drawn on a photomicrograph, and the number average value of the lengths of portions of the straight line passing through a phase containing the resin as a main component is defined as a structural period. In the continuous structure, the structure period is the size of the phase separation structure. The predetermined length is set as follows based on a transmission electron micrograph. When the structural period is expected to be on the order of 0.01 μm (10 nm or more and less than 100 nm), take a photograph at a magnification of 20,000 times, and randomly place 3 pieces of 20 mm length (1 μm length on the sample) on the photograph. The selected one. Similarly, when the phase separation structure period is expected to be on the order of 0.1 μm (100 nm or more and less than 1 μm), a photograph is taken at a magnification of 2,000 times, and a length of 20 mm on the photograph (10 μm on the sample) Length) A selection of 3 bottles. When the phase separation structure period is expected to be on the order of 1 μm (1 μm or more and less than 10 μm), a photograph was taken at a magnification of 200 times, and three pieces of 20 mm length (100 μm length on the sample) were randomly selected on the photograph. It shall mean something. If the measured phase separation structure period is out of the expected order, the corresponding length is measured again at the magnification corresponding to the corresponding order, and this is adopted.

In the case of a sea-island structure, the major axis of the island phase existing in a predetermined region is measured, and the number average value of these is taken as the island phase diameter. In the sea-island structure, the diameter of the island phase is the size of the phase separation structure. Here, when the island phase is elliptical, the major axis is taken, and when it is indefinite, the diameter of the circumscribed circle is used. In the case of a circle or ellipse having two or more layers, the diameter of the outermost layer circle or the major axis of the ellipse is used. The predetermined area is set as follows based on a transmission electron micrograph. When the diameter of the island phase is expected to be less than 0.01 μm or on the order of 0.01 μm (10 nm or more and less than 100 nm), a photograph is taken at a magnification of 20,000 times, and a random 20 mm square area on the photograph (1 μm on the sample Four areas) are selected. Similarly, when the diameter of the island phase is expected to be on the order of 0.1 μm (100 nm or more and less than 1 μm), a photograph is taken at a magnification of 2,000 times, and an area of 20 mm square on the photograph (10 μm square on the sample) 3) Select 3 locations. If the island phase diameter is expected to be on the order of 1 μm (1 μm or more and less than 10 μm), take a photograph at a magnification of 200 times, and randomly select three 20 mm square areas (100 μm square area on the sample) on the photograph. . If the measured island phase diameter deviates from the expected order, the corresponding region is measured again at the magnification corresponding to the corresponding order, and this is adopted.

The size of the phase separation structure of the cured epoxy resin can be observed with a scanning electron microscope or a transmission electron microscope. You may dye | stain with osmium etc. as needed. Dyeing can be performed by a usual method.

In addition, in order to confirm the phase structure of such a cured epoxy resin by other methods, it is also possible to determine whether there is a single Tg detected by a method of thermodynamic property analysis such as DMA or DSC. is there. For example, in the scatter diagram of loss tangent (tan δ) and temperature obtained by DMA temperature rise measurement of such a cured epoxy resin, in addition to the tan δ peak derived from the cross-linked structure composed of the component [A], the component [C When a tan δ peak derived from] appears, it can be determined that the phases are separated.

As an example of the cured epoxy resin of the present invention, a sea-island structure phase-separated structure having a phase mainly composed of the epoxy resin of the component [A] and a phase mainly composed of the block copolymer of the component [C] An epoxy resin cured product having

The epoxy resin composition of the present invention is a coupling agent, a thermosetting resin particle, or a thermoplastic resin other than the component [B], a thermoplastic resin particle, a component [ Inorganic fillers such as elastomers other than C], silica gel, carbon black, clay, carbon nanotube, metal powder, and the like can be contained.

In the epoxy resin composition of the present invention, components other than the component [D], which is an epoxy resin curing agent, are first heated and kneaded uniformly at a temperature of about 150 to 170 ° C., and then cooled to a temperature of about 80 ° C. After that, it is preferable to add component [D] and knead, but the blending method of each component is not particularly limited to this method.

Examples of the reinforcing fiber used in the present invention include glass fiber, carbon fiber, graphite fiber, aramid fiber, boron fiber, alumina fiber, and silicon carbide fiber. Two or more kinds of these reinforcing fibers may be mixed and used, but in order to obtain a molded product that is lighter and more durable, it is preferable to use carbon fibers or graphite fibers. In particular, in applications where there is a high demand for weight reduction and high strength of materials, it is preferable that the reinforcing fibers are carbon fibers because of their excellent specific modulus and specific strength.

The carbon fiber preferably used in the present invention can be any type of carbon fiber depending on the application, but is preferably a carbon fiber having a tensile elastic modulus of 400 GPa or less from the viewpoint of impact resistance. From the viewpoint of strength, a carbon fiber having a tensile strength of preferably 4.4 to 6.5 GPa is preferably used because a composite material having high rigidity and mechanical strength can be obtained. Also, the tensile elongation is an important factor, and it is preferable that the carbon fiber is a high strength and high elongation carbon fiber of 1.7 to 2.3%. Accordingly, carbon fibers having the characteristics that the tensile modulus is at least 230 GPa, the tensile strength is at least 4.4 GPa, and the tensile elongation is at least 1.7% are most suitable.

