JP2020176239A - Epoxy resin composition, prepreg, method for producing prepreg, and method for producing fiber-reinforced composite material - Google Patents

Abstract

To provide an epoxy resin composition which has excellent room temperature storage property and high cycle property and releasability, and is particularly suitable for press molding, and a prepreg.SOLUTION: An epoxy resin composition contains at least [A] an epoxy resin, [B] a polyarylate resin and [C] an anionic polymerization-based catalyst. The epoxy resin composition preferably contains 50-170 pts.mass of [B] the polyarylate resin and 0.01-20 pts.mass of [C] the anionic polymerization-based catalyst, with respect to 100 pts.mass of [A] the epoxy resin. The polyarylate resin preferably has a weight average molecular weight Mw of 1,000-10,000, and the anionic polymerization-based catalyst is preferably an imidazole-based catalyst having a tertiary amine.SELECTED DRAWING: None

Description

The present invention relates to an epoxy resin composition, a prepreg, a method for producing a prepreg, and a method for producing a fiber-reinforced composite material. More specifically, the present invention relates to an epoxy resin composition having excellent room temperature storage property and excellent mold releasability, and a prepreg and a fiber-reinforced composite material using such an epoxy resin composition.

Fiber-reinforced composite materials (simply called composite materials or FRPs) consisting of reinforcing fibers and resins have features such as light weight, high strength, and high elastic modulus, and are widely applied to aircraft, sports / leisure, and general industry. ing. This fiber-reinforced composite material is often produced via a prepreg in which reinforcing fibers and a resin called a matrix resin or a resin composition serving as a precursor thereof are preliminarily integrated. As the resin constituting the prepreg, a thermosetting resin or a thermoplastic resin is used. In particular, thermosetting resins, especially prepregs using epoxy resins, are widely used because of their high degree of freedom in molding due to their tackiness and drapeability.

The prepreg impregnated with the thermosetting resin usually needs to be stored refrigerated or frozen in order to suppress the curing reaction. Therefore, a storage facility having a refrigerating / freezing function is required. In addition, when a prepreg is usually used for molding a composite material, it is necessary to return the temperature of the prepreg to room temperature from the viewpoint of moldability, but complicated control is required for the pot life at room temperature. There is.

In general, in order to obtain a composite material having excellent mechanical properties from a prepreg using an epoxy resin, it is heated for 1 hour or more by using autoclave molding or vacuum back molding that can control the environment at high temperature and high pressure. It needs to be cured. However, including the time for raising and lowering the temperature of the molding apparatus, a molding time of about 3 to 6 hours was required for one molding.

In recent years, in order to shorten the molding time and reduce the molding cost, in order to improve these molding cycles (improve the cycleability), a method of molding a prepreg by using press molding has been studied. As a prepreg used for press molding, for example, Patent Documents 1 and 2 propose a prepreg in which a latent curing agent and a curing accelerator are combined and an epoxy resin composition having a relatively short curing time is used as a matrix resin. However, in the methods described in Patent Documents 1 and 2, since the epoxy resin composition contains a curing accelerator together with a latent curing agent, the effect reaction gradually proceeds even at room temperature, so that the epoxy resin composition can be used at room temperature. The time is shortened, and the room temperature storage property is insufficient. In addition, the mold release property from the mold after molding the prepreg disclosed in these is not satisfactory, and therefore, a mold release agent is applied to the mold during molding in order to ensure sufficient mold release property. It has to be applied, and there is a problem that the labor and time for applying the release agent prolongs the molding cycle.

Therefore, there is a demand for a prepreg suitable for press molding, which is excellent in storage at room temperature and has high cycleability and releasability.

Japanese Unexamined Patent Publication No. 2003-128764 Japanese Unexamined Patent Publication No. 2011-57770

An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide an epoxy resin composition having excellent room temperature storage property, high cycle property and releasability, and particularly suitable for press molding, and a prepreg. That is.

The present invention that achieves the above object is an epoxy resin composition containing at least [A] epoxy resin, [B] polyarylate resin, and [C] anionic polymerization catalyst. In the present invention, it is preferable to contain 50 to 170 parts by mass of [B] polyarylate resin and 0.01 to 20 parts by mass of [C] anionic polymerization catalyst with respect to 100 parts by mass of [A] epoxy resin.

The polyarylate resin used in the present invention preferably has a weight average molecular weight of Mw1000 to 10000, and the anionic polymerization catalyst is preferably an imidazole catalyst having a tertiary amine.

The present invention includes a prepreg in which the reinforcing fiber base material is impregnated with the epoxy resin composition, a method for producing the prepreg, and a fiber-reinforced composite material obtained by curing the prepreg.

The epoxy resin composition of the present invention is excellent in room temperature storage property, and can obtain a prepreg having high cycle property and excellent mold releasability in press molding.

Since the prepreg of the present invention is excellent in room temperature storage property, cycle property and mold release property, a fiber-reinforced composite material can be obtained with good productivity.

