JP2009292866A - Epoxy resin composition for fiber-reinforced composite material and fiber-reinforced composite material using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epoxy resin composition capable of giving a fiber-reinforced composite material simultaneously indicating high rigidity and heat resistance as a matrix resin for the fiber-reinforced composite material. <P>SOLUTION: The epoxy resin composition for the fiber-reinforced composite material contains component (A): a silica particle, component (B): a two-functional epoxy resin, component (C): a multi-functional epoxy resin and component (D): an amine type curing agent as indispensable components. An amount of the component (A) is 10-70 pts.mass based on the total 100 pts.mass of the component (B) and the component (C), and an amount of component (B1): a two-functional epoxy resin having an epoxy equivalent of 200 or more contained in the component (B) is 15 pts.mass or less. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an epoxy resin composition for fiber reinforced composite materials and a fiber reinforced composite material using the same. In particular, the present invention provides an epoxy resin composition for obtaining a fiber-reinforced composite material suitable for use in automotive applications, marine applications, sports applications, and other general industrial applications, including aircraft structural materials, and the use thereof. Prepreg and fiber reinforced composite material.

  Carbon fiber reinforced composite materials composed of carbon fibers and matrix resin cured products are widely used in aircraft, automobiles, and industrial applications because of their excellent mechanical properties. In recent years, the application range of fiber reinforced composite materials has been expanded more and more as the use results are accumulated. As the matrix resin constituting such a composite material, a thermosetting resin excellent in impregnation and heat resistance is often used, and the thermosetting resin is excellent in moldability and is highly sophisticated even in a high temperature environment. It is necessary to develop mechanical strength. As such a thermosetting resin, phenol resin, melanin resin, bismaleimide resin, unsaturated polyester resin, epoxy resin, etc. are used. Among them, epoxy resin is excellent in heat resistance and moldability, and carbon fiber. Since a high mechanical strength can be obtained when a composite material is used, it is widely used.

  In the conventional carbon fiber reinforced composite material, the tensile strength in the fiber direction is good, but the carbon fiber is fibrous and the fiber diameter is extremely small. Therefore, when compressed in the fiber direction, the fiber buckling and / or shearing occurs. Therefore, the fiber is easily broken and the compressive strength in the fiber direction is low. Therefore, it is strongly desired to improve the compressive strength. On the other hand, it is known that increasing the rigidity of the matrix resin is effective in improving the compressive strength of the fiber-reinforced composite material. For this reason, attempts have been made to improve the elastic modulus of the matrix resin in order to suppress fiber breakage due to fiber buckling and / or shear and to improve compressive strength.

  In addition, it is known that increasing the heat resistance of the matrix resin is effective for developing high mechanical strength in a high temperature environment. In order to increase the heat resistance of the matrix resin, it is necessary to increase the crosslink density. However, if the crosslink density is increased, the resin rigidity is improved to a certain level, but if the crosslink density becomes too high, It is known that the free volume increases and the resin rigidity is difficult to increase. For this reason, it has been considered very difficult to achieve both high rigidity and heat resistance of the matrix resin.

  However, Patent Document 1 discloses a prepreg and a fiber-reinforced composite material that use an epoxy resin as a matrix and have excellent compression system mechanical properties. However, in the resin composition of Patent Document 1, the rigidity of the matrix resin is not yet sufficient, and further improvement of the rigidity of the matrix resin is desired.

  Patent Document 2 discloses a prepreg and a fiber reinforced composite material that use a resin composition mainly composed of a benzoxazine resin as a matrix and exhibit high mechanical strength not only under room temperature drying but also in a moist heat environment. ing. However, in the resin composition of Patent Document 2, since a large amount of epoxy resin is added for viscosity adjustment, the high rigidity of the benzoxazine resin itself is impaired, and it is difficult to obtain sufficient resin rigidity.

JP-A-8-259713 JP 2006-233188 A

  Accordingly, an object of the present invention is to provide an epoxy resin composition that can provide a fiber-reinforced composite material that simultaneously exhibits high rigidity and heat resistance as a matrix resin for a fiber-reinforced composite material.

  As a result of diligent research to solve the above problems, the present inventors have found that the problems can be solved by the resin composition of the present invention having the following constitution.

