JP2010144052A - Isocyanate-modified epoxy resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epoxy resin having a low viscosity and being excellent in the balance of heat-resistance and toughness. <P>SOLUTION: The isocyanate-modified epoxy resin contains a structure represented by general formula (1) (wherein R<SB>1</SB>-R<SB>8</SB>are each independently hydrogen, halogen, alkyl which may have a substituent, alkoxy which may have a substituent, aryl which may have a substituent, amino, nitro or carboxyl which may have a substituent; and R<SB>9</SB>is a divalent or more of functional group which may have a substituent). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an isocyanate-modified epoxy resin and an epoxy resin composition containing the same.

  Epoxy resins have excellent performance in terms of mechanical properties, electrical properties, thermal properties, chemical resistance, adhesiveness, etc., such as paints, insulating materials for electrical and electronic devices, adhesives, etc. It is used for a wide range of applications. Recently, there is a demand for higher functionality such as further strengthening, heat resistance, and weight reduction of epoxy resins.

Patent Document 1 discloses a tolylene diisocyanate-modified epoxy resin of bisphenol A type epoxy resin as an epoxy resin that can achieve both heat resistance and flexibility.
As a resin modified with a compound other than tolylene diisocyanate, Patent Document 2 discloses an epoxy resin obtained by modifying a bisphenol A type epoxy resin using polymethylene isocyanate.
Patent Document 3 discloses glycidyl ether of 4,4′-bis-3,3 ′, 5,5′-tetramethylbiphenyl as a resin having improved heat resistance.
In Patent Document 4, as a resin with further improvements, 4,4′-bis-3,3 ′, 5,5′-tetramethylbiphenyl glycidyl ether was modified with polyhydric phenol to lower the softening point. A resin is disclosed.

JP-A-5-222160 Japanese National Patent Publication No. 4-506678 JP 58-39677 A JP-A-3-14816

When the resin disclosed in Patent Documents 1 and 2 is intended to increase heat resistance, it simultaneously increases in viscosity and cannot achieve both heat resistance and low viscosity.
Although the resin disclosed in Patent Document 3 has high heat resistance, it has a high softening point and has a sharp viscosity drop, so it is not suitable for composite materials.
The resin disclosed in Patent Document 4 shows no improvement in heat resistance, and the resulting resin is brittle.

  In view of the above circumstances, the problem to be solved by the present invention is to provide an epoxy resin having a low viscosity and an excellent balance between heat resistance and toughness.

  As a result of intensive studies in order to solve the above problems, the present inventors have found that an isocyanate-modified epoxy resin containing a specific structure having a biphenyl skeleton and an oxazolidone ring can solve the above problems, and completed the present invention. It was.

That is, the present invention is as follows.
[1]
An isocyanate-modified epoxy resin having a structure represented by the following general formula (1).

(In the formula, each of R _{1 to} R ₈ independently has a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or a substituent. An aryl group that may be substituted, an amino group that may have a substituent, a nitro group, or a carboxyl group, and R ₉ represents a divalent or higher functional group that may have a substituent.
[2]
The isocyanate-modified epoxy resin according to the above [1], comprising at least one skeleton selected from biphenyl, bisphenol A, bisphenol F, bisphenol AF, bisphenol AC, bisphenol S, phenol novolac, and cresol novolac.
[3]
The isocyanate-modified epoxy resin (A) according to the above [1] or [2],
An epoxy resin (B) other than (A),
A curing agent (C);
An epoxy resin composition comprising:
[4]
The epoxy resin composition [5] according to the above [3], further comprising a plasticizer (D).
The epoxy resin composition according to the above [3] or [4], further comprising a filler (E).

  According to the present invention, an epoxy resin having a low viscosity and an excellent balance between heat resistance and toughness can be obtained.

  Hereinafter, the best mode for carrying out the present invention (hereinafter, this embodiment) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

  The epoxy resin of this embodiment is an isocyanate-modified epoxy resin including a structure represented by the following general formula (1).

In general formula (1), R _{1 to} R ₈ are each independently a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or a substituent. An aryl group which may have a group, an amino group which may have a substituent, a nitro group or a carboxyl group, and R ₉ represents a bivalent or higher functional group which may have a substituent. Show.

