JP2013142123A - Prepreg, and method for producing prepreg - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a prepreg capable of making a fiber-reinforced composite material excellent in impact resistance and interlayer toughness, and having excellent storage stability.SOLUTION: This prepreg 100 has: a primary prepreg 10 formed by impregnating into a reinforcing fiber base material 11, an epoxy resin composition [A] 13 containing at least a 5-50 pts.mass epoxy resin-soluble thermoplastic resin, and a 30-65 pts.mass curing agent other than a curing agent represented by formula NH-Ar-X-Ar'-NH, with respect to a 100 pts.mass epoxy resin; and a surface layer 16 comprising an epoxy resin composition [B] containing at least a 55-85 pts.mass aromatic diamine-based curing agent represented by the formula, and a 5-50 pts.mass epoxy resin-soluble thermoplastic resin, with respect to the 100 pts.mass epoxy resin.

Description

  The present invention relates to a prepreg and a prepreg manufacturing method.

  Fiber reinforced plastic (FRP) is a thermosetting resin such as unsaturated polyester resin and epoxy resin, and a thermoplastic resin matrix resin such as polyethylene, polypropylene, polyamide, polyphenylene sulfide (PPS), polyether ether ketone (PEEK), etc. And a fiber reinforced composite material comprising a fiber reinforcing material such as carbon fiber, glass fiber, and aramid fiber. Since fiber reinforced plastics are lightweight and have excellent strength characteristics, they have been used in a wide range of fields from the aerospace industry to general industrial fields in recent years, and the application areas of fiber reinforced plastics are expanding in the aircraft field. . In connection with this, the request | requirement of the mechanical characteristic improvement with respect to a fiber reinforced plastic is also increasing.

  Fiber-reinforced plastics are often manufactured using a prepreg obtained by impregnating a reinforcing fiber with a resin composition as an intermediate material. The prepreg is required to have excellent room temperature storage stability. When fiber-reinforced plastics are used in the aircraft field, prepregs are often manufactured by impregnating carbon fibers with an epoxy resin having a high degree of freedom in molding as a matrix resin. Generally, the cured epoxy resin has poor toughness and is brittle. Therefore, a fiber reinforced composite material using an epoxy resin as a matrix resin does not satisfy demands for improving mechanical properties due to impact resistance, interlayer toughness, and the like. Further, fiber reinforced plastics are also required to be improved in heat resistance and moist heat resistance so that mechanical properties do not deteriorate even under high temperature and high humidity conditions.

  As methods for solving these problems, Patent Documents 1 to 5 disclose a method for imparting toughness to an epoxy resin by blending a thermoplastic resin with the epoxy resin. These methods can improve the toughness of the epoxy resin, but cannot suppress the gradual progress of the curing reaction between the epoxy resin and the curing agent at room temperature. Therefore, the obtained prepreg has poor storage stability, and tackiness and draping properties deteriorate with time. Furthermore, the fiber reinforced composite material produced using the prepreg in which the curing reaction has proceeded excessively has defects such as the generation of many voids, and significantly reduces the mechanical properties of the composite structure. In addition, it is difficult to suppress deterioration of mechanical properties under high temperature and high humidity conditions.

  Patent Document 6 discloses a prepreg that uses an aromatic diamine having a specific structure as a part of a curing agent and gives good mechanical properties even in a high-temperature and high-humidity environment in combination with a thermoplastic resin. . However, the prepreg obtained by this method cannot suppress the reaction between the epoxy resin and the curing agent, and it is difficult to maintain good room temperature storage stability.

JP 60-243113 A JP 07-41575 A JP 07-41576 A JP 07-41577 A Japanese Patent Application Laid-Open No. 08-259713 JP 2010-275492 A

  The object of the present invention is to solve the above-mentioned problems of the prior art, and to produce a fiber-reinforced composite material having excellent mechanical properties such as impact resistance and interlayer toughness and wet heat resistance, and excellent storage stability, and its production It is to provide a method.

