Epoxy resin composition for fiber-reinforced composite materials, epoxy resin cured product, preform and fiber-reinforced composite material

Abstract

An epoxy resin composition for fiber-reinforced composite materials which contains 70% by mass or more of a crystalline epoxy resin as component (A) and 10% by mass or more of a crystalline amine curing agent as component (B) based on 100% by mass of the epoxy resin composition. The difference between the melting points of component (A) and component (B) is in a range of 0 to 60° C.

Claims

1. An epoxy resin cured product obtained by curing an epoxy resin composition for fiber-reinforced composite materials comprising a crystalline epoxy resin as component [A], 20% by mass or more of a crystalline amine hardener as component [B] and 80% by mass or more of a crystalline component in 100% by mass of the epoxy resin composition, wherein a difference between the component [A] and component [B] melting points is 0 to 50° C., component [A] comprises at least one selected from the group consisting of biphenyl epoxy resin, naphthalene epoxy resin, anthracene epoxy resin, hydroquinone epoxy resin, thioether epoxy resin, phenylene ether epoxy resin, tris hydroxyphenyl methane epoxy resin, terephthalic acid epoxy resin, isocyanurate epoxy resin, phthalimide epoxy resin, and tetraphenylethane epoxy resin, and wherein the epoxy resin cured product has a glass transition temperature X (° C.) and a rubbery state elastic modulus Y (MPa) satisfying the following formula (1):
25X−37≤Y≤0.25X−19  (1) and a glass transition temperature X (° C.) that is higher than 170° C.

2. The epoxy resin composition for fiber-reinforced composite materials according to claim 1, wherein component [A] contains a bifunctional crystalline epoxy resin.

3. The epoxy resin composition for fiber-reinforced composite materials according to claim 2, wherein component [A] contains one or more crystalline epoxy resins selected from the group consisting of biphenyl epoxy resin and bisphenol epoxy resin.

4. The epoxy resin composition for fiber-reinforced composite materials according to claim 1, wherein component [B] contains a bifunctional crystalline amine hardener.

5. The epoxy resin composition for fiber-reinforced composite materials according to claim 1, wherein the number of moles of active hydrogen contained in component [B] is 1.05 to 1.70 times the number of moles of epoxy groups contained in the entire epoxy resin composition.

6. The epoxy resin composition for fiber-reinforced composite materials according to claim 1, further comprising a crystalline curing accelerator as a component [C].

7. A preform comprising the epoxy resin composition for fiber-reinforced composite materials according to claim 1 and a dry reinforcing-fiber base.

8. A fiber-reinforced composite material obtained by impregnating and curing the preform according to claim 7, wherein the epoxy resin composition cures to form an epoxy resin cured product.

9. The epoxy resin composition for fiber-reinforced composite materials according to claim 1, wherein component [A] comprises at least one selected from the group consisting of biphenyl epoxy resin, hydroquinone epoxy resin, phenylene ether epoxy resin, terephthalic acid epoxy resin, and isocyanurate epoxy resin.

10. The epoxy resin composition for fiber-reinforced composite materials according to claim 1, wherein component [A] comprises biphenyl epoxy resin.

11. A fiber-reinforced composite material obtained by impregnating and curing a preform comprising an epoxy resin composition for fiber-reinforced composite materials and a dry reinforcing-fiber base, wherein the epoxy resin composition cures to form an epoxy resin cured product, wherein the epoxy resin composition for fiber-reinforced composite materials comprises a crystalline epoxy resin as component [A], 20% by mass or more of a crystalline amine hardener as component [B] and 80% by mass or more of a crystalline component in 100% by mass of the epoxy resin composition, wherein a difference between the component [A] and component [B] melting points is 0 to 50° C. and component [A] comprises at least one selected from the group consisting of biphenyl epoxy resin, naphthalene epoxy resin, anthracene epoxy resin, hydroquinone epoxy resin, thioether epoxy resin, phenylene ether epoxy resin, tris hydroxyphenyl methane epoxy resin, terephthalic acid epoxy resin, isocyanurate epoxy resin, phthalimide epoxy resin, and tetraphenylethane epoxy resin, wherein the epoxy resin cured product has a glass transition temperature X (° C.) and a rubbery state elastic modulus Y (MPa) satisfying the following formula (1): 0.25X−37≤Y≤0.25X−19 . . . (1) and a glass transition temperature X (° C.) that is higher than 170° C.

Description

EXAMPLES

(1) Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited by these Examples.

(2) <Input Resin Material>

(3) The following input resin materials were used to prepare an epoxy resin composition in each Example. In Table 1-1 and Table 1-2, the contents of the epoxy resin compositions are expressed in “parts by mass” unless otherwise specified.

(4) 1. Component [A]: Crystalline Epoxy Resin

(5) “jER (registered trademark)” YX4000 (manufactured by Mitsubishi Chemical Corporation): biphenyl epoxy resin, melting point=105° C.

(6) “jER (registered trademark)” YL6121H (manufactured by Mitsubishi Chemical Corporation): biphenyl epoxy resin, melting point=120° C.