  The epoxy resin of the present embodiment is a resin having a structure including a biphenyl skeleton represented by the general formula (1) and an oxazolidone ring. By having the structure, the viscosity of the epoxy resin and the epoxy resin composition including the epoxy resin is included. And the cured product has excellent heat resistance and fracture toughness.

Hereinafter, each symbol in the present embodiment will be described.
In the general formula (1), examples of the halogen atom represented by R _{1 to} R ₈ include a fluorine atom, a chlorine atom, and a bromine atom.

In the general formula (1), the “alkyl group” of the optionally substituted alkyl group represented by R _{1 to} R ₈ is linear or branched having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. A chain alkyl group is exemplified, and examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and a hexyl group. Among these, since the branched chain tends to have higher heat resistance than the straight chain, it is preferably an isopropyl group, an isobutyl group, or a tert-butyl group, and more preferably a tert-butyl group.

In the general formula (1), the “alkoxy group” of the optionally substituted alkoxy group represented by R _{1 to} R ₈ is linear or branched having 1 to 6, preferably 1 to 4 carbon atoms. A chain alkoxy group, for example, methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, sec-butoxy group, tert-butoxy group, pentyloxy group, hexyloxy group and the like, preferably A methoxy group and an ethoxy group.

In the general formula (1), examples of the “aryl group” of the optionally substituted aryl group represented by R _{1 to} R ₈ include a phenyl group and a naphthyl group, and a phenyl group is preferable.

The alkyl group, aryl group, alkoxy group and amino group represented by R _{1 to} R ₈ may be substituted with one or two or more substituents at substitutable positions. Examples of such a substituent include a halogen atom (for example, fluorine atom, chlorine atom, bromine atom), an alkyl group having 1 to 6 carbon atoms (for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl). Group, sec-butyl group, tert-butyl group, pentyl group, hexyl group), aryl group (for example, phenyl group, naphthyl group), aralkyl group (for example, benzyl group, phenethyl group), alkoxy group (for example, methoxy group) Ethoxy group) and the like.

Examples of the divalent or higher functional group represented by R ₉ include a single bond, an optionally substituted alkylene group, and an optionally substituted arylene group.

  “Alkylene group” means a divalent group derived by further removing one hydrogen atom at any position from the above-defined “alkyl group”. For example, methylene group, ethylene group, methylethylene group, ethyl And ethylene group, 1,1-dimethylethylene group, 1,2-dimethylethylene group, trimethylene group, 1-methyltrimethylene group, 2-methyltrimethylene group, tetramethylene group, etc., preferably methylene group, Examples include an ethylene group, a methylethylene group, a 1,1-dimethylethylene group, and a trimethylene group.

As "arylene group" of the arylene group which may be substituted represented by R _9, the from the "aryl group" means a divalent group derived one more except for a hydrogen atom at an arbitrary position .

Optionally substituted alkylene group represented by R _9, an arylene group, a substitutable position may be substituted with one or more substituents. Examples of the substituent include a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom), an alkyl group having 1 to 6 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group), aryl group (for example, phenyl group, naphthyl group), aralkyl group (for example, benzyl group, phenethyl group), alkoxy group (for example, methoxy group, ethoxy group) Group) and the like.

  The isocyanate-modified epoxy resin of the present embodiment is selected from biphenyl, bisphenol A, bisphenol F, bisphenol AF, bisphenol AC, bisphenol S, phenol novolac, and cresol novolac in addition to the structure represented by the general formula (1). One or more skeletons may be included.

  The weight average molecular weight of the isocyanate-modified epoxy resin of this embodiment is preferably 800 or more, more preferably 900 or more, and still more preferably 1000 or more. When the weight average molecular weight is less than 800, the heat resistance of the cured product tends to be low, and at the same time, the toughness tends to decrease and become brittle. Here, the weight average molecular weight refers to a value measured by gel permeation chromatography in terms of polystyrene.

  The epoxy equivalent of the isocyanate-modified epoxy resin of the present embodiment is preferably 250 or more, more preferably 350 or more, and still more preferably 400 or more. When the epoxy equivalent is larger than 250, the toughness tends to increase. Here, an epoxy equivalent means the value measured by the potentiometric titration method by JIS-K-7236.