This inventor came to produce the prepreg which contains each hardening | curing agent in the state isolate | separated using the epoxy resin composition [A] and epoxy resin composition [B] which each contain a different hardening | curing agent. . The prepreg of the present invention described below is laminated on the surface of the primary prepreg using a primary prepreg obtained by impregnating a reinforcing fiber substrate with an epoxy resin composition [A] and the epoxy resin composition [B]. And a surface layer.
[1] A primary prepreg obtained by impregnating an epoxy resin composition [A] into a sheet-like reinforcing fiber base, and at least one surface of the primary prepreg, the following formula (1)

(In Formula (1), X represents —CH ₂ —, —CH (CH ₃ ) —, —C (CH ₃ ) ₂ —, and Ar—NH ₂ and Ar′—NH ₂ represent the following formulas ( Represents any one of the structures of 2) to (9).

(R ₁ and R ₂ in the above formulas (2) to (9) each represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.)
And a surface layer made of an epoxy resin composition [B] containing an aromatic diamine-based curing agent represented by: The epoxy resin composition [A] is based on 100 parts by mass of the epoxy resin, An epoxy resin composition containing at least 5 to 50 parts by mass of an epoxy resin-soluble thermoplastic resin and 30 to 65 parts by mass of a curing agent other than the curing agent represented by the above formula (1), the epoxy resin The composition [B] is at least 55 to 85 parts by mass of the aromatic diamine-based curing agent represented by the above formula (1) and 5 to 50 parts by mass of the epoxy resin-soluble thermoplastic resin with respect to 100 parts by mass of the epoxy resin. A prepreg which is an epoxy resin composition containing
[2] The prepreg according to [1], wherein the curing agent contained in the epoxy resin composition [A] is 4,4′-diaminodiphenylsulfone and / or 3,3′-diaminodiphenylsulfone.
[3] The prepreg according to [1] or [2], wherein the epoxy resin composition [B] contains the same epoxy resin as that contained in the epoxy resin composition [A].
[4] At least a cured product of the epoxy resin composition [B] has a sea-island phase separation structure, and the sea-island phase separation structure is an epoxy resin-soluble heat containing a sea component in the epoxy resin composition [B]. The prepreg according to any one of [1] to [3], including a plastic resin and including, as an island component, at least a reaction product of an epoxy resin and a curing agent contained in the epoxy resin composition [B].
[5] The prepreg according to [4], wherein the island component has an average particle size of 0.01 to 10 μm.
[6] At least one of the epoxy resin-soluble thermoplastic resins contained in the epoxy resin composition [B] has a functional group capable of forming a hydrogen bond with the epoxy resin. Prepreg.
[7] Any one of [1] to [6], wherein at least the epoxy resin-soluble thermoplastic resin contained in the epoxy resin composition [B] has a hydroxyl group, a carboxylic acid group, an imino group, or an amino group. The prepreg as described.
[8] The prepreg according to any one of claims 1 to 7, wherein the epoxy resin composition [A] further contains 5 to 60 parts by mass of an epoxy resin-insoluble thermoplastic resin with respect to 100 parts by mass of the epoxy resin. .
[9] The epoxy resin-insoluble thermoplastic resin contained in the epoxy resin composition [A] is any one of amorphous nylon, nylon 6, nylon 12, and amorphous polyimide. Prepreg.
[10] The epoxy resin composition [A] and the epoxy resin composition contained in the prepreg as a compatibilizer for compatibilizing the epoxy resin and the epoxy resin-soluble thermoplastic resin in the epoxy resin composition [B]. The prepreg according to any one of [1] to [9], which is contained in an amount of 0.01 to 15 parts by mass with respect to 100 parts by mass of the total amount of [B].
[11] At least one surface of a reinforcing fiber layer formed by forming the reinforcing fiber base into a sheet shape, at least 5 to 50 parts by mass of an epoxy resin-soluble thermoplastic resin with respect to 100 parts by mass of the epoxy resin, and the following formula (1)

(In Formula (1), X represents —CH ₂ —, —CH (CH ₃ ) —, —C (CH ₃ ) ₂ —, and Ar—NH ₂ and Ar′—NH ₂ represent the following formulas ( Represents any one of the structures of 2) to (9).

