JP5723505B2 - Resin composition, cured product, prepreg, and fiber reinforced composite material - Google Patents

Description

  The present invention relates to a resin composition, a cured product thereof, a prepreg obtained by impregnating a reinforcing fiber with the resin composition as a matrix resin, and a fiber-reinforced composite material obtained by molding the prepreg.

  Fiber reinforced composite materials that use carbon fiber, aramid fiber, etc. as reinforcing fibers are aerospace / industrial applications such as structural materials for aircraft and automobiles, tennis rackets, and golf shafts because of their high specific strength and specific modulus. Widely used in sports and leisure applications such as fishing rods.

  As a method for producing a fiber-reinforced composite material, there is a method in which a plurality of prepregs are laminated and then heat-cured. A prepreg is a sheet-like intermediate material in which reinforcing fibers are impregnated with an uncured matrix resin.

  A typical matrix resin used for the prepreg includes a thermosetting resin from the viewpoint of heat resistance and productivity.

  In general, thermosetting resins, especially epoxy resins, are excellent in heat resistance, adhesion to reinforcing fibers, dimensional stability, and chemical resistance, but are hard and brittle. For this reason, when an epoxy resin is used as the matrix resin, the fiber-reinforced composite material is excellent in mechanical properties such as dimensional stability, strength and rigidity, but on the other hand, the low toughness derived from the epoxy resin is also reflected.

  Conventionally, various attempts have been made to improve the toughness and impact resistance of thermosetting resins used as matrix resins.

  For example, a sea-island phase separation structure in which fine particles of a rubber component or a thermoplastic resin are dispersed in a thermosetting resin, an island component is a rubber component or a thermoplastic resin, and a sea component is a thermosetting resin cured product. There is a method of forming. The matrix resin obtained by this method has improved impact resistance due to the excellent impact strength and bending / tensile strength derived from the island components. However, with this method, it is difficult to reduce the size of the island component, and a sufficient surface area for absorbing energy cannot be obtained. Therefore, it has been difficult to dramatically increase the toughness of the fiber-reinforced composite material by this method.

  As another method, there is a method of forming a nano-sized phase separation structure using a block copolymer composed of two or three components (Patent Documents 1 to 3). For example, a method is proposed in which a styrene-butadiene copolymer, a styrene-butadiene-methacrylic acid copolymer, or a butadiene-methacrylic acid copolymer is added to a specific epoxy resin. However, with these methods, the heat resistance of the matrix resin is lowered, and the mechanical properties of the fiber-reinforced composite material are still insufficient. In addition, these block copolymers are very expensive and have low cost competitiveness.

International Publication No. 2006/075153 Pamphlet JP 2007-154160 A JP 2008-7682 A

  An object of the present invention is to provide a resin composition that exhibits excellent toughness, impact resistance, heat resistance, chemical resistance and elastic modulus by a curing reaction, and a prepreg using the resin composition at low cost. .

  Another object of the present invention is to provide a fiber-reinforced composite material having excellent toughness and mechanical strength obtained from the prepreg.

  As a result of intensive studies on the above problems, the present inventors have determined that the matrix resin is a sea-island phase in which the main component of the island component is a reaction product of a thermosetting resin and a curing agent, and the main component of the sea component is a thermoplastic resin. It has been found that the above problem can be solved by using a cured product having a separation structure.

  In the resin composition that undergoes a curing reaction to obtain the above cured product, the blending ratio of the thermoplastic resin and the selection of the combination of the thermosetting resin and the thermoplastic resin are devised, the average particle size of the island component of the cured product, etc. By controlling the above, the present invention has been completed.

  The resin composition of the present invention comprises at least a thermosetting resin, a curing agent, and a thermoplastic resin, and the resin composition is a reaction product of an island component of a thermosetting resin and a curing agent by a curing reaction. A cured product having a sea-island phase separation structure in which the sea component is mainly composed of a thermoplastic resin.

  The resin composition of the present invention includes a resin composition to which a compatibilizing agent for compatibilizing a thermoplastic resin and a thermosetting resin is added.

Also included is a resin composition having a viscosity of 10 to 1000 Pa · s at 80 ° C. and a shear rate of 1000 s ⁻¹ .

  The thermosetting resin contained in the resin composition of the present invention is preferably an epoxy resin or a modified epoxy resin.

  The thermoplastic resin contained in the resin composition of the present invention is preferably polyimide, polyetherimide, polyethersulfone, polysulfone, polyamideimide, polycarbonate, derivatives thereof, or combinations thereof. These thermoplastic resins preferably have a functional group capable of reacting with the thermosetting resin, and in particular, the functional group capable of reacting with the thermosetting resin is a hydroxyl group, a carboxylic acid group, an imino group, or an amino group. It is preferable. It is preferable that the compounding quantity of a thermoplastic resin is 5-60 mass% of the total weight of a resin composition.

  The cured product of the present invention is a cured product obtained by the curing reaction of the above resin composition, the island component is mainly composed of a reaction product of a thermosetting resin and a curing agent, and the sea component is composed mainly of a thermoplastic resin. It has a sea-island phase separation structure. It is preferable that the glass transition point of hardened | cured material is 150 degreeC or more. Moreover, it is preferable that the average particle diameter of an island component is 0.01-10 micrometers, and it is more preferable that it is 0.01-1 micrometer.

  The present invention includes a prepreg obtained by impregnating a reinforcing fiber with the above resin composition. Examples of the reinforcing fiber include carbon fiber, silicon carbide fiber, glass fiber, aromatic polyamide fiber, polyimide fiber, polybenzoxazine fiber, and aromatic polyester fiber. Among these, carbon fiber is particularly preferable.

  The present invention also includes a fiber reinforced composite material obtained by impregnating a reinforced fiber with the cured product of the present invention. The fiber-reinforced composite material of the present invention is obtained by molding the above-mentioned prepreg.

  According to the present invention, it is possible to provide a resin composition that exhibits excellent toughness, heat resistance, chemical resistance, and elastic modulus by a curing reaction, and a prepreg in which reinforcing fibers are impregnated with the resin composition.

  The fiber reinforced composite material of the present invention using the cured product as a matrix resin is superior in impact resistance and interlaminar fracture toughness compared to the prior art, and is suitable for aerospace applications, industrial applications, and sports / leisure applications.

<Resin composition>
The resin composition of the present invention comprises at least a thermosetting resin, a curing agent, and a thermoplastic resin, and the island component is mainly composed of a reaction product of the thermosetting resin and the curing agent by a curing reaction, The component forms a sea-island phase separation structure mainly composed of a thermoplastic resin.

  The resin composition of the present invention may be added with a compatibilizing agent that makes the thermoplastic resin and the thermosetting resin compatible.

  The kind of the compatibilizer is not particularly limited, but a compound having a chemical structure close to that of the monomer unit of the thermoplastic resin is preferable. In particular, in order not to leave the compatibilizer as an uncured product after the curing reaction of the resin composition, it is preferable to use a compound that can react with the thermosetting resin as the compatibilizing agent, and to cure the thermosetting resin. It is more preferable to use an agent.

  By adding a compatibilizing agent, the average particle size of the island components in the cured product obtained by curing the resin composition can be controlled. The greater the amount of compatibilizer added, the higher the compatibility between the thermosetting resin and the thermoplastic resin. As a result, the average particle size of the island component can be reduced. The addition amount of the compatibilizer is preferably 0.01 to 15% by mass with respect to the total weight of the resin composition.