(7) YSLV-80DE (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.): phenylene ether type epoxy resin, melting point=82° C.

(8) YSLV-80XY (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.): bisphenol F epoxy resin, melting point=81° C.

(9) YDC-1312 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.): hydroquinone type epoxy resin, melting point=142° C.

(10) “DENACOL (registered trademark)” EX-711 (manufactured by Nagase ChemteX Corporation): terephthalic acid type epoxy resin, melting point=106° C.

(11) TEPIC-S (manufactured by Nissan Chemical Corporation): isocyanurate epoxy resin, melting point=110° C.

(12) 2. Other Epoxy Resins

(13) YD-128 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.): bisphenol A epoxy resin, liquid

(14) “jER” (registered trademark) 1001 (manufactured by Mitsubishi Chemical Corporation): bisphenol A epoxy resin, glassy solid.

(15) 3. Component [B]: Crystalline Amine Hardener.

(16) “Lonzacure (registered trademark)” M-DEA (manufactured by Lonza): 4,4′-diamino-3,3′,5,5′-tetraethyldiphenylmethane, melting point=89° C.

(17) 3,3′-DAS (manufactured by Konishi Chemical Inc Co., Ltd.): 3,3′-diaminodiphenyl sulfone, melting point=170° C.

(18) Bisaniline M (manufactured by Mitsui Fine Chemicals, Inc Co., Ltd.): 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene, melting point=114° C.

(19) “Lonzacure (registered trademark)” CAF (manufactured by Lonza): 9,9-bis(4-amino-3-chlorophenyl) fluorene, melting point=201° C.

(20) 4. Other Hardeners

(21) Bisphenol A (manufactured by Kanto Chemical Co., Inc.): 4,4′-isopropyridene diphenol, melting point=158° C.

(22) 5. Component [C]: Crystalline Curing Accelerator

(23) DIC-TBC (manufactured by DIC Corporation): 4-tert-butylcatechol, melting point=53° C.

(24) <Preparation of Epoxy Resin Composition>

(25) The epoxy resin, the hardener, and the curing accelerator, of which the raw materials and compounding ratios were shown in Table 1-1 and Table 1-2, were melted and mixed homogeneously by stirring while heating under temperature/time conditions under which a curing reaction did not proceed substantially, cast into a mold, and then quenched to prepare the epoxy resin composition.

(26) <Measurement of Melting Point of Crystalline Component>

(27) The melting point of each input resin material used was measured by differential scanning calorimetry (DSC) according to JIS K 7121: 2012. The measure equipment used was Pyrisl DSC (manufactured by Perkin Elmer). About 10 mg of crystalline component was sampled on an aluminum sample pan and subjected to measurement in a nitrogen atmosphere at a temperature ramp rate of 10° C./min. In the obtained DSC curve, the top temperature of the endothermic peak due to melting of the components was measured as the melting point.

(28) <Measurement of Complex Viscosity η* of Epoxy Resin Composition>

(29) The epoxy resin composition prepared as described above was used as a sample and measured by dynamic viscoelasticity measurement. The measure equipment used was ARES-G2 (manufactured by TA Instruments). The sample was set on an 8 mm parallel plate so as to have a thickness of 1 mm, a traction cycle of 0.5 Hz was applied, and measurement was performed at 25° C. to measure the complex viscosity η*.

(30) <Measurement of Curing Time of Epoxy Resin Composition>

(31) The epoxy resin composition prepared as described above was used as a sample, about 5 g of the sample was put into a stage heated to 180° C. using a thermosetting measurement device ATD-1000 (manufactured by Alpha Technologies), and dynamic viscoelasticity measurement was performed at a frequency of 1.0 Hz with a strain of 1.0%. At this time, a time required for the complex viscosity η* to reach 1.0×10.sup.7 Pa.Math.s was defined as the curing time. When the complex viscosity η* did not reach 1.0×10.sup.7 Pa.Math.s, a time when an increase in the complex viscosity η* was saturated was defined as the curing time.

(32) <Measurement of Glass Transition Temperature X and Rubbery State Elastic Modulus Y of Epoxy Resin Cured Product>

(33) The epoxy resin composition prepared as described above was heated and melted, and poured into a mold set to have a thickness of 2 mm. Curing was performed at a temperature of 180° C. for 4 hours to provide a resin cured product with a thickness of 2 mm. Then, the resulting resin cured product plate was cut to prepare a test piece with a width of 10 mm and a length of 40 mm, a dynamic viscoelasticity measuring device (ARES: manufactured by TA Instruments) was used, and the test piece was set to a solid twisting jig and subjected to measurement over a temperature range from 30° C. to 300° C. under the conditions of a temperature ramp rate of 5° C./min, a frequency of 1 Hz, and a strain of 0.1%. At this time, the glass transition temperature was the temperature where the tangent drawn in the glass region and the tangent drawn in the glass transition region intersect each other in the graph between storage modulus and temperature obtained above. The rubbery state elastic modulus was the storage modulus at a temperature 50° C. higher than the glass transition temperature in the graph between storage modulus and temperature obtained above.