  That is, the present invention contains component (A) silica fine particles, component (B) bifunctional epoxy resin, component (C) polyfunctional epoxy resin and component (D) amine-type curing agent as essential components, The amount of the component (A) is 10 to 70 parts by mass with respect to a total of 100 parts by mass of the component (C), and the component (B1) epoxy equivalent contained in the component (B) is 200 or more. An epoxy resin composition for fiber-reinforced composite materials having an amount of 15 parts by mass or less is provided.

  The present invention also provides a prepreg and a fiber reinforced composite material obtained by using the above epoxy resin composition for fiber reinforced composite material.

  ADVANTAGE OF THE INVENTION According to this invention, when using as a matrix resin for fiber reinforced composite materials, the epoxy resin composition which gives the fiber reinforced composite material which shows high rigidity and heat resistance simultaneously can be provided.

  Preferred embodiments of the present invention will be described below, but the present invention is not limited to these embodiments, and it will be understood that various modifications can be made within the spirit and scope of the present invention. I want.

  The component (A) used in the present invention is silica fine particles. The compounding quantity of a silica fine particle is 10-70 mass parts with respect to a total of 100 mass parts of a component (B) and a component (C). If the compounding quantity of a silica fine particle is 10 mass parts or more with respect to a total of 100 mass parts of a component (B) and a component (C), the rigidity of a resin composition can be improved. Preferably it is 20 mass parts or more, More preferably, it is 30 mass parts or more, More preferably, it is 45 mass parts or more. On the other hand, when the compounding amount of the silica fine particles is excessively large, the specific gravity of the resin composition is increased and the dispersibility with respect to the epoxy resin is deteriorated. The specific gravity of the resin composition can be suppressed by adjusting the blending amount of the silica fine particles to 70 parts by mass or less with respect to 100 parts by mass in total of the component (B) and the component (C). Dispersibility can be improved. More preferably, it is 50 parts by weight or less.

  When used as a matrix resin for a fiber reinforced composite material, it is important that silica fine particles are highly dispersed in the epoxy resin of component (B) and component (C). In order to produce a fiber reinforced composite material, a reinforcing fiber is impregnated with a resin composition, and if silica fine particles are not highly dispersed in the epoxy resin of component (B) and component (C), the dispersion A so-called filtration phenomenon may occur in which the silica fine particles aggregated without being filtered out into the reinforcing fibers. The fiber reinforced composite material in which this filtration phenomenon occurs causes deterioration in physical properties such as toughness and heat resistance, and appearance defects such as “resin withering” in which the resin does not penetrate part of the fiber reinforced composite material.

  Specifically, it is preferable that the silica fine particles dispersed in the component (B) and the component (C) have a secondary particle diameter of 1000 nm or less because the above-mentioned filtration phenomenon does not occur. More preferably, it is 500 nm or less, More preferably, it is 100 nm or less. The secondary particle diameter can be measured by observing a cross section of the cured product of the resin composition with a microscope such as a TEM, but it can also be confirmed simply using an optical microscope capable of observing on a 1000 nm scale. it can. Specifically, when the cross section of the cured product is observed and there is no aggregate of silica fine particles, it can be determined that there is no aggregate having a particle diameter that is at least discernable with an optical microscope. When the silica fine particles are not aggregated and are monodispersed, the particle diameter of the monodispersed particles may be 1000 nm or less, more preferably 500 nm or less, and still more preferably 100 nm or less.

  As a means for obtaining such a state that the silica fine particles are highly dispersed in the epoxy resin of the component (B) and the component (C), various methods can be taken. The first method is a method of mechanically dispersing silica fine particles, component (B) and component (C). This is a method in which the silica fine particles and the component (B) and the component (C) are dispersed by a dispersing machine such as an extruder, a kneader, or a three roll mill. At that time, it is preferable to add a dispersant as an additive because the dispersion effect is enhanced. The second method is a method using colloidal silica dispersed in an epoxy resin as silica fine particles. The colloidal silica dispersed in the epoxy resin is dispersed in the epoxy resin almost without agglomeration of the silica fine particles, so the silica fine particles are highly dispersed just by blending such colloidal silica dispersed epoxy resin. Since the obtained epoxy resin composition can be obtained, the dispersion process can be greatly simplified, which is very preferable.