Hereinafter, the details of the epoxy resin composition, the prepreg, the fiber-reinforced composite material of the present invention, and the method for producing them will be described.

(1) Epoxy Resin Composition The epoxy resin composition of the present invention is an epoxy resin composition containing at least [A] epoxy resin, [B] polyarylate resin, and [C] anionic polymerization system catalyst. As a result of diligent studies, the inventor of the present invention found that when the epoxy resin composition contained both the [B] polyarylate resin and the [C] anionic polymerization catalyst, an ester was formed between the epoxy resin and the polyarylate resin. We have found that an intercalation reaction occurs. By this reaction, when the epoxy resin composition of the present invention is heated to a specific temperature, a cured product of the resin composition is formed. On the other hand, at a temperature less than a specific temperature, the ester interposition reaction is suppressed and the cured product is not formed. Therefore, at a temperature less than a specific temperature, the resin composition has excellent storage stability.

The resin composition of the present invention is preferably an epoxy resin composition containing 50 to 170 parts by mass of a polyarylate resin and 0.01 to 2 parts by mass of an anionic polymerization catalyst with respect to 100 parts by mass of the epoxy resin. Further, it is more preferable that the polyarylate resin is 80 to 120 parts by mass with respect to 100 parts by mass of the epoxy resin. In addition to these, the epoxy resin composition of the present invention may contain a thermoplastic resin and other additives. In the present invention, the amount of the epoxy resin curing agent or curing accelerator other than the polyarylate resin and the anion polymerization catalyst contained in the epoxy resin composition is based on 100 parts by mass of the epoxy resin from the viewpoint of room temperature storage stability. It is preferably 5 parts by mass or less, more preferably 1 part by mass or less, and further preferably 0.1 part by mass or less.

The epoxy resin composition of the present invention preferably has a viscosity at 100 ° C. of 1 to 1000 Pa · s, more preferably 10 to 500 Pa · s. When the viscosity is in this range, the outflow of the resin during the molding process is suppressed, and the fiber layer is sufficiently impregnated with the resin, so that the formation of voids is suppressed, and a composite material having excellent mechanical properties can be obtained. .. If the viscosity is too low, the resin tends to flow out of the prepreg during molding. If the viscosity is too high, unimpregnated portions may easily form in the prepreg. As a result, voids and the like tend to be easily formed in the obtained fiber-reinforced composite material.

(1-1) [A] Epoxy Resin A known epoxy resin can be used in the epoxy resin composition of the present invention without particular limitation. Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, triglycidyl aminophenol resin and the like.

Specifically, those exemplified below can be used. Among these, an epoxy resin containing an aromatic group is preferable, and an epoxy resin containing either a glycidylamine structure or a glycidyl ether structure is preferable. Further, an alicyclic epoxy resin can also be preferably used.

Examples of the epoxy resin containing a glycidylamine structure include tetraglycidyldiaminodiphenylmethane, N, N, O-triglycidyl-p-aminophenol, N, N, O-triglycidyl-m-aminophenol, N, N, O-. Examples thereof include triglycidyl-3-methyl-4-aminophenol and various isomers of triglycidylaminocresol.

Examples of the epoxy resin containing the glycidyl ether structure include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, and cresol novolac type epoxy resin.

Further, these epoxy resins may have a non-reactive substituent in the aromatic ring structure or the like, if necessary. Examples of the non-reactive substituent include an alkyl group such as methyl, ethyl and isopropyl, an aromatic group such as phenyl, an alkoxyl group, an aralkyl group, and a halogen group such as chlorine and bromine.

(1-2) [B] Polyarylate Resin The epoxy resin composition of the present invention comprises a polyarylate resin. As the polyarylate resin, a known polyarylate resin can be used without particular limitation. The polyarylate resin is an amorphous thermoplastic resin produced by polycondensing a dihydric phenol with a dibasic acid such as phthalic acid or carboxylic acid as a basic skeleton. As the polyarylate resin, a polyarylate resin having a terminal OH group, a polyarylate resin having a closed end, or the like can be preferably used. Specific examples of such a polyarylate resin include "Unifiner (registered trademark)" (manufactured by Unitika Ltd.).

The polyarylate resin blended in the epoxy resin composition preferably has a weight average molecular weight of 300 to 10,000, more preferably 1000 to 30,000. If the weight average molecular weight is too small, the number of reaction starting points due to the ester insertion reaction is reduced, resulting in insufficient curing. On the other hand, if the weight average molecular weight is too large, the viscosity of the resin composition becomes too high, and processing problems such as difficulty in impregnating the reinforcing fiber layer with the resin composition are likely to occur. Further, it is preferable that the molecular weight distribution of the polyarylate resin blended in the epoxy resin composition is uniform. In particular, the polydispersity (Mw / Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably in the range of 1 to 10, and preferably in the range of 1.1 to 5. More preferred.

The polyarylate resin blended in the epoxy resin composition can be used by dissolving it in the epoxy resin, or it may be used by dispersing it as a powder. When the polyarylate resin blended in the epoxy resin composition is dissolved and used, the viscosity of the epoxy resin composition can also be adjusted by dissolving the polyarylate resin.