(34) <Measurement of Resin Toughness of Epoxy Resin Cured Product>

(35) The epoxy resin composition prepared as described above was heated and melted, and poured into a mold set to have a thickness of 6 mm. Curing was performed at a temperature of 180° C. for 4 hours to provide a resin cured product with a thickness of 6 mm. This resin cured product was cut into a size of 12.7×150 mm to obtain a test piece. Processing and experiments of the test piece were carried out in accordance with ASTM D5045 (1999) using an Instron type universal tester (manufactured by Instron Corporation). Initial introduction of pre-cracks into the test piece was performed in the following manner: the edge of a razor cooled to the temperature of liquid nitrogen was brought into contact with the test piece, and an impact was applied to the razor with a hammer. Toughness of the resin cured product as referred to herein is a critical stress expansion factor in deformation Mode I (opening type).

(36) <Production of Fiber-Reinforced Composite Material>

(37) A fiber-reinforced composite material was produced by the following press forming method. In a metal mold having a plate-shaped cavity measuring 350 mm×700 mm×2 mm provided and held at a predetermined temperature (molding temperature), a preform in which 290 g of the epoxy resin composition prepared as described above was placed was set on a base with nine pieces of the carbon-fiber woven fabric CO6343 (carbon fiber: T300-3K, structure: plain weave, basis weight: 198 g/m.sup.2, manufactured by Toray Industries, Inc.) laminated as the dry reinforcing-fiber base. After that, mold-clamping was performed using press equipment. At this time, the inside of the metal mold was lowered to atmospheric pressure −0.1 MPa using a vacuum pump, and then pressed at a maximum pressure of 4 MPa. The temperature of the metal mold was set to a temperature 10° C. higher than the temperature of the highest melting point of the crystalline components contained in the thermosetting resin composition used. However, if the temperature was 180° C. or lower, the temperature was set to 180° C. Four hours after pressing began, the metal mold was opened, and a fiber-reinforced composite material was obtained by demolding.

(38) <Resin Impregnating Property Into Dry Reinforcing-Fiber Base>

(39) When the above-mentioned fiber-reinforced composite material was produced, the impregnating property of the resin into the dry reinforcing-fiber base was compared and evaluated in the following three grades, based on the void content in the fiber-reinforced composite material.

(40) When the void content in the fiber-reinforced composite material was less than 1% and therefore substantially no void was present, it was evaluated as “A”. When the void content in the fiber-reinforced composite material was 1% or more though the appearance of the fiber-reinforced composite material did not indicate the presence of unimpregnated regions, it was evaluated as “B”. When the appearance of the fiber-reinforced composite material indicated the presence of unimpregnated regions, it was evaluated as “C”.

(41) For the void content in the fiber-reinforced composite material, a surface obtained by smoothly polishing a cross-section arbitrarily selected with the smoothly-polished fiber-reinforced composite material was observed with an oblique optical microscope, and the void content was calculated from an area ratio of the void in the fiber-reinforced composite material.

Example 1

(42) As shown in Table 1-1, 100 parts by mass of biphenyl epoxy resin “jER (registered trademark)” YX4000, and 42 parts by mass of 4,4′-diamino-3,3′,5,5′-tetraethyldiphenylmethane “Lonzacure (registered trademark)” M-DEA were melted and mixed, then quenched to room temperature, and crystallized to prepare an epoxy resin composition. This resin composition had a complex viscosity at 25° C. of 3.0×10.sup.8 Pa.Math.s, did not deform even when lifted by hand, and was excellent in handleability at room temperature. The glass transition temperature of the epoxy resin cured product obtained by curing this resin composition was 187° C., and the epoxy resin cured product had excellent heat resistance. The resin toughness of the cured product was 0.8 MPa.Math.m.sup.1/2, and was thus sufficient. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry reinforcing-fiber base had no unimpregnated region on the surface and almost no internal voids, and was excellent in impregnating property.

Example 2

(43) As shown in Table 1-1, an epoxy resin composition was prepared in the same manner as in Example 1 except that the component [A] used was 100 parts by mass of the biphenyl epoxy resin “jER (registered trademark)” YL6121H, and the component [B] used was 35 parts by mass of 3,3′-diaminodiphenyl sulfone “3,3′-DAS”. This resin composition had a complex viscosity at 25° C. of 3.0×10.sup.8 Pa.Math.s, and was excellent in handleability at room temperature. The glass transition temperature of the epoxy resin cured product obtained by curing this resin composition was 181° C., the resin toughness was 1.1 MPa.Math.m.sup.1/2, and the epoxy resin cured product had excellent heat resistance and resin toughness. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry reinforcing-fiber base was excellent in impregnating property.