  The method for producing the isocyanate-modified epoxy resin of the present embodiment is not particularly limited. For example, by reacting an isocyanate compound and a glycidyl compound having a biphenyl skeleton in the presence of an oxazolidone ring-forming catalyst, it is almost the theoretical amount. Obtainable. The isocyanate compound and the glycidyl compound are preferably reacted in an equivalent ratio of 1: 2 to 1:10. When the ratio of the two is in the above range, the heat resistance and water resistance of the cured epoxy resin are better. There is a tendency.

  In this embodiment, you may use together glycidyl compounds other than the glycidyl compound which has a biphenyl skeleton as a raw material for obtaining an isocyanate modified epoxy resin. Specific examples thereof include dihydric phenols such as bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetramethyl bisphenol A, tetramethyl bisphenol F, tetramethyl bisphenol AD, tetramethyl bisphenol S, and tetrabromobisphenol A. 1,1,1-tris (4-hydroxyphenyl) methane, 1,1,1- (4-hydroxyphenyl) ethane, 4,4- [1- [4- [1- (4 Compounds obtained by glycidylating tris (glycidyloxyphenyl) alkanes such as -hydroxyphenyl) -1-methylethyl] phenyl] ethylidene] bisphenol; and novolacs such as phenol novolak, cresol novolak, and bisphenol A novolak Rishijiru of the compounds, and the like, but not particularly limited thereto.

Specific examples of the isocyanate compound used as the raw material include, for example, methane diisocyanate, butane-1,1-diisocyanate, ethane-1,2-diisocyanate, butane-1,2-diisocyanate, transvinylene diisocyanate, propane-1,3- Diisocyanate, butane-1,4-diisocyanate, 2-butene-1,4-diisocyanate, 2-methylbutene-1,4-diisocyanate, 2-methylbutane-1,4-diisocyanate, pentane-1,5-diisocyanate, 2, 2-dimethylpentane-1,5-diisocyanate, hexane-1,6-diisocyanate, heptane-1,7-diisocyanate, octane-1,8-diisocyanate, nonane-1,9-diisocyanate, decane-1,10- Isocyanate, dimethylsilane diisocyanate, diphenylsilane diisocyanate, ω, ω′-1,3-dimethylbenzene diisocyanate, ω, ω′-1,4-dimethylbenzene diisocyanate, ω, ω′-1,3-dimethylcyclohexane diisocyanate, ω , Ω′-1,4-dimethylcyclohexane diisocyanate, ω, ω′-1,4-dimethylnaphthalene diisocyanate, ω, ω′-1,5-dimethylnaphthalene diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1, 4-diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 1-methylbenzene-2,4-diisocyanate, 1-methylbenzene 2,5-diisocyanate, 1-methylbenzene-2,6-diisocyanate, 1-methylbenzene-3,5-diisocyanate, diphenyl ether-4,4′-diisocyanate, diphenyl ether-2,4′-diisocyanate, naphthalene-1, 4-diisocyanate, naphthalene-1,5-diisocyanate, biphenyl-4,4′-diisocyanate, 3,3′-dimethylbiphenyl-4,4′-diisocyanate, 2,3′-dimethoxybisphenyl-4,4′- Diisocyanate, diphenylmethane-4,4′-diisocyanate, 3,3′-dimethoxydiphenylmethane-4,4′-diisocyanate, 4,4′-dimethoxydiphenylmethane-3,3′-diisocyanate, diphenylsulfite-4,4′- Diisocyanate, di Bifunctional isocyanate compounds such as Enirusurufon-4,4'-diisocyanate;
Polyfunctional isocyanate compounds such as polymethylene polyphenyl isocyanate, triphenylmethane triisocyanate, tris (4-phenylisocyanate thiophosphate) -3,3 ′, 4,4′-diphenylmethane tetraisocyanate;
Examples include, but are not limited to, a multimer such as a dimer or trimer of the isocyanate compound, a blocked isocyanate masked with alcohol or phenol, and a bisurethane compound. Two or more of these isocyanate compounds may be used in combination.

  Among the above isocyanate compounds, since heat resistance tends to be improved, a bifunctional or trifunctional isocyanate compound is preferable, a bifunctional isocyanate compound is more preferable, isophorone, benzene, toluene, diphenylmethane, naphthalene, poly It is a bifunctional isocyanate compound having a skeleton selected from methylene polyphenylene polyphenyl and hexamethylene. When the number of functional groups of the isocyanate compound is too large, the storage stability tends to decrease, and when it is too small, the heat resistance tends to decrease.