On the other hand, when the polyarylate resin blended in the epoxy resin composition is dispersed and used, the polyarylate resin is dissolved in the epoxy resin by being heated in the curing process of the epoxy resin, and the viscosity of the epoxy resin composition is increased. be able to. This makes it possible to prevent the flow of the epoxy resin composition (a phenomenon in which the resin composition flows out from the prepreg) due to the decrease in viscosity in the curing process.

(1-3) [C] Anionic Polymerization Catalyst The epoxy resin composition of the present invention comprises an anionic polymerization catalyst. The anionic polymerization catalyst used in the present invention is not particularly limited, and a known anionic polymerization catalyst can be used. Among them, as the anionic polymerization catalyst, an imidazole catalyst and a catalyst having a tertiary amine are preferably used from the viewpoint of stability of prepreg storage at room temperature because the reactivity can be easily controlled by temperature.

(1-4) Other Additives The epoxy resin composition of the present invention may contain a flame retardant, an inorganic filler, an internal mold release agent, conductive particles, or the like, if necessary.

Examples of the flame retardant include phosphorus-based flame retardants. The phosphorus-based flame retardant is not particularly limited as long as it contains a phosphorus atom in the molecule, and examples thereof include organic phosphorus compounds such as phosphoric acid ester, condensed phosphoric acid ester, phosphazene compound, and polyphosphate, and red phosphorus. Be done.

Examples of the inorganic filler include aluminum borate, calcium carbonate, silicon carbonate, silicon nitride, potassium titanate, basic magnesium sulfate, zinc oxide, graphite, calcium sulfate, magnesium borate, magnesium oxide, and silicate minerals. Can be mentioned. In particular, it is preferable to use silicate minerals. Examples of commercially available silicate minerals include THIXOTROPIC AGENT DT 5039 (manufactured by Huntsman Japan Corporation).

Examples of the internal mold release agent include metal soaps, vegetable waxes such as polyethylene wax and carbana wax, fatty acid ester mold release agents, silicon oil, animal wax, and fluorine-based nonionic surfactant. The blending amount of these internal mold release agents is preferably 0.1 to 5 parts by mass, and more preferably 0.2 to 2 parts by mass with respect to 100 parts by mass of the epoxy resin. Within this range, the mold release effect from the mold is preferably exhibited.

Commercially available internal mold release agents include "MOLD WIZ (registered trademark)" INT1846 (AXEL PLASTICS RESEARCH LABORATORIES INC.), Licowax S, Licowax P, Licowax OP, Licowax PE190, Licowax PE190, Licowax PE190, Licowax Stearyl stearate (SL-900A; manufactured by RIKEN Vitamin Co., Ltd.) can be mentioned.

The conductive particles include conductive polymer particles such as polyacetylene particles, polyaniline particles, polypyrrole particles, polythiophene particles, polyisothianaften particles and polyethylenedioxythiophene particles ;, carbon particles ;, carbon fiber particles ;, metal particles ;, Examples thereof include particles in which a core material made of an inorganic material or an organic material is coated with a conductive substance.

(1-5) Method for Producing Epoxy Resin Composition In the epoxy resin composition of the present invention, [A] epoxy resin, [B] polyarylate resin, [C] anionic polymerization catalyst and other components are mixed. Can be manufactured by. The order in which these resins are mixed is not particularly limited, but it is preferable to knead the [A] epoxy resin and the [B] polyarylate resin, and finally add the [C] anionic polymerization catalyst.

The method for producing the epoxy resin composition is not particularly limited, and any conventionally known method may be used. The mixing temperature of the [A] epoxy resin and the [B] polyarylate resin is preferably in the range of 50 to 160 ° C. In this temperature range, the self-polymerization effect reaction of the epoxy resin is unlikely to occur, so that the resin composition can be mixed stably and uniformly. If the temperature exceeds 160 ° C., the epoxy resin may partially undergo a self-polymerization curing reaction, and the prepreg may not be stably produced. If the temperature is lower than 50 ° C., the viscosity of the epoxy resin composition may be high, which may make mixing substantially difficult. It is preferably in the range of 50 to 140 ° C, more preferably 80 to 120 ° C.

Next, as a method of mixing the [C] anionic polymerization catalyst with the mixture of the [A] epoxy resin and the [B] polyarylate resin, the temperature is 80 ° C. or lower in order to partially suppress the self-polymerization curing reaction of the epoxy resin. Is preferable. It is preferably in the range of 50 to 80 ° C, more preferably 60 to 70 ° C. If the mixing temperature is too low, the viscosity of the epoxy resin composition may be high, making mixing substantially difficult.

