JPH0481422A - Epoxy resin composition, cured material of resin, prepreg and fiber reinforced plastics - Google Patents

Abstract

PURPOSE:To obtain the title composition providing cured materials having extremely high toughness, high modulus of elasticity, low water absorption, high heat resistance, high solvent resistance, etc., and high stability of these properties by blending an epoxy resin with a specific polyimide. CONSTITUTION:The objective composition comprising (A) an epoxy resin and (B) a polyimide composed of a component essentially having structure shown by the formula and containing an amino end group. A combination of a glycidyl type epoxy resin such as triglycidyl-p-aminophenol and a glycidyl ether type epoxy resin such as bisphenol A type epoxy resin is preferable as the component A. An amine terminated polyimide oligomer prepared by copolymerizing 2,2- bis[4-(4-aminophenoxy)phenyl] propane with 2,2-bis[4-(4-aminophenoxy) phenyl]hexafluoropropane and biphenyltetracarboxylic acid dianhydride is used as the component B.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is an epoxy resin that provides a cured resin product with high toughness, high modulus of elasticity, heat resistance, thermal decomposition resistance, low water absorption, and solvent resistance. The present invention relates to a resin composition, a prepreg made from the resin composition, a cured product thereof, and a fiber-reinforced plastic.

[Prior Art] Epoxy resins are widely used in various industrial fields such as molding, lamination, adhesives, and sealants due to their excellent mechanical properties and chemical resistance. In particular, epoxy resins are often used in fiber-reinforced composite materials that include reinforcing fibers and Mado IJx resin as essential components. However, on the other hand, epoxy resins have the disadvantage of being brittle and have problems such as poor impact resistance of the cured product. In particular, when used as structural materials for aircraft, automobiles, etc., poor impact resistance is a major problem.

Various attempts have been made to improve the drawbacks of these epoxy resins, particularly their brittleness.

■ As described by Diamant et al. in 29th National Sanpe Symposium (1984), p. 422-436, rubbery polymers with terminal functional groups (e.g., carboxyl-terminated butadiene acrylonitrile rubber) are combined with epoxy resins. By adding , resin toughness is improved. However, it has the disadvantage that the elastic modulus (particularly the elastic modulus at high temperatures) decreases significantly.

■ In addition, this improvement in toughness by adding rubber is only effective for epoxy resins with low crosslinking density, and cannot be applied to epoxy resins with high crosslinking density. “Nasa Contractor Report 3852 p. 20 (19
84)).

(2) In an attempt to increase the toughness of epoxy resins with high crosslink density, attempts have been made to add thermoplastic resins to epoxy resin compositions. Polymer Vo1.30p, 213 (
In 1989), C.B. Bucknall et al. investigated polyetherimide as a modifier. The cured resin has a microphase-separated structure, and as the amount of polyetherimide added increases, the morphology changes from one in which polyetherimide forms domains to one in which polyetherimide forms a continuous phase; It is stated that the toughness of the cured resin is improved. However, it has the disadvantage of poor solvent resistance, as stated that the polyetherimide phase is easily dissolved by methylene chloride. Another disadvantage is that the viscosity of the composition increases significantly due to the addition of a high molecular weight thermoplastic resin, resulting in a significant decrease in workability.

(2) Attempts have also been made to use a thermoplastic resin as a modifier, which has a functional group that reacts with epoxy at the end and has a molecular weight in the oligomer range so that it can be added in large amounts. For example, U.S. Pat.
No. 16 discusses adding a polysulfone oligomer having an epoxy-reactive functional group at the end to an epoxy resin composition. It is said that the cured resin has a microphase-separated structure (sea-island structure), and the continuous phase contains a high concentration of polysulfone, resulting in high toughness. A similar study was conducted at the 31st Sanpe Symposium P580 (198
6), J.E. Matsufglas et al. It is stated that resin toughness increases as the molecular weight of polysulfone increases and as the amount added increases, but the viscosity of the system also increases and workability decreases. European Patent Publication No. 0
No. 311,349 (1989) also discusses adding an amine-terminated polyallylsulfone to an epoxy resin composition. The morphology of the cured resin cannot be clearly seen as the photo is unclear, but some have a uniform structure due to the skeletal structure of polyallylsulfone, some have a phase separation into a polyallylsulfone phase and an epoxy resin phase, and some have a continuous structure, and some have a continuous structure. It is said that polyarylsulfone changes between an island phase and an epoxy phase. It also states that the toughness is highest when both the polyallyl sulfone phase and the epoxy resin phase have a continuous structure. However, when a polysulfone-based modifier is used, the heat resistance of the epoxy resin cannot be improved, and depending on the epoxy resin selected, the heat resistance may be reduced.