  When the addition amount of the compatibilizer is less than 0.01% by mass, the thermosetting resin and the thermoplastic resin cannot be sufficiently compatible, and the average particle size of the island component exceeds 10 μm. When the average particle size of the island component exceeds 10 μm, it is not preferable because the heat resistance and chemical resistance derived from the thermosetting resin are hardly expressed.

  When the addition amount of the compatibilizer exceeds 15% by mass, the compatibility between the thermosetting resin and the thermoplastic resin becomes too high and the both are completely compatible. For this reason, a sea-island phase separation structure cannot be formed, which is not preferable.

  Moreover, although it changes with the kind of thermosetting resin and thermoplastic resin, the addition amount of a compatibilizing agent is in the range of 0.05 to 10% by mass, particularly in the range of 0.1 to 3% by mass. Since the average particle size of the island component in the cured product obtained by curing the resin composition can be controlled to 0.01 to 1 μm, it is more preferable.

The resin composition of the present invention preferably has a viscosity of 10 to 3000 Pa · s at 80 ° C. and a shear rate of 1000 s ⁻¹ . It is more preferably 10 to 1500 Pa · s, further preferably 50 to 1000 Pa · s, and particularly preferably 60 to 800 Pa · s.
The predetermined viscosity can be obtained by adjusting the blending ratio of the thermoplastic resin described later.

  There is a correlation between the viscosity of the resin composition and the average particle size of the island component in the cured product obtained by curing the resin composition, and the average particle size of the island component tends to increase as the viscosity of the resin composition decreases. is there. Moreover, there exists a tendency for the average particle diameter of an island component to become small, so that the viscosity of a resin composition becomes high. The cause of this is not clear, but it is presumed that the relative relationship between the phase separation rate and the curing reaction rate affects the average particle size of the island components.

  For example, when the viscosity of the resin composition increases, the phase separation rate decreases, and the curing rate becomes faster than the phase separation rate. In this case, since a cured network is formed in the initial stage, it is considered that the thermoplastic resin cannot form an island component and becomes a sea component. Moreover, it is considered that a network structure having a small molecular size becomes a domain (island component).

  When the viscosity of the resin composition is less than 10 Pa · s, the thermoplastic resin may not be able to form a sea component even if the resin composition is heat-cured. On the other hand, when it exceeds 3000 Pa · s, the thermoplastic resin can form a sea component due to the relative relationship between the phase separation rate and the curing rate. However, due to the high viscosity, the handleability may be significantly reduced, making it difficult to handle with conventional manufacturing equipment.

  The thermosetting resin contained in the resin composition of the present invention is preferably a thermosetting resin that is cured by heat or external energy such as light or electron beam to at least partially form a three-dimensional cured product. .

  Preferred thermosetting resins are listed below. These thermosetting resins can be appropriately selected and used alone or in combination of two or more.

  Preferred examples of the thermosetting resin include an epoxy resin, a modified epoxy resin, a vinyl ester resin, and a benzoxazine resin. Particularly preferred are epoxy resins and modified epoxy resins.

  As the epoxy resin, any known epoxy resin can be used and is not particularly limited. Examples thereof include bifunctional epoxy resins such as bisphenol-type epoxy resins, alcohol-type epoxy resins, biphenyl-type epoxy resins, hydrophthalic acid-type epoxy resins, dimer acid-type epoxy resins, and alicyclic epoxy resins.

  Bifunctional epoxy resins represented by the bisphenol type have various grades ranging from liquid to solid depending on the difference in molecular weight, and are intended components for adjusting viscosity by mixing as appropriate. Examples of the bisphenol type epoxy resin include bisphenol A type resin, bisphenol F type resin, bisphenol AD type resin, bisphenol S type resin, and the like. Specific product names include jER815 (product name), jER828 (product name), jER834 (product name), jER1001 (product name), jER807 (product name) manufactured by Japan Epoxy Resin Co., Ltd. -710 (trade name), EXA1514 (trade name) manufactured by Dainippon Ink & Chemicals, Inc. can be exemplified. Specific product names of alicyclic epoxy resins include Araldite CY-179 (product name), CY-178 (product name), CY-182 (product name), CY-183 (product name), etc. manufactured by Huntsman. Can be illustrated. Examples of other epoxy resins include glycidyl ether type epoxy resins such as tetrakis (glycidyloxyphenyl) ethane and tris (glycidyloxyphenyl) methane, glycidylamine type epoxy resins such as tetraglycidyldiaminodiphenylmethane, and naphthalene type epoxy resins. And a phenol novolac epoxy resin which is a novolac epoxy resin, a polyfunctional epoxy resin such as a cresol novolac epoxy resin, a phenol epoxy resin, and the like.

  Various modified epoxy resins such as urethane-modified epoxy resin and rubber-modified epoxy resin can also be used. Specific examples of the trade name of the urethane-modified bisphenol A epoxy resin include Adeka Resin EPU-6 (trade name) and EPU-4 (trade name) manufactured by Asahi Denka. Specific product names of the phenol novolac type epoxy resin include jER152 (product name), jER154 (product name) manufactured by Japan Epoxy Resin, DEN431 (product name), DEN485 (product name), and DEN438 (product name) manufactured by Dow Chemical. Name), Epicron N740 (trade name) manufactured by DIC, and the like.

  Specific product names of the cresol novolak type epoxy resin include Araldite ECN1235 (product name), ECN1273 (product name), ECN1280 (product name), Nippon Kayaku EOCN102 (product name), and EOCN103 (product name) manufactured by Huntsman. ), EOCN104 (trade name), and the like.

  As the curing agent contained in the resin composition of the present invention, a known curing agent that cures the thermosetting resin can be used. The curing agent is a compound necessary for reacting with the thermosetting resin to obtain a cured resin having heat resistance, chemical resistance, and high elastic modulus. When using a hardening | curing agent as a compatibilizing agent, you may use together 2 or more types of hardening | curing agents.

  Specific examples of curing agents include 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, 4,4′-diamino-3,3′-diethyl-5,5′-dimethyldiphenylmethane and These mixtures are preferred because they give excellent mechanical properties.

  It is also possible to use diaminodiphenyl sulfone (mc-DDS) microencapsulated with a coating agent. In mc-DDS, the surface layer of DDS particles is coated with a low-reactivity substance by physical and chemical bonding so as to prevent reaction with a thermosetting resin at room temperature. Specific examples of the coating agent for coating the surface layer of the DDS particles include polyamide, modified urea resin, modified melamine resin, polyolefin, polyparaffin (including modified products), and the like. These coating agents may be used alone or in combination, and DDS microencapsulated with various coating agents other than those described above can also be used.

  In the resin composition of the present invention, an amine compound such as tertiary amine and imidazole, a phosphine, a phosphorus compound such as phosphonium, N, N-dimethyl, and the like, as necessary, within a range not impairing the effects of the present invention. You may contain various additives, such as hardening accelerators, such as a urea derivative, a reactive diluent, a filler, antioxidant, a flame retardant, and a pigment.

  Examples of the thermoplastic resin contained in the resin composition of the present invention include polyimide, polyetherimide (PEI), polyethersulfone (PES), polyamideimide, polysulfone, polycarbonate, polyetheretherketone, nylon 6, nylon 12, Examples thereof include polyamide such as amorphous nylon, aramid, arylate, polyester carbonate, acrylonitrile butadiene rubber, acrylic resin, and the like.