[catalyst]
The catalyst used in the present embodiment is not particularly limited as long as it is used for oxazolidone ring formation, but may be a catalyst that selectively generates an oxazolidone ring in the reaction of a glycidyl compound and an isocyanate compound. preferable.

The catalyst for selectively producing such an oxazolidone ring is not particularly limited, and examples thereof include lithium compounds such as lithium chloride and butoxy lithium, and complex salts such as boron trifluoride;
Quaternary ammonium salts such as tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium iodide, tetrabutylammonium bromide;
Tertiary amines such as dimethylaminoethanol, triethylamine, tributylamine, benzyldimethylamine, N-methylmorpholine;
Phosphines such as triphenylphosphine;
Allyltriphenylphosphonium bromide, diallyldiphenylphosphonium bromide, ethyltriphenylphosphonium chloride, ethyltriphenylphosphonium iodide, tetrabutylphosphonium acetate / acetic acid complex, tetrabutylphosphonium acetate, tetrabutylphosphonium chloride, tetrabutylphosphonium bromide, tetrabutylphosphonium Phosphonium compounds such as iodide;
A combination of triphenylantimony and iodine;
Imidazoles such as 2-phenylimidazole and 2-methylimidazole;
Etc. These catalysts can be used individually by 1 type or in combination of 2 or more types.

  The amount of the oxazolidone ring-forming catalyst is not particularly limited, and is usually used in the range of about 5 ppm to 2% by mass, preferably 10 ppm to 1% by mass with respect to the total amount of the glycidyl compound and isocyanate compound as raw materials. %, More preferably 20 to 5000 ppm, still more preferably 20 to 1000 ppm. When the amount of the catalyst used is 2% by mass or less, a decrease in moisture resistance tends to be suppressed. On the other hand, when the amount is 5 ppm or more, production efficiency tends to be improved.

  The epoxy resin composition of this embodiment contains the isocyanate-modified epoxy resin (A) described above, an epoxy resin (B) other than (A), and a curing agent (C).

[Epoxy resin (B)]
The epoxy resin (B) is not particularly limited, and various known resins can be appropriately selected and used. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, hindered-in type epoxy resin, biphenyl type epoxy resin, alicyclic epoxy resin, triphenylmethane type epoxy resin, phenol novolac type epoxy resin, cresol Novolak type epoxy resin, naphthol novolak type epoxy resin, bis A novolak type epoxy resin, dicyclopentadiene / phenol epoxy resin, alicyclic amine epoxy resin, aliphatic amine epoxy resin, and epoxy resins halogenated from these Can be mentioned. These can be used alone or in combination of two or more.

[Curing agent (C)]
The curing agent (C) is not particularly limited, and various known materials can be appropriately selected and used. From the viewpoint of the reaction rate at the time of curing, a guanidine derivative, an aromatic amine compound, and a novolak type. It is preferably at least one selected from the group consisting of phenol resins. These guanidine derivatives, aromatic amine compounds, and novolac type phenol resins can be used singly or in combination of two or more.

  Specific examples of guanidine derivatives include dicyandiamide derivatives such as dicyandiamide, dicyandiamide-aniline adduct, dicyandiamide-methylaniline adduct, dicyandiamide-diaminodiphenylmethane adduct, dicyandiamide-diaminodiphenyl ether adduct, guanidine nitrate, guanidine carbonate, phosphorus Guanidine salts such as guanidine acid, guanidine sulfamate, aminoguanidine bicarbonate, acetylguanidine, diacetylguanidine, propionylguanidine, dipropionylguanidine, cyanoacetylguanidine, guanidine succinate, diethylcyanoacetylguanidine, dicyandiamidine, N-oxymethyl -N'-cyanoguanidine, N, N'-dicarboethoxyguanidine, etc. It is not particularly limited to these.

  Specific examples of the aromatic amine compound include, for example, metaphenylene diamine, paraphenylene diamine, 3,3′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl methane, 4, 4 ′. -Diamino diphenyl ether etc. are mentioned, However, It does not specifically limit to these.