(2) An attempt was made to improve the toughness of epoxy resins and at the same time increase the glass transition temperature (Tg) in a wet state in JP-A No. 2-622. If a polyamide, imide, or amide-imide oligomer with reactive terminals is used as a toughness modifier, the Tg of the oligomer is equal to or higher than that of the epoxy resin, so not only the toughness but also the Tg in a wet state is improved. It is. Aromatic polyimides are generally not easily soluble in solvents, and it is known that the solubility of polyimides can be improved by introducing bulky substituents into the benzene ring of aromatic diamines.
In the case of No. 622, polyimide synthesized using a diamine having a substituent on the benzene ring, such as p-bis(4-isopropylidene-26-dimethylaniline)benzene, which is also shown in the example, has a temperature of about 80°C. It is described below as being soluble in epoxy resins. It is a polyimide that is so easily soluble in solvents that it dissolves in acetone and methyl ethyl ketone. The toughness value of the cured epoxy resin prepared by adding 30 wt% of the imide oligomer is K + c =
It is about 1.5 MPa, /-m, which is not sufficient (
If the elastic modulus is 3.5 GPa, it is converted to G, C = 6301ard).

[Problem to be solved by the invention] The present inventors have achieved outstanding high toughness, high elastic modulus,
Epoxy resin compositions that have low water absorption, high heat resistance, high heat decomposition resistance, and high solvent resistance and provide cured products with high stability in these physical properties, as well as prepregs using these as matrix resins, and cured products thereof. and fiber-reinforced plastics.

[Means for Solving the Problems] In order to achieve the above object, the present invention employs the following configuration.

That is, the epoxy resin composition of the present invention essentially includes the following constituent elements [A] and [B].

[A]: Epoxy resin [B]: Polyimide F3 which essentially includes a component of the structure of formula (■) and has an amine group at the end.The present invention also provides a prepreg using the above resin as a matrix resin, a cured product thereof, and a fiber-reinforced plastic. It is something to do.

Each component will be explained below.

The element used as component [A] in the present invention is an epoxy resin. An epoxy resin is a resin having an average of two or more epoxy groups per molecule. Particularly preferred are epoxy resins whose precursors are amines, phenols, and compounds having carbon-carbon double bonds. Specifically, as an epoxy resin using amines as a precursor, various isomers of tetraglycidyldiaminodiphenylmethane, triglycidyl-p-aminophenol, triglycidyl-m-aminophenol, triglycidyl aminocresol, and phenols are used as precursors. As the epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, resorcinol type epoxy resin, compound having a carbon-carbon double bond. Examples of the epoxy resin used as a precursor include alicyclic epoxy resins.

Brominated epoxy resins obtained by brominating these epoxy resins may also be used. These epoxy resins may be used in a mixed system of two or more types, or may contain a monoepoxy compound. For example, a composition made of a combination of a glycidylamine type epoxy resin and a glycidyl ether type epoxy resin is preferable because it has heat resistance, water resistance, and agricultural workability.

In particular, combinations of glycidylamine type epoxy resins such as triglycidyl-p-aminophenol and triglycidyl-m-aminophenol derivatives and glycidyl ether type epoxy resins such as bisphenol A type epoxy resins, bisphenol F type epoxy resins, and resorcinol type epoxy resins. These provide resin compositions with excellent workability due to the low viscosity of each resin.

Typically, epoxy resins are used in combination with hardeners. Any compound having an active group capable of reacting with an epoxy group can be used as the curing agent.

Preferably, compounds having an amino group, an acid anhydride group, an azide group, or a hydroxyl group are suitable. Examples include, but are not limited to, dicyandiamide, various isomers of diaminodiphenylsulfone, aminobenzoic acid esters, various acid anhydrides, phenol novolak resin, and cresol novolac resin. Dicyandiamide is preferably used because it has excellent pre-preg stability. When aromatic cyamine is used as a curing agent, a cured epoxy resin with good heat resistance can be obtained. In particular, various isomers of diaminodiphenylsulfone are most suitable for the present invention because they give cured products with good heat resistance. As aminobenzoic acid esters, trimethylene glycol di-p-aminobenzoate and neopentyl glycol di-p-aminobenzoate are preferably used, and although they have lower heat resistance than diaminodiphenylsulfone, they have a higher tensile elongation. Because of its excellent toughness, it is selected and used depending on the application. When an acid anhydride represented by methylhexahydrophthalic anhydride is used as a curing agent, a cured product with high heat resistance can be obtained, and an epoxy resin composition with low viscosity and excellent workability can be obtained. Phenol novolac resins or cresol novolac resins are preferred because, when used as a curing agent, ether bonds with excellent hydrolysis resistance are introduced into the molecular chains and the moisture resistance of the cured product is improved. Furthermore, various curing catalysts can also be used in combination. A typical example is a monoethylamine complex of boron trifluoride. Further, cyanate resin (trianne resin) is also preferably used in combination with epoxy resin. In this case, cyanate causes a curing reaction with epoxy to give a cured resin with low water absorption.

Component [B] uses an aromatic polyimide oligomer in order to further improve the heat resistance of the epoxy resin and not impair its high elastic modulus and high solvent resistance.