  From the viewpoint of improving the heat resistance of the cured product, polyimide, polyetherimide, polyethersulfone, polysulfone, polyamideimide, polycarbonate, derivatives thereof, or combinations thereof are more preferable. These thermoplastic resins may be used alone or in combination of two or more at any ratio.

  The resin composition of the present invention preferably forms a so-called LCST (Lower Critical Solution Temperature) phase diagram. In the low temperature region of the phase diagram, the thermosetting resin and the thermoplastic resin are compatible. In the high temperature range, with the increase in the molecular weight of the thermosetting resin due to the cross-linking reaction, the two-phase region expands and the compatible region decreases. Phase separation occurs in the process of decreasing the compatibility zone, and a sea-island phase separation structure is formed.

  In the present invention, phase separation is induced by the curing reaction of the resin composition. In order to form an LCST phase diagram, it is preferable that the thermoplastic resin forms a hydrogen bond with the thermosetting resin. Thermosetting resins and curing agents have atoms with large electronegativity such as nitrogen, oxygen, sulfur, and halogen in the molecule. The thermoplastic resin used in the present invention preferably has a functional group that easily forms a hydrogen bond with these atoms having a large electronegativity.

  Therefore, it is preferable that the thermoplastic resin contained in the resin composition of the present invention has a functional group capable of reacting with the thermosetting resin. When the thermoplastic resin reacts with the thermosetting resin, the thermoplastic resin is taken into the three-dimensional network of the cured product. Thereby, the chemical resistance which is the fault of a thermoplastic resin can be improved remarkably.

  The thermoplastic resin included in the present invention preferably has a functional group such as a hydroxyl group, a carboxylic acid group, an imino group, or an amino group as a functional group, and more preferably has a hydroxyl group. The thermoplastic resin is bonded to a curing agent or a thermosetting resin dissolved in the thermoplastic resin through these functional groups. As a result, the resin composition of the present invention forms a sea-island phase-separated structure by the curing reaction, in which the island component is a reaction product of a thermosetting resin and a curing agent as a main component and the sea component is a thermoplastic resin as a main component. To do.

  As the number of functional groups, it is preferable to have one functional group such as a hydroxyl group, a carboxylic acid group, an imino group, and an amino group with respect to a mass average molecular weight of 10,000 to 70,000 of the thermoplastic resin, and further to 10,000 to 30,000. It is more preferable to have one functional group.

  When having one functional group with respect to the mass average molecular weight of 70,000 or more of the thermoplastic resin, hydrogen bonding between the thermoplastic resin and the thermosetting resin is reduced. In that case, the resin composition cannot take an LCST phase diagram, and it is difficult to form a sea-island phase separation structure during the curing process. In the case of having one functional group with respect to the mass average molecular weight of the thermoplastic resin of less than 10,000, intramolecular hydrogen bonding between the thermoplastic resins becomes dominant. In that case, the compatibility with the thermosetting resin tends to be significantly reduced.

  The resin composition of the present invention preferably has a thermoplastic resin content of 5 to 60% by mass, more preferably 10 to 55% by mass, still more preferably 15 to 45% by mass, based on the total weight of the resin composition. 19-45 mass% is especially preferable, and 25-45 mass% is the most preferable.

  When the blending ratio of the thermoplastic resin exceeds 60% by mass of the total weight of the resin composition, the viscosity of the resin composition increases, and the processability of prepreg production tends to deteriorate. On the other hand, when the blending ratio of the thermoplastic resin is less than 5% by mass of the total weight of the resin composition, the fluidity is good and the processability is improved. However, it is not preferable because the main component of the sea phase of the cured product is a reaction product of the thermosetting resin and the curing agent, causing a significant decrease in toughness of the cured product.

  The resin composition of the present invention is produced by adding and kneading at least a thermoplastic resin, a thermosetting resin, and a curing agent. The kneading of each component may be performed in a single stage, or may be performed in multiple stages by sequentially adding each component. When adding each component sequentially, it can add in arbitrary orders. As a kneading / adding method of each component, the viscosity is adjusted by kneading a part or all of the thermoplastic resin in advance in the thermosetting resin, and then sequentially adding the curing agent and the remaining thermoplastic resin. There is a method of kneading. The order of kneading and addition is not particularly limited, but it is preferable to add the curing agent last from the viewpoint of the storage stability of the resin composition.

  The thermoplastic resin may be added as solid particles in a timely manner for viscosity adjustment. Thereby, the handleability of a resin composition and a moldability are also maintained favorable. The average particle diameter of the thermoplastic resin is preferably in the range of 1 to 100 μm, more preferably 1 to 50 μm. When it is smaller than 1 μm, the bulk density is increased, and the viscosity of the resin composition may be remarkably increased. When it is larger than 100 μm, it becomes difficult to disperse the particles in the resin composition, and the thermoplastic resin cannot be blended almost uniformly into the resin composition. Moreover, when forming the resin composition obtained in a sheet form, it may be difficult to obtain a sheet having a uniform thickness.

  The kneading temperature during production of the resin composition is preferably in the range of 10 to 150 ° C. When it exceeds 150 degreeC, a partial hardening reaction will start and the storage stability of the resin composition obtained may fall. If it is lower than 10 ° C., the viscosity of the resin composition is high, and it may be difficult to knead substantially. Preferably it is 20-120 degreeC, More preferably, it is the range of 30-100 degreeC.

  As the kneading machine apparatus used at the time of producing the resin composition, a conventionally known apparatus can be used. Specific examples include a roll mill, a planetary mixer, a kneader, an extruder, a Banbury mixer, a mixing vessel provided with a stirring blade, and a horizontal mixing vessel.

<Hardened product>
The cured product of the present invention is a cured product having a sea-island phase separation structure obtained by the curing reaction of the above resin composition. In the sea-island phase separation structure, the island component has a reaction product of a thermosetting resin and a curing agent as a main component, and the sea component has a thermoplastic resin as a main component.

  Since the sea component of the cured product of the present invention is mainly composed of a thermoplastic resin, it has excellent impact strength and bending / tensile strength properties derived from the thermoplastic resin, and low toughness derived from the thermosetting resin. Significantly improved.

  The thermoplastic resin constituting the sea component accounts for 5 to 60% by mass of the total weight. In the conventional sea-island phase separation structure, a small amount of components becomes island components. However, in the present invention, the thermoplastic resin becomes a sea component in the range of 5 to 60% by mass of the total weight to form a so-called “reverse sea island phase separation structure”. Due to this feature, the cured product of the present invention exhibits excellent impact strength and bending / tensile strength characteristics that cannot be achieved by a conventional cured product having a thermosetting resin as a sea component.

  When the thermoplastic resin is less than 5% by mass of the total weight, the thermoplastic resin does not become a main component of the sea component, and the low toughness derived from the thermosetting resin appears remarkably, which is not preferable. On the other hand, if the thermoplastic resin exceeds 60% by mass of the total weight, it is not preferable because the low elastic modulus and chemical resistance, which are disadvantages of the thermoplastic resin, are significantly reduced.

  The cured product of the present invention preferably has an average particle size of 0.01 to 10 μm of an island component mainly composed of a reaction product of a thermosetting resin and a curing agent. The thickness is preferably 0.01 to 5 μm, more preferably 0.01 to 1 μm, and particularly preferably 0.01 to 0.6 μm.