(R ₁ and R ₂ in the above formulas (2) to (9) each represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms) 30 to 65 parts by mass of a curing agent other than the curing agent represented by And an epoxy resin composition [A] sheet containing, and the first laminated body obtained is heated and pressurized to impregnate the epoxy resin composition [A] into the reinforcing fiber layer. The primary prepreg manufacturing step for obtaining the next prepreg, and at least one surface of the primary prepreg, at least on the surface of 100 parts by mass of the epoxy resin, the aromatic diamine-based curing agent 55 represented by the above formula (1) is provided. A step of laminating the epoxy resin composition [B] sheet containing ~ 85 parts by mass and 5 to 50 parts by mass of an epoxy resin-soluble thermoplastic resin, and heating and pressurizing the obtained second laminate. 1] to [10 Method for producing a prepreg according to any one of.

  In the prepreg of the present invention, at least two kinds of curing agents are blended, and each curing agent is blended separately in the prepreg, so that significant improvement in storage stability such as tackiness and drapeability is recognized. Moreover, the fiber reinforced composite material produced using the prepreg of the present invention is excellent in mechanical properties such as impact resistance and interlayer toughness, and is excellent in wet heat resistance.

It is a section conceptual diagram of the prepreg of the present invention. It is a section conceptual diagram of the primary prepreg which constitutes the prepreg of the present invention. In FIG. 2, FIG. 2 (a) is a cross-sectional conceptual diagram of the reinforcing fiber sheet before impregnating the epoxy resin composition [A]. FIG. 2B is a conceptual cross-sectional view of a primary prepreg obtained by impregnating a reinforcing fiber sheet with an epoxy resin composition [A]. FIG.2 (c) is a cross-sectional conceptual diagram which shows the 2nd laminated body which has arrange | positioned the epoxy resin composition [B] sheet | seat on the surface of a primary prepreg. It is a conceptual diagram which shows an example of the manufacturing process of the prepreg of this invention.

  Hereinafter, the details of the prepreg of the present invention will be described.

(1) Prepreg The prepreg of the present invention has a primary prepreg formed by impregnating the reinforcing fiber base sheet with the epoxy resin composition [A]. A surface layer made of the epoxy resin composition [B] is formed integrally with the primary prepreg on at least one surface of the primary prepreg.

  FIG. 1 is a conceptual cross-sectional view of a prepreg 100 of the present invention in which surface layers are formed on both front and back surfaces. 10 is a primary prepreg, and 16 is a surface layer of a prepreg 100 made of an epoxy resin composition [B]. In the primary prepreg 10, 11 is a reinforcing fiber, and 13 is an epoxy resin composition [A] impregnated in a sheet made of the reinforcing fiber 11.

  The mass ratio of the epoxy resin contained in the epoxy resin composition [A] used for the primary prepreg and the epoxy resin contained in the epoxy resin composition [B] used for the surface layer is 1: 1 to 9: 1. Preferably there is.

  The epoxy resin composition [B] contains a predetermined aromatic diamine-based curing agent. The epoxy resin composition [A] contains a curing agent different from the curing agent contained in the epoxy resin composition [B]. That is, the predetermined aromatic diamine-based curing agent is mainly contained in the surface layer 16 of the prepreg 100, and the curing agent other than the predetermined aromatic diamine-based curing agent is mainly contained in the sheet composed of the reinforcing fibers of the prepreg 100. Contained. The content of each curing agent is adjusted to an appropriate amount for curing all epoxy resins contained in the epoxy resin composition [A] and the epoxy resin composition [B] according to the type of epoxy resin and curing agent used. .

  The prepreg of the present invention is remarkably improved in storage stability. The reason is not clear, but the prepreg contains the curing agent contained in the epoxy resin composition [A] and the curing agent contained in the epoxy resin composition [B] in a separated state. Conceivable.