As the mixing machine device, a conventionally known one can be used. Specific examples include a roll mill, a planetary mixer, a kneader, an extruder, a vanbury mixer, a mixing vessel equipped with a stirring blade, a horizontal mixing tank, and the like. The mixing of each component can be carried out in the air or in an atmosphere of an inert gas. When mixing is performed in the air, an atmosphere in which the temperature and humidity are controlled is preferable. Although not particularly limited, for example, it is preferable to mix in a temperature controlled to a constant temperature of 30 ° C. or lower or a low humidity atmosphere having a relative humidity of 50% RH or less.

Since the epoxy resin composition of the present invention as described above is excellent in storage at room temperature, has a high curing rate, and is also excellent in releasability, it is possible to produce a fiber-reinforced composite material with good productivity. it can. The epoxy resin composition of the present invention is particularly suitable for obtaining a fiber-reinforced composite material by press molding.

(2) Prepreg The prepreg of the present invention comprises a reinforcing fiber base material and the epoxy resin composition impregnated in the reinforcing fiber base material.

The prepreg of the present invention is a prepreg in which a part or the whole of a reinforcing fiber base material is impregnated with the epoxy resin composition. The content of the epoxy resin composition in the entire prepreg is preferably 15 to 60% by mass based on the total mass of the prepreg. When the resin content is less than 15% by mass, voids or the like may be generated in the obtained fiber-reinforced composite material, which may reduce the mechanical properties. If the resin content exceeds 60% by mass, the reinforcing effect of the reinforcing fibers may be insufficient, and the mechanical properties relative to the mass may be substantially low. The resin content is preferably 20 to 55% by mass, more preferably 25 to 50% by mass.

(2-1) Reinforcing fiber base material The reinforcing fiber base material used in the present invention is not particularly limited, and for example, carbon fiber, glass fiber, aramid fiber, silicon carbide fiber, polyester fiber, ceramic fiber, alumina fiber, and boron. Examples include fibers, metal fibers, mineral fibers, rock fibers and slug fibers.

Among these reinforcing fibers, carbon fiber, glass fiber, and aramid fiber are preferable. Carbon fiber is more preferable because it has good specific strength and specific elastic modulus, and a lightweight and high-strength fiber-reinforced composite material can be obtained. Polyacrylonitrile (PAN) -based carbon fibers are particularly preferable because they are excellent in tensile strength.

When a PAN-based carbon fiber is used as the reinforcing fiber, its tensile elastic modulus is preferably 100 to 600 GPa, more preferably 200 to 500 GPa, and particularly preferably 230 to 450 GPa. The tensile strength is preferably 2000 MPa to 10000 MPa, more preferably 3000 to 8000 MPa. The diameter of the carbon fiber is preferably 4 to 20 μm, more preferably 5 to 10 μm. By using such carbon fibers, the mechanical properties of the obtained fiber-reinforced composite material can be improved.

The reinforcing fiber may be a bundle of reinforcing fibers, or may be used as a reinforcing fiber sheet in which reinforcing fibers are formed in a sheet shape. It is preferable to form it in a sheet shape and use it. Examples of the reinforcing fiber sheet include a sheet in which a large number of reinforcing fibers are arranged in one direction, a bidirectional woven fabric such as plain weave and twill weave, a multi-axis woven fabric, a non-woven fabric, a mat, a knit, a braid, and a paper made from reinforcing fibers. Can be mentioned. Among these, it is preferable to use a unidirectionally aligned sheet, a bidirectional woven fabric, or a multi-axis woven fabric base material in which reinforcing fibers are formed into a sheet as continuous fibers because a fiber-reinforced composite material having more excellent mechanical properties can be obtained. The thickness of the sheet-shaped reinforcing fiber base material is preferably 0.01 to 3 mm, more preferably 0.1 to 1.5 mm.

(2-2) Method for producing prepreg The method for producing a prepreg of the present invention is not particularly limited, and any conventionally known method can be adopted. Specifically, the hot melt method and the solvent method can be preferably adopted.

In the hot melt method, a resin composition is applied in the form of a thin film on a release paper to form a resin composition film, and the resin composition film is laminated on a reinforcing fiber base material and heated under pressure. This is a method of impregnating the resin composition into the reinforcing fiber base material layer.

The method for forming the resin composition into a resin composition film is not particularly limited, and any conventionally known method can be used. Specifically, a resin composition film is obtained by casting and casting a resin composition on a support such as a paper pattern or a film using a die extrusion, an applicator, a reverse roll coater, a comma coater, or the like. Can be done. The resin temperature at the time of producing the film is appropriately determined according to the composition and viscosity of the resin composition. Specifically, the same temperature conditions as the mixing temperature in the method for producing the epoxy resin composition described above are preferably used. The impregnation of the resin composition into the reinforcing fiber base material layer may be performed once or may be performed in a plurality of times.

The solvent method is a method in which an epoxy resin composition is formed into a varnish using an appropriate solvent, and the varnish is impregnated in the reinforcing fiber base material layer.

Among these conventional methods, the prepreg of the present invention can be suitably produced by a hot melt method that does not use a solvent.