  If the average particle size of the island component is less than 0.01 μm, the cured product tends to have mechanical properties and thermal characteristics, which is not preferable. If the average particle size of the island component exceeds 10 μm, the mechanical properties, thermal properties, and chemical resistance of the cured product tend to be remarkably lowered, which is not preferable.

  The average particle size of the island component in the cured product can be adjusted by adding a compatibilizing agent to the thermoplastic resin, the thermosetting resin, and the curing agent and kneading them during the production of the resin composition. The greater the amount of compatibilizer added, the higher the compatibility between the thermosetting resin and the thermoplastic resin. As a result, the average particle size of the island component can be reduced.

  150 degreeC or more is preferable, as for the glass transition temperature of the hardened | cured material of this invention, 180 degreeC or more is more preferable, 200 degreeC or more is further more preferable, and 230 degreeC or more is especially preferable. When glass transition temperature exceeds 300 degreeC, the viscosity of a resin composition becomes remarkably high and may adversely affect processability. If the glass transition temperature of the cured product is less than 150 ° C., an uncured product may remain in the cured product. In that case, problems such as decomposition of the cured product, poor long-term stability, poor flame resistance and poor heat resistance may occur, which is not preferable.

  The cured product of the present invention may be produced by any method as long as it is obtained by curing reaction of the resin composition of the present invention. For example, there is a method in which a thermosetting resin, a curing agent, and a thermoplastic resin are kneaded to produce a resin composition, and then the resin composition is heated to cause a curing reaction. This method is described below.

  As the heat treatment conditions for the resin composition, it is preferable that the temperature is raised to a range of 120 to 300 ° C. at a temperature rising rate of 0.5 to 20 ° C./min and then held at the maximum temperature for 0 to 500 minutes. The maximum temperature reached is preferably in the range of 150 to 250 ° C. When the maximum temperature reached is less than 120 ° C., the thermoplastic resin particles remaining in the resin composition may not be dissolved. On the other hand, when it exceeds 300 ° C., the thermosetting resin may be decomposed. The holding time at the highest temperature is preferably less than 500 minutes from the viewpoint of productivity. A pressure of 0.1 to 7 MPa may be applied during the heat treatment.

  The cured product produced by this method has a sea-island phase separation structure in which the main component of the island component is a reaction product of a thermosetting resin and a curing agent, and the main component of the sea component is a thermoplastic resin. Thereby, the hardened | cured material of this invention is excellent in toughness, impact resistance, heat resistance, chemical resistance, and elastic modulus. In addition, since the main component of the sea component is a thermoplastic resin, it flows like a thermoplastic resin by heating despite containing a large amount of thermosetting resin. For this reason, it also has formability by heating, and when a cured product cracks, it can be self-repaired by heating without using an adhesive or the like.

<Prepreg>
The prepreg of the present invention can be obtained by impregnating the reinforcing fiber with the resin composition of the present invention.

  Examples of the reinforcing fiber used in the prepreg of the present invention include carbon fiber, silicon carbide fiber, glass fiber, aromatic polyamide fiber, polyimide fiber, polybenzoxazole fiber, polybenzoxazine fiber, and aromatic polyester fiber. . Among these, carbon fibers having high strength and high elastic modulus are particularly preferable. As the carbon fiber, either pitch-based or PAN-based carbon fiber may be used. Moreover, these reinforcing fibers may be used independently and may use 2 or more types together.

  The form and arrangement of the reinforcing fibers are not particularly limited, and for example, long fibers arranged in one direction, a single tow, a woven fabric, a nonwoven fabric, a mat, a knit, a braid, and the like can be employed.

The basis weight of the reinforcing fiber is preferably in the range of 30 to 700 g / m ² . When the basis weight of the reinforcing fiber is less than 30 g / m ² , the fiber-reinforced composite material can be reduced in weight, but it is not preferable because sufficient strength cannot be provided. When it exceeds 700 g / m ² , it is difficult to reduce the weight of the fiber-reinforced composite material, which is not preferable. A more preferable range of the basis weight of the reinforcing fiber is 50 to 300 g / m ² .

  25-45 mass% is preferable and, as for the content rate of the resin composition in the prepreg of this invention, 30-40 mass% is more preferable.

  The prepreg can be prepared by a conventionally known production method such as a wet method in which a resin composition is dissolved in a solvent to lower the viscosity and impregnated, or a hot melt method (dry method) in which the viscosity is decreased by heating and impregnated. Among them, it is preferable to produce the product by a hot melt method. The prepreg obtained by the hot melt method is not affected by the residual solvent and has a long storage stability.

  When preparing a prepreg by the hot melt method, first, a resin composition to be impregnated into reinforcing fibers is formed into a sheet shape.

  As a method for forming the resin composition into a sheet, a conventionally known method can be used without any particular limitation. Specifically, there is a method in which a resin composition whose viscosity has been reduced by heating is cast and cast on a support such as a release paper or a release film. When casting or casting on a support, a die, applicator, reverse roll coater, comma coater, or the like can be used.

  The resin temperature at the time of casting on the support can be appropriately set according to the resin composition and viscosity, but is preferably 20 to 160 ° C, more preferably 60 to 145 ° C, and further preferably 70 to 140 ° C. preferable.

  Although the thickness of a sheet-like resin composition changes with the fabric weight of the fiber reinforced sheet | seat to be used, it is preferable to set it as 8-350 micrometers in general, and it is more preferable to set it as 10-200 micrometers.

  Next, the reinforcing fiber is impregnated with the sheet-shaped resin composition formed by the above method.

  In order to impregnate the resin composition with the reinforcing fiber, first, the sheet-shaped resin composition and the sheet-shaped reinforcing fiber are stacked. Subsequently, the stacked sheet-shaped resin composition and the sheet-shaped reinforcing fibers are heated under pressure.

  The pressurizing pressure at this time can be set to an arbitrary pressure of 1 to 10 MPa in consideration of the viscosity and resin flow of the resin composition.

  The range of the heating temperature at the time of pressurization is 50-160 degreeC, More preferably, it is 60-155 degreeC, More preferably, it is 70-145 degreeC. When the temperature is lower than 50 ° C., the viscosity of the resin composition is not sufficiently lowered, and the reinforcing fiber may not be sufficiently impregnated with the resin composition. When the temperature is 160 ° C. or higher, the curing reaction of the resin composition is started, and the storage stability of the prepreg may be reduced, or the drapeability may be reduced.

  The sheet width and production rate of the sheet-like reinforcing fiber and the sheet-shaped resin composition are not particularly limited, but when industrially produced continuously, from the viewpoint of productivity and economy, the following are available: preferable.

  The sheet width is preferably 30 cm or more, and is substantially up to about 5 m. If it exceeds 5 m, the production stability may decrease. The production rate is preferably 1 m / min or more, more preferably 3 m / min or more, and further preferably 5 m / min or more.

  The number of times the resin composition is impregnated into the reinforcing fiber can be divided into a plurality of times instead of once, and can be impregnated in multiple stages at an arbitrary pressure and temperature. In general, when the viscosity of the resin composition increases, the impregnation property of the reinforcing fiber is lowered, and it may be difficult to achieve both improvement in tackiness of the prepreg and reduction in internal porosity. In such a case, it is desirable to improve both the tackiness of the prepreg and reduce the internal porosity by impregnating the reinforcing fiber in a plurality of times.