  Examples of such colloidal silica-dispersed epoxy resins include Nanopox series manufactured by Nanoresin, Nanopox F400, Nanopox F430, Nanopox F440, NanopoF F520, NanopoX F630, Nanopox F630, Nanopox F640, Nanopox F640, Nanopox F640, Nanopox F640, Nanopox F640, Nanopox F640, Nanopox F640, Nanopox F640 Examples include E630, Nanopox E640, and LENANOC E as a LENANOC series manufactured by Nissan Chemical Industries, but are not limited to these products as long as colloidal silica is dispersed in an epoxy resin.

  The shape of the silica fine particles is not particularly limited. However, when the aspect ratio is high, the resin composition containing the silica fine particles exhibits thixotropic properties, so that the compounding amount cannot be increased. If it is spherical, such thixotropic properties are less likely to occur, and the amount of silica fine particles can be increased, which is preferable.

  Although there is no restriction | limiting in particular as a particle size of a silica fine particle, since a filtration phenomenon does not generate | occur | produce when impregnating a reinforcement fiber, it is preferable that it is 100 nm or less. More preferably, it is 50 nm or less.

  Component (B) used in the present invention is a bifunctional epoxy resin. The bifunctional epoxy resin may include a bifunctional epoxy resin having a component (B1) epoxy equivalent of 200 or more for the purpose of adjusting viscosity and improving toughness. If the compounding quantity of a component (B1) is 15 mass parts or less with respect to a total of 100 mass parts of a component (B) and a component (C), the rigidity of a resin composition can be made high. Preferably it is 12 mass parts or less, More preferably, it is 7 mass parts or less.

  As component (B), bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol B type epoxy resin, naphthalene type epoxy resin, epoxy resin having a fluorene skeleton, epoxy having a dicyclopentadiene skeleton Resins, epoxy resins having a biphenyl skeleton, epoxy resins having an oxadizolidone ring skeleton, and the like can be used. Among epoxy resins having such a structure, it is very preferable to use a resin having a functional group in the meta position or the ortho position because the rigidity of the epoxy resin composition can be increased. Any epoxy resin may be used as long as it has a single piece, and the structure is not limited to these epoxy resins.

  Component (C) is a polyfunctional epoxy resin. When component (C) is blended in an amount of 60 parts by mass or more with respect to 100 parts by mass in total of component (B) and component (C), heat resistance can be increased with the rigidity of the epoxy resin composition, which is preferable. More preferably, it is 70 mass parts or more.

  Component (C) includes glycidyl ether type epoxy resin such as tetrakis (glycidyloxyphenyl) ethane, tris (glycidyloxyphenyl) methane, tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, triglycidylaminocresol, tetraglycidylxylenediamine Glycidylamine type epoxy resin, naphthalene type epoxy resin, novolak type epoxy resin, cresol novolak type epoxy resin, etc. can be used, but any epoxy resin having more than two epoxy groups in the molecule can be used. Such a structure may be sufficient and it is not limited to these epoxy resins.

  Preferable components (C) include aminophenol type epoxy resins and aminocresol type epoxy resins. By using these epoxy resins, the heat resistance can be increased together with the rigidity of the epoxy resin composition. Moreover, among the epoxy resins having such a structure, it is more preferable to use a resin having a functional group blended at the meta position or the ortho position because the rigidity of the epoxy resin composition can be increased.

  Component (D) is an amine type curing agent. Examples of amine-type curing agents include aromatic amines such as diaminodiphenylmethane and diaminodiphenylsulfone, aliphatic amines, imidazole derivatives, dicyandiamide, tetramethylguanidine, thiourea-added amines, and isomers and modified products thereof. Can be used. Among these, dicyandiamide is particularly preferable because it has excellent prepreg storage stability. Further, various isomers of diaminodiphenylsulfone are most suitable for the present invention because they give a cured product having good heat resistance. In particular, 3,3'-diaminodiphenylsulfone is optimal because it can increase the rigidity of the cured product.

  These curing agents can be combined with an appropriate curing aid in order to increase the curing activity. Preferred examples include dicyandiamide and 3-phenyl-1,1-dimethylurea, 3- (3,4-dichlorophenyl) -1,1-dimethylurea (DCMU), 3- (3-chloro-4-methylphenyl). Examples of combining urea derivatives such as -1,1-dimethylurea and 2,4-bis (3,3-dimethylureido) toluene as curing aids, tertiary amines for carboxylic anhydrides and novolak resins In some cases, diaminodiphenylsulfone is combined with an urea complex such as an imidazole compound or phenyldimethylurea (PDMU), or an amine complex such as monoethylamine trifluoride or an amine trichloride complex as a curing aid.

  Moreover, 1 or more types of resin chosen from the group which consists of a thermoplastic resin, a thermoplastic elastomer, and an elastomer can be added to the epoxy resin composition of this invention as an additive. This additive has the role of improving the toughness of the matrix resin composition and changing the viscoelasticity to optimize the viscosity, storage elastic modulus and thixotropic properties. The thermoplastic resin, thermoplastic elastomer or elastomer used as an additive may be used alone or in combination of two or more.

  The thermoplastic resin includes a group consisting of a carbon-carbon bond, amide bond, imide bond, ester bond, ether bond, carbonate bond, urethane bond, urea bond, thioether bond, sulfone bond, imidazole bond and carbonyl bond in the main chain. A thermoplastic resin having a bond selected from is preferably used.

  As a thermoplastic resin, for example, a group of thermoplastic resins belonging to engineering plastics such as polyacrylate, polyamide, polyaramid, polyester, polycarbonate, polyphenylene sulfide, polybenzimidazole, polyimide, polyetherimide, polysulfone and polyethersulfone Is more preferably used. From the viewpoint of excellent heat resistance, polyimide, polyetherimide, polysulfone, polyethersulfone and the like are particularly preferably used. Moreover, it is a preferable aspect that these thermoplastic resins have a functional group reactive with a thermosetting resin from the viewpoint of improving toughness and maintaining the environmental resistance of the cured resin. Particularly preferred functional groups include a carboxyl group, an amino group, and a hydroxyl group.

  A fiber-reinforced composite material can be obtained by impregnating a reinforcing fiber with the epoxy resin of the present invention and curing it by heating.

  The reinforcing fiber combined with the epoxy resin composition of the present invention is not limited, and carbon fiber, glass fiber, organic fiber, boron fiber, steel fiber, etc. can be used in the form of tow, cloth, chopped fiber, mat and the like.

  Among these reinforcing fibers, carbon fibers and graphite fibers are preferable in the present invention because they have good specific elastic modulus and a great effect on weight reduction. Any type of carbon fiber or graphite fiber can be used depending on the application, but carbon fiber or graphite fiber having a tensile strength of 3500 MPa or more and a tensile modulus of 190 GPa or more is particularly preferable.

  In addition, there are no restrictions on the use of the fiber reinforced composite material, and it can be used for general-purpose products such as tennis rackets and golf shafts. However, the fiber reinforced composite material using the resin composition of the present invention has excellent compressive strength in the fiber direction. Therefore, it is particularly suitable for use in aircraft parts.

  Fiber reinforced composite materials can be produced by processing into a sheet-like molding intermediate called prepreg, molding methods such as autoclave molding, sheet wrap molding, and press molding, and epoxy resin composition for reinforcing fiber filaments and preforms. Molding methods such as RTM, VaRTM, filament winding, and RFI that directly impregnate a product to obtain a molded product can be used, but are not limited to these molding methods.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited at all by these Examples.

Preparation of Resin Composition Each raw material was simply weighed and heated and mixed at 70 ° C. in a glass flask to obtain a resin composition.

Preparation of heat-cured resin plate The obtained resin composition was poured between two pieces of glass (2 mm thick) with a 2 mm-thick polytetrafluoroethylene spacer in between, and heated and cured at 180 ° C. for 2 hours. To obtain a heat-cured resin plate.

Measurement of flexural modulus of resin plate The obtained resin plate is processed into a test piece (length 60 mm x width 8 mm x thickness 2 mm), and a three-point bending jig (3.2 mmR for both indenter and support, distance between supports 32 mm) is used. Bending characteristics were measured using an installed Instron universal testing machine. The loading speed was 2 mm / min.

Measurement of heat resistance The obtained resin plate was processed into a test piece (length 55 mm × width 12.5 mm × thickness 2 mm), and measured using a rheometer ARES-RDA manufactured by TA Instruments, with a measurement frequency of 1 Hz and a heating rate. The log G ′ was plotted against the temperature at 5 ° C./min, and the glass transition temperature obtained from the intersection of the approximate straight line of the flat region of log G ′ and the approximate straight line of the region where G ′ transitions was recorded as G′Tg. .