In general, polyimide has particularly excellent heat resistance and solvent resistance among aromatic thermoplastic resins. The fact that it has excellent solvent resistance means that it does not dissolve easily in epoxy resin monomers. However, the present inventors have discovered that the fluorine-containing polyimide having the skeleton of the above formula (2) does not dissolve in general-purpose solvents such as acetone and methyl ethyl ketone, but does dissolve in epoxy resin monomers. By using this as a modifier, they invented an epoxy resin composition that has particularly remarkable toughness, high heat resistance, low water absorption, and high solvent resistance.

In the case of the above-mentioned well-known JP-A No. 2-622, p-bis(4-isopropylidene-2,6
A diamine with a specific structure such as -dimethylaniline)benzene is used. This may be due to the fact that the aromatic ring has a substituent group to improve solubility, but when an imide oligomer having such a structure was used, the effect of improving the toughness of the cured epoxy product was insufficient. Furthermore, in the description of imide oligomers in JP-A-2-622, there is no example of copolymerization of an amine component.

However, the present inventors obtained a polyimide with high toughness by using a polyimide oligomer having a skeleton of formula (2), which does not have bulky substituents on the aromatic ring of the main chain, and surprisingly found that this polyimide is epoxy-soluble. They discovered this and succeeded in dramatically improving the toughness of epoxy resin.

Furthermore, component [B] is preferably a copolymerization of the structure of formula I and other diamine monomers represented by the structures of formulas (1) and (2). In particular, in formula ■ and formula ■, X or 10-, -3
O2-+ -c (cIl(3) 2 bonds are particularly preferred in terms of improving resin toughness.Also, as the acid dianhydride used in the synthesis, in formula (■), Y is 10- or 100- It is particularly preferable that n be O in order to increase the solubility of the epoxy and to improve the toughness of the cured resin.

If a particularly preferred copolymerized polyimide is used, the GIc of the epoxy resin modified thereby is 1000 J/
Exceeds rd.

x is -Co-, -3o2-, -0-, -3 or -C(
M) 2- (M is hydrogen, alkyl, allyl or haloalkyl), n is O or 1;

Y is -co-, -5o2-. -〇--8 or -c (
M) 2- (M is hydrogen, alkyl, or haloalkyl), and n is 0 or 1.

The copolymerization ratio (molar ratio) of the diamine structure of formula (1) and the diamine structure of formula (2) and/or formula (2) in component [B] is preferably 0.5:9.5 to 10:0. Component[
B] is preferably 37 to 10.0, particularly preferably 55 to 100, from the viewpoint of the viscosity when dissolved in the epoxy resin monomer. In addition, from the viewpoint of the toughness of the cured resin, it is 19 to 9
A river is even more preferable.

Examples of diamines and acid dianhydrides preferred for oligomer synthesis are listed below, but the present invention is not limited thereto.

When this fluorine-containing aromatic polyimide is used as the component [B], at least a phase mainly composed of the component [B] or a three-dimensionally continuous microphase-separated structure is formed in the cured product. This resulted in a cured product with high toughness that had not been previously available.

An example of the morphology of a cured product produced by the resin composition of the present invention is shown in FIG. This is a photograph of the polished surface of the cured epoxy resin of Example 1 stained with osmic acid and a backscattered electron image taken using a scanning electron microscope. It is clear that there are two phases with different compositions, and that there is a dispersed phase of another phase in the continuous phase. By elementally analyzing the same field of view using an X-ray microanalyzer, it is also possible to distinguish between a phase in which component [A] is the main component and a phase in which component [B] is the main component. In the case of Example 1, it is found that either the continuous phase or the other phases contain a relatively high concentration of fluorine element, and it can be easily determined that the constituent element [B] is the main phase.

The size of the dispersed phase (island phase) mainly composed of component [A] that exists in the continuous phase (sea phase) mainly composed of component [B] is:
Approximately 101 to 50 microns is preferred.

If it is 0.01 micron or less, the depth of the irregularities on the fractured surface will be shallow, making it difficult to develop high toughness. On the other hand, if the thickness exceeds 50 microns, the effect of increasing toughness will be diminished. More preferably 0.1 to 10
The thickness is about microns, more preferably about 05 to 3 microns.

Due to the phase separation structure and the inherent water repellency of fluorine-containing polyimide, the water absorption of the cured product is significantly lower than that of the original epoxy resin. Furthermore, the polyimide oligomer which has become epoxy-soluble due to the structure of formula (2) is not inherently soluble in general-purpose solvents such as acetone and methyl ethyl ketone. Furthermore, since it has a functional group that reacts with the epoxy resin, it is incorporated into the crosslinked structure, and as a result, the cured product has excellent solvent resistance. Regarding the heat resistance of polyimide oligomers, it is possible to arbitrarily set the glass transition temperature within a fairly wide range by changing the type of copolymerization monomer.
It has sufficiently high heat resistance when compared to epoxy resins, and together with the above-mentioned low water absorption property, it improves the heat resistance of epoxy resins in a wet state.

It is preferable to have a functional group capable of reacting with component [A] in the structure of component [B] from the viewpoint of solvent resistance and resin toughness. Most preferred is the component [B
] is the case where an amine group is present at the end. During oligomer synthesis, it is easy to terminate the oligomer with an amino group by using a 1 molar excess of diamine relative to the acid dianhydride.