  When the resin composition is divided into a plurality of times and impregnated into the reinforcing fibers, first, the first sheet-shaped resin composition is stacked on the sheet-shaped reinforcing fibers. The reinforcing fiber on which the sheet-shaped resin composition is stacked is heated to 50 ° C. to 150 ° C. under pressure to impregnate the reinforcing fiber with the resin composition. Next, the second sheet-shaped resin composition is stacked on the same surface of the sheet-shaped reinforcing fiber impregnated with the first sheet-shaped resin composition, and heated from 50 ° C. to 90 ° C. under pressure. . Repeat as necessary.

  This operation can be performed not only on one side of the sheet-like reinforcing fiber but also on both sides. In that case, two sheet-shaped resin compositions can be impregnated simultaneously by stacking one sheet-shaped resin composition on each of both surfaces.

  Since the resin composition is excellent in molding processability regardless of the blending amount of the thermoplastic resin, when impregnated a plurality of times, the composition of the cured product to be impregnated is the same for the first impregnation and the second and subsequent impregnations. Or may be changed between the first impregnation and the second and subsequent impregnations.

  When the prepreg is obtained by a method in which the sheet-like cured product is impregnated into the reinforcing fiber in two or more times, the reinforcing fiber layer and the resin layer can be formed on the prepreg. The reinforcing fiber layer is composed of reinforcing fibers and a resin composition impregnated between the reinforcing fibers. The resin layer is a layer that covers one side or both sides of the reinforcing fiber layer. The resin layer formed on the surface of the reinforcing fiber layer is formed of a sheet-like resin composition that is stacked after the second time. A prepreg having this structure is excellent in tackiness.

  When forming a resin layer in a prepreg, it is preferable that a resin layer does not contain a reinforced fiber and coat | covers the surface of a reinforced fiber layer with predetermined thickness. The thickness of the resin layer is preferably 2 to 50 μm, more preferably 5 to 45 μm, and particularly preferably 10 to 40 μm. When the thickness of the resin layer is less than 2 μm, the tackiness becomes insufficient, and the moldability of the prepreg may be significantly lowered. If it exceeds 50 μm, it will be difficult to wind the prepreg into a roll with a uniform thickness, and the molding accuracy may be significantly reduced.

<Fiber-reinforced composite material>
The fiber-reinforced composite material of the present invention is a fiber-reinforced composite material using the cured product as a matrix resin.

  The fiber-reinforced composite material of the present invention is manufactured by kneading short fibers of reinforcing fibers into a resin composition before being cured, and setting them into a mold and curing them. Moreover, it can also manufacture even if it heat-hardens, after laminating | stacking several prepreg of this invention. For example, a fiber-reinforced composite material can be manufactured by laying a prepreg on the surface of a mold and heating and curing the prepreg in a state where the prepreg is pressed in the thickness direction toward the surface of the mold. The heating temperature is preferably 150 to 200 ° C. and the pressurizing pressure is preferably 0.3 to 7 MPa. In the fiber-reinforced composite material obtained by this manufacturing method, the orientation of the reinforcing fibers is strictly controlled. In addition, since the degree of freedom in designing the laminated structure is high, the performance is high.

  The fiber reinforced composite material of the present invention has excellent mechanical properties. Particularly excellent in impact resistance, interlayer toughness, and chemical resistance. Moreover, hardened | cured material flows by heating by using the hardened | cured material of this invention for a fiber reinforced composite material. For this reason, it also has formability. Accordingly, when a crack occurs in the fiber reinforced composite material, it can be self-repaired.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In addition, evaluation of operating conditions and measurement of each physical property were performed by the following methods. The evaluation results and measurement results of Example 1 and Example 2 are shown in Table 1. Table 2 shows the evaluation results and measurement results of Comparative Examples 1 to 3 and Comparative Examples 5 and 6.

[Detection of hydroxyl group / carboxylic acid group]
Detection of functional groups such as hydroxyl groups, carboxylic acid groups, imino groups and amino groups in the thermoplastic resin in the present invention is carried out by dissolving the thermoplastic resin in chloroform / hexafluoroisopropanol and measuring it by ¹ H-NMR method. The bonding site of the group was confirmed.

[Mass average molecular weight]
For the mass average molecular weight of the thermoplastic resin in the present invention, the molecular weight measured by gel permeation chromatography (GPC) was converted to the molecular weight of standard polystyrene. In the GPC measuring instrument, a differential refractometer (RID-6A manufactured by Shimadzu Corporation) was used as a detector, and a column in which SHODEX manufactured by Shoko Tsusho Co., Ltd. was connected in series. Dimethylformamide was used as an eluent, and the temperature was 40 ° C. and the flow rate was 1.0 mL / min. 10 μL of a sample having a concentration of 1 mg / ml (chloroform containing 1% hexafluoroisopropanol) was injected, and the molecular weight was measured.

[Glass-transition temperature]
The cured product was heated from room temperature to 300 ° C. at a rate of temperature increase of 10 ° C./min using a DSC measuring device (DSC2920: manufactured by TA Instrument), and the glass transition temperature was measured.

[Measurement of viscosity of resin composition]
The viscosity at 80 ° C. and 1000 s ⁻¹ of the resin composition was evaluated with a capillograph 1D manufactured by Toyo Seiki Seisakusho.

[Confirmation of main components of sea and island components]
Elemental mapping of the sea component and the island component of the cured product was performed by TEM-EELS spectroscopy (JEM2010 manufactured by JEOL Ltd.), and the main components of each component were confirmed.

[Average particle size of island components]
Cross-section processing of the cured product was performed, and the sea-island phase separation structure appearing in the cross-section was confirmed with a transmission electron microscope (JEM 2010 manufactured by JEOL) having high resolution. The particle diameter of 500 island components was measured, and the average value was defined as the average particle diameter.

[Solvent resistance test]
The cured plate was immersed in methyl ethyl ketone at 25 ° C. and allowed to stand for 30 days, and the visual appearance and mass change after drying at 150 ° C. for 1 hour were measured.

[Interlaminar fracture toughness of specimens (GIIC)]
The prepreg produced using the resin composition was cut to prepare two laminates in which 10 layers were laminated in the 0 ° direction. In order to generate an initial crack, a release film (width 80 mm, length 130 mm) was sandwiched between the two laminates, and both were combined to obtain a prepreg laminate having a laminate configuration [0] ₂₀ . Using the vacuum autoclave molding method, the laminate was molded under the condition of 180 ° C. under a pressure of 0.5 MPa for 2 hours. The obtained molded product was cut into a size of width 12.7 mm × length 304.8 mm to obtain a GIIC test piece. A GIIC test was conducted using this test piece.

  First, the test piece was placed at a position where the crack produced by the release film was 38.1 mm from the fulcrum, and an initial crack was formed by applying a bending load at a speed of 2.54 mm / min. Thereafter, the test piece was placed at a position where the crack was 25.4 mm from the fulcrum, and three GIIC tests were performed on one test piece. The test speed of the GIIC test was 2.54 mm / min.

[Compressive strength after impact (CAI) test]
The prepreg was cut, and four layers of the prepreg were laminated to obtain a laminate having a laminated structure [+ 45/0 / −45 / 90] _3S . Using an autoclave molding method, molding was performed for 2 hours at 180 ° C. under a pressure of 0.5 MPa. The obtained molded product was cut into a size of width 101.6 mm × length 152.4 mm to obtain a test piece for a compression strength test after impact. The test piece was given an impact energy of 6.67 J per 1 mm thickness. Using this test piece, the CAI after 30.5 kJ impact was measured.