Commercially available carbon fibers include “Torayca (registered trademark)” T800G-24K, “Torayca (registered trademark)” T800S-24K, “Torayca (registered trademark)” T700G-24K, and “Torayca (registered trademark)” T300- 3K, and “Torayca (registered trademark)” T700S-12K (manufactured by Toray Industries, Inc.).

The form and arrangement of the carbon fibers can be appropriately selected from long fibers and woven fabrics arranged in one direction. However, in order to obtain a carbon fiber reinforced composite material that is lighter and more durable, It is preferably in the form of continuous fibers such as long fibers (fiber bundles) or woven fabrics arranged in one direction.

The prepreg of the present invention is obtained by impregnating the above reinforcing fiber with the epoxy resin composition of the present invention. The fiber mass fraction of the prepreg is preferably 40 to 90% by mass, more preferably 50 to 80% by mass. When the fiber mass fraction is too low, the mass of the resulting composite material becomes excessive, and the advantages of the fiber-reinforced composite material having excellent specific strength and specific elastic modulus may be impaired. On the other hand, if the fiber mass fraction is too high, poor impregnation of the resin composition occurs, and the resulting composite material tends to have a lot of voids, so that its mechanical properties may be greatly deteriorated.

The form of the reinforcing fibers is not particularly limited, and for example, long fibers, tows, woven fabrics, mats, knits, braids and the like that are aligned in one direction are used. In particular, for applications that require high specific strength and high specific modulus, an array in which reinforcing fibers are aligned in a single direction is most suitable. Arrangements are also suitable for the present invention.

The prepreg of the present invention is prepared by dissolving the epoxy resin composition used as a matrix resin in a solvent such as methyl ethyl ketone or methanol to lower the viscosity and impregnating the reinforced fiber (wet method), or by heating the matrix resin by heating. It can be produced by a hot melt method (dry method) or the like in which the viscosity is increased and the reinforcing fibers are impregnated.

The wet method is a method in which a reinforcing fiber is immersed in a solution of an epoxy resin composition that is a matrix resin, and then lifted and the solvent is evaporated using an oven or the like. The hot melt method (dry method) is a method of impregnating reinforcing fibers directly with an epoxy resin composition whose viscosity has been reduced by heating, or a film in which an epoxy resin composition is once coated on release paper or the like, Next, the reinforcing fiber is impregnated with resin by overlapping the film from both sides or one side of the reinforcing fiber and heating and pressing. According to the hot melt method, the solvent remaining in the prepreg is substantially absent, and therefore, this is a preferred embodiment in the present invention.

The first aspect of the fiber-reinforced composite material of the present invention is obtained by curing the prepreg of the present invention. Such a fiber reinforced composite material can be produced by, for example, a method of laminating the prepreg of the present invention and then heating and curing the matrix resin while applying pressure to the laminate.

Here, as a method of applying heat and pressure, a press molding method, an autoclave molding method, a bagging molding method, a wrapping tape method, an internal pressure molding method, or the like is employed.

The second embodiment of the fiber-reinforced composite material of the present invention comprises the cured epoxy resin of the present invention and reinforcing fibers. Such a fiber-reinforced composite material is obtained by impregnating an epoxy resin composition directly into a reinforcing fiber without using a prepreg, followed by heat-curing, for example, a hand lay-up method, a filament winding method, a pultrusion method, a resin It can be produced by a molding method such as an injection molding method or a resin transfer molding method. In these methods, it is preferable to prepare an epoxy resin composition by mixing two liquids of an epoxy resin main component and an epoxy resin curing agent immediately before use.

Hereinafter, the epoxy resin composition of the present invention will be described more specifically with reference to examples. The production methods and evaluation methods of the resin raw materials used in the examples are shown below.

<Component [A]: Epoxy resin>
(Amine type epoxy resin)
"JER (registered trademark)" 630 (triglycidylaminophenol, manufactured by Mitsubishi Chemical Corporation)
"Araldite (registered trademark)" MY0600 (triglycidylaminophenol, manufactured by Huntsman Advanced Materials)
"Sumiepoxy (registered trademark)" ELM434 (tetraglycidyldiaminodiphenylmethane, manufactured by Sumitomo Chemical Co., Ltd.).

(Other epoxy resins)
・ "JER (registered trademark)" 828 (bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation))
"Epiclon (registered trademark)" 830 (bisphenol F type epoxy resin, manufactured by DIC Corporation)
"JER (registered trademark)" 152 (phenol novolac type epoxy resin, manufactured by Mitsubishi Chemical Corporation)).