Example 3

(44) As shown in Table 1-1, an epoxy resin composition was prepared in the same manner as in Example 1 except that the component [A] used was 100 parts by mass of the phenylene ether type epoxy resin “YSLV-80DE”, and the component [B] used was 45 parts by mass of 4,4′-diamino-3,3′,5,5′-tetraethyldiphenylmethane “Lonzacure (registered trademark)” M-DEA. This resin composition had a complex viscosity at 25° C. of 3.0×10.sup.8 Pa.Math.s, and was excellent in handleability at room temperature. The glass transition temperature of the epoxy resin cured product obtained by curing this resin composition was 140° C., the resin toughness was 0.6 MPa.Math.m.sup.1/2, and the epoxy resin cured product had sufficient heat resistance and resin toughness. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry reinforcing-fiber base was excellent in impregnating property.

Example 4

(45) As shown in Table 1-1, an epoxy resin composition was prepared in the same manner as in Example 1 except that the component [A] used was 100 parts by mass of the bisphenol F epoxy resin “YSLV-80XY”, and the component [B] used was 40 parts by mass of 4,4′-diamino-3,3′,5,5′-tetraethyldiphenylmethane “Lonzacure (registered trademark)” M-DEA. This resin composition had a complex viscosity at 25° C. of 3.0×10.sup.8 Pa.Math.s, and was excellent in handleability at room temperature. The glass transition temperature of the epoxy resin cured product obtained by curing this resin composition was 176° C., the resin toughness was 0.7 MPa.Math.m.sup.1/2, and the epoxy resin cured product had sufficient heat resistance and resin toughness. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry reinforcing-fiber base was excellent in impregnating property.

Example 5

(46) As shown in Table 1-1, an epoxy resin composition was prepared in the same manner as in Example 1 except that the component [A] used was 100 parts by mass of the hydroquinone type epoxy resin “YDC-1312”, and the component [B] used was 44 parts by mass of 4,4′-diamino-3,3′,5,5′-tetraethyldiphenylmethane “Lonzacure (registered trademark)” M-DEA. This resin composition had a complex viscosity at 25° C. of 3.0×10.sup.8 Pa.Math.s, and was excellent in handleability at room temperature. The glass transition temperature of the epoxy resin cured product obtained by curing this resin composition was 180° C., the resin toughness was 0.7 MPa.Math.m.sup.1/2, and the epoxy resin cured product had sufficient heat resistance and resin toughness. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry reinforcing-fiber base had a slightly large difference in melting points between the components [A] and [B], so that sufficient impregnating property was obtained although the melt-stability of the components differed during impregnation.

Example 6

(47) As shown in Table 1-1, an epoxy resin composition was prepared in the same manner as in Example 1 except that the component [A] used was 100 parts by mass of the terephthalic acid type epoxy resin “EX-711”, and the component [B] used was 53 parts by mass of 4,4′-diamino-3,3′,5,5′-tetraethyldiphenylmethane “Lonzacure (registered trademark)” M-DEA. This resin composition had a complex viscosity at 25° C. of 3.0×10.sup.8 Pa.Math.s, and was excellent in handleability at room temperature. The glass transition temperature of the epoxy resin cured product obtained by curing this resin composition was 179° C., the resin toughness was 0.8 MPa.Math.m.sup.1/2, and the epoxy resin cured product had sufficient heat resistance and resin toughness. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry reinforcing-fiber base was excellent in impregnating property.

Example 7

(48) As shown in Table 1-1, an epoxy resin composition was prepared in the same manner as in Example 1 except that the component [A] used was 100 parts by mass of the isocyanurate epoxy resin “TEPIC-S”, and the component [B] used was 79 parts by mass of 4,4′-diamino-3,3′,5,5′-tetraethyldiphenylmethane “Lonzacure (registered trademark)” M-DEA. This resin composition had a complex viscosity at 25° C. of 3.0×10.sup.8 Pa.Math.s, and was excellent in handleability at room temperature. The glass transition temperature of the epoxy resin cured product obtained by curing this resin composition was 263° C., the resin toughness was 0.6 MPa.Math.m.sup.1/2, and the epoxy resin cured product had excellent heat resistance and sufficient resin toughness. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry reinforcing-fiber base was excellent in impregnating property.

Example 8

(49) As shown in Table 1-1, an epoxy resin composition was prepared in the same manner as in Example 1 except that the component [A] used was 100 parts by mass of the biphenyl epoxy resin “jER (registered trademark)” YL6121H, and the component [B] used was 49 parts by mass of 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene “Bisaniline M”. This resin composition had a complex viscosity at 25° C. of 3.0×10.sup.8 Pa.Math.s, and was excellent in handleability at room temperature. The glass transition temperature of the epoxy resin cured product obtained by curing this resin composition was 181° C., the resin toughness was 1.2 MPa.Math.m.sup.1/2, and the epoxy resin cured product had excellent heat resistance and resin toughness. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry reinforcing-fiber base was excellent in impregnating property.