[Example 1]
10 parts by mass of polyethersulfone (Sumika Excel PES-5003P manufactured by Sumitomo Chemical Co., Ltd.) pulverized to an average particle size of 10 μm was added to 100 parts by mass of glycidylamine type epoxy resin (Ep604 manufactured by Japan Epoxy Resin Co., Ltd.), and 80 ° C. with a planetary mixer. To obtain an epoxy resin solution in which polyethersulfone is completely dissolved in Ep604.

^{From the 1} H-NMR method measurement, the polymer terminal of polyethersulfone was a hydroxyl group, and the mass average molecular weight estimated by GPC was 56100. That is, it was confirmed that the polymer had one hydroxyl group per mass average molecular weight 28050.

  In a roll mill set at 70 ° C., the total amount of the epoxy resin solution described above and 129 parts by mass of polyethersulfone pulverized to an average particle size of 10 μm were kneaded. The amount of polyethersulfone charged was 46.1% by mass relative to the total mass.

Next, 6,4′-diamino-3,3′-diethyl-5,5′-dimethyldiphenylmethane (Cure Hard MED manufactured by Ihara Chemical) as a curing agent is 60.7 parts by mass, and 3,3′-diaminodiphenylsulfone is 2 masses. Parts were kneaded to obtain a resin composition. The viscosity of the resin composition at 80 ° C. and a shear rate of 1000 s ⁻¹ was 823 Pa · s. Note that 3,3′-diaminodiphenylsulfone also has characteristics as a compatibilizer for epoxy resin and polyethersulfone.

  This resin composition was charged into a mold, heated from room temperature to 180 ° C. at 3 ° C./min by an autoclave method, and then held at that temperature for 60 minutes to obtain a cured product.

  When the cross section of the cured product was processed and observed with a transmission electron microscope (TEM), the average particle size of the island components was 387 nm.

  From the S and N element mapping of the TEM-EELS spectroscopy measurement, it was confirmed that the S element derived from the polyether sulfone was mainly observed in the sea component. It was confirmed that the N element derived from the epoxy resin and the curing agent was mainly observed from the island component. From this, it was confirmed that the main component of the island component was a thermosetting resin and a curing agent, and the main component of the sea component was a thermoplastic resin.

  The glass transition temperature of the cured product was 238 ° C.

  A plate of the cured product (width 1 cm, length 5 cm, thickness 2 mm) was immersed in methyl ethyl ketone at 25 ° C. and left for 30 days. Thereafter, the cured product was taken out from the solvent and vacuum dried at 150 ° C. for 1 hour. There was no change in the appearance of the cured product after drying, and no change in mass was observed.

The above resin composition was applied onto a release film with a film coater to prepare a resin composition sheet with a release film having a basis weight of 51.2 g / m ² . Next, carbon fibers [Toho Tenax Co., Ltd .: Tenax (registered trademark) UTS-50] are arranged in parallel, sandwiched between two resin composition sheets, and heated at a temperature of 100 ° C. and a pressure of 0.3 MPa to obtain a resin composition. Impregnation between carbon fibers. As a result, a unidirectional prepreg having a carbon fiber basis weight of 190 g / m ² and a resin content of 35% by mass was obtained. The production of the prepreg was carried out continuously, the production speed was 5 m / min, and the production width was 50 cm.

Using this prepreg, a test piece made of a fiber-reinforced composite material was produced by the method described in the above test method. The fiber reinforced composite material specimen had an interlaminar fracture toughness (GIIC) of 4050 kJ / m ² and a post-impact compressive strength (CAI) of 527 MPa, both of which were high.

[Example 2]
10 parts by mass of polyethersulfone (Sumika Excel PES-5003P manufactured by Sumitomo Chemical Co., Ltd.) pulverized to an average particle size of 10 μm was added to 100 parts by mass of glycidylamine type epoxy resin (Ep604 manufactured by Japan Epoxy Resin Co., Ltd.), and 80 ° C. with a planetary mixer. To obtain an epoxy resin solution in which polyethersulfone is completely dissolved in Ep604.

^{From the 1} H-NMR method measurement, the polymer terminal of polyethersulfone was a hydroxyl group, and the mass average molecular weight estimated by GPC was 56100. That is, it was confirmed that the polymer had one hydroxyl group per mass average molecular weight 28050.

  In a roll mill set at 70 ° C., the total amount of the epoxy resin solution described above and 30 parts by mass of polyethersulfone pulverized to an average particle size of 10 μm were kneaded. The amount of polyethersulfone charged was 19.8% by mass relative to the total mass.

Next, 4,4′-diamino-3,3′-diethyl-5,5′-dimethyldiphenylmethane (Ihara Chemical Cure Hard MED) 60.7 parts by mass, 3,3′-diaminodiphenylsulfone 1 mass as a curing agent Parts were kneaded to obtain a resin composition. The viscosity of the resin composition at 80 ° C. and a shear rate of 1000 s ⁻¹ was 323 Pa · s. Note that 3,3′-diaminodiphenylsulfone also has characteristics as a compatibilizer for epoxy resin and polyethersulfone.

  This resin composition was charged into a mold, heated from room temperature to 180 ° C. at 3 ° C./min by an autoclave method, and then held at that temperature for 60 minutes to obtain a cured product.

  When the cross section of the cured product was processed and observed with a transmission electron microscope (TEM), the average particle size of the island components was 2.1 μm.

  From the S and N element mapping of the TEM-EELS spectroscopy measurement, it was confirmed that the S element derived from the polyether sulfone was mainly observed in the sea component. It was confirmed that the N element derived from the epoxy resin and the curing agent was mainly observed from the island component. From this, it was confirmed that the main component of the island component was a thermosetting resin and a curing agent, and the main component of the sea component was a thermoplastic resin.

  The glass transition temperature of the cured product was 239 ° C.

  A plate of the cured product (width 1 cm, length 5 cm, thickness 2 mm) was immersed in methyl ethyl ketone at 25 ° C. and left for 30 days. Thereafter, the cured product was taken out from the solvent and vacuum dried at 150 ° C. for 1 hour. There was no change in the appearance of the cured product after drying, and no change in mass was observed.

The above resin composition was applied onto a release film with a film coater to prepare a resin composition sheet with a release film having a basis weight of 51.2 g / m ² . Next, carbon fibers [Toho Tenax Co., Ltd .: Tenax (registered trademark) UTS-50] are arranged in parallel, sandwiched between two resin composition sheets, and heated at a temperature of 100 ° C. and a pressure of 0.3 MPa to obtain a resin composition. Impregnation between carbon fibers.

As a result, a unidirectional prepreg having a carbon fiber basis weight of 190 g / m ² and a resin composition content of 35% by mass was obtained. The production of the prepreg was carried out continuously, the production speed was 5 m / min, and the production width was 50 cm.

Using this prepreg, a test piece made of a fiber-reinforced composite material was produced by the method described in the above test method. The test specimen of the obtained fiber reinforced composite material had an interlaminar fracture toughness (GIIC) of 3250 kJ / m ² and a compressive strength after impact (CAI) of 437 MPa, both of which were high.