<Thermoplastic resin>
(Constituent element [B]: Thermoplastic resin containing 80 mol% or more of the structural unit represented by formula (1) and soluble in epoxy resin)
"Virantage (registered trademark)" VW-10700RP (polyethersulfone, manufactured by Solvay Advanced Polymers Co., Ltd., component [B] contains 100 mol% or more of the structural unit represented by formula (1), Mw = 21,000 g / Mol)
Polyethersulfone P1 (component [B] contains 100 mol% of the structural unit represented by formula (1), Mw = 5,000 g / mol)
In a three-necked flask equipped with a stirrer, nitrogen introduction tube, thermometer, and cooling tube, 25.03 g (0.1 mol) of 4,4′-dihydroxydiphenylsulfone, 50 ml of toluene, 1,3-dimethyl-2-imidazolidinone 125.4 g and 28.0 g of 40% potassium hydroxide aqueous solution were taken, and nitrogen gas was passed through with stirring, and the reaction system was completely replaced with nitrogen. The mixture was heated to 130 ° C. while passing nitrogen gas. As the temperature of the reaction system rose, the reflux of toluene was started. Water in the reaction system was removed by azeotropy with toluene, and azeotropic dehydration for returning toluene to the reaction system was performed at 130 ° C. for 4 hours. Thereafter, 28.7 g of 4,4′-dichlorodiphenylsulfone was added to the reaction system together with 20 g of toluene, and the reaction system was heated to 150 ° C. The reaction was carried out for 3 hours while distilling toluene to obtain a high-viscosity brown solution. The temperature of the reaction solution was cooled to room temperature, the reaction solution was discharged into 500 g of methanol, and polymer powder was deposited. The polymer powder was collected by filtration and transferred to a beaker. 500 g of water was added thereto, and 1N hydrochloric acid was further added. After collecting the polymer powder by filtration, the polymer powder was washed twice with 500 g of water. Further, it was washed with 500 g of methanol and dried under reduced pressure at 150 ° C. for 12 hours. To 5.0 g of the obtained intermediate product, 2.5 g of 4,4′-dihydroxydiphenylsulfone, 200 ml of N-methyl-2-pyrrolidone (NMP), and 3.0 g of anhydrous potassium carbonate were weighed. While stirring the NMP reaction solution, the reaction temperature was raised to 150 ° C., and the reaction was completed in a reaction time of 10 hours. The reaction solution was dropped into 500 ml of methanol, and the precipitated solid was pulverized and washed twice with 500 ml of water. Vacuum drying was performed at 130 ° C. to obtain 5.8 g of a white powder.

Polyethersulfone P2 (component [B] contains 100 mol% of the structural unit represented by formula (1), Mw = 8,000 g / mol)
Into a three-necked flask equipped with a stirrer, nitrogen introducing tube, thermometer, and cooling tube, 1.5 g of 4,4′-dihydroxydiphenylsulfone and N-methyl were added to 5.0 g of the intermediate product obtained in the same manner as P1. 200 ml of -2-pyrrolidone (NMP) and 2.0 g of anhydrous potassium carbonate were weighed. While stirring the NMP reaction solution, the reaction temperature was increased to 150 ° C., and the reaction was completed in a reaction time of 6 hours. The reaction solution was dropped into 500 ml of methanol, and the precipitated solid was pulverized and washed twice with 500 ml of water. Vacuum drying was performed at 130 ° C. to obtain 6.4 g of a white powder.

(Thermoplastic resin other than component [B])
“Virantage®” VW-30500RP (Polysulfone, manufactured by Solvay Advanced Polymers).

· "ULTEM (registered trademark)" 1010 (polyetherimide, manufactured by Sabic).

<Block copolymer>
(Constituent element [C]: block copolymer consisting of block [c1] and block [c2] satisfying conditions (i) to (iii))
Block copolymer X1 (block copolymer connected with the structure represented by formula (2))
Block [c1] -Block [c2] = [PES]-[Si] {Poly (ethersulfone) -block-poly (siloxane), (Block [c1] contains 100 mol% of the structural unit represented by formula (1) , [Si] / [PES]-[Si] block weight fraction = 0.35, Mw = 7,500 g / mol, [PES] and [Si] are block copolymers and blocks connected by an ether bond [C2] SP = 7.4)}.

In a 300 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube, a thermometer, and a cooling tube, "Virantage (registered trademark)" VW-10700RP (polyethersulfone, Solvay Advanced Polymers Co., Ltd.) "5.0 g, KF-2201 (phenol-modified silicone, manufactured by Shin-Etsu Chemical Co., Ltd.) 10.0 g, dehydrated dimethyl sulfoxide (dehydrated DMSO) 120 ml, dehydrated toluene 30 ml, and anhydrous potassium carbonate 2.3 g were weighed in a dehydrated DMSO / dehydrated toluene reaction solution. The reaction temperature was raised to 150 ° C. with stirring, and the nucleophilic substitution reaction of the phenolic hydroxyl group was completed in 3 hours of reaction time.The reaction solution was dropped into 500 ml of methanol, the precipitated solid was pulverized, and 500 ml of water was used. Washed twice, vacuum dried at 130 ° C. There was obtained a white powder 2.7 g.