Example 9

(50) As shown in Table 1-1, an epoxy resin composition was prepared in the same manner as in Example 1 except that the component [A] used was 100 parts by mass of the hydroquinone type epoxy resin “YDC-1312”, and the component [B] used was 59 parts by mass of 9,9-bis(4-amino-3-chlorophenyl)fluorene “Lonzacure (registered trademark)” CAF. This resin composition had a complex viscosity at 25° C. of 3.0×10.sup.8 Pa.Math.s, and was excellent in handleability at room temperature. The glass transition temperature of the epoxy resin cured product obtained by curing this resin composition was 200° C., the resin toughness was 0.9 MPa.Math.m.sup.1/2, and the epoxy resin cured product had excellent heat resistance and resin toughness. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry reinforcing-fiber base had a slightly large difference in melting points between the components [A] and [B], so that sufficient impregnating property was obtained although the melt-stability of the components differed during impregnation.

Examples 10 to 13

(51) As shown in Table 1-2, an epoxy resin composition was prepared in the same manner as in Example 1 except that the component [A] used was 100 parts by mass of the biphenyl epoxy resin “jER (registered trademark)” YL6121H, the component [B] used was 3,3′-diaminodiphenyl sulfone “3,3′-DAS”, and the amount of the component [B] added was changed such that the number of moles of active hydrogen contained in the component [B] was 1.1 times (Example 9), 1.25 times (Example 10), 1.5 times (Example 11), and 1.75 times (Example 12), respectively, the number of moles of the epoxy group contained in the entire epoxy resin composition. These resin compositions had a complex viscosity at 25° C. of 3.0×10.sup.8 Pa.Math.s, and were excellent in handleability at room temperature. The glass transition temperature of the epoxy resin cured product obtained by curing this resin composition was 179° C., 169° C., 155° C., and 135° C., respectively. The resin toughness was 1.2 MPa.Math.m.sup.1/2, 1.5 MPa.Math.m.sup.1/2, 1.3 MPa.Math.m.sup.1/2, and 1.0 MPa.Math.m.sup.1/2, respectively, and the epoxy resin cured product had more than sufficient heat resistance and resin toughness. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry reinforcing-fiber base was excellent in impregnating property.

Examples 14, 15

(52) As shown in Table 1-2, an epoxy resin composition was prepared in the same manner as in Example 1 except that the component [A] used was 100 parts by mass of the biphenyl epoxy resin “jER (registered trademark)” YX4000, the component [B] used was 42 parts by mass of 4,4′-diamino-3,3′,5,5′-tetraethyldiphenylmethane “Lonzacure (registered trademark)” M-DEA, and 3 parts by mass (Example 13) or 5 parts by mass (Example 14) of 4-tert-butylcatechol “DIC-TBC” as the component [C] was added. These resin compositions had a complex viscosity at 25° C. of 3.0×10.sup.8 Pa.Math.s, and were excellent in handleability at room temperature. The glass transition temperature of the epoxy resin cured product obtained by curing this resin composition was 180° C. and 170° C., respectively. The resin toughness in each Example was 0.7 MPa.Math.m.sup.1/2, and the epoxy resin cured product had sufficient heat resistance and resin toughness. By adding the component [C], the curing time of the resin composition was 184 minutes and 178 minutes, respectively, and the curing time was significantly shortened as compared with 226 minutes in a case where the component [C] was not added. The fiber-reinforced composite material produced by using the preform composed of the dry reinforcing-fiber base using this resin composition was excellent in impregnating property.

Example 16

(53) As shown in Table 1-2, an epoxy resin composition was prepared in the same manner as in Example 1 except that the component [A] used was 80 parts by mass of the biphenyl epoxy resin “jER (registered trademark)” YX4000, the other epoxy resin was 20 parts by mass of the bisphenol A epoxy resin “jER” (registered trademark) 1001, and the component [B] was 37 parts by mass of 4,4′-diamino-3,3′,5,5′-tetraethyldiphenylmethane “Lonzacure (registered trademark)” M-DEA. These resin compositions had a complex viscosity at 25° C. of 3.0×10.sup.8 Pa.Math.s, and were excellent in handleability at room temperature. The glass transition temperature of the epoxy resin cured product obtained by curing this resin composition was 180° C., the resin toughness was 0.8 MPa.Math.m.sup.1/2, and the epoxy resin cured product had sufficient heat resistance and resin toughness. The fiber-reinforced composite material produced by using the preform composed of the dry reinforcing-fiber base using this resin composition was excellent in impregnating property.

Example 17

(54) As shown in Table 1-2, an epoxy resin composition was prepared in the same manner as in Example 1 except that the component [A] used was 70 parts by mass of the biphenyl epoxy resin “jER (registered trademark)” YX4000, the other epoxy resin was 30 parts by mass of the bisphenol A epoxy resin “jER” (registered trademark) 1001, and the component [B] was 34 parts by mass of 4,4′-diamino-3,3′,5,5′-tetraethyldiphenylmethane “Lonzacure (registered trademark)” M-DEA. These resin compositions had a complex viscosity at 25° C. of 2.0×10.sup.8 Pa.Math.s, and were excellent in handleability at room temperature. The glass transition temperature of the epoxy resin cured product obtained by curing this resin composition was 169° C., the resin toughness was 0.8 MPa.Math.m.sup.1/2, and the epoxy resin cured product had sufficient heat resistance and resin toughness. The fiber-reinforced composite material produced by using the preform composed of the dry reinforcing-fiber base using this resin composition had sufficient impregnating property.