  Specific examples of the novolak type phenol resin include, but are not limited to, phenol novolak, bisphenol A novolak, cresol novolak, naphthol novolak, and the like.

  The blending amount of the curing agent (C) is not particularly limited and is appropriately set according to the desired design. When the curing agent (C) is a guanidine derivative, the isocyanate-modified epoxy resin (A) It is preferable that it is 1-9 mass% with respect to the total amount, and when a hardening | curing agent (C) is an aromatic amine compound, it is 10-50 mass% with respect to the total amount of an isocyanate modified epoxy resin (A). Preferably, when the curing agent (C) is a novolak type phenol resin, the content is preferably 20 to 60% by mass with respect to the total amount of the isocyanate-modified epoxy resin (A). Setting the blending amount of the curing agent (C) in the above range is preferable from the viewpoint of suppressing the decrease in the crosslinking density and the decrease in Tg of the cured product and ensuring the moisture resistance.

[Plasticizer (D)]
The epoxy resin composition of this embodiment may further contain a plasticizer (D). Examples of the plasticizer (D) include thermoplastic elastomers and crosslinked rubbers.

  Examples of thermoplastic elastomers include polyester-based thermoplastic elastomers and polyamide-based thermoplastic elastomers, but the latter tends to be superior in physical properties such as compression strength and interlayer shear strength of fiber-reinforced composite materials. preferable.

  Examples of the crosslinked rubber include acrylonitrile-butadiene copolymer, styrene-butadiene copolymer, and the like. The former is preferable because the compatibility with the epoxy resin tends to be good.

  Content of a plasticizer (D) becomes like this. Preferably it is 1-30 mass% with respect to the whole epoxy resin composition, More preferably, it is 2-20 mass%. Setting the content of the plasticizer (D) to 30% by mass or less is preferable from the viewpoint of preventing the resin viscosity from increasing and impairing the resin into the prepreg. On the other hand, the content of 1% by mass or more is preferable from the viewpoint of maintaining good prepreg tackiness and suppressing molding defects.

[Filler (E)]
The epoxy resin composition of this embodiment may further contain a filler (E). The inclusion of the filler (E) is preferable because of rheology control, that is, thickening and thixotropy imparting effects.

  Examples of the filler (E) include talc, aluminum silicate, finely divided silica, calcium carbonate, mica, alumina hydrate, zinc powder, carbon black, silicon carbide and the like, and fine particles from the viewpoint of imparting thixotropic properties. Silica is preferred.

  The content of the filler (E) is preferably 1 to 10% by mass and more preferably 1 to 5% by mass with respect to the entire epoxy resin composition. Setting the filler (E) content to 10% by mass or less is preferable from the viewpoint of preventing the resin viscosity from being too high and impregnating the resin into the prepreg and preventing the adhesive strength between the prepregs from decreasing. It is. On the other hand, the content of 1% by mass or more is preferable from the viewpoint of suppressing the occurrence of resin fading on the surface of the molded product.

[Curing accelerator]
It is also possible to adjust the curing rate of the epoxy resin composition by further blending a curing accelerator with the epoxy resin composition. Various known accelerators can be used without particular limitation, and examples thereof include urea compounds, imidazoles, tertiary amines, phosphines, aminotriazoles and the like. Moreover, you may use combining the said epoxy resin and a well-known hardening accelerator.

Next, the present embodiment will be described more specifically with reference to examples and comparative examples. However, the present embodiment is not limited to the following examples unless departing from the gist thereof.
The physical properties in the examples were measured by the following methods.

(1) Epoxy resin melt viscosity (80 ° C)
About 0.5 g of an epoxy resin sample was placed on the disk plate, rotated with the distance between the rotor and the plate being 0.1 mm, and the viscosity at which the measurement ambient temperature was stable at 80 ° C. was measured.

(2) Solvent solubility 3 g of epoxy resin and 3 g of each solvent were mixed and heated at 40 ° C. Thereafter, the occurrence of turbidity was observed when cooled to room temperature and left for 3 days. No turbidity when heated to 40 ° C, turbidity does not occur when heated to 40 ° C, △ turbidity occurs after standing at room temperature for 3 days, turbidity occurs even when left at room temperature for 3 days What did not do was set as (circle). As the solvent, methyl ethyl ketone, propylene glycol monomethyl ether (PGM), and acetone were used.