  When two curing agents are contained without being separated, one curing agent dissolves in the epoxy resin, and acts as a compatibilizer between the other curing agent and the epoxy resin, thereby dissolving the epoxy resin. The properties may change, and the amount of the other curing agent dissolved may increase significantly, and the curing reaction may proceed. When each curing agent is contained in a separated state, it is presumed that an increase in the amount of such curing agent dissolved can be suppressed.

  In the prepreg of the present invention, the content of reinforcing fibers is preferably 40 to 80% by mass, particularly preferably 50 to 70% by mass, with the total mass of the prepreg being 100% by mass. When the content of the reinforcing fiber is less than 40% by mass, the strength of the composite produced using this prepreg is insufficient. When the reinforcing fiber content exceeds 80% by mass, the amount of the matrix resin impregnated in the reinforcing fiber layer of the prepreg is insufficient, so that generation of voids in the resulting composite cannot be sufficiently suppressed.

(2) Primary prepreg The primary prepreg constituting the present invention can be obtained by impregnating an epoxy resin composition [A] described later into the voids of a sheet-like fiber reinforced base material. FIG. 2A is a conceptual cross-sectional view showing a first laminate in which the epoxy resin composition [A] sheet 13 and the reinforcing fiber sheet 12 before impregnating the epoxy resin composition [A] sheet 13 are arranged. It is. FIG. 2B is a conceptual cross-sectional view of the primary prepreg 10 obtained by impregnating the reinforcing fiber sheet 12 with the epoxy resin composition [A] sheet 13. FIG. 2C is a conceptual cross-sectional view showing a second laminate in which the epoxy resin composition [B] sheet 15 is arranged on the surface 10 a of the primary prepreg 10. In the prepreg of the present invention, the epoxy resin composition [B] sheet 15 is disposed on the surface 10 a of the primary prepreg 10, heated and pressed, and the epoxy resin composition [B] sheet is applied to the surface 10 a of the primary prepreg 10. The surface layer 16 is formed by thermocompression bonding 15 (FIG. 1).

(2-1) Reinforcing fiber substrate Examples of reinforcing fibers used in the reinforcing fiber substrate sheet of the primary prepreg include, for example, carbon fibers, glass fibers, aramid fibers, silicon carbide fibers, polyester fibers, ceramic fibers, alumina fibers, Boron fibers, metal fibers, mineral fibers, rock fibers and slug fibers can be used. Among these reinforcing fibers, carbon fibers, glass fibers, and aramid fibers are preferable, carbon fibers that provide a lightweight and high-strength fiber-reinforced composite material with favorable specific strength and specific elastic modulus are more preferable, and are excellent in tensile strength. Acrylonitrile (PAN) based carbon fibers are particularly preferred.

When PAN-based carbon fiber is used as the reinforcing fiber, the tensile elastic modulus is preferably 170 to 600 GPa, and particularly preferably 220 to 450 GPa. The tensile strength is preferably 3920 MPa (400 kgf / mm ² ) or more. By using such a carbon fiber, the mechanical properties of the composite can be improved.

  As the reinforcing fiber base sheet, for example, a sheet-like product in which a large number of reinforcing fibers and reinforcing fiber bundles are aligned in one direction, bi-directional woven fabrics such as plain weave and twill weave, multiaxial woven fabric, non-woven fabric, mat, knit, Examples include braided paper and paper made of reinforcing fibers. The thickness of the sheet is preferably 0.01 to 3 mm, and more preferably 0.1 to 1.5 mm. These reinforcing fiber base sheets include a case where a known sizing agent is contained in a known content.

(2-2) Epoxy resin composition [A]
The epoxy resin composition [A] comprises at least an epoxy resin, an epoxy resin-soluble thermoplastic resin, and a curing agent other than the aromatic diamine-based curing agent contained in the epoxy resin composition [B] described later. An epoxy resin-insoluble thermoplastic resin may be further added to the epoxy resin composition [A]. Hereinafter, each component of the epoxy resin composition [A] will be described.