Comparative Example 1

(55) As shown in Table 1-2, an epoxy resin composition was prepared in the same manner as in Example 1 except that the component [A] used was 100 parts by mass of the phenylene ether type epoxy resin “YSLV-80DE”, and the component [B] used was 35 parts by mass of 3,3′-diaminodiphenyl sulfone “3,3′-DAS”. This resin composition had a complex viscosity at 25° C. of 3.0×10.sup.8 Pa.Math.s, and was excellent in handleability at room temperature. The glass transition temperature of the epoxy resin cured product obtained by curing this resin composition was 148° C., the resin toughness was 0.6 MPa.Math.m.sup.1/2, and the epoxy resin cured product was slightly inferior in resin toughness. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry reinforcing-fiber base had a large difference in melting points between the components [A] and [B], and uniform impregnation was not performed because the melt-stability of the components differed during impregnation. Thus, the impregnating property was inferior.

Comparative Example 2

(56) As shown in Table 1-2, an epoxy resin composition was prepared in the same manner as in Example 1 except that the component [A] used was 40 parts by mass of the biphenyl epoxy resin “jER (registered trademark)” YX4000, the other epoxy resin was 60 parts by mass of the bisphenol A epoxy resin “YD-128”, and the component [B] used was 42 parts by mass of 4,4′-diamino-3,3′,5,5′-tetraethyldiphenylmethane “Lonzacure (registered trademark)” M-DEA. This resin composition had a complex viscosity at 25° C. of 3.0×10.sup.5 Pa.Math.s, was sticky at room temperature, and was inferior in handleability because its shape was deformed. The glass transition temperature of the epoxy resin cured product obtained by curing this resin composition was 160° C., the resin toughness was 0.6 MPa.Math.m.sup.1/2, and the epoxy resin cured product was slightly inferior in resin toughness. The fiber-reinforced composite material produced by using the preform composed of the dry reinforcing-fiber base using this resin composition was excellent in impregnating property.

Comparative Example 3

(57) As shown in Table 1-2, an epoxy resin composition was prepared in the same manner as in Example 1 except that the component [A] used was 55 parts by mass of the biphenyl epoxy resin “jER (registered trademark)” YX4000, the other epoxy resin was 45 parts by mass of the bisphenol A epoxy resin “jER” (registered trademark) 1001, and the component [B] used was 31 parts by mass of 4,4′-diamino-3,3′,5,5′-tetraethyldiphenylmethane “Lonzacure (registered trademark)” M-DEA. This resin composition had a complex viscosity at 25° C. of 7.0×10.sup.7 Pa.Math.s, and was excellent in handleability at room temperature. The glass transition temperature of the epoxy resin cured product obtained by curing this resin composition was 154° C., the resin toughness was 0.6 MPa.Math.m.sup.1/2, and the epoxy resin cured product was slightly inferior in resin toughness. The fiber-reinforced composite material produced by using the preform composed of the dry reinforcing-fiber base using this resin composition had a high viscosity of the resin composition due to glassy solid bisphenol A epoxy at room temperature, and was inferior in impregnating property.

Comparative Example 4

(58) As shown in Table 1-2, an epoxy resin composition was prepared in the same manner as in Example 1 except that the component [A] used was 100 parts by mass of the biphenyl epoxy resin “jER (registered trademark)” YX4000, the component [B] used was 8 parts by mass of 4,4′-diamino-3,3′,5,5′-tetraethyldiphenylmethane “Lonzacure (registered trademark)” M-DEA, and the other hardener was 49 parts by mass of “Bisphenol A”. This resin composition had a complex viscosity at 25° C. of 3.0×10.sup.8 Pa.Math.s, and was excellent in handleability at room temperature. The glass transition temperature of the epoxy resin cured product obtained by curing this resin composition was 123° C., the resin toughness was 0.5 MPa.Math.m.sup.1/2, and the epoxy resin cured product was inferior in heat resistance and toughness. The fiber-reinforced composite material produced by using the preform composed of the dry reinforcing-fiber base using this resin composition had sufficient impregnating property.