Furthermore, polyimide oligomers suitable for the present invention are not necessarily 1
It may have a partially amic acid state which requires an imidization rate of 0.00%, and this is preferable in some cases from the viewpoint of phase interface adhesion.

The amount of component [B] is preferably 10 to 50% by weight in the resin composition. If it is less than this, the toughness improvement effect will be small.
Moreover, if the amount is more than this, the workability is significantly reduced. More preferably, it is 15 to 40% by weight.

The molecular weight of component [B] is approximately 200 in terms of number average molecular weight.
A range of 0 to 20,000 is preferred. When the molecular weight is smaller than this, the effect of improving toughness is small, and when the molecular weight is larger than this, the increase in resin viscosity is significant. As a result, it becomes difficult to coat the prepreg with resin or impregnate fibers with the resin, and the tackiness and drape properties of the prepreg are impaired, resulting in a significant decrease in workability. More preferably, it is in the range of about 2,000 to 10,000, and even more preferably in the range of about 3,000 to 6,000.

The present invention provides a fiber-reinforced plastic with high toughness and high strength consisting of an epoxy resin composition comprising components [A] and [B] and reinforcing fibers [C], and a prepreg providing the same. The reinforcing fibers used in this case are fibers with good heat resistance and tensile strength that are generally used as advanced composite materials. For example, the reinforcing fibers include carbon fiber, graphite fiber, aramid fiber, silicon carbide fiber, alumina fiber, poron fiber, tungsten carbide fiber, and glass fiber. Among these, carbon fibers and graphite fibers are most suitable for the present invention because they have good specific strength and specific modulus and are recognized to contribute greatly to weight reduction. All kinds of carbon fibers and graphite fibers can be used depending on the purpose, but high strength and high elongation carbon with a bow tensile strength of 450 kgf/mm2 and a tensile elongation of 1.7% or more is preferable. Fiber or most suitable. Carbon fibers and graphite fibers may be used in combination with other reinforcing fibers. Further, the reinforcing fibers are not limited in their shape or arrangement, and can be used in, for example, a single direction, a random direction, a sheet shape, a mat shape, a woven fabric shape, or a braided cord shape. In particular, for applications that require high specific strength and specific modulus, it is important to know whether an arrangement in which the reinforcing fibers are aligned in a single direction is the most suitable, or whether it is easier to handle or in a loss (woven) arrangement. It is suitable for the present invention.

The resin in the fiber-reinforced plastic has the microphase-separated structure described above. The optimal range of the size of the dispersed phase, which is mainly composed of the component [part A], is smaller than the distance between fibers. Therefore, the optimum range is influenced by the fiber content and is in the range of about 0.001 to 10 microns, more preferably about 0.1 to 3 microns. In the fiber-reinforced plastic, if a phase mainly consisting of the component [B] exists separately from a phase mainly consisting of the component [A part], the phase mainly consisting of the component [A part] is the reinforcing fiber [C ]
It is preferable for the fibers to be unevenly distributed around the fibers from the viewpoint of adhesion between the fibers and the resin.

The fracture strain energy release rate Gic of the cured resin produced using the composition of the present invention is measured by the tuple torsion (DT) method. An outline of the measurement method is shown in Figure 2. The DT method is described in detail in Journal of Materials Science 20 (1985) p. 77-84. G. is calculated by the following formula from the crack initiation load P, the slope ΔC/Δa1 of the compliance C with respect to the crack propagation distance a1, and the sample thickness t at the crack propagation part.

G,,,=P2 (△C/△at)/2t (However, compliance C is the amount of crosshead displacement δ at the time of crack occurrence)
and crack initiation load P. C-δ/P
) The speed of the crosshead that applies the load is 1 mm/min.
And so.

[Function] In the present invention, the addition of the component [B] forms a microphase separation structure with good phase interface adhesion in the cured epoxy resin, and the phase mainly composed of the component [B] or the three-dimensional brings about a continuous structure. The size of the component in the continuous phase mainly composed of component [B] [the dispersed phase mainly composed of part A] is about 0.
It is characterized by having a diameter of 0.01 to 50 microns.

By forming such a microphase-separated structure,
Provides an epoxy resin with significantly improved fracture toughness. Moreover, the addition of component [B] has a remarkable effect of improving the heat resistance of the epoxy resin and reducing the water absorption rate. Moreover, the addition of component [B] increases the inherent high elastic modulus of the thermosetting resin.
It maintains high solvent resistance.

[Example] The following example is for explaining the present invention in more detail, and is not limited to the content thereof.

Example I Part A 140 g (0.34 mol) of 2.2-bis[4-(4 -aminophenoxy)phenyl 1-propane (BA P P ), 176 g (0.34 mol)
2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP) [manufactured by Wakade Seika Kogyo Co., Ltd.] was added to 1200 ml of N-methyl-2-
The mixture was stirred and dissolved in pyridone (NMP). There, solid biphenyltetracarboxylic dianhydride (S-BPDA)
[Made by Mitsubishi Kasei Corporation] 180g (0.61mol)
was added little by little and stirred at room temperature for 3 hours, then heated to 120°C.
and stirred for 1 hour. After returning the flask to room temperature and adding 50 ml of triethylamine and 5 ml of toluene, the temperature was raised again and azeotropic dehydration was performed at 160°C to obtain about 22 ml of water. After cooling the reaction mixture, double the amount of NMP
and slowly poured into 201 g of acetone to precipitate the amine-terminated polyimide oligomer as a solid product. The precipitate was then vacuum dried at 180°C.

The number average molecular weight (Mn) of this oligomer was measured by gel permeation chromatography (GPC) using dimethylformamide (DMF) as a solvent, and found to be 4,200 (polyethylene glycol (PEG)). Further, the glass transition point was 239°C according to a differential thermal analyzer (DSC). In addition, imidization has proceeded almost completely, and the amine terminal ratio is approximately 95%.
% from the NMR spectrum.

In a beaker of Part B, 36 g of the polyimide oligomer of Part A and resorcinol diglycidyl ether (HELOXY
57 g of WC-69 (manufactured by Wilmington Chemical Company) was added. This was heated and dissolved at 150°C for 1 hour, and then 27 g of Sumicure S (4,4DDS) [manufactured by Sumima Kagaku Kogyo Co., Ltd.] was added and dissolved for 10 minutes.

After connecting a vacuum pump to the container and vacuum degassing, the contents were warmed and molded into a mold that had been preheated to 120°C and subjected to mold release treatment (the dimensions of the cavity were 120 x 120 x 3 mm).
). A cured resin plate with a thickness of 3 mm was prepared by performing a curing reaction in an oven at 180°C for 2 hours.

The Tg of the obtained cured resin was 178°C and 206°C by DSC measurement. The above-mentioned sample was cut out from this, and the fracture strain energy release rate GIC was measured to be 15101/n (the flexural modulus E was 370 kg/n).
It was mm2. From here, the resin toughness KIC is determined by the following formula:
was calculated to be 2.3 MPa, frn.

K, C= (GIC-E)''2 When a 60×1 (l×2 mm) resin plate was boiled for 20 hours, its water absorption rate was 28%.

When the polished surface of the cured resin was stained with osmic acid and a backscattered electron image was observed using a scanning electron microscope, a microphase-separated structure was observed in which one phase was a continuous structure and a spherical dispersed phase existed within it. This photo is shown in Figure 1. The diameter of the dispersed phase is 05
It was ~4 μm.

Furthermore, elemental analysis of the same field of view using an X-ray microanalyzer revealed that fluorine elements were densely distributed in the high-contrast continuous phase that appeared black in the photograph, and it was determined that this continuous phase was a polyimide-rich phase.

0 copies The prepreg was prepared as follows.

A resin with the above composition was prepared in a kneader, and a silicone mold release agent was applied to a thin layer of release paper to a certain thickness. A prepreg was obtained by aligning carbon fibers in one direction between two sheets of resin-coated paper prepared in 1.

At this time, the weight fraction of resin in the prepreg was 35%,
The basis weight of the carbon fiber was 145 g/m. This prepreg has a pseudo-isotropic configuration ((+45°790°/-45°70°
°) 45) to form 32 layers, and using the usual vacuum bag autoclave molding method, under a pressure of 6 kg/ad, 180
A cured plate was obtained by heating at °C for 2 hours.

Its fiber volume was 56 layers and 2%. A 4" x 6" test piece was cut out, subjected to impact energy of 1500 in·lb/in, and then subjected to a compression test. As a result, 52k
The residual compressive strength of si is shown. Further, when 16 sheets of the above prepreg were laminated in a single direction and a similarly molded cured plate was used, the 90' tensile elongation was measured and found to be 1.4%.

Example 2 Part A 147 g (0,357 mol) of 2.2-bis[4
-(4-aminophenoxy)phenyl]propane (BA
PP), 79 g (0152 mol) of 2,2-bis(
4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP) [manufactured by Wakade Seika Kogyo Co., Ltd.] and biphenyltetracarboxylic dianhydride (S-B
PDA) [manufactured by Mitsubishi Kasei Corporation] 135g (0.46m
A polyimide oligomer was synthesized in the same manner as in the example except that ol) was used as a raw material monomer.

The number average molecular weight (Mn) of this oligomer was 4500 in terms of polyethylene glycol (PEG).

Also, the glass transition point is 2 according to a differential thermal analyzer (DSC).
It was 34°C. Also, the imidization rate is about 96% and the amine terminal rate is about 92%.
It was removed from the R spectrum.

In a beaker of Part B, 36 g of the polyimide oligomer of Part A and resorcinol diglycidyl ether (HELOXY
WC-69) [manufactured by Wilmington Chemical Co.] 57g
added. This was heated and dissolved at 150'C for 1 hour, and then 27 g of Sumicure S (4,4DDS) [manufactured by Sumima Kagaku Kogyo Co., Ltd.] was added and dissolved for 10 minutes.