Block copolymer X2 (block copolymer connected with the structure represented by formula (2))
Block [c1] -Block [c2] = [PES]-[Si] {Poly (ethersulfone) -block-poly (siloxane), (Block [c1] contains 100 mol% of the structural unit represented by formula (1) , [Si] / [PES]-[Si] block weight fraction = 0.3, Mw = 9,000 g / mol, [PES] and [Si] are block copolymers and blocks connected by an ether bond [C2] SP = 7.4)}.

In a 300 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube, a thermometer, and a cooling tube, "Virantage (registered trademark)" VW-10700RP (polyethersulfone, Solvay Advanced Polymers Co., Ltd.) "5.0 g, BY16-752A (phenol-modified silicone, manufactured by Toray Dow Corning Co., Ltd.) 8.2 g, 120 ml of dehydrated dimethyl sulfoxide (dehydrated DMSO), 30 ml of dehydrated toluene, and 2.5 g of anhydrous potassium carbonate were weighed. The reaction temperature was raised to 150 ° C. while stirring the solution, and the nucleophilic substitution reaction of the phenolic hydroxyl group was completed within 4 hours of reaction time.The reaction solution was dropped into 500 ml of methanol, the precipitated solid was pulverized, and 500 ml of water Washed twice at 130 ° C. And vacuum dried to give a white powder 2.5 g.

Block copolymer X3 (block copolymer connected with the structure represented by formula (3))
Block [c1] -Block [c2] = [PES]-[Si] {Poly (ethersulfone) -block-poly (siloxane), (Block [c1] contains 100 mol% of the structural unit represented by formula (1) , [Si] / [PES]-[Si] block weight fraction = 0.2, Mw = 10,000 g / mol, [PES] and [Si] are block copolymers and blocks connected by an ether bond [C2] SP = 7.4)}.

In a 30 mL autoclave, 0.3 g of P2 (polyethersulfone), 1.4 g of X-22-163B (epoxy-modified silicone, manufactured by Shin-Etsu Chemical Co., Ltd.), N-methyl-2-pyrrolidone (NMP) 15 ml was added. After carrying out nitrogen substitution of 99 volume% or more, the reaction temperature was raised to 150 ° C. with stirring, and the nucleophilic substitution reaction of the phenolic hydroxyl group was completed in a reaction time of 12 hours. The reaction solution was dropped into 100 ml of methanol, and the precipitated solid was pulverized and washed twice with 100 ml of water. Vacuum drying was performed at 130 ° C. to obtain 0.26 g of a white powder.

(Block copolymer other than component [C])
・ Block copolymer Y1
[MMA]-[BA] {poly (methyl methacrylate) -block-poly (butyl acrylate), ([MMA] is a random copolymer chain of methyl methacrylate and a polar acrylic monomer, and [MMA] and [BA ] Is a block copolymer linked by a C—C bond, [BA] SP = 10)}.
Synthesized according to the description of MBuAM-2 by WO 2006/075153.
・ Block copolymer Y2
[PEI]-[Si] {poly (ether imide) -block-poly (siloxane), [PEI] and [Si] are block copolymers connected by imide bonds, [Si] SP = 7.4 )}
The compound was synthesized as described in Example 1 of JP-A-7-278212.

・ Block copolymer Y3
[PSU]-[Si] {poly (sulfone) -block-poly (siloxane), ([[PSU] and [Si] are block copolymers connected by CN bonds, [Si] SP = 7.4)}
“Journal of Applied Polymer Science”, 119, p. 2933 (2011) by Di Hu, Sixun Zheng, described in “Morphology and Thermochemical Properties of Epoxy Thermosets Modified with Polysulfide-Blocky-Polymolecule-Block-Polydipolys.

<Other ingredients>
Particle 1 (thermoplastic resin particles made from “Grillamide (registered trademark)” TR55 as a raw material)
(Production method of particle 1: International Publication No. 2009/142231 was referred to.)
In a 100 ml four-necked flask, 2.5 g of amorphous polyamide (Mw = 18,000 g / mol, “Glilamide (registered trademark)” TR55, manufactured by Mzavelke) as polymer A, and N-methyl-2-pyrrolidone as the organic solvent 42.5 g and 5 g of polyvinyl alcohol (“GOHSENOL (registered trademark)” GL-05) as polymer B were added, heated to 80 ° C., and stirred until the polymer was dissolved. After returning the temperature of the system to room temperature, 50 g of ion-exchanged water as a poor solvent was dropped at a speed of 0.41 g / min via a liquid feed pump while stirring at 450 rpm. When 12 g of ion exchange water was added, the system turned white. After all the amount of water had been added, the mixture was stirred for 30 minutes, and the resulting suspension was filtered, washed with 100 g of ion-exchanged water, and vacuum-dried at 80 ° C. for 10 hours to obtain 2.2 g of a white solid. . When the obtained powder was observed with a scanning electron microscope, it was polyamide fine particles having an average particle diameter of 16.1 μm.