(59) TABLE-US-00001 TABLE 1-1 Melting Exam- Exam- Exam- Exam- Exam- point [° C.] ple 1 ple 2 ple 3 ple 4 ple 5 Component Biphenyl epoxy resin YX4000 105 100 [A] Biphenyl epoxy resin YL6121H 120 100 Crystalline Phenylene ether type epoxy resin YSLV-80DE 82 100 epoxy resin Bisphenol F epoxy resin YSLV-80XY 81 100 Hydroquinone type epoxy resin YDC-1312 142 100 Terephthalic acid type epoxy resin EX-711 106 Isocyanurate epoxy resin TEPIC-S 110 Other epoxy Bisphenol A epoxy resin YD-128 — resin Bisphenol A epoxy resin 1001 — Component 4,4′-Diamino-3,3′,5,5′- M-DEA 89 42 45 40 44 [B] tetraethyldiphenylmethane Crystalline 3,3′-Diaminodiphenyl sulfone 3,3′-DAS 170 35 amine 1,3-Bis[2-(4-aminophenyl)-2- Bisaniline M 114 hardener propyl] benzene 9,9′-Bis(4-amino-3-chlorophenyl) CAF 201 fluorene Other 4,4′-Isopropyridene diphenol Bisphenol A 158 hardener Component 4-tert-Butylcatechol DIC-TBC 53 [C] Crystalline curing accelerator Resin Content [% by mass] of crystalline component 100 100 100 100 100 properties Difference [° C.] in melting point between 16 50 7 8 53 component [A] and component [B] Number of moles of active hydrogen/number 1.00 1.00 1.00 1.00 1.00 of moles of epoxy group [—] Complex viscosity η* [Pa .Math. s] at 25° C. 3.0 × 3.0 × 3.0 × 3.0 × 3.0 × 10.sup.8 10.sup.8 10.sup.8 10.sup.8 10.sup.8 Glass transition temperature X [° C.] of cured product 187 181 140 176 180 Rubbery state elastic modulus Y [MPa] of cured product 27 15 31 25 23 Formula (1): 0.25X − 37 < Y ≤ 0.25X − 19 10 ≤ 8 ≤ −2 ≤ 7 ≤ 8 ≤ Y ≤ 28 Y ≤ 26 Y ≤ 16 Y ≤ 25 Y ≤ 26 Resin toughness of cured product [MPa .Math. m.sup.1/2] 0.8 1.1 0.6 0.7 0.7 Composite Resin impregnating property A A A A B material properties Melting Exam- Exam- Exam- Exam- point [° C.] ple 6 ple 7 ple 8 ple 9 Component Biphenyl epoxy resin YX4000 105 [A] Biphenyl epoxy resin YL6121H 120 100 Crystalline Phenylene ether type epoxy resin YSLV-80DE 82 epoxy resin Bisphenol F epoxy resin YSLV-80XY 81 Hydroquinone type epoxy resin YDC-1312 142 100 Terephthalic acid type epoxy resin EX-711 106 100 Isocyanurate epoxy resin TEPIC-S 110 100 Other epoxy Bisphenol A epoxy resin YD-128 — resin Bisphenol A epoxy resin 1001 — Component 4,4′-Diamino-3,3′,5,5′- M-DEA 89 53 79 [B] tetraethyldiphenylmethane Crystalline 3,3′-Diaminodiphenyl sulfone 3,3′-DAS 170 amine 1,3-Bis[2-(4-aminophenyl)-2- Bisaniline M 114 49 hardener propyl] benzene 9,9′-Bis(4-amino-3-chlorophenyl) CAF 201 59 fluorene Other 4,4′-Isopropyridene diphenol Bisphenol A 158 hardener Component 4-tert-Butylcatechol DIC-TBC 53 [C] Crystalline curing accelerator Resin Content [% by mass] of crystalline component 100 100 100 100 properties Difference [° C.] in melting point between 17 21 9 59 component [A] and component [B] Number of moles of active hydrogen/number 1.00 1.00 1.00 1.00 of moles of epoxy group [—] Complex viscosity η* [Pa .Math. s] at 25° C. 3.0 × 3.0 × 3.0 × 3.0 × 10.sup.8 10.sup.8 10.sup.8 10.sup.8 Glass transition temperature X [° C.] of cured product 179 263 181 200 Rubbery state elastic modulus Y [MPa] of cured product 24 50 19 13 Formula (1): 0.25X − 37 < Y ≤ 0.25X − 19 8 ≤ 29 ≤ 8 ≤ 13 ≤ Y ≤ 26 Y ≤ 47 Y ≤ 26 Y ≤ 31 Resin toughness of cured product [MPa .Math. m.sup.1/2] 0.8 0.6 1.2 0.9 Composite Resin impregnating property A A A B material properties