(2-2-1) Epoxy Resin The epoxy resin contained in the epoxy resin composition [A] is a conventionally known epoxy resin. Among known epoxy resins, an epoxy resin having an aromatic group in the molecule is preferably used, and an epoxy resin having either a glycidylamine structure or a glycidyl ether structure is preferable. Moreover, an alicyclic epoxy resin can also be used suitably.

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

  Examples of the epoxy resin containing a 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.

  These epoxy resins may have a non-reactive substituent in the aromatic ring structure or the like as necessary. Examples of non-reactive substituents include alkyl groups such as methyl, ethyl and isopropyl, aromatic groups such as phenyl, alkoxyl groups, aralkyl groups, and halogen groups such as chlorine and bromine. These epoxy resins may be used independently and may use 2 or more types together.

(2-2-2) Curing Agent As the curing agent contained in the epoxy resin composition [A], the aromatic diamine curing agent contained in the epoxy resin composition [B] described later is not used. That is, a known curing agent other than the curing agent represented by the following formula (1) is used.

(X represents —CH ₂ —, —CH (CH ₃ ) —, —C (CH ₃ ) ₂ —, and Ar—NH ₂ and Ar′—NH ₂ represent the following formulas (2) to (9) Represents one of the structures.)

(R ₁ and R ₂ in the above formulas (2) to (9) each represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.)
By using a curing agent different from the aromatic diamine curing agent contained in the epoxy resin composition [B], rather than using the aromatic diamine curing agent contained in the epoxy resin composition [B] alone, It is possible to suppress the change with time of the obtained prepreg, and to further improve the heat resistance and mechanical properties of the cured prepreg.

  Specific examples of the curing agent contained in the epoxy resin composition [A] include 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, and mixtures thereof that give excellent mechanical properties. preferable. 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 an epoxy 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.

  It is preferable that content of the hardening | curing agent contained in an epoxy resin composition [A] is 30-65 mass parts with respect to 100 mass parts of epoxy resins contained in an epoxy resin composition [A].

  Moreover, the total content of the curing agent contained in the epoxy resin composition [A] and the epoxy resin composition [B] is the total content contained in the epoxy resin composition [A] and the epoxy resin composition [B]. It is sufficient that the amount is sufficient to cure the epoxy resin, and is appropriately adjusted depending on the type of the epoxy resin and the curing agent.

(2-2-3) Thermoplastic resin The epoxy resin composition [A] contains at least an epoxy resin-soluble thermoplastic resin. Furthermore, it is preferable to contain an epoxy resin insoluble thermoplastic resin. A conventionally well-known thing can be used for the epoxy resin soluble thermoplastic resin and epoxy resin insoluble thermoplastic resin which are contained in an epoxy resin composition [A].

  The epoxy resin-soluble thermoplastic resin is a thermoplastic resin that can be partially or wholly dissolved in the epoxy resin by heating or the like. The epoxy resin-insoluble thermoplastic resin is a thermoplastic resin that does not dissolve in the epoxy resin even when subjected to a treatment such as heating. The fact that the thermoplastic resin does not dissolve in the epoxy resin means that the particle size changes when the thermoplastic resin is put into the epoxy resin and stirred at a processing temperature of 100 to 190 ° C., which is a processing temperature at the time of general composite molding. When not.

  By containing a thermoplastic resin, toughness can be imparted to the epoxy resin composition [A], and the impact resistance of the resulting composite can be improved.

  The epoxy resin-soluble thermoplastic resin can be dissolved in the epoxy resin during the curing process of the epoxy resin composition [A] to increase the viscosity of the epoxy resin composition [A]. Thereby, the flow of epoxy resin composition [A] by the viscosity fall which arises in a hardening process can be prevented.

(2-2-3a) Epoxy resin-soluble thermoplastic resin Epoxy resin-soluble thermoplastic resin is soluble in the curing process, imparted toughness to the composite material obtained after curing, chemical resistance, heat resistance, and moist heat resistance. In this respect, those containing a reactive group reactive with an epoxy resin or a functional group forming a hydrogen bond are preferred. The reactive group having reactivity with the epoxy resin preferably has a functional group such as a hydroxyl group, a carboxylic acid group, an imino group, and an amino group. Examples of the epoxy resin-soluble thermoplastic resin include polyethersulfone, polysulfone, polyetherimide, and polycarbonate. These may be used alone or in combination of two or more.