<Component [D]: Epoxy resin curing agent>
・ 3,3′-DAS (3,3′-diaminodiphenylsulfone, manufactured by Mitsui Chemicals Fine Co., Ltd.)
・ Seika Cure-S (4,4'-diaminodiphenyl sulfone, manufactured by Wakayama Seika Co., Ltd.)
(1) Preparation of the epoxy resin composition In the kneader, a predetermined amount of components other than the epoxy resin curing agent and the curing accelerator is added, and while kneading, the temperature is increased to 160 ° C, and kneading is performed at 160 ° C for 1 hour. A clear viscous liquid was obtained. After the temperature was lowered to 80 ° C. while kneading, a predetermined amount of an epoxy resin curing agent and a curing accelerator were added and further kneaded to obtain an epoxy resin composition.

(2) Measurement of flexural modulus of cured epoxy resin After defoaming the epoxy resin composition prepared in (1) above in a vacuum, the thickness is 2 mm using a 2 mm thick “Teflon (registered trademark)” spacer. Was poured into the mold set to Curing was performed at a temperature of 180 ° C. for 2 hours to obtain a cured epoxy resin having a thickness of 2 mm. Next, a test piece having a width of 10 mm and a length of 60 mm was cut out from the obtained cured epoxy resin plate, measured at a three-point bend of 32 mm between spans, and the flexural modulus was obtained according to JIS K7171-1994.

(3) Measurement of toughness (K _IC ) of cured epoxy resin After defoaming the epoxy resin composition prepared in (1) above in a vacuum, the thickness was reduced to 6 mm using a 6 mm thick “Teflon (registered trademark)” spacer. In the mold set so that it may become, it hardened | cured at the temperature of 180 degreeC for 2 hours, and obtained the epoxy resin hardened | cured material of thickness 6mm. This cured epoxy resin was cut into a size of 12.7 × 150 mm to obtain a test piece. Using an Instron universal testing machine (manufactured by Instron), the specimens were processed and tested according to ASTM D5045 (1999). The initial precrack was introduced into the test piece by applying a razor blade cooled to liquid nitrogen temperature to the test piece and applying an impact to the razor with a hammer. Here, the toughness of the cured epoxy resin refers to the critical stress intensity factor of deformation mode I (opening type).

(4) Measurement of glass transition temperature of cured epoxy resin From the cured epoxy resin plate prepared in (2) above, 7 mg of the cured epoxy resin is taken out and 30 ° C. or higher using DSC2910 (model number) manufactured by TA Instruments. The measurement was performed in a temperature range of 350 ° C. at a rate of temperature increase of 10 ° C./min, and the midpoint temperature determined based on JIS K7121-1987 was used as the glass transition temperature Tg to evaluate the heat resistance.

(5) Measurement of size of phase separation structure (structure period or island phase diameter) of cured epoxy resin The foamed epoxy resin composition prepared in (1) above was degassed in a vacuum and heated to 30 ° C to 180 ° C. After the temperature range was raised at a rate of 1.5 ° C./minute, a cured epoxy resin cured at a temperature of 180 ° C. for 2 hours was obtained. After the cured epoxy resin was dyed, it was cut into thin sections and a transmission electron image was obtained under the following conditions using a transmission electron microscope (TEM). As the staining agent, OsO ₄ and RuO ₄ were properly used according to the resin composition so that the morphology was sufficiently contrasted.
・ Device: H-7100 transmission electron microscope (manufactured by Hitachi, Ltd.)
・ Acceleration voltage: 100 kV
-Magnification: 10,000 times.

Accordingly, the size of the phase separation structure (structure period or island phase diameter) of the phase mainly composed of the epoxy resin of the component [A] and the phase mainly composed of the block copolymer of the component [C]. Was observed. The phase separation structure of the epoxy resin cured product forms a continuous structure, a sea-island structure, or both depending on the types and ratios of the component [A] and the component [C], and each was measured as follows. Hereinafter, the case where the size of the phase separation structure of the phase mainly composed of the component [C] is measured will be described as an example, but the same applies to the case where the phase mainly composed of other components is measured.

When the constituent element [C] forms a continuous structure, a straight line having a predetermined length is drawn on the photomicrograph, and the length of the portion of the straight line passing through the phase having the constituent element [C] as a main component is drawn. The number average value was taken as the structure period. The predetermined length was set as follows based on a micrograph. When the structural period is expected to be on the order of 0.01 μm (10 nm or more and less than 100 nm), take a photograph at a magnification of 20,000 times, and randomly place 3 pieces of 20 mm length (1 μm length on the sample) on the photograph. Elected. Similarly, when the structural period is expected to be on the order of 0.1 μm (100 nm or more and less than 1 μm), a photograph is taken at a magnification of 2,000 times, and the length is randomly 20 mm on the photograph (the length of 10 μm on the sample). ) Three were selected. When the structural period is expected to be on the order of 1 μm (1 μm or more and less than 10 μm), a photograph was taken at a magnification of 200 times, and three pieces of 20 mm length (100 μm length on the sample) were randomly selected on the photograph. If the measured structural period was out of the expected order, the corresponding length was measured again at the magnification corresponding to the corresponding order and adopted.