When the epoxy resin composition film is impregnated into the reinforcing fiber base material layer by a hot melt method, the impregnation temperature is preferably in the range of 50 to 120 ° C. When the impregnation temperature is less than 50 ° C., the viscosity of the epoxy resin is high, and the reinforcing fiber base material layer may not be sufficiently impregnated. When the impregnation temperature exceeds 120 ° C., the curing reaction of the epoxy resin composition proceeds, and the storage stability of the obtained prepreg may decrease or the drape property may decrease. The impregnation temperature is more preferably 60 to 110 ° C, particularly preferably 70 to 100 ° C.

The impregnation pressure when the epoxy resin composition film is impregnated into the reinforcing fiber base material layer by the hot melt method is appropriately determined in consideration of the viscosity and resin flow of the resin composition.

The specific impregnation pressure is 1 to 250 (N / cm), preferably 10 to 200 (N / cm).

Since the prepreg of the present invention as described above is excellent in storage at room temperature, has a high curing rate, and is also excellent in releasability, it is possible to produce a fiber-reinforced composite material with good productivity. The prepreg of the present invention can be preferably used by press molding, and in particular, can be preferably used by high cycle press molding of a fiber reinforced composite material (FRP) for applications such as automobile members.

(3) Fiber Reinforced Composite Material The epoxy resin composition of the present invention can be preferably used as a matrix resin for a fiber reinforced composite material. A composite material can be produced by curing the reinforcing fiber base material and the epoxy resin composition of the present invention in a composite state. The method for producing the fiber-reinforced composite material is not particularly limited, but it is preferably produced using the prepreg of the present invention in which the reinforcing fiber base material and the epoxy resin composition are previously composited.

Examples of the method for producing FRP using the prepreg of the present invention include known molding methods such as autoclave molding and press molding. The prepreg of the present invention can be preferably used by press molding, and in particular, can be preferably used by high cycle press molding of a fiber reinforced composite material (FRP) for applications such as automobile members.

Further, as exemplified by the resin transfer molding method (RTM method), the hand lay-up method, the filament winding method, and the plutrusion method, the reinforcing fiber base material and the epoxy resin composition may be composited at the same time as molding.

(3-1) Press forming method In the present invention, a press forming method is preferably used as a method for producing a composite material. The press molding method is a method of obtaining a fiber-reinforced composite material by curing a molding material such as a prepreg or a preform formed by laminating prepregs at a high temperature and high pressure with a mold. The mold is preferably preheated to a curing temperature.

The mold used for press molding may be any mold that can cure the molding material under high temperature and high pressure, and has a structure that can keep the inside of the mold airtight when the mold is closed. It is preferable to use a mold. Here, airtightness means that an epoxy resin composition constituting a molding material actually leaks from the mold even when a sufficient amount of molding material is put into the mold and pressure is applied. Say no.

The temperature of the die during press molding is preferably 150 to 180 ° C. When the molding temperature is 150 ° C. or higher, a sufficient curing reaction can be caused, the Tg of the molded plate can be improved to 180 ° C. or higher, and the molding plate is not deformed at the time of mold removal. As a result, the temperature of the mold can be maintained at a constant temperature, so that FRP can be obtained with high productivity. Further, when the molding temperature is 180 ° C. or lower, the resin viscosity does not become too low, and excessive flow of the resin in the mold can be suppressed. As a result, it is possible to suppress the outflow of resin from the mold and the meandering of fibers, so that high quality FRP can be obtained.

The pressure at the time of molding is 0.2 to 10 MPa. When the pressure is 0.2 MPa or more, an appropriate flow of the resin can be obtained, and poor appearance and generation of voids can be prevented. Moreover, since the prepreg is sufficiently adhered to the mold, it is possible to manufacture an FRP having a good appearance. When the pressure is 10 MPa or less, the resin does not flow more than necessary, so that the appearance of the obtained FRP is unlikely to deteriorate. In addition, since the mold is not loaded more than necessary, the mold is unlikely to be deformed. The molding time is preferably 1 to 10 minutes.

(3-2) Autoclave molding method In the present invention, an autoclave molding method is also preferably used as a method for producing a composite material. In the autoclave molding method, a prepreg and a film bag are sequentially laid on the lower mold of the mold, the prepreg is sealed between the lower mold and the film bag, and the space formed by the lower mold and the film bag is evacuated. At the same time, it is a molding method in which heating and pressurization are performed with an autoclave molding apparatus. The conditions at the time of molding are preferably such that the heating rate is 1 to 50 ° C./min, and heating and pressurization are performed at 0.2 to 0.7 MPa and 150 to 180 ° C. for 1 to 10 minutes.

The epoxy resin composition of the present invention is excellent in storage at room temperature, has a high curing rate, is excellent in cycleability, and is also excellent in releasability. Therefore, when the fiber-reinforced composite material is produced by using the epoxy resin composition of the present invention as the matrix resin as described above, the fiber-reinforced composite material can be produced with high productivity.