(60) TABLE-US-00002 TABLE 1-2 Melting Exam- Exam- Exam- Exam- Exam- Exam- Exam- point [° C.] ple 10 ple 11 ple 12 ple 13 ple 14 ple 15 ple 16 Component Biphenyl epoxy resin YX4000 105 100 100 80 [A] Biphenyl epoxy resin YL6121H 120 100 100 100 100 Crystalline Phenylene ether type epoxy resin YSLV-80DE 82 epoxy resin Bisphenol F epoxy resin YSLV-80XY 81 Hydroquinone type epoxy resin YDC-1312 142 Terephthalic acid type epoxy resin EX-711 106 Isocyanurate epoxy resin TEPIC-S 110 Other epoxy Bisphenol A epoxy resin YD-128 — resin Bisphenol A epoxy resin 1001 — 20 Component 4,4′-Diamino-3,3′,5,5′- M-DEA 89 42 42 37 [B] tetraethyldiphenylmethane Crystalline 3,3′-Diaminodiphenyl sulfone 3,3′-DAS 170 39 44 53 62 amine 1,3-Bis[2-(4-aminophenyl)-2- Bisaniline M 114 hardener propyl] benzene 9,9′-Bis(4-amino-3-chlorophenyl) CAF 201 fluorene Other 4,4′-Isopropyridene diphenol Bisphenol A 158 hardener Component 4-tert-Butylcatechol DIC-TBC 53 3 5 [C] Crystalline curing accelerator Resin Content [% by mass] of crystalline component 100 100 100 100 100 100 85 properties Difference [° C.] in melting point between 50 50 50 50 16 16 16 component [A] and component [B] Number of moles of active hydrogen/number 1.10 1.25 1.50 1.75 1.00 1.00 1.00 of moles of epoxy group [—] Complex viscosity η* [Pa .Math. s] at 25° C. 3.0 × 3.0 × 3.0 × 3.0 × 3.0 × 3.0 × 3.0 × 10.sup.8 10.sup.8 10.sup.8 10.sup.8 10.sup.8 10.sup.8 10.sup.8 Glass transition temperature X [° C.] of cured product 179 169 155 135 180 170 180 Rubbery state elastic modulus Y [MPa] of cured product 13 10 5 2 26 23 24 Formula (1): 0.25X − 37 < Y ≤ 0.25X − 19 8 ≤ 5 ≤ 2 ≤ −3 ≤ 8 ≤ 6 ≤ 8 ≤ Y ≤ 26 Y ≤ 23 Y ≤ 20 Y ≤ 20 Y ≤ 26 Y ≤ 24 Y ≤ 26 Resin toughness of cured product [MPa .Math. m.sup.1/2] 1.2 1.5 1.3 1.0 0.7 0.7 0.8 Composite Resin impregnating property A A A A A A A material properties Melting Exam- Comparative Comparative Comparative Comparative point [° C.] ple 17 Example 1 Example 2 Example 3 Example 4 Component Biphenyl epoxy resin YX4000 105 70 40 55 100 [A] Biphenyl epoxy resin YL6121H 120 Crystalline Phenylene ether type epoxy resin YSLV-80DE 82 100 epoxy resin Bisphenol F epoxy resin YSLV-80XY 81 Hydroquinone type epoxy resin YDC-1312 142 Terephthalic acid type epoxy resin EX-711 106 Isocyanurate epoxy resin TEPIC-S 110 Other epoxy Bisphenol A epoxy resin YD-128 — 60 resin Bisphenol A epoxy resin 1001 — 30 45 Component 4,4′-Diamino-3,3′,5,5′- M-DEA 89 34 42 31 8 [B] tetraethyldiphenylmethane Crystalline 3,3′-Diaminodiphenyl sulfone 3,3′-DAS 170 35 amine 1,3-Bis[2-(4-aminophenyl)-2- Bisaniline M 114 hardener propyl] benzene 9,9′-Bis(4-amino-3-chlorophenyl) CAF 201 fluorene Other 4,4′-Isopropyridene diphenol Bisphenol A 158 49 hardener Component 4-tert-Butylcatechol DIC-TBC 53 [C] Crystalline curing accelerator Resin Content [% by mass] of crystalline component 78 100 58 66 100 properties Difference [° C.] in melting point between 16 88 16 16 53 component [A] and component [B] Number of moles of active hydrogen/number 1.00 1.00 1.00 1.00 1.00 of moles of epoxy group [—] Complex viscosity η* [Pa .Math. s] at 25° C. 2.0 × 3.0 × 3.0 × 7.0 × 3.0 × 10.sup.8 10.sup.8 10.sup.5 10.sup.7 10.sup.8 Glass transition temperature X [° C.] of cured product 169 148 160 154 123 Rubbery state elastic modulus Y [MPa] of cured product 20 30 16 15 3 Formula (1): 0.25X − 37 < Y ≤ 0.25X − 19 6 ≤ 0 ≤ 3 ≤ 2 ≤ −6 ≤ Y ≤ 24 Y ≤ 18 Y ≤ 21 Y ≤ 20 Y ≤ 12 Resin toughness of cured product [MPa .Math. m.sup.1/2] 0.8 0.6 0.6 0.6 0.5 Composite Resin impregnating property B C A C B material properties

(61) The epoxy resin composition for fiber-reinforced composite materials of the present invention has excellent handleability at room temperature, does not require an auxiliary material at the time of resin preparation, reduces resin loss, and has excellent impregnating property into reinforcing fibers, and it is possible to more easily provide a high-quality fiber-reinforced composite material with high productivity by a press forming method or the like. In addition, because of its excellent heat resistance and toughness, the fiber-reinforced composite material is being applied especially to automobile applications and aircraft applications, and further weight reduction can be expected to contribute to improved fuel efficiency and reduction of global warming gas emissions.