  The content of the epoxy resin-soluble thermoplastic resin contained in the epoxy resin composition [A] is appropriately adjusted according to the viscosity of the primary prepreg. From the viewpoint of workability of the primary prepreg, 5 to 50 parts by mass is preferable with respect to 100 parts by mass of the epoxy resin contained in the epoxy resin composition [A].

  Moreover, 5-40 mass parts is preferable and, as for content of the epoxy resin soluble thermoplastic resin with respect to 100 mass parts of all the epoxy resins contained in an epoxy resin composition [A] and an epoxy resin composition [B], 15-35. Part by mass is more preferable. If the amount is less than 5 parts by mass, the resulting fiber-reinforced composite material may have insufficient impact resistance. When it exceeds 40 mass parts, a viscosity may become remarkably high and a handleability may deteriorate remarkably.

  The shape of the epoxy resin-soluble thermoplastic resin blended when producing the epoxy resin composition [A] is not particularly limited, but it is homogeneously blended in the epoxy resin composition, and the resulting prepreg has good moldability. It is preferable that it is a particulate form so that can be exhibited.

  The average particle diameter of the epoxy resin-soluble thermoplastic resin particles is preferably 1 to 50 μm, and more preferably 3 to 30 μm. If it is smaller than 1 μm, the bulk density increases, and the viscosity of the epoxy resin composition may increase significantly, or it may be difficult to add a sufficient amount. When it is larger than 50 μm, it may be difficult to produce a sheet with a uniform thickness when the resulting epoxy resin composition is formed into a sheet shape to be described later.

  The epoxy resin composition [A] in the present invention, like the epoxy resin composition [B] described later, has a reaction product of an epoxy resin and a curing agent as an island component in the course of its curing reaction, and is an epoxy resin-soluble thermoplastic. It is preferable to form a sea-island phase separation structure containing resin as a sea component.

(2-2-3b) Epoxy Resin Insoluble Thermoplastic Resin The epoxy resin insoluble thermoplastic resin is an island component of the sea-island phase separation structure that is formed when the epoxy resin composition [A] produces a composite.

  Epoxy resin-insoluble thermoplastic resin particles are dispersed as interlayer particles in a composite matrix resin produced using the prepreg of the present invention. The interlayer particles absorb the impact from the outside of the composite, suppress the propagation of the impact, and improve the impact resistance of the composite. The interlayer particles are preferably present in an amount of 5 to 60 parts by mass with respect to 100 parts by mass of the total epoxy resin in the composite.

  The average particle diameter of the epoxy resin-insoluble thermoplastic resin particles is preferably 1 to 50 μm, and more preferably 3 to 30 μm. When the average particle size is smaller than 1 μm, the bulk density is increased, the viscosity of the epoxy resin composition is remarkably increased, and the handleability is lowered. In addition, the epoxy resin-insoluble thermoplastic resin particles enter the reinforcing fiber base material and stay inside the base material, and cannot function as interlayer particles. If it is larger than 50 μm, it may be difficult to produce the sheet with a uniform thickness when the epoxy resin composition [A] is formed into a sheet.

  Examples of epoxy resin insoluble thermoplastic resins include polyamide, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyester, polyamideimide, polyimide, polyetherketone, polyetheretherketone, polyethylene naphthalate, polyaramid, polyethernitrile, and polybenzimidazole. Is done. Among these, polyamide, polyamideimide, and polyimide are preferable because of high toughness and good heat resistance. These may be used alone or in combination of two or more. Moreover, these copolymers can also be used. For example, polyimide and polyamide are particularly excellent in the effect of imparting toughness to the composite.

  In particular, amorphous polyimide, nylon 6 (registered trademark) (polyamide obtained by ring-opening polycondensation reaction of caprolactam), nylon 12 (polyamide obtained by ring-opening polycondensation reaction of lauryