JPH10101772A - Cured item of epoxy resin composition and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cured item of an epoxy resin compsn. excellent in toughness flexibility, and adhesiveness and to provide a process for producing the same. SOLUTION: This cured item is obtd. by thermally curing an epoxy resin compsn. which contains, as the essential ingredients, an epoxy resin having at least two epoxy groups, a curative therefor, and a modified polyphenylene ether prepd. by the redistribution reaction of a high-mol.-wt. polypheylene ether with a polyphenolic compd. in the presence of a free-radical initiator and which has a compatibility range wherein the epoxy resin is compatible with the modified polyphenylene ether. In this case, the compsn. separates into a phase mainly comprising the epoxy resin and a phase mainly comprising the modified polyphenylene ether resin and has a period wherewith these phases regularly entangles with each other. This period is 0.1-10μm as calculated from the diffusion max. in the light diffusion measurement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cured product of an epoxy resin composition and a method for producing the same, which comprises a film for a circuit, a laminated board, a structural material department, an accessory material department, a molding material department, and a sealing material. It is useful for departments and other uses.

[0002]

2. Description of the Related Art Epoxy resins are generally used as heat-resistant adhesives, printed circuit boards, and sealing materials for ICs.
There is a problem in toughness and the like. Conventionally, as an improvement method, an epoxy resin composition containing a filler represented by an elastomer has been proposed. For example, a liquid nitrile rubber having carboxyl groups or amino groups at both ends (Hycar
CTBN, Hycar ATBN) to bisphenol A
Compositions blended with epoxy resins are known. This composition has a so-called "sea-island structure" in which spherical domains of rubber are dispersed in an epoxy resin matrix. This is a mixed resin of epoxy resin / nitrile rubber,
This is because the phase separation speed is too fast as compared with the curing reaction, so that significant structure control cannot be performed. Also, epoxy resin /
It is also known that mixed resins of nitrile rubber have poor heat resistance and electrical properties. At the same time, as the crosslink density of the epoxy resin increases, that is, as the number of epoxy groups in the epoxy compound before curing increases from 2 to 3, 4 (from bifunctional to trifunctional, 4 functional), the nitrile rubber has It is known that the disadvantages of epoxy resins cannot be improved. On the other hand, a technique in which polyphenylene ether (hereinafter, referred to as PPE) is added to the epoxy resin and the curing agent to improve the disadvantages of the epoxy resin is disclosed in Japanese Patent Publication No. 64-322.
No. 3 and the like. This epoxy resin / PPE
The cured product of the mixed resin has excellent electrical properties and heat resistance as compared with the above-mentioned epoxy resin / nitrile rubber mixed resin. Due to poor compatibility, it lacked toughness, flexibility and adhesiveness.

[0003]

The epoxy resin / P
It is considered that the above-mentioned disadvantage of the mixed resin cured product of PE is that the phase mainly composed of the epoxy resin after curing and the phase mainly composed of PPE have an irregular and coarse phase separation structure. Is presumed to be due to the fact that PPE usually has a high molecular weight of 10,000 to 30,000, and therefore has poor compatibility with the epoxy resin in a mixed state before curing. Heretofore, there is no reference to the phase structure after curing.

In view of this, the present inventors have conducted intensive studies and as a result, in a mixed system of an epoxy compound having two or more epoxy groups and a modified PPE having a reduced molecular weight,
It has been found that the microphase separation structure can be controlled in the range of 0.1 to 10 μm, and the present invention has been completed. That is, the present invention provides a cured product of an epoxy resin composition having excellent toughness, flexibility and adhesiveness, and a method for producing the same.

[0005]

In order to solve the above-mentioned problems, a cured product of the epoxy resin composition according to the first aspect of the present invention is an epoxy resin containing at least two epoxy groups, and a curing of the epoxy resin. Resin composition comprising, as essential components, a modified PPE obtained by redistributing a polyphenolic compound with a high molecular weight PPE in the presence of a radical initiator, and a high molecular weight PPE, and having a compatibility region between the epoxy resin and the modified PPE. A cured product of an epoxy resin composition obtained by heat-curing the epoxy resin composition. The epoxy resin composition is separated into a phase mainly composed of the epoxy resin and a phase mainly composed of the modified PPE resin, and has a period in which both phases are regularly intertwined. And the period is 0.1 calculated from the scattering maximum in the light scattering measurement.
-10 μm.

A cured product of the epoxy resin composition according to claim 2 is the cured product of the epoxy resin composition according to claim 1, wherein the modified PPE has a number average molecular weight of 1,000 to 400.
It is characterized by being 0.

A cured product of the epoxy resin composition according to claim 3 is the cured product of the epoxy resin composition according to claim 1 or 2, wherein the content of the modified PPE resin is the same as that of the epoxy resin and the curing agent. The amount is 10 to 60% by weight based on the total amount of the modified PPE.

According to a fourth aspect of the present invention, there is provided the cured epoxy resin composition according to any one of the first to third aspects, wherein the terminal of the modified PPE is epoxidized. Is what you do.

A cured product of the epoxy resin composition according to a fifth aspect is the cured product of the epoxy resin composition according to any one of the first to fourth aspects, wherein the curing agent is dicyandiamide. .

The cured product of the epoxy resin composition according to claim 6 is the cured product of the epoxy resin composition according to any one of claims 1 to 5, wherein the epoxy resin composition contains a urea compound derivative as a curing accelerator. It is characterized by having.

A method for producing a cured product of an epoxy resin composition according to claim 7 is a method for producing an epoxy resin containing at least two epoxy groups, a curing agent for the epoxy resin, and a high molecular weight PPE comprising a polyphenol compound and a radical initiator. A modified PPE that has undergone a redistribution reaction in the presence is blended as an essential component to prepare an epoxy resin composition in which the epoxy resin and the modified PPE are compatible with each other, and the epoxy resin composition is heated at 60 to 210 ° C. It is characterized by being thermally cured to separate the above-mentioned phase mainly composed of the epoxy resin and the phase mainly composed of the PPE resin, and that these two phases exhibit a continuous period and are regularly intertwined.

[0012] The method for producing an epoxy resin composition cured product according to claim 8 is the method for producing an epoxy resin composition cured product according to claim 7, wherein the epoxy resin and the modified PPE are mixed with each other. The compatibility is performed using at least one solvent selected from the group consisting of toluene, benzene, ethylbenzene, xylene, and chloroform.

According to a ninth aspect of the present invention, there is provided the method for producing a cured epoxy resin composition according to the seventh or eighth aspect, wherein the terminal of the modified PPE is obtained after a redistribution reaction. It is further characterized by being epoxidized by reacting with epichlorohydrin.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

The cured epoxy resin composition according to the present invention comprises an epoxy resin containing at least two epoxy groups, a curing agent for the epoxy resin, and a high-molecular-weight PPE in the presence of a polyphenol compound and a radical initiator. A modified PPE that has been subjected to a partitioning reaction, as an essential component, and is obtained by thermally curing an epoxy resin composition having a compatibility region between the epoxy resin and the modified PPE, and the microphase separation structure is characterized by Separation into a phase mainly composed of an epoxy resin and a phase mainly composed of the modified PPE resin, and both phases have a period in which both phases are regularly intertwined, and the period is calculated from a scattering maximum in light scattering measurement. 0.
The structure is 1 to 10 μm.

First, the epoxy resin composition will be described. The epoxy resin is not particularly limited as long as it contains at least two epoxy groups, and bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin,
Novolak type epoxy resin, isocyanurate type epoxy resin, hydantoin type epoxy resin, alicyclic type epoxy resin, biphenyl type epoxy resin, trifunctional or higher polyfunctional epoxy resin, flame retardant epoxy resin obtained by brominating these, etc. These can be used alone or in combination of two or more. More specifically, preferred examples include a bisphenol A type (bifunctional) epoxy resin epoxy resin represented by the following general formula [Chemical Formula 1] and a bisphenol F type (bifunctional) epoxy resin represented by [Chemical Formula 2]. , A biphenyl-type epoxy resin represented by [Chemical Formula 3], a trifunctional epoxy resin represented by [Chemical Formula 4], and a glycidylamine-type (tetrafunctional) epoxy resin represented by [Chemical Formula 5].

[0017]

Embedded image

[0018]

Embedded image

[0019]

Embedded image

[0020]

Embedded image

[0021]

Embedded image

The curing agent used in the curing reaction of the epoxy resin is not particularly limited, and amines such as commonly used primary and secondary amines, bisphenol A,
Phenols including polyphenols such as bisphenol F, acid anhydrides and the like are mentioned.
For example, a latent curing agent dicyandiamide can be used.
The content of the curing agent is preferably in the range of 1 to 30 parts by weight, particularly preferably 3 to 20 parts by weight, based on 100 parts by weight of the epoxy resin.

A curing accelerator for the epoxy resin can be added to the above epoxy resin composition, if necessary.
In this case, the curing accelerator is not particularly limited. For example, tertiary amines such as triethylamine and imidazoles can be used, and a preferable example thereof is N- (3.4-dichlorophenyl). -N '
N'-dimethylurea (DIUR0N), N- (4-chlorophenyl) -N ', N'-dimethylurea (MON
UR0N) and the like. The content of the curing accelerator is preferably in the range of 0.5 to 15 parts by weight, particularly preferably 1 to 10 parts by weight, based on 100 parts by weight of the epoxy compound.

In the present invention, a modified PPE obtained by subjecting a high molecular weight PPE to a redistribution reaction in the presence of a polyphenol compound and a radical initiator in combination with the above epoxy resin is used.

The high-molecular-weight PPE used as a raw material of the modified PPE is represented by, for example, a general formula shown in [Chemical Formula 6]. As one example, poly (2,6-dimethyl-1,4-phenylene) ether is used. No.

[0026]

Embedded image

The high molecular weight PPE is, for example, USP 40
It can be produced by the synthesis method disclosed in US Pat. Generally, PPE produced industrially has a high molecular weight, and a low molecular weight having a molecular weight of less than 10,000 is not commercially available. For example, the number average molecular weight (Mn) of PPE obtained industrially by the above synthesis method is 10,000. ~ 3000
0. This is because it is difficult to control the polymerization reaction to produce a low-molecular weight polymer with good reproducibility by industrially controlling the reactivity of the monomer of PPE. Even if this high molecular weight PPE is used in combination with an epoxy resin as it is, its compatibility is poor due to its large molecular weight.

The modified PPE used in the present invention is:
The high molecular weight PPE is reduced in molecular weight by a redistribution reaction in the presence of a polyphenolic compound and a radical initiator, and has a wide compatibility area with an epoxy resin because of its low molecular weight. It is preferable to use the modified PPE having a number average molecular weight in the range of 1,000 to 4,000. If the number average molecular weight is larger than this, the melt viscosity increases and moldability decreases, and if it is smaller than this, mechanical strength and heat resistance are reduced. Decrease. (Note that the redistribution reaction is described in the academic literature, Journal of organic chemistry, 34, 297-
303 (1968) describes the method. As the polyphenolic compound used in the redistribution reaction, polyfunctional phenols having two or more phenolic hydroxyl groups in a molecule, such as bisphenol A, phenol novolak, and cresol novolak, can be used.

The radical initiator used in the above redistribution reaction includes dicumyl peroxide, tert-
Butyl cumyl peroxide, di-tert-butyl peroxide, 2.5-dimethyl-2,5-di-ter
t-butyl peroxide, α, α′-bis (tert
-Butylperoxy-m-isopropyl) benzene [1
4 (or 1.3) -bis (tert-butylperoxyisopropyl) benzene], peroxides such as benzoyl peroxide and the like, which are used in radical reactions can be used.

In order to reduce the molecular weight of the high-molecular-weight PPE by redistribution and to obtain the denaturation, it is preferable to adjust the number-average molecular weight by using a combination of benzoyl peroxide and bisphenol A from the aforementioned literature. ,
The appropriate amount of benzoyl peroxide is 3 to 10 parts by weight and the amount of bisphenol A is 3 to 20 parts by weight based on 100 parts by weight of high molecular weight PPE. That is, if the added amount of benzoyl peroxide and bisphenol A is excessive, the number average molecular weight is too low, and if it is too small, the number average molecular weight is hardly reduced. The redistribution reaction has a reaction temperature in the range of 80 to 120 ° C and a reaction time of 10-
100 minutes is preferred. In this redistribution reaction, it is preferable to use an aromatic carbon-based solvent such as toluene, benzene, or xylene from the viewpoint of reactivity. The modified PPE obtained by the above-described redistribution reaction has a phenolic hydroxyl group introduced into its terminal.

As the above-mentioned modified PPE, those whose terminals are epoxidized can also be used. In this case, after adjusting the molecular weight by performing a redistribution reaction of high molecular weight PPE,
By reacting epichlorohydrin, the terminal hydroxyl group is ethoxylated. The amount of epichlorohydrin used in the terminal epoxidation is at least 1 and preferably at least 2 times the number of moles of the epoxy group with respect to the terminal phenolic hydroxyl group. -10
Time is preferred. In this reaction, as a catalyst, a basic catalyst equivalent to the terminal hydroxyl group, for example, sodium hydroxide,
It is effective to use an aqueous solution (50%) of potassium hydroxide or the like, and the addition amount is 1.0 equivalent or more, preferably 1.2 equivalent or more, particularly preferably 1.5 equivalent or more, based on the epoxy group of epichlorohydrin. It is more than equivalent. In this reaction, the solvent used in the above-described redistribution reaction of high-molecular-weight PPE may be continuously used, or may be switched to another solvent. After the reaction, the system was cooled, and the reaction mixture was poured into a poor solvent of PPE such as methanol to precipitate as a precipitate. The precipitate was separated by filtration, washed with water or methanol, and reacted with unreacted epichlorohydrin or the above. After the removal of the basic catalyst, drying under reduced pressure at 50 to 80 ° C. can obtain the desired terminal-epoxidized modified PPE.

The terminally epoxidized modified PPE obtained as described above has a low melt viscosity, a high fluidity, and a high compatibility with the epoxy resin. Further, it is also effective as a raw material for obtaining a modified PPE having a terminal amination or terminal carboxylation by further reacting a polyamine or a polycarboxylic acid compound.

In the present invention, by including the epoxy resin, the curing agent and the modified PPE as essential components, an epoxy resin composition having a compatible region between the epoxy resin and the modified PPE before curing can be obtained. In this epoxy resin composition, the epoxy resin and the modified P
PE can be compatibilized by appropriately selecting and heating the temperature according to the type and composition. Further, regarding the mixing ratio of the modified PPE in the epoxy resin composition, the epoxy resin, the curing agent, the modified PP
It is preferable that the content is 10 to 60% by weight based on the total amount of E.

Further, various additives, fillers and the like can be appropriately added to the epoxy resin composition as needed.

The above-mentioned epoxy resin composition can be used as an adhesive, used as a material for a printed board by impregnating it with glass cloth or the like, and can also be used as a resin for SMC and FRP.

The cured product of the epoxy resin composition according to the present invention is separated into a phase mainly composed of the epoxy resin and a phase mainly composed of the modified polyphenylene ether resin by heat-curing the epoxy resin composition. And a cured product in a microphase-separated state having a period in which these two phases are regularly entangled.

Here, the principle of the appearance of the phase separation structure in the present invention and a method for confirming the principle will be described.

In general, when two different kinds of organic substances A and B are mixed, a "phase diagram" is displayed for the composition ratio and the temperature.
You can draw a figure called. There is a case where they are compatible with each other in a practical whole region or a case where they are not compatible with each other in the whole region. This phenomenon is based on whether the free energy when they are compatible is lower than the sum of the free energies in the two phases that are not compatible, that is, the composition dependency of the difference in free energy (ΔG _mix ). Is determined by

FIG. 3 shows an example of a phase diagram. This phase diagram is referred to as a lower critical solution temperature (LCST) phase diagram, and is an example in which the same composition facilitates compatibility at a low temperature side. On the contrary, there is an example in which the material is dissolved on the high temperature side. In this case, a high-temperature melting type (abbreviated as UC
ST) It is called a phase diagram. Such a curve on the phase diagram that distinguishes the incompatible region and the compatible region is called a binodal curve (see FIG. 4). When the point of ∂ ² ΔG _mix / ∂φ ² = 0 is combined in the phase diagram shown in FIG. 4, the vertex coincides with the binodal curve, and the spinodal curve (FIG. It is shown by a broken line in the middle.)
Can be drawn. Inside the spinodal curve, ∂
It is a _{^{2 ΔG mix / ∂φ 2 <0}} , on the outside ∂ ² ΔG _mix
/ ∂φ ² > 0. Among the incompatible regions, the region inside the spinal curve is called an unstable region, and the region between the spinodal curve and the binodal curve is called a metastable region.

According to the detailed theory, as shown in FIG. 5, the temperature of the mixed system, which is uniformly compatible in the stable compatible region at the temperature T ₁ , is rapidly increased to T ₂ and becomes unstable. When it is brought into the region, it rapidly starts to separate into coexisting compositions φ ₁ and φ ₂ . At this time, as shown in FIG. 6, a structure is formed in which the two separated phases are continuously and regularly intertwined with each other with a constant wavelength Λm (structure period). If such a structure is referred to as a “modulation structure (mutually continuous structure)”, the period Λm of this modulation structure is determined by the position (φ, T
_{According to 2} ), it is thermodynamically defined as follows.

[0041] Λm = 2πL [3 | T _s one T ₂ | / T _s] ^1/2 where, L is the intermolecular interaction distance, typically 30nm
Take values before and after.

When such a structure is observed two-dimensionally under a microscope, computer simulation has revealed that an arabesque pattern as shown in FIG. 7 is obtained. In fact, such a structure has been confirmed in various systems.

Normally, this process is an early phenomenon in a phase separation mode called spinodal decomposition, and similar structural enlargement occurs at the end, and finally the structure as shown in FIG. Instead of (modulation structure), “sea-island structure” is detected.

"Mutually continuous structure" by spinodal decomposition
It is effective to fix one or both components of the phase-separated phase in a short period of time by quenching etc. in order to immobilize it, but when the temperature is raised again, the structure changes and the `` sea-island structure '' is created. It turned out to be meaningless.

However, when one of the components is a thermosetting component,
It has recently been shown that structural fixation occurs permanently, since the phases of the thermosetting component become unable to move freely by the end of the spinodal decomposition process.

Using an epoxy resin as the thermosetting resin,
Polyether sulfone (PES) as a thermoplastic resin,
Examples combining polyetherimide (PEI) are already known. (Reference (1): K. Yamanaka, T. Inoue, Poly
mer, 30, 662 (1989) Reference (2): Hiroshi Yamamoto, Takashi Inoue, No. 40
Proceedings of the Annual Meeting of the Society of Polymer Science, 40 (3) 793 (1991) Article (3): Hiroshi Yamamoto, Takashi Inoue, Proceedings of the 41st Annual Meeting of the Society of Polymer Science, 41
(3) 1185 (1992)] However, an example in which the “modulation structure” when an epoxy resin is used as a thermosetting resin and modified PPE is used as a thermoplastic resin is fixed has not yet been known. On the other hand, FIG.
In the metastable region, the "sea-island structure" is formed from the beginning, so that the effects of the present invention cannot be obtained.

As described above, the present invention comprises an epoxy resin and a modified PPE as essential components, and the "deformation structure", that is, the two phase separations, is obtained from the phase decomposition (phase separation) of the epoxy resin and the modified PPE during curing. It is a thermosetting product of a composition in which the phases are continuous and form a regularly intertwined structure. To confirm such a structure,
The two points are important.

A regular periodic structure is confirmed. This item is usually achieved by an optical method. FIG. 2 shows a schematic diagram of the apparatus. The appearance of a scattering maximum in light scattering measurement is a proof of a regular phase-separated structure with a certain period, and the period size Λm gives the light scattering wavelength λ, the refractive index N of the cured product, and the scattering maximum. It can be calculated by the following equation using the scattering angle θm.

Δm = (λ / 2N) / sin (θm / 2) Normally, when the “modulation structure” of spinodal decomposition can be fixed, Δm is in the range of 0.1 to 10 μm, and 10 μm.
It is suspected that the structure exceeding m is enlarged to the “sea-island structure”.

The structure as shown in FIG. 7 is observed by an optical microscope. In contrast, the “sea-island structure”
Then, a structure in which one component is dispersed in a spherical shape is observed.

Furthermore, in addition to the direct confirmation as described above, the cured product must be completely compatible before curing. Also helps to confirm.

The present invention is, as described above, a thermosetting product of a composition containing an epoxy resin and a modified PPE as essential components, and a cured product having a mutually continuous phase-separated structure. The method is not particularly limited.
However, as described in the above expression mechanism, it is premised that they are once compatibilized. For example, when powder is mixed, the epoxy resin and the modified PPE are mixed without adding a curing agent, or do not cure. It is necessary to make them compatible with each other. However, once the casting method is used in which the common solvent is used for uniform mixing in the order of molecules and the solvent is removed, there is no need to limit any manufacturing conditions since the components are instantaneously and uniformly compatible in the compatible region. The curing speed is adjusted by, for example, adjusting the curing temperature or using or not using a curing accelerator. Adjustment of the curing rate is a means of controlling the structural period of the phase separation. The point is that, within the scope of the present invention, it is only necessary to set the conditions for producing a cured product such that the separated phases of the phase mainly composed of the epoxy resin and the phase mainly composed of the modified PPE can have a mutually continuous structure. It is. Typical examples of the conditions for preparing a cured product are described below, but these conditions are different depending on the composition of the system and the like, and are not limited.

First, one or more polar solvents such as toluene, benzene, ethylpentene, xylene, chloroform and the like are used, and the components are mixed and dissolved to prepare a varnish having a concentration of 5 to 60% by weight. The varnish is cast to form a casting film and the solvent is removed. The obtained film is heated at 60 to 210 ° C, preferably 70 to 15 ° C.
The structure is fixed by curing at 0 ° C. for 1 to 7 hours, preferably 2 to 5 hours. Further, at a high temperature of 160 to 240 ° C.,
Post-curing may be carried out for 4 hours, preferably at 170-230 ° C.

Of course, when a film-like molded product is produced, the uncured casting film may be roughly pulverized and molded and cured, or a curing agent may be added to the epoxy resin and the modified PPE without using a solvent. Without powder mixing,
After leaving or kneading them at a temperature at which they are compatible, for example, 70-200 ° C. to make them compatible, a method of lowering the temperature, adding a curing agent, and heating to a molding temperature may be performed.

[0055]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples.

In the following Examples and Comparative Examples, the state of phase separation due to curing of the epoxy resin composition,
The final measurement of the structural period was performed by observing the temporal change of the profile by the light scattering method. Light scattering device shown in FIG. 2 (for measurement, light scattering device GP-5 manufactured by Optec Co., Ltd.)
The appearance of a scattering maximum in the measurement of the light scattering profile by means of “) indicates that there is an ordered phase-separated structure with a certain structural period Λm”, and the structural period Λm is the wavelength of the irradiating light of light scattering. λ, the refractive index N of the cured product, and the scattering angle θm giving the maximum can be calculated by the following formula: 式 m = (λ / 2N) / sin (θm / 2) In addition, the phase separation structure was observed with an optical microscope to confirm the micro phase separation structure.

In Examples and Comparative Examples, epoxy resins were selected from the following three types (A) to (C) and used. Epoxy resin (A): bisphenol A type epoxy resin (manufactured by Yuka Shell Epoxy Co., Ltd., Epicoat 828, molecular weight: about 380, epoxy equivalent: 184 to 194) Epoxy resin (B): tetraglycidyl diaminodiphenylmethane (tetrafunctional epoxy resin) (Epicoat 604, molecular weight of about 470, epoxy equivalent 230 to 270, manufactured by Yuka Shell Epoxy Co., Ltd.) Epoxy resin (C): biphenyl type epoxy resin (Epicoat YX-4000, manufactured by Yuka Shell Epoxy Co., Ltd.)
H, epoxy equivalent 195) In Examples and Comparative Examples, the following seven types (D) to (J) were used as modified PPE. Modified PPE
The production methods of (D) to (J) are shown below, and the contents are summarized in Table 1.

Preparation of Modified PPEs (D) to (J) As shown in Table 1, PPE (manufactured by Nippon GE Plastics Co., Ltd., Mn = 2000 to 25000), benzoyl peroxide (BPO), bisphenol A (BPA) was blended in a toluene solvent, and a redistribution reaction was performed with stirring at 90 ° C. for 60 minutes. The obtained solution was subjected to gel permeation chromatography (column composition: TSKgel superHM-M, manufactured by Tosoh Corporation).
(1) + superHM-H (1)) to measure the molecular weight distribution, and the number average molecular weight calculated from the results is shown in Table 1.

With respect to the modified PPE (D) (F) to (J), the toluene in the above solution was removed at this time, and then washed with methanol or water to obtain a single modified PPE.

For the modified PPE (E), 8 parts of epichlorohydrin and 8 parts of an aqueous Na0H solution (50% by weight) were added to the above solution after the redistribution reaction, and the mixture was stirred at 100 ° C. for 4 hours. After the reaction mixture was cooled to room temperature, 1 L of methanol was added to precipitate a precipitate. This precipitate was separated by filtration, washed with 1 L of methanol, further washed twice with 1 L of pure water, and washed again with 1 L of methanol. After, 70 ℃
And dried under reduced pressure to obtain a modified PPE with terminal epoxidation.
The reaction rate between the phenolic hydroxyl group of the modified PPE and epichlorohydrin was measured by measuring the infrared absorption spectrum of a 1.5 wt% carbon tetrachloride solution of the modified PPE using a quartz cell having an optical path length of 10 mm. went. That is, the reaction rate was calculated based on the value of the absorbance (3622 cm ^-1 ) of the phenolic hydroxyl group before and after the reaction. This proved that 91% of the terminal hydroxyl groups of the modified PPE had reacted.

[0061]

[Table 1]

Example 1 As shown in Table 2, 100 parts by weight of the epoxy resin (A) shown above as an epoxy resin, 15 parts by weight of the modified PPE (D) shown above as a modified PPE, and dicyandiamide (oil) as a curing agent 6 parts by weight of EpiCure DlCY7 (manufactured by Kasei Shell Epoxy Co., Ltd., average particle diameter 7 μm) were mixed with toluene as a solvent to prepare a 10% by weight toluene solution (however, in Example 3, N- was used as a curing accelerator as a curing accelerator).
(3.4-Dichlorophenyl) -N'N'-dimethylurea (DIUR0N manufactured by Tokyo Chemical Industry Co., Ltd.) was added. The solution was cast on a cover glass, and dried at room temperature for 24 hours under reduced pressure to remove the solvent. The thin film obtained was cured at 150 ° C. for 3 hours, and was used for light scattering measurement and optical microscope observation. Of the exam. Light scattering measurements revealed a scattering maximum in the profile. FIG. 1 shows the temporal change of the structural period Δm obtained from the angle showing the scattering maximum for this sample. In the early stage of curing, they are homogeneously compatible, but after a certain time, a phase separation structure grows (phase separation starts) with time, and the structure is fixed at a certain time. When observed with an optical microscope, a phase-separated structure having a structural period well corresponding to the result obtained from the light scattering measurement (FIG. 1) was observed. Table 3 shows the measurement results of the structural period Δm.

Next, the cured product after curing at 150 ° C. for 3 hours was further post-cured at 200 ° C. for 3 hours, and the fracture toughness value (K _IC ) was measured. 3
It was shown to. The measurement of the fracture toughness value was carried out on a compact tension (Compact Tension) test piece using an Instron type tensile tester in accordance with ASTM E-399-72 at 23 ± 2 ° C. and a crosshead speed of 0.5 mm /
Minutes.

Examples 2 to 6, Examples 8 to 11, Comparative Example 1
~ 4 As shown in Table 2, one of the epoxy resins (A) to (C) shown above was selected as the epoxy resin, and the modified PPE (D) to (J) was used as the modified PPE. Dicyandiamide (manufactured by Yuka Shell Epoxy Co., Ltd., EpiCure DlCY7, average particle diameter 7 μm) was used as a curing agent, and these were compounded in the amounts shown in Table 2 using toluene as a solvent and the concentration was adjusted. A 10% by weight toluene solution was obtained. This solution was cast on a cover glass, cured in the same manner as in Example 1 to obtain a sample, and subjected to measurement of the structural period Λm by light scattering and observation with an optical microscope.
Table 3 shows the results.

Next, the cured product after curing at 150 ° C. for 3 hours was post-cured in the same manner as in Example 1, and the fracture toughness value (K _IC ) was measured. The obtained results are shown in Table 3. Was.

Example 7 An epoxy resin and modified PP were used in the formulation shown in Table 2 without using a solvent.
Example 1 was repeated except that E and E were stirred and mixed at 200 ° C. for 2 hours to uniformly dissolve them, then the temperature was lowered to 100 ° C., dicyandiamide was added as a curing agent, and cast on a cover glass. A cured product was obtained in the same manner as described above. Also in this case, measurement of the structural period Δm by light scattering and observation with an optical microscope were performed in the same manner as in Example 1, and the results are shown in Table 3. The cured product after curing at 150 ° C. for 3 hours was post-cured in the same manner as in Example 1, and the fracture toughness value (K _IC ) was measured. The obtained results are shown in Table 3.

[0067]

[Table 2]

[0068]

[Table 3]

As shown in Table 3, in the cured products of Examples 1 to 11, a phase-separated structure of a modulated structure having a structural period appeared, and the values of the fracture toughness were generally higher than those of Comparative Examples 1 to 4. became.

[0070]

The cured product of the epoxy resin composition of the present invention
It is separated into a phase mainly composed of an epoxy resin and a phase mainly composed of a modified PPE, and both phases have a period in which both phases are regularly intertwined, and the period is calculated as 0. 0 from a scattering maximum in light scattering measurement. Since it has a micro phase separation structure of 1 to 10 μm, it has excellent mechanical properties such as toughness, flexibility and adhesiveness.

According to the method for producing a cured epoxy resin composition of the present invention, the cured epoxy resin composition can be produced.

[Brief description of the drawings]

FIG. 1 is a graph showing the change over time in the structural period of a phase separation structure of a sample obtained in Example 1.

FIG. 2 is a schematic diagram of an apparatus used for light scattering measurement.

FIG. 3 is a low-temperature dissolution type phase diagram (LCST type phase diagram) representing the relationship between the temperature and the composition in a system in which a uniform solution is formed at low temperature (compatibility) and the phase is separated into two phases by raising the temperature. ).

FIG. 4 shows a binodal curve and a spinodal curve in the phase diagram of FIG. 3;

5 shows a phase separation structure when the temperature of a uniformly mixed mixed system is rapidly increased in the phase diagram of FIG. 4;

FIG. 6 is a schematic diagram showing a three-dimensional modulation structure having a structural period Λm and a density fluctuation.

FIG. 7 is a schematic diagram showing a two-dimensional modulation structure having a structural period Δm.

Claims (9)

[Claims] An epoxy resin containing at least two epoxy groups, a curing agent for the epoxy resin, and a modified polyphenylene ether obtained by redistributing a high molecular weight polyphenylene ether with a polyphenol compound in the presence of a radical initiator. Is an epoxy resin composition cured product obtained by heat-curing an epoxy resin composition having a compatibility region between the epoxy resin and the modified polyphenylene ether, wherein the epoxy resin and the modified polyphenylene ether have a compatible region. The modified polyphenylene ether resin is separated into a main phase, and both phases have a period in which both phases are regularly intertwined, and the period is 0.1 to 10 μm as calculated from the scattering maximum in light scattering measurement. A cured product of an epoxy resin composition, characterized in that: 2. The cured epoxy resin composition according to claim 1, wherein the modified polyphenylene ether has a number average molecular weight of 1,000 to 4,000. 3. The content of the modified polyphenylene ether resin is 10 to 60 with respect to the total amount of the epoxy resin, the curing agent, and the modified polyphenylene ether.
The epoxy resin composition cured product according to claim 1 or 2, which is in terms of% by weight. 4. The cured epoxy resin composition according to claim 1, wherein the terminal of the modified polyphenylene ether is epoxidized. 5. The cured epoxy resin composition according to claim 1, wherein the curing agent is dicyandiamide. 6. The cured epoxy resin composition according to claim 1, wherein the epoxy resin composition contains a urea compound derivative as a curing accelerator. 7. An epoxy resin containing at least two epoxy groups, a curing agent for the epoxy resin, and a modified polyphenylene ether obtained by redistributing a high-molecular-weight polyphenylene ether with a polyphenol compound in the presence of a radical initiator. Is blended as an essential component to prepare an epoxy resin composition in which the epoxy resin and the modified polyphenylene ether are compatible, and the epoxy resin composition is thermally cured at 60 to 210 ° C. A method for producing a cured product of an epoxy resin composition, characterized in that the two phases are separated into a main phase and a phase mainly composed of a polyphenylene ether resin, and these two phases exhibit a continuous period and are intertwined regularly. 8. In the epoxy resin composition, compatibility between the epoxy resin and the modified polyphenylene ether is determined by using toluene, benzene, ethylbenzene, xylene,
8. The method for producing a cured epoxy resin composition according to claim 7, wherein the method is performed using at least one solvent selected from the group consisting of chloroform. 9. The cured epoxy resin composition according to claim 7, wherein the terminal of the modified polyphenylene ether is epoxidized by further reacting with epichlorohydrin after the redistribution reaction. Method.