The use of the epoxy resin composition of the present invention is not particularly limited, and in addition to the fiber-reinforced composite material described above, for example, a printed wiring board material, a resin composition for a flexible wiring board, and a build-up substrate. Insulation materials for circuit boards such as interlayer insulation materials, semiconductor encapsulation materials, semiconductor devices, conductive pastes, conductive films, build-up substrates, adhesive films for build-up, resin casting materials, adhesives, coating agents, transparent materials, Examples include optical materials, electronic materials, additives to other resins, and the like. Among these various applications, in the applications of printed wiring board materials, insulating materials for circuit boards, and adhesive films for build-up, passive components such as capacitors and active components such as IC chips are embedded in the substrate, so-called substrates for built-in electronic components. Can be used as an insulating material for Examples of the adhesive include an adhesive for civil engineering, construction, automobiles, general office work, medical use, and an adhesive for electronic materials.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the Examples. The components and test methods used in this example and comparative example are described below.
[Resin composition]
[A] Epoxy resin jER828: Bisphenol A type epoxy, manufactured by Mitsubishi Chemical Corporation jER828 (product name)
-JER807: Bisphenol F type epoxy, manufactured by Mitsubishi Chemical Corporation jER807 (product name)
MY0510: Triglycidyl-paraaminophenol, Huntsman Advanced Materials' Araldite MY0510 (product name)

[B] Polyarylate resin V-575: Terminal OH type polyarylate resin, average particle size 15 μm, number average molecular weight (Mn) 1400, functional group equivalent 210 g / eq Unifiedr V575 (product name)
W-575: End-blocking polyarylate resin, average particle diameter 15 μm, number average molecular weight (Mn) 1400, Unitika Ltd. Unifier W-575 (product name)

[C] Anionic polymerization catalyst, 2E4Mz: Imidazole catalyst having a tertiary amine, Curesol 2E4Mz manufactured by Shikoku Chemicals Corporation (product name)
2PzPw: Imidazole-based catalyst having a tertiary amine, Curesol 2PzPw (product name) manufactured by Shikoku Chemicals Corporation

[Other ingredients]
(Thermoplastic resin)
-PKHP-200: Phenoxy resin, PKHP-200 manufactured by Gabriel Performance Products (product name)
-PES-5003P: Terminal hydroxyl group type polyether sulfone resin, Sumika Excel PES-5003P (product name) manufactured by Sumitomo Chemical Industries, Ltd., average particle size 20 μm, glass transition temperature 230 ° C, 100 hydroxyl groups per polymerization repeating unit 0 .6 to 1.4 (catalog value)
(Hardener)
-DDA 5: dicyandiamide, Omicure-DDA 5 (product name) manufactured by Emerald Performance Materials.
・ 3,3'-DDS: 3,3'-diaminodiphenyl sulfone, manufactured by Konishi Chemical Industry Co., Ltd. (curing accelerator)
U24: 2,4-Toluene bis Dimethylurea, Emerald Performance Materials Omicure-U24 (product name)

〔Carbon fiber〕
-Teijin Limited carbon fiber strand "Tenax" (registered trademark) STS40 F22 24000tex, tensile strength 4.0 GPa, tensile elastic modulus 235 GPa

〔Evaluation methods〕
(1) Evaluation of cycle moldability The mold releasability and cycle moldability of the prepreg were evaluated by cycle molding in which the process of molding a molded product of a fiber-reinforced composite material with a set of molds was repeated. The prepreg was cut into a length of 295 mm and a width of 208 mm, and 10 sheets were laminated in the fiber direction of [0 °] to prepare a preform (thickness 2.3 mm). The upper and lower molds of the mold were preheated to 170 ° C., and a mold release agent (Chem Lease HT-S manufactured by Chemtrend) was sprayed on the mold molding surface. The preform was placed in a mold having a length of 297 mm and a width of 210 mm, heated and pressurized at 3 MPa, held for 3 minutes, and cured. After curing, the mold was removed from the mold to obtain a flat plate molded product having a length of 297 mm, a width of 210 mm, and a thickness of about 1.9 mm. Subsequently, repeated molding was carried out under the above-mentioned conditions without newly spraying a mold release agent. The number of repeated moldings in which the molded product can be removed from the mold was measured.
◯: The molded product can be satisfactorily removed from the mold without defects such as resin defects and cracks. The number of repeated moldings is 20 or more. Δ: The molded product is molded without defects such as resin defects and cracks. The number of repetitive moldings that allows the product to be successfully removed from the mold is 11 or more. ×: The number of repetitive moldings that allows the molded product to be successfully removed from the mold without defects such as resin defects and cracks is 10. Less than once

(2) Evaluation of Formability by Autoclave A prepreg was cut into a length of 297 mm × 210 mm, and 10 preforms (thickness 2.3 mm) were prepared. The temperature was raised at 5 ° C./min in an autoclave, heat-cured at 170 ° C. for 10 minutes, and lowered to 50 ° C. at 5 ° C./min to prepare a molded plate. During this time, the inside of the autoclave was pressurized to 0.5 MPa, and the inside of the bag was kept in a vacuum. The voids of the obtained molded plate were evaluated by the following method.
◯: Molding is possible without voids ×: Molding is not possible due to voids

(3) Storage stability After the prepreg was stored at a temperature of 70 ° C. for 10 days, the prepreg was cut to prepare a molded plate in the same manner as in the above autoclave moldability evaluation, and the presence or absence of voids was confirmed. The evaluation results are represented by the following criteria (○ to ×).
◯: Molding is possible without voids ×: The curing reaction of the prepreg proceeds, the resin fluidity decreases, and voids are generated.