(3) Glass transition temperature About the hardened | cured material of an epoxy resin composition, using the dynamic viscoelasticity measuring device DDV-25FP (made by Orientec Co., Ltd.), the test piece of length 20mm x width 4mm x thickness 2mm was used. The temperature was raised at 2 ° C./min, and the temperature at which tan δ was maximized was determined.

(4) The cured product of the fracture toughness test _{(K IC)} epoxy resin composition was compliant with the elastic-plastic fracture toughness testing method (JSME S 001-1981) measurement. As a test method, a test piece of length 20 mm × width 4 mm × thickness 2 mm with a crack of about 2.5 mm in the center of the test piece was measured at an indenter moving speed of 0.5 mm / min and a distance between fulcrums of 17.6 mm. Measurement was performed by a three-point bending test.

(5) Infrared absorption spectrum (IR)
Measurement was performed in the range of 600 to 4000 cm ⁻¹ using FT / IR6100 manufactured by JASCO Corporation.

[Example 1]
In the reactor, 100 parts by mass of a biphenol type epoxy resin (trade name: YX4000, manufactured by Japan Epoxy Resin Co., Ltd., epoxy equivalent 185 g / eq) as a raw material glycidyl compound, and tetrabutylammonium bromide (trade name: tetrabromide bromide) 0.04 parts by mass of -n-butylammonium (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was stirred and heated to adjust the internal temperature to 175 ° C. Furthermore, 11.8 parts by mass of tolylene diisocyanate (trade name: Coronate T80 (trademark), manufactured by Nippon Polyurethane Co., Ltd.) as a raw material isocyanate compound was charged into the reactor over 90 minutes. After completion of the addition, the reaction temperature was kept at 175 ° C. and the mixture was stirred for 8 hours to obtain an isocyanate-modified epoxy resin I. The resulting resin was IR measurement, a peak was observed at 1750 cm ^-1 and 910 cm ^-1, it was confirmed to contain oxazolidone ring and an epoxy group.

[Example 2]
The raw material glycidyl compound was mixed with biphenol type epoxy resin (trade name: YX4000H, manufactured by Japan Epoxy Resin Co., Ltd., epoxy equivalent 185 g / eq) and bisphenol A type epoxy (trade name: AER260, manufactured by Asahi Kasei Chemicals Co., Ltd.). Except having changed to 20 mass parts, it reacted by the method similar to Example 1, and obtained the isocyanate modified epoxy resin II. When the obtained resin was subjected to IR measurement, peaks were observed at 1750 cm ⁻¹ and 910 cm ⁻¹ , and it was confirmed that the resin contained an oxazolidone ring and an epoxy group.

[Example 3]
Reaction was performed in the same manner as in Example 2 except that bisphenol A type epoxy (trade name: AER260, manufactured by Asahi Kasei Chemicals Corporation) was changed to bisphenol F type epoxy (trade name: Epicoat 830, manufactured by DIC Corporation). To obtain an isocyanate-modified epoxy resin III. When the obtained resin was subjected to IR measurement, peaks were observed at 1750 cm ⁻¹ and 910 cm ⁻¹ , and it was confirmed that the resin contained an oxazolidone ring and an epoxy group.

[Example 4]
A reaction was carried out in the same manner as in Example 2 except that the bisphenol A type epoxy was changed to epoxy phenol novolak (trade name: EPN1182, manufactured by Asahi Kasei Chemicals Corporation) to obtain an isocyanate-modified epoxy resin IV. When the obtained resin was subjected to IR measurement, peaks were observed at 1750 cm ⁻¹ and 910 cm ⁻¹ , and it was confirmed that the resin contained an oxazolidone ring and an epoxy group.

[Example 5]
An isocyanate-modified epoxy resin V was obtained by reacting in the same manner as in Example 2 except that the bisphenol A type epoxy was changed to epoxy cresol novolak (trade name: ECN1299, manufactured by Asahi Kasei Chemicals Corporation). When the obtained resin was subjected to IR measurement, peaks were observed at 1750 cm ⁻¹ and 910 cm ⁻¹ , and it was confirmed that the resin contained an oxazolidone ring and an epoxy group.