[Comparative Example 1]
7 parts by mass of polyethersulfone (Sumitomo Chemical Co., Ltd. Sumika Excel PES-5003P) pulverized to an average particle size of 10 μm was added to 100 parts by mass of a glycidylamine type epoxy resin (Ep604 manufactured by Japan Epoxy Resin Co., Ltd.). This mixture was kneaded at 80 ° C. with a planetary mixer to obtain an epoxy resin solution in which polyethersulfone was completely dissolved in Ep604.

^{From the 1} H-NMR method measurement, the polymer terminal of polyethersulfone was a hydroxyl group, and the mass average molecular weight estimated by GPC was 56100. That is, it was confirmed that the polymer had one hydroxyl group per mass average molecular weight 28050.

In a roll mill set at 70 ° C., 60.7 parts by mass of the above epoxy resin and 4,4′-diamino-3,3′-diethyl-5,5′-dimethyldiphenylmethane (Cure Hard MED manufactured by Ihara Chemical) as a curing agent; Were kneaded to obtain a resin composition. The amount of polyethersulfone charged was 4.2% by mass with respect to the total mass. The viscosity of the resin composition at 80 ° C. and a shear rate of 1000 s ⁻¹ was 9 Pa · s.

  This resin composition was charged into a mold, heated from room temperature to 180 ° C. at 3 ° C./min by an autoclave method, and then held at that temperature for 60 minutes to obtain a cured product.

  When the cross-section of the cured product was processed and observed with a transmission electron microscope (TEM), the average particle size of the island component was 1.5 μm.

  From the S and N element mapping of the TEM-EELS spectroscopy measurement, it was confirmed that the S element derived from the polyethersulfone was mainly observed in the island component. It was confirmed that the N element derived from the epoxy resin and the curing agent was mainly observed from the sea component. From this, unlike Example 1 and Example 2, Comparative Example 1 confirms that the main component of the island component is a thermoplastic resin and the main component of the sea component is a thermosetting resin and a curing agent. did.

  The glass transition temperature of the cured product was 243 ° C.

  A plate of the cured product (width 1 cm, length 5 cm, thickness 2 mm) was immersed in methyl ethyl ketone at 25 ° C. and left for 30 days. Thereafter, the cured product was taken out from the solvent and vacuum dried at 150 ° C. for 1 hour. There was no change in the appearance of the resin plate after drying, and no change in mass was observed.

The above resin composition was applied onto a release film by a film coater to prepare a resin composition sheet with a release film having a basis weight of 51.2 g / m ² . Next, carbon fibers [Toho Tenax Co., Ltd .: Tenax (registered trademark) UTS-50] are arranged in parallel, sandwiched between two resin composition sheets, and heated at a temperature of 100 ° C. and a pressure of 0.3 MPa to obtain a resin composition. Impregnation between carbon fibers. As a result, a unidirectional prepreg having a carbon fiber basis weight of 190 g / m ² and a resin composition content of 35% by mass was obtained. The production of the prepreg was carried out continuously, the production speed was 5 m / min, and the production width was 50 cm.

Using this prepreg, a test piece made of a fiber-reinforced composite material was produced by the method described in the above test method. The test specimen of the obtained fiber reinforced composite material has an interlaminar fracture toughness (GIIC) of 1020 kJ / m ² and a compressive strength after impact (CAI) of 258 MPa, both of which are lower than those of Examples 1 and 2. Met.

[Comparative Example 2]
65 parts by mass of a glycidylamine type epoxy resin (Ep604 made by Japan Epoxy Resin), 15 parts by mass of a bisphenol A type epoxy resin (Ep828 made by Japan Epoxy Resin), and 20 parts by mass of a urethane-modified epoxy resin (EPU-6 made by Adeka) 10 parts by mass of polyethersulfone (Sumitomo Chemical Co., Ltd. Sumika Excel PES-5003P) pulverized to an average particle size of 10 μm was added to the part. These were kneaded at 80 ° C. with a planetary mixer to obtain an epoxy resin solution in which polyethersulfone was completely dissolved in the epoxy resin.

^{From the 1} H-NMR method measurement, the polymer terminal of polyethersulfone was a hydroxyl group, and the mass average molecular weight estimated by GPC was 56100. That is, it was confirmed to have one hydroxyl group with respect to the mass average molecular weight 28050.

In a roll mill set at 70 ° C., the total amount of the epoxy resin solution described above and 25 parts by mass of polyethersulfone pulverized to an average particle size of 10 μm were kneaded. Thereafter, 45 parts by mass of microencapsulated 4,4′-diaminodiphenylsulfone having 10% by mass of melanin resin fine particles as a coating agent was kneaded to obtain a resin composition. The amount of polyethersulfone charged was 19.4% by mass relative to the total mass. The viscosity of the resin composition at 80 ° C. and a shear rate of 1000 s ⁻¹ was 498 Pa · s.

  This resin composition was charged into a mold, heated from room temperature to 180 ° C. at 3 ° C./min by an autoclave method, and then held at that temperature for 60 minutes to obtain a cured product.

  As a result of the transmission electron microscope of the cured product, the average particle size of the island component was 9.8 μm.

  From the S and N element mapping of the TEM-EELS spectroscopy measurement, it was confirmed that the S element derived from the polyethersulfone was mainly observed in the island component. It was confirmed that the N element derived from the epoxy resin and the curing agent was mainly observed from the sea component. From this, unlike Example 1 and Example 2, Comparative Example 2 confirms that the main component of the island component is a thermoplastic resin and the main component of the sea component is a thermosetting resin and a curing agent. did.

  The glass transition temperature of the cured product was 213 ° C.

  A plate of the cured product (width 1 cm, length 5 cm, thickness 2 mm) was immersed in methyl ethyl ketone at 25 ° C. and left for 30 days. Thereafter, the cured product was taken out from the solvent and vacuum dried at 150 ° C. for 1 hour. There was no change in the appearance of the resin plate after drying, and no change in mass was observed.

The above resin composition was applied onto a release film by a film coater to prepare a resin composition sheet with a release film having a basis weight of 51.2 g / m ² . Next, carbon fibers [Toho Tenax Co., Ltd .: Tenax (registered trademark) UTS-50] are arranged in parallel, sandwiched between two resin composition sheets, and heated at a temperature of 100 ° C. and a pressure of 0.3 MPa to obtain a resin composition. Impregnation between carbon fibers. As a result, a unidirectional prepreg having a basis weight of carbon fiber of 190 g / m ² and a resin composition content of 35% by mass was obtained.

The production of the prepreg was carried out continuously, the production speed was 5 m / min, and the production width was 50 cm. Using this prepreg, a test piece made of a fiber-reinforced composite material was produced by the method described in the above test method. The test specimen of the obtained fiber reinforced composite material has an interlaminar fracture toughness (GIIC) of 2203 kJ / m ² and a post-impact compressive strength (CAI) of 318 MPa, both of which are lower than those of Examples 1 and 2. Met.

[Comparative Example 3]
5 parts by mass of polyethersulfone (Sumitomo Chemical Co., Ltd., Sumika Excel PES-5003P) pulverized to an average particle size of 10 μm was added to 100 parts by mass of a glycidylamine type epoxy resin (Ep604 manufactured by Japan Epoxy Resin Co., Ltd.). These were kneaded at 80 ° C. with a planetary mixer to obtain an epoxy resin solution in which polyethersulfone was completely dissolved in Ep604.