Examples 1-11 and Comparative Examples 1-6
As described above, an epoxy resin composition comprising the raw material composition shown in Table 1 (parts represent parts by mass) was prepared, a cured resin plate was then prepared, and the physical properties of the cured resin plate were measured. Table 2 shows the evaluation results of the physical properties of the components contained in the epoxy resin composition (parts represent parts by mass) and the cured resin plate.

Details of the raw materials used for the blending are shown below.
Nanopox E430: Epoxy resin in which silica fine particles are colloidally dispersed in an epoxy resin, bisphenol type epoxy resin (bifunctional) having an epoxy equivalent of 200 eq / g or less, 60% component, JER4004P: Bisphenol F type epoxy resin (Bifunctional), epoxy equivalent 880 eq / g, manufactured by Japan Epoxy Resin Co., Ltd. JER1002: bisphenol A type epoxy resin (bifunctional), epoxy equivalent 650 eq / g, manufactured by Japan Epoxy Resin Co., Ltd. JER1009: bisphenol A type epoxy resin (bifunctional) , Epoxy equivalent 28500 eq / g, Japan Epoxy Resin JER807: Bisphenol F type epoxy resin (bifunctional), epoxy equivalent 168 eq / g, Japan Epoxy Resin JER8 8: Bisphenol F type epoxy resin (bifunctional), epoxy equivalent 189 eq / g, manufactured by Japan Epoxy Resin Co. ELM-100: Paraaminocresol type epoxy resin (trifunctional), epoxy equivalent 107 eq / g, manufactured by Sumitomo Chemical Co., Ltd. JER630: Paraamino Phenol type epoxy resin (trifunctional), epoxy equivalent of 97 eq / g, manufactured by Japan Epoxy Resin Co., Ltd. JER604: Tetraglycidyldiaminodiphenylmethane type epoxy resin (tetrafunctional), epoxy equivalent of 120 eq / g, manufactured by Japan Epoxy Resin Co., Ltd. EPPN502H: Tri Phenylmethane novolac type epoxy resin (number of functional groups is greater than 3), epoxy equivalent 168 eq / g, manufactured by Nippon Kayaku Co., Ltd. JER1031S: novolac type epoxy resin (tetrafunctional), epoxy equivalent 200 eq / g, di 3,3′-DDS: 3,3′-diaminodiphenylsulfone, amine type curing agent, Nippon Synthetic Chemical Industry Co., Ltd. PES5003P: polyethersulfone, thermoplastic resin, manufactured by Sumitomo Chemical Co., Ltd.

As can be seen from Table 2, the resin compositions obtained in Examples 1 to 11 had very high elastic modulus and very high heat resistance.
On the other hand, the cured resin plates obtained in Comparative Examples 1 to 6 all exhibited low elastic modulus.

  As described in detail above, the resin composition for prepreg of the present invention has high rigidity and heat resistance of the matrix itself after curing, and is suitable as a matrix resin for a fiber-reinforced composite material. Therefore, the present invention is industrially useful.

Claims (7)

  Component (A) silica fine particles, component (B) bifunctional epoxy resin, component (C) polyfunctional epoxy resin and component (D) amine type curing agent are included as essential components, and the sum of component (B) and component (C) The amount of the component (A) is 10 to 70 parts by mass with respect to 100 parts by mass, and the amount of the bifunctional epoxy resin having an epoxy equivalent of 200 or more contained in the component (B) is 15 parts by mass or less. An epoxy resin composition for fiber-reinforced composite materials.   The epoxy resin composition according to claim 1, wherein the amount of the component (C) is 60 parts by mass or more with respect to 100 parts by mass in total of the component (B) and the component (C).   The epoxy resin composition according to claim 1 or 2, wherein the component (C) is an aminophenol type epoxy resin.   The epoxy resin composition according to claim 1 or 2, wherein the component (C) is an aminocresol type epoxy resin.   A fiber-reinforced composite material obtained by impregnating and curing the resin composition for fiber-reinforced composite material according to any one of claims 1 to 4 and a reinforcing fiber.   A prepreg comprising the resin composition for fiber-reinforced composite material according to claim 1 and reinforcing fibers.   A fiber-reinforced composite material obtained by curing the prepreg according to claim 6.