[Example 6]
Except that bisphenol A type epoxy was changed to bisphenol S type epoxy obtained by glycidylation of bisphenol S (trade name: BS-PN, manufactured by Konishi Chemical Co., Ltd.), the reaction was conducted in the same manner as in Example 2 to modify the isocyanate. Epoxy resin VI was obtained. When the obtained resin was subjected to IR measurement, peaks were observed at 1750 cm ⁻¹ and 910 cm ⁻¹ , and it was confirmed that the resin contained an oxazolidone ring and an epoxy group.

[Comparative Example 1]
As a raw material glycidyl compound, 90 parts by mass of a bisphenol A type epoxy resin (trade name: AER260, manufactured by Asahi Kasei Chemicals Corporation, epoxy equivalent 186 g / eq) was heated to 150 ° C. and filled with nitrogen. Thereto was added 0.03 part by mass of 2-methylimidazole (manufactured by Wako Pure Chemical Industries, Ltd.), and the mixture was stirred and heated to an internal temperature of 160 ° C. Furthermore, 10 parts by mass of 4,4′-methylenebis (phenylisocyanate) (trade name: Millionate MT (trademark), manufactured by Nippon Polyurethane Co., Ltd.) as a raw material isocyanate compound was charged into the reactor over 30 minutes. After completion of the addition, the reaction temperature was kept at 160 ° C. and the mixture was stirred for 15 minutes to obtain an isocyanate-modified epoxy resin VII. When the obtained resin was subjected to IR measurement, peaks were observed at 1750 cm ⁻¹ and 910 cm ⁻¹ , and it was confirmed that the resin contained an oxazolidone ring and an epoxy group.

[Comparative Example 2]
The reaction was carried out in the same manner as in Example 1 except that a bisphenol F type epoxy resin was used as the raw material glycidyl compound to obtain an isocyanate-modified epoxy resin VIII. When the obtained resin was subjected to IR measurement, peaks were observed at 1750 cm ⁻¹ and 910 cm ⁻¹ , and it was confirmed that the resin contained an oxazolidone ring and an epoxy group.

[Comparative Example 3]
The reaction was carried out in the same manner as in Example 1 except that an epoxyphenol novolak resin was used as the raw material glycidyl compound, but gelation occurred during the reaction, and an isocyanate-modified epoxy resin could not be obtained.

[Comparative Example 4]
The reaction was conducted in the same manner as in Example 1 except that an epoxy cresol novolak resin was used as the raw material glycidyl compound, but gelation occurred during the reaction, and an isocyanate-modified epoxy resin could not be obtained.

[Measurement result]
Table 1 shows the physical properties of the resulting isocyanate-modified epoxy resins I to VIII and YX4000 (Comparative Example 5). Since the epoxy resin VII of Comparative Example 1 and YX4000 of Comparative Example 5 did not melt at 80 ° C., the melt viscosity at 80 ° C. could not be measured.

  As is clear from the results in Table 1, the isocyanate-modified epoxy resins (Examples 1 to 6) of this embodiment had a low viscosity and an excellent balance between heat resistance and toughness.

  The isocyanate-modified epoxy resin of the present invention has a low viscosity and an excellent balance between heat resistance and toughness, and a cured product obtained by curing it has a wide range of coating materials, insulating materials for electrical and electronic use, adhesives, and the like. Has industrial applicability to applications.

Claims (5)

An isocyanate-modified epoxy resin having a structure represented by the following general formula (1).

(In the formula, each of R _{1 to} R ₈ independently has a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or a substituent. An aryl group that may be substituted, an amino group that may have a substituent, a nitro group, or a carboxyl group, and R ₉ represents a divalent or higher functional group that may have a substituent.   The isocyanate-modified epoxy resin according to claim 1, comprising at least one skeleton selected from biphenyl, bisphenol A, bisphenol F, bisphenol AF, bisphenol AC, bisphenol S, phenol novolac, and cresol novolac. The isocyanate-modified epoxy resin (A) according to claim 1 or 2,
An epoxy resin (B) other than (A),
A curing agent (C);
An epoxy resin composition comprising:   The epoxy resin composition according to claim 3, further comprising a plasticizer (D).   The epoxy resin composition according to claim 3 or 4, further comprising a filler (E).