In addition, when the component [C] forms a sea-island structure, the major axis of the island phase whose main component is all the components [C] existing in a predetermined region is measured, and the number average value of these is calculated as the island phase. Of the diameter. Here, when the island region diameter is predicted to be less than 0.01 μm or 0.01 μm order (10 nm or more and less than 100 nm) from the obtained image, the predetermined region is taken at a magnification of 20,000 times, Three areas of 20 mm square (1 μm square area on the sample) were randomly selected on the photograph. Similarly, when the diameter of the island phase is expected to be on the order of 0.1 μm (100 nm or more and less than 1 μm), a photograph is taken at a magnification of 2,000 times, and an area of 20 mm square on the photograph (10 μm square on the sample) 3 areas) were selected. When the diameter of the island phase is expected to be on the order of 1 μm (1 μm or more and less than 10 μm), a photograph was taken at a magnification of 200 times, and three regions of 20 mm square (100 μm square region on the sample) were randomly selected on the photograph. . If the measured island phase diameter deviated from the expected order, the corresponding region was measured again at the magnification corresponding to the corresponding order and adopted.

(6) Morphological variation of cured epoxy resin The epoxy resin composition prepared in (1) above was degassed in vacuum, and the temperature range from 30 ° C to 180 ° C was 1.5 ° C / min, 5 ° C / min. Then, the temperature was raised at a speed of 1 ° C., followed by curing at 180 ° C. for 2 hours to obtain cured epoxy resins having different molding conditions. A transmission electron image was obtained by the above method (5), the size of the phase separation structure was obtained, and the fluctuation range of the size of the phase separation structure was calculated by the following equation. When multiple components were phase-separated, the phase having a large phase separation structure was measured and adopted.

Fluctuation width (%) = {(5 ° C./min. Size of phase separation structure at temperature forming) / (1.5 ° C./min. Size of phase separation structure at temperature forming) −1)} × 100.

(7) Preparation of prepreg The epoxy resin composition was applied onto release paper using a knife coater to prepare a resin film. Next, two resin films are stacked on both sides of the carbon fiber on Toray Co., Ltd. carbon fiber “Treca (registered trademark)” T800G-24K-31E arranged in one direction in a sheet shape, and heated and pressurized. The resin was impregnated with carbon fiber to obtain a unidirectional prepreg having a carbon fiber basis weight of 190 g / m ² and a matrix resin mass fraction of 35.5%. In that case, when using the epoxy resin composition which mix | blended the thermoplastic resin particle, the following two-stage impregnation methods were applied, and the prepreg which the thermoplastic resin particle highly localized in the surface layer was produced.

First, a primary prepreg containing no thermoplastic resin particles was produced. The epoxy resin composition which does not contain the thermoplastic resin particle insoluble in an epoxy resin among the raw material components described in Tables 1 and 2 was prepared by the procedure (1) above. This epoxy resin composition for primary prepreg was applied onto release paper using a knife coater to prepare a resin film for primary prepreg of 30 g / m ² having a normal basis weight of 60% by mass. Next, these two primary prepreg resin films are stacked on both sides of the carbon fiber on Toray Industries, Inc. carbon fiber “Treca (registered trademark)” T800G-24K-31E arranged in one direction in a sheet shape. In addition, using a heat roll, the resin was impregnated into carbon fiber while heating and pressurizing at a temperature of 100 ° C. and an atmospheric pressure of 1 atm to obtain a primary prepreg.

Furthermore, in order to produce a resin film for two-stage impregnation, among the raw material components listed in Tables 1 and 2, the thermoplastic resin particles insoluble in the epoxy resin were made 2.5 times the stated amount using a kneader. An epoxy resin composition was prepared by the procedure (1) above. This two-stage impregnation epoxy resin composition was applied onto release paper using a knife coater to prepare a 20-gram / m ² two-stage impregnation resin film having a normal basis weight of 40% by mass. This was superposed on both sides of the primary prepreg and heated and pressed at a temperature of 80 ° C. and an atmospheric pressure of 1 atm using a heat roll to obtain a prepreg in which thermoplastic resin particles were highly localized on the surface layer.