(4) Void evaluation method The molded plate is cut and polished in the order of 600, 1000, 2000 using sandpaper, and buffing with colloidal silica is applied as the final finish to make the cross section a mirror surface. Finished. Using an optical microscope (magnification: 500 times), the mirror-polished cross section was observed to confirm the presence or absence of voids.

(5) Glass transition temperature (DMA-Tg)
The glass transition temperature (Tg) of the carbon fiber reinforced resin composite material was measured using a dynamic viscoelasticity measuring device (DMA) according to the ASTM D7028-07 method.

The molded plate of the fiber-reinforced composite material obtained in the same manner as in the evaluation of moldability by the autoclave was used as a 50 mm × 6 mm × 2 mm cutout test piece. Using a dynamic viscoelasticity measuring device Rheogel-E400 manufactured by UBM, the distance between chucks is set to 30 mm under the conditions of a measurement frequency of 1 Hz, a temperature rise rate of 5 ° C./min, and a strain of 0.0167%, and a rubber elastic region from 50 ° C. The storage elastic modulus E'was measured up to. LogE'was plotted against temperature, and the temperature obtained from the intersection of the approximate straight line of the flat region of logE'and the approximate straight line of the region where E'transitioned was recorded as the glass transition temperature (Tg).

(6) Three-point bending test A prepreg was cut in the 0 ° direction to a length of 297 mm and a width of 210 mm, and a preform (thickness 2.3 mm) in which 10 sheets were laminated was prepared. Using an autoclave, molding was performed under a heating condition of 5 ° C./min under a molding condition of 180 ° C. for 20 minutes and 0.5 MPa to obtain a fiber-reinforced composite material molded plate having a thickness of 2.0 mm. Mechanical physical properties (bending characteristics) were evaluated using the obtained molded plate.

An evaluation test piece having a length of 100 mm, a width of 15 mm, and a thickness of 2.0 mm was cut out from the obtained molded plate in the fiber axis 0 ° direction. A three-point bending test was carried out at a span length of 80 mm and a test speed of 5 mm / min in accordance with the JIS K 7074 test standard, and the bending strength and flexural modulus were calculated from the maximum point stress and displacement.

(Example 1)
Half the amount (40 parts by mass) of the polyarylate resin was dissolved in the epoxy resin at 120 ° C. using a stirrer at the ratio shown in Table 1. The polyarylate resin was added in the form of pulverized powder. Then, the temperature was lowered to 70 ° C., the remaining polyarylate resin powder and anionic polymerization catalyst were added and mixed for 30 minutes to prepare an epoxy resin composition.

The obtained epoxy resin composition was applied onto a paper pattern using a film coater to prepare a resin film having a basis weight of 50 g / m ² .

Next, the carbon fibers were arranged in one direction so that the fiber mass per unit area was 190 g / m ^2, and a sheet-shaped reinforcing fiber base material layer was prepared. The resin film was stacked on both sides of the reinforcing fiber base material layer and heated and pressed under the conditions of a temperature of 130 ° C. and 200 N / cm to prepare a unidirectional prepreg having a carbon fiber content of 65% by mass. Table 1 shows the mold releasability, moldability and storage stability of the obtained prepreg. In addition, the Tg and three-point bending characteristics of the composite material obtained from the prepreg of Example 1 were evaluated, and the results are shown in Table 1.

The prepreg obtained in Example 1 has excellent moldability and mold releasability, can be cycle-molded, and further has excellent storage stability that can be molded with a voidless even after the prepreg is stored at a temperature of 70 ° C. for 10 days. Had had. Moreover, the obtained composite material was an excellent composite material having a high three-point bending strength.

(Examples 2 to 7)
A prepreg was prepared in the same manner as in Example 1 except that the composition of the resin was changed to the ratio shown in Table 1. The mold releasability, moldability and storage stability of the obtained prepreg, and the Tg and three-point bending characteristics of the composite material obtained from the prepreg of each example were evaluated, and the results are shown in Table 1.

All of the prepregs obtained in each example have excellent moldability and mold releasability, and can be cycle-molded. Furthermore, even after the prepreg is stored at a temperature of 70 ° C. for 10 days, it can be molded with a voidless. Had.