After connecting a vacuum pump to the container and vacuum degassing, the contents were preheated to 120°C and molded into a mold that had been subjected to mold release treatment (the dimensions of the cavity were 120 x 120 x 3 mm).
). A cured resin plate with a thickness of 3 mm was prepared by performing a curing reaction in an oven at 180°C for 2 hours.

The Tg of the obtained cured resin was 180°C and 210°C by DSC measurement. The above-mentioned sample was cut out from this, and the fracture strain energy release rate G Ic was measured to be 14701/m, and the flexural modulus was 370 kg/m.
There was m2. From this, the resin toughness C was calculated to be 2.3 to IPa,/-m. Also, 60X fo
When a x 2nuc resin plate was boiled for 20 hours, its water absorption rate was 28%.

When the polished surface of the cured resin was stained with osmic acid and a backscattered electron image was observed using a scanning electron microscope, a microphase-separated structure was observed, with one phase being a continuous structure and a spherical dispersed phase existing within it. Furthermore, when the same field of view was subjected to elemental analysis using an X-ray microanalyzer, it was found that the fluorine element was densely distributed in the continuous phase, and it was found that this continuous phase was a polyimide-rich phase.

Example 3 Part A 14,03 g (0,0342 mol) of 2,2-bis[4-(4-aminophenoxy)phenyl-1-propane (BAPP), 4], 27 g (0,0796 mol)
l) 2,2-bis[4-(4-aminophenoxy)phenyl-1 hexafluoropropane (HFBAPP) [manufactured by Wakade Seika Kogyo Co., Ltd.] and biphenyltetracarboxylic dianhydride (SBPDA) [Mitsubishi Chemical Co., Ltd.] 3
A polyimide oligomer was synthesized in the same manner as in Example 1, except that 0 g (0.102 mol) was used as a starting material and the amount of solvent was changed to match the solid content concentration.

The number average molecular weight (Mn) of this oligomer was 4,600 in terms of polyethylene glycol (PEG).

Further, the glass transition point was 238°C according to a differential thermal analyzer (DSC). Further, it was found from the NMR spectrum that imidization had proceeded almost completely and that the amine terminal ratio was about 93%.

In a beaker of Part B, 25 g of the polyimide oligomer of Part A and triglycidyl-p-aminophenol (MYO510
) [manufactured by Ciba Geigy] 20g and bisphenol F
Type epoxy resin (Epc830) [Inu Nippon Ink Chemical (
Co., Ltd.] 20g was added.

It was heated and dissolved at 150°C for 1 hour, and then 18.5
Sumicure S (4,4'-DDS) [manufactured by Sumima Kagaku Kogyo Co., Ltd.] was added and dissolved for 10 minutes.

After connecting a vacuum pump to the container and vacuum degassing, the contents were preheated to 120°C and molded into a mold with release treatment (dimensions of void space: 120 x 20 x 3 mm).
). A cured resin plate with a thickness of 3 mm was prepared by performing a curing reaction in an oven at 180° C. for 2 hours.

The Tg of the obtained cured resin is 202°C and 220°C
There was. The above sample was cut out from this, and the fracture strain energy release rate GIC was measured: 11001/
rd, and the flexural modulus was 380 kg/mm2.

Now on to resin toughness. Calculating 2.0MPafm
It became. In addition, two 60X lox 2mm resin plates
When boiled for 0 hours, its water absorption rate was 2.4%.

When the polished surface of the cured resin was stained with osmic acid and a backscattered electron image was observed using a scanning electron microscope, it was found that a microphase-separated structure was formed in which a spherical dispersed phase of another phase existed within a continuous phase.

Further elemental analysis of the same field of view using an X-ray microanalyzer revealed that elemental fluorine was heavily distributed in the continuous phase.

Example 4 Li8.4 g (0,228 mol) as A part diamine
2,2-his[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP) [manufactured by Wakade Seika Kogyo Co., Ltd.] and biphenyltetracarboxylic dianhydride (S- A polyimide oligomer was synthesized in the same manner as in Example 1, except that 60 g (0,204 mol) of BPDA) [manufactured by Mitsubishi Kasei Corporation] was used as the raw material monomer.

The number average molecular weight (Mn) of this oligomer was 4200 in terms of polyethylene glycol (PEG).

Also, the glass transition point is 2 according to a differential thermal analyzer (DSC).
The temperature was 28°C. Further, the NMR spectrum showed that the imidization rate was about 95% and the amine terminal rate was about 92%.

In a beaker of Part B, 36 g of the polyimide oligomer of Part A and resorcinol diglycidyl ether (HELOXY
WC-69) [manufactured by Wilmington Chemical Co.] 57g
added. This was heated and dissolved at 150° C. for 1 hour, and then 27 g of Sumicure S (4,4'DDS) [manufactured by Sumima Kagaku Kogyo Co., Ltd.] was added and dissolved for 10 minutes.

After connecting a vacuum pump to the container and vacuum degassing, the contents were warmed and molded into a mold that had been preheated to 120°C and subjected to mold release treatment (the dimensions of the cavity were 120 x 120 x 3 mm).
). A cured resin plate with a thickness of 3 mm was prepared by performing a curing reaction in an oven at 180°C for 2 hours.

The Tg of the obtained cured resin was 180°C and 220°C as measured by DSC. The above-mentioned sample was cut out from this, and the fracture strain energy release rate G1c was measured to be 10001/n (and the bending elastic modulus was 310 kg/m
It was m2. From here, the resin toughness K is determined by the following formula. When calculated, it was 1.9MPa4m. Also, 60×10
When a 10×2 resin plate was boiled for 20 hours, its water absorption rate was 28%.

When the polished surface of the cured resin was stained with osmic acid and a backscattered electron image was observed using a scanning electron microscope, a microphase-separated structure was observed, with one phase being a continuous structure and a spherical dispersed phase existing within it. Furthermore, elemental analysis of the same field of view using an X-ray microanalyzer revealed that fluorine elements were densely distributed in the high-contrast continuous phase that appeared black in the photograph.
This continuous phase was found to be a polyimide rich phase.

Example 5 Part A 14, 79 g (0,0342 mol) of 2,2-bis[4-(3-aminophenoxy)phenyl-1-sulfone (BAPS-M), 41.27 g (0,0796 mol)
ol) 2,2-bis[4-(4-aminophenoxy)
phenyl] hexafluoropropane (HFBAPP) [
Wakade Seika Kogyo Co., Ltd.] and biphenyltetracarboxylic dianhydride (S-BPDA) [Mitsubishi Kasei Co., Ltd.] 30 g (0,102 mol) were used as raw material monomers, and the solid content was adjusted to match. A polyimide oligomer was synthesized in the same manner as in Example 1, except that the amount of solvent was changed.

The number average molecular weight (Mn) of this oligomer was 5000 in terms of polyethylene glycol (PEG).

The glass transition point was 250°C according to a differential thermal analyzer (DSC). Also, the NMR spectrum showed that imidization had progressed almost completely and the amine terminal ratio was approximately 93%. I got it.

In a beaker of Part B, 286 g of the polyimide oligomer of Part A and bisphenol A type epoxy resin (Ep825) [
Add 50g of Yuka Shell Epoxy Co., Ltd. and heat to 150°C.
The mixture was heated and dissolved for 11 hours, and then 16.8 g of SUMICURE SC4,4'-DDS (manufactured by Sumima Kagaku Kogyo Co., Ltd.) was added and dissolved for 10 minutes.

A vacuum pump was connected to the container to perform vacuum defoaming, and then the contents were poured into a mold that had been preheated to 130° C. and subjected to mold release treatment. 2 in the oven at 180℃
A cured resin plate with a thickness of 3 mm was prepared by performing a time curing reaction.

Otherwise, the same procedure as in Example 1 was repeated.

The Tg of the obtained cured resin is 200°C and 220°C
There was. In addition, the fracture strain energy release rate G Ic is 1
4801/lr? The bending modulus is 370 kg/m
There was m2. Calculating 1c for resin toughness from here,
It was 2.3MPa1m. Also, 60XIOX2mm
When a resin board was boiled for 20 hours, its water absorption rate was 1.
It was 4%.

When the polished surface of the cured resin was stained with osmic acid and a backscattered electron image was observed using a scanning electron microscope, it was found that a microphase-separated structure was formed in which a spherical dispersed phase of another phase existed within the continuous phase. Further elemental analysis of the same field of view using an X-ray microanalyzer revealed that fluorine element was densely distributed in the continuous phase.

Comparative Example I Part A 280 g (0.68 mol) of 2,2- was placed in a 3000 ml separable flask equipped with a nitrogen inlet, thermometer, stirrer and dehydration trap under nitrogen purge.
Bis[4(4-aminophenoxy)phenyl]propane (BAPP) was dissolved in 1200 ml of N-methyl-2-pyrrolidone (NMP) with stirring. To this, 1100 g (0.61 mol) of solid biphenyltetracarboxylic dianhydride (BPDA-3) manufactured by Mitsubishi Kasei Corporation was added little by little, and after stirring at room temperature for 3 hours, the temperature was raised to 120°C. Stirred for 1 hour. After returning the flask to room temperature and adding 50 ml of triethylamine and 50 ml of toluene, the temperature was raised again and azeotropic dehydration was performed at 160°C to obtain about 20 ml of water, but during this process polyimide oligomer precipitated and became a precipitate. . After the reaction mixture was cooled, it was poured into 201 acetone and washed. Further, the sample was transferred to 101 ml of water and washed by boiling, and then vacuum-dried at 180°C. The glass transition point of this oligomer was 240° C. according to a differential thermal analyzer (DSC).

In a beaker of Part B, 36 g of the polyimide oligomer of Part A and resorcinol diglycidyl ether (HELOXY
WC-69) [Manufactured by Illmington Chemical Co.]
Added 57g. It was heated at 150° C. for 2 hours, but the oligomer did not dissolve in the epoxy.