(8) Evaluation Method of 90 ° Bending Strength of Fiber Reinforced Composite Material The unidirectional laminate produced by the method (7) was cut out to have a thickness of 2 mm, a width of 15 mm, and a length of 60 mm. Three-point bending was performed according to JIS K7074 (1988) using an Instron universal testing machine (Instron). Measurement was performed at a span of 40 mm, a crosshead speed of 1.0 mm / min, a thickness of 10 mm, a fulcrum diameter of 4.0 mm, and a 90 ° bending strength was measured. The average value of the values measured with the number of samples n = 6 was taken as the value of 90 ° bending strength.

Example 1
In a kneading apparatus, 60 parts by mass of “jER (registered trademark)” 630 (triglycidylaminophenol, manufactured by Mitsubishi Chemical Corporation), 40 parts by mass of “Epiclon (registered trademark)” 830 (bisphenol F type epoxy resin, DIC) Co., Ltd.), 55 parts by weight of “Virantage (registered trademark)” VW-10700RP (polyethersulfone, manufactured by Solvay Advanced Polymers Co., Ltd.), 10 parts by weight of block copolymer X1, An epoxy resin composition was prepared by kneading 55 parts by mass of 3,3′-DAS, which is the epoxy resin curing agent of [D]. Table 1 shows the composition and ratio (in Table 1, the numbers represent parts by mass). About the obtained epoxy resin composition, (2) bending elastic modulus of the cured epoxy resin, (3) toughness of the cured epoxy resin (K _IC ), (4) glass transition temperature of the cured epoxy resin, ( 5) Size of phase-separated structure of cured epoxy resin, (6) Morphological variation of cured epoxy resin, and (8) 90 ° bending strength of fiber reinforced composite material. The results are shown in Table 1.

(Examples 2 to 10)
An epoxy resin composition was prepared in the same manner as in Example 1 except that the epoxy resin, thermoplastic resin, block copolymer, other components, epoxy resin curing agent and blending amount were changed as shown in Table 1. did. About the obtained epoxy resin composition, (2) flexural modulus of cured epoxy resin, (3) toughness of cured epoxy resin (K _IC ), (4) glass transition temperature of cured epoxy resin, (5) The size of the phase separation structure of the cured epoxy resin, (6) Morphological variation of the cured epoxy resin, and (8) 90 ° bending strength of the fiber reinforced composite material were measured. The results are shown in Table 1.

In the cured epoxy resins obtained in Examples 1 to 10, the constituent element [A], the constituent element [B], and the constituent element [D] form a uniform phase without phase separation, and the constituent element [C ] Has a phase separation structure of 0.01 to 0.5 μm and good mechanical properties. Moreover, it was found that the material can exhibit stable mechanical properties with little variation in the phase separation structure due to molding conditions. Furthermore, it was revealed that excellent adhesiveness can be sufficiently secured without impairing the bending strength of the fiber reinforced composite material.

(Comparative Example 1)
An epoxy resin composition was produced in the same manner as in Example 4 except that the component [C] was not included. About the obtained epoxy resin composition, (2) bending elastic modulus of the cured epoxy resin, (3) toughness of the cured epoxy resin (K _IC ), (4) glass transition temperature of the cured epoxy resin, ( 5) Size of phase-separated structure of cured epoxy resin, (6) Morphological variation of cured epoxy resin, and (8) 90 ° bending strength of fiber reinforced composite material. As shown in Table 2, all the components of the obtained cured epoxy resin were uniformly compatible with the epoxy resin phase, and the toughness was insufficient.

(Comparative Example 2)
An epoxy resin composition was produced in the same manner as in Example 4 except that the requirements for the component [B] were not satisfied. In Comparative Example 2, the toughness of the obtained cured epoxy resin was insufficient. When the content of the constituent element [B] is less than the range, the toughness of the epoxy resin phase remains brittle, and even if the constituent element [C] is contained, the effect of improving the toughness tends to be insufficient.

(Comparative Example 3)
An epoxy resin composition was produced in the same manner as in Example 4 except that the requirements for the component [B] were not satisfied. However, the processability deteriorated due to thickening, and an epoxy resin cured product could not be obtained. .

(Comparative Example 4)
Comparative Example 4 has a resin composition equivalent to that of Example 7 of Patent Document 1 (Japanese Patent Laid-Open No. 61-228016). In Comparative Example 4, the use of polysulfone instead of component [B] resulted in the formation of micron-sized phase separation and high toughness, but morphological fluctuations due to molding conditions were observed. Furthermore, the heat resistance of the cured epoxy resin was lowered, and the adhesiveness of the fiber reinforced composite material was insufficient.

(Comparative Example 5)
Comparative Example 5 has a resin composition equivalent to Example 3 of Patent Document 2 (International Publication No. 2006/075153). In the comparative example 5, it originated in the mixing | blending of a rubber component, and the elasticity modulus of the epoxy resin hardened | cured material fell.

(Comparative Example 6)
Comparative Example 6 has a resin composition equivalent to that of Example 1 of Patent Document 3 (Japanese Patent Laid-Open No. 7-278212). In Comparative Example 6, a phase separation structure in which a rubber phase was dispersed in a continuous phase derived from a micron-sized thermoplastic resin was obtained. However, the structure is largely dependent on molding conditions, and the phase structure is stabilized. It was not obtained. Furthermore, the adhesiveness at the phase-separated interface deteriorated, and the adhesiveness of the fiber reinforced composite material became insufficient.