(Comparative Example 1)
In Comparative Example 1, a prepreg was prepared using a dicyandiamide-based curing agent and a urea-based curing accelerator instead of using a polyarylate resin and an anionic polymerization-based catalyst. The phenoxy resin was dissolved in the epoxy resin at 120 ° C. using a stirrer at the ratio shown in Table 2. Then, the temperature was lowered to 70 ° C., a curing agent and a curing accelerator were added, and the mixture was mixed for 30 minutes to obtain an epoxy resin composition. As for other steps, a prepreg was prepared by the same steps as in Example 1. Table 2 shows the mold releasability, moldability and storage stability of the obtained prepreg. In addition, the Tg and 3-point bending characteristics of the composite material obtained from the prepreg of Comparative Example 1 were evaluated, and the results are shown in Table 2.

Since the Tg of the molded plate was lower than the mold temperature (170 ° C.), the composite material obtained from the prepreg of Comparative Example 1 was deformed and the resin was chipped. In addition, the storage stability at room temperature was poor, and the cycle moldability was also insufficient.

(Comparative Example 2)
The polyether sulfone resin was dissolved in the epoxy resin at 120 ° C. using a stirrer at the ratio shown in Table 2. Then, the temperature was lowered to 70 ° C., a curing agent and a curing accelerator were added, and the mixture was mixed for 30 minutes to obtain an epoxy resin composition. As for other steps, a prepreg was prepared by the same steps as in Example 1. Table 2 shows the mold releasability, moldability and storage stability of the obtained prepreg. In addition, the Tg and 3-point bending characteristics of the composite material obtained from the prepreg of Comparative Example 2 were evaluated, and the results are shown in Table 2.

Since the Tg of the molded plate was lower than the mold temperature (170 ° C.), the composite material obtained from the prepreg of Comparative Example 2 was deformed and the resin was chipped. In addition, the storage stability at room temperature was poor, and the cycle moldability was also insufficient.

(Comparative Example 3)
In Comparative Example 3, a prepreg was prepared using a dicyandiamide-based curing agent and a urea-based curing accelerator instead of using an anionic polymerization catalyst. The polyarylate resin was dissolved in the epoxy resin at 120 ° C. using a stirrer at the ratio shown in Table 2. Then, the temperature was lowered to 70 ° C., a curing agent and a curing accelerator were added, and the mixture was mixed for 30 minutes to obtain an epoxy resin composition. As for other steps, a prepreg was prepared by the same steps as in Example 1. Table 2 shows the mold releasability, moldability and storage stability of the obtained prepreg. In addition, the Tg and 3-point bending characteristics of the composite material obtained from the prepreg of Comparative Example 3 were evaluated, and the results are shown in Table 2.

Since the Tg of the molded plate was lower than the mold temperature (170 ° C.), the composite material obtained from the prepreg of Comparative Example 3 was deformed and the resin was chipped. In addition, the storage stability at room temperature was poor, and the cycle moldability was also insufficient. Furthermore, since polyarylate having a low molecular weight is not inserted into the epoxy skeleton, the physical properties (three-point bending strength) of the obtained composite material are significantly reduced.

(Comparative Example 4)
In Comparative Example 4, a prepreg was prepared using a phenoxy resin instead of using a polyarylate resin. The phenoxy resin was dissolved in the epoxy resin at 120 ° C. using a stirrer at the ratio shown in Table 2. Then, the temperature was lowered to 70 ° C., an anionic polymerization catalyst was added, and the mixture was mixed for 30 minutes to obtain an epoxy resin composition. As for other steps, a prepreg was prepared by the same steps as in Example 1. Table 2 shows the mold releasability, moldability and storage stability of the obtained prepreg.

In the obtained prepreg, the curing reaction hardly proceeded within the specified time, and a cured product could not be obtained.

(Comparative Example 5)
The polyether sulfone resin was dissolved in the epoxy resin at 120 ° C. using a stirrer at the ratio shown in Table 2. Then, the temperature was lowered to 70 ° C., a curing agent was added, and the mixture was mixed for 30 minutes to obtain an epoxy resin composition. As for other steps, a prepreg was prepared by the same steps as in Example 1. Table 2 shows the mold releasability, moldability and storage stability of the obtained prepreg.

The obtained prepreg had an insufficient curing reaction within a specified time, and a cured product could not be obtained.

Claims (7)

An epoxy resin composition comprising at least [A] epoxy resin, [B] polyarylate resin, and [C] anionic polymerization catalyst. The epoxy resin composition according to claim 1, which contains 50 to 170 parts by mass of [B] polyarylate resin and 0.01 to 20 parts by mass of [C] anionic polymerization catalyst with respect to 100 parts by mass of [A] epoxy resin. Stuff. The epoxy resin composition according to claim 1 or 2, wherein the component [B] polyarylate resin has a weight average molecular weight of Mw300 to 10000. The epoxy resin composition according to any one of claims 1 to 3, wherein the component [C] anionic polymerization catalyst is an imidazole catalyst having a tertiary amine. A prepreg comprising the epoxy resin composition according to any one of claims 1 to 4 and a reinforcing fiber base material. A method for producing a prepreg, which impregnates a reinforcing fiber base material with the epoxy resin composition according to any one of claims 1 to 4. A method for producing a fiber-reinforced composite material, wherein the prepreg according to claim 5 is heated and pressed to be cured.