Comparative Example 2 An epoxy resin plate was prepared by repeating the same procedure as in Example 1 without adding the imide oligomer as the component [Part B]. The Tg of the obtained cured resin was 172°C. When the fracture strain energy release rate GIC was measured, it was 1
501/rrr, and the bending modulus is 385 kg/mm.
There were two. Moreover, the 20-hour boiling water absorption rate was 4.0%.

The post-impact compressive strength and tensile elongation in the 90° direction of a composite using a unidirectional prepreg using the same resin composition as a matrix were measured.

The prepreg was prepared in the same manner as in Example 1.

At this time, the weight fraction of resin in the prepreg was 35%,
The weight per area of the prepreg was 145 g/bo. This prepreg has a pseudo-isotropic configuration ((+45°/90°
/-45°70°)4. ) and laminated in 32 layers using the normal vacuum bag autoclave molding method, 5kg/cnf
A cured plate was obtained by heating at 180° C. for 2 hours under pressure. Its fiber volume was 56 layers and 2%. A 4" x 6" test piece was cut out, subjected to impact energy of 1500 in.b/in, and then subjected to a compression test. As a result, the residual compressive strength was 21.5 ksi. Further, when 90° bow elongation was measured using a cured plate formed by laminating 16 sheets of the above prepreg in a single direction and molded in the same manner, it was 07%.

Comparative Example 3 An epoxy resin plate was prepared by repeating the same procedure as in Example 3 without adding the imide oligomer as the component [Part B]. The Tg of the obtained cured resin was 202°C. The fracture strain energy release rate G Ic was measured and was 1.20j/rrr, and the bending elastic modulus was 385kg/rrr.
It was mm2. In addition, the water absorption rate after 20 hours of boiling is 3.6%.
Met.

Comparative Example 4 Components [A resin plate was prepared by repeating the same procedure as in Example 5 without adding the imide oligomer as part B.

The Tg of the obtained cured resin was 2070C.

The fracture strain energy release rate GIC was measured and was 150.
J/i, and the flexural modulus was 365 kg/mm2. In addition, the 20-hour boiling water absorption rate was 2.2%.

[Effects of the Invention] The thermosetting resin composition of the present invention has good workability, excellent toughness, high modulus of elasticity, high heat resistance, low water absorption, and high solvent resistance, and has various physical properties. Provides a cured resin product with high stability. Furthermore, the prepreg using this as a matrix resin has good tack and drape properties,
The cured fiber reinforced composite material has high toughness, high impact resistance,
It has high strength, high elongation, high heat resistance, low water absorption, and high solvent resistance.

[Brief explanation of the drawing]

FIG. 1 is an electron micrograph of the cured resin described in Example 1. Figure 2 shows the fracture strain energy release rate GIC of cured resin.
This is an explanation of the double torsion (DT) method for measuring.

Claims (13)

[Claims] (1) An epoxy resin composition that essentially contains the following components [A] and [B]. [A]: Epoxy resin [B]: Polyimide that has the essential components of the structure of formula I and has an amino group at the end ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼Formula I (2) The epoxy resin composition according to claim 1, wherein the component [B] contains a structure of formula II or formula III. ▲There are mathematical formulas, chemical formulas, tables, etc.▼Formula II ▲There are mathematical formulas, chemical formulas, tables, etc.▼Formula III X is -CO-, -SO_2-, -O-, -S-, or -C(M)_2- (M means hydrogen, alkyl, allyl or haloalkyl), and n is 0 or 1. (3) The copolymerization ratio (molar ratio) of Formula I and Formula II and/or Formula III in component [B] is 0.5:9.5 to
The epoxy resin composition according to claim 2, characterized in that the ratio is 10:0. (4) The epoxy resin composition according to claim 3, wherein the component [B] contains the structure of formula IV. ▲There are mathematical formulas, chemical formulas, tables, etc.▼Formula IV Y means -CO-, -SO_2-, -O-, -S-, or -C(M)_2- (M is hydrogen, alkyl, or haloalkyl) and n is 0 or 1. (5) A cured resin product, characterized in that a phase mainly composed of component [B] of the composition according to claim 1 forms a three-dimensional continuous phase in the cured product. (6) The epoxy resin composition according to claim 4, wherein the component [A] is a resin composition containing a triglycidylaminophenol derivative, a bisphenol A type or bisphenol F type epoxy resin, or resorcinol diglycidyl ether. (7) The epoxy resin composition according to claim 4, wherein the component [A] is an epoxy resin using an aromatic amine as a curing agent. (8) The amount of component [B] is the same as that of component [A] and [B].
] Claim 4 is 10 to 45% by weight based on the total weight of
The epoxy resin composition described. (9) Number average molecular weight of component [B] is 2000 to 10
The epoxy resin composition according to claim 4, which has a molecular weight of 000. (10) A prepreg comprising the epoxy resin composition according to claims 1 to 9 and reinforcing fiber [C]. (11) A fiber reinforced plastic obtained by curing the prepreg according to claim 10. (12) The prepreg according to claim 10, wherein the reinforcing fiber [C] is carbon (graphite) fiber. (13) A fiber reinforced plastic obtained by curing the prepreg according to claim 10.