(Comparative Example 7)
Comparative Example 7 is “Journal of Applied Polymer Science”, 119, p. 2933 (2011) by Di Hu, Sixun Zheng, described in “Morphology and Thermochemical Properties of Epoxy Thermosets Modified with Polysulphone-Block-Polydipolys”. In Comparative Example 7, the toughness of the obtained cured epoxy resin was insufficient. Further, the elastic modulus and heat resistance of the cured epoxy resin are insufficient, and the adhesiveness of the fiber reinforced composite material is insufficient.

According to the present invention, an epoxy resin composition and an epoxy resin that stably form a fine phase separation structure with a wide range of molding conditions and stably give a cured epoxy resin having excellent heat resistance, elastic modulus, and toughness In order to obtain a cured product, a prepreg, and a fiber-reinforced composite material excellent in adhesiveness, it is particularly suitably used for a structural material. For example, for aerospace applications, primary aircraft structural materials such as main wings, tail wings and floor beams, secondary structural materials such as flaps, ailerons, cowls, fairings and interior materials, rocket motor cases and satellite structural materials Preferably used. In general industrial applications, structural materials for moving objects such as automobiles, ships, and railway vehicles, drive shafts, leaf springs, windmill blades, various turbines, pressure vessels, flywheels, paper rollers, roofing materials, cables, reinforcing bars, It is also suitable for civil engineering and building material applications such as repair and reinforcement materials. Furthermore, in sports applications, it is suitably used for golf shafts, fishing rods, tennis, badminton and squash rackets, hockey sticks, and ski pole applications.

The block copolymer of the present invention is excellent in heat resistance and toughness, and is therefore suitably used in various applications. For example, it is suitably used for applications such as a reinforcing material for matrix resin for fiber-reinforced composite materials, electronic materials, paints, and adhesives.

Claims (14)

1. An epoxy resin composition comprising at least the following constituent elements [A] to [D] and comprising 16 to 50 mass% of the constituent element [B] with respect to 100 mass% of the total amount of the epoxy resin composition.
   [A] Epoxy resin [B] Thermoplastic resin containing 80 mol% or more of the structural unit represented by formula (1) and capable of being dissolved in the epoxy resin
   

   

   [C] A block copolymer consisting of block [c1] and block [c2] that satisfies all of the following conditions (i) to (iii) (i) The block [c1] is a structural unit represented by the above formula (1). (Ii) Block [c2] containing 80 mol% or more has a solubility parameter (SP value) of 10 (cal / cm ³ ) ^1/2 or less. (Iii) Block [c1] and block [c2] are ether bonds. Connected [D] epoxy resin curing agent
2. The epoxy resin composition according to claim 1, wherein the component [B] is polyethersulfone.
3. The epoxy resin composition according to claim 1 or 2, wherein the component [C] is a block copolymer in which the block [c1] is polyethersulfone and the block [c2] is polysiloxane.
4. The epoxy resin composition according to any one of claims 1 to 3, wherein the constituent element [A] contains an amine type epoxy resin, and the content thereof exceeds 50 parts by mass with respect to 100 parts by mass of the total amount of the constituent element [A]. object.
5. A prepreg obtained by impregnating a reinforcing fiber with the epoxy resin composition according to any one of claims 1 to 4.
6. The prepreg according to claim 5, wherein the reinforcing fiber is a carbon fiber.
7. An epoxy resin cured product obtained by curing the epoxy resin composition according to any one of claims 1 to 4.
8. The cured epoxy resin product according to claim 7, wherein the size of the phase separation structure mainly composed of component [C] is in the range of 0.01 to 0.5 µm.
9. A fiber-reinforced composite material obtained by curing the prepreg according to claim 5 or 6.
10. A fiber-reinforced composite material comprising the cured epoxy resin according to claim 7 or 8 and reinforcing fibers.
11. A block copolymer consisting of block [c1] and block [c2] that satisfies all of the following conditions (i) to (iii).
    (I) The block [c1] contains 80 mol% or more of the structural unit represented by the formula (1)
    

    

    (Ii) The block [c2] has a solubility parameter (SP value) of 10 (cal / cm ³ ) ^1/2 or less. (Iii) The block [c1] and the block [c2] are connected by an ether bond.
12. The block copolymer cage of claim 11, wherein the block [c1] is a polyethersulfone and the block [c2] contains a siloxane bond.
13. The block copolymer according to claim 11 or 12, wherein the block [c1] and the block [c2] are connected by a structure represented by the formula (2) or the formula (3).
    

    

    
14. A method for producing a block copolymer according to any one of claims 11 to 13, wherein the block copolymer is obtained by a nucleophilic substitution reaction of a phenolic hydroxyl group.