^{From the 1} H-NMR method measurement, the polymer terminal of polyethersulfone was a hydroxyl group, and the mass average molecular weight estimated by GPC was 56100. That is, it was confirmed that the polymer had one hydroxyl group per mass average molecular weight 28050.

  The total amount of the epoxy resin solution described above and 33.4 parts by mass of polyethersulfone pulverized to an average particle size of 10 μm were kneaded with a roll mill set at 70 ° C. The amount of polyethersulfone charged was 20% by mass relative to the total mass.

4,4′-diamino-3,3′-diethyl-5,5′-dimethyldiphenylmethane (Cure Hard MED manufactured by Ihara Chemical) as a curing agent, 28.3 parts by mass, 3,3′-diaminodiphenylsulfone 24.9 parts by mass The parts were kneaded to obtain a resin composition. The viscosity of the resin composition at 80 ° C. and a shear rate of 1000 s ⁻¹ was 385 Pa · s.

  The resin composition was charged into a mold, heated from room temperature to 180 ° C. at 3 ° C./min by an autoclave method, and held at that temperature for 60 minutes to obtain a transparent cured product. When a cross-section of the cured product was processed and observed with a transmission electron microscope (TEM), no sea-island phase separation structure was observed.

[Comparative Example 4]
Polyethersulfone (Sumika Excel PES-5003P manufactured by Sumitomo Chemical Co., Ltd.) pulverized to an average particle size of 10 μm was press-molded to produce a resin plate having a width of 1 cm, a length of 5 cm, and a thickness of 2 mm.

  This resin plate was immersed in 25 ° C. methyl ethyl ketone and allowed to stand for 30 days. Thereafter, an attempt was made to remove the resin plate from the solvent, but most of it was dissolved, and the remaining part (about 10% by mass) was whitened and adhered to the container, and could not be recovered.

[Comparative Example 5]
5 parts by weight of polyethersulfone (Sumitomo Chemical Sumika Excel 3600P) pulverized to an average particle size of 10 μm was added to 100 parts by weight of glycidylamine type epoxy resin (Ep604 manufactured by Japan Epoxy Resin Co., Ltd.), and at 80 ° C. with a planetary mixer. By kneading, an epoxy resin solution in which polyethersulfone was completely dissolved in Ep604 was obtained.

^{From the 1} H-NMR method measurement, the polymer terminal of polyethersulfone was a hydroxyl group, and the mass average molecular weight estimated by GPC was 14,200. That is, it was confirmed that the polymer had one hydroxyl group per mass average molecular weight of 7,100.

  In a roll mill set at 70 ° C., 33.4 parts by mass of polyethersulfone pulverized to an average particle size of 10 μm was kneaded with the total amount of the epoxy resin solution described above. The amount of polyethersulfone charged was 20% by mass relative to the total mass.

Next, 28.3 parts by mass of 4,4′-diamino-3,3′-diethyl-5,5′-dimethyldiphenylmethane (Cure Hard MED manufactured by Ihara Chemical) as a curing agent, 3,3′-diaminodiphenylsulfone 24. 9 parts by mass was kneaded to obtain a resin composition. The viscosity of the resin composition at 80 ° C. and a shear rate of 1000 s ⁻¹ was 235 Pa · s.

  This cured product was charged into a mold, heated from room temperature to 180 ° C. at 3 ° C./min by an autoclave method, and held at that temperature for 60 minutes to obtain a transparent cured product. When a cross-section of the cured product was processed and observed with a transmission electron microscope (TEM), no sea-island phase separation structure was observed.

[Comparative Example 6]
10 parts by mass of polyethersulfone (Sumika Excel PES-5003P manufactured by Sumitomo Chemical Co., Ltd.) pulverized to an average particle size of 10 μm was added to 100 parts by mass of glycidylamine type epoxy resin (Ep604 manufactured by Japan Epoxy Resin Co., Ltd.), and 80 ° C. with a planetary mixer. To obtain an epoxy resin solution in which polyethersulfone is completely dissolved in Ep604.

^{From the 1} H-NMR method measurement, the polymer terminal of polyethersulfone was a hydroxyl group, and the mass average molecular weight estimated by GPC was 56100. That is, it was confirmed that the polymer had one hydroxyl group per mass average molecular weight 28050.

In a roll mill set at 70 ° C., the total amount of the above epoxy resin solution and 4,4′-diamino-3,3′-diethyl-5,5′-dimethyldiphenylmethane (Cure Hard MED manufactured by Ihara Chemical) 60.7 as a curing agent 2 parts by mass of 2,3 parts of 3,3′-diaminodiphenylsulfone and 240 parts by mass of polyethersulfone pulverized to an average particle size of 10 μm were kneaded to obtain a resin composition. The amount of polyethersulfone charged was 60.6% by mass relative to the total mass. The viscosity of the resin composition at 80 ° C. and a shear rate of 1000 s ⁻¹ was 9732 Pa · s.

This resin composition was charged into a mold, and after an increase in temperature from room temperature to 180 ° C. at room temperature by 3 ° C./min, an attempt was made to obtain a cured product by holding at that temperature for 60 minutes. It was not possible to obtain a cured product that could be evaluated by embedding the bubbles. Further, the above resin composition was applied on a release film with a film coater to produce a resin composition sheet with a release film having a basis weight of 51.2 g / m ^2. However, the resin composition has a high viscosity. Therefore, the resin film could not be manufactured.

Claims (11)

At least a thermosetting resin, a curing agent, a thermoplastic resin, and a compatibilizing agent that compatibilizes the thermoplastic resin and the thermosetting resin, and the island component is converted into the thermosetting by a curing reaction. A resin composition containing a reaction product of a resin, the curing agent, and the compatibilizer, wherein a sea component forms a sea-island phase separation structure containing the thermoplastic resin,
It said compatibilizing agent is a compound capable of curing by reacting with the thermosetting resin, the addition amount of the compatibilizer Ri 0.01 to 15% by mass relative to the total amount of the resin composition,
The thermosetting resin is an epoxy resin,
The thermoplastic resin is a polyethersulfone;
The resin composition, wherein the compatibilizer is diaminodiphenyl sulfone .   The resin composition according to claim 1, wherein the curing agent is 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane. 3. The resin composition according to claim 1, wherein the resin composition has a viscosity at 80 ° C. and a shear rate of 1000 s ⁻¹ of 10 to 1000 Pa · s. The resin composition according to any one of claims 1 to 3 , wherein the thermoplastic resin has a functional group capable of reacting with the thermosetting resin. The resin composition according to claim 4 , wherein the thermoplastic resin has a hydroxyl group, a carboxylic acid group, an imino group, or an amino group. The resin composition according to any one of claims 1 to 5 , comprising the thermoplastic resin in a blending ratio of 5 to 60% by mass of the total weight of the resin composition. A cured product having a sea-island phase separation structure obtained by a curing reaction of the resin composition according to claim 1,
The sea-island phase separation structure, the island component comprises a reaction product of the curing agent and the compatibilizer with the thermosetting resin, cured sea component comprises the thermoplastic resin. The cured product according to claim 7 , wherein an average particle diameter of a reaction product of the thermosetting resin, the curing agent, and the compatibilizing agent is 0.01 to 10 μm. The cured product according to claim 7 or 8 , wherein a glass transition temperature of the cured product is 150 ° C or higher.   A prepreg obtained by impregnating a reinforcing fiber with the resin composition according to claim 1. Fiber-reinforced composite material with the matrix resin cured product according to any one of claims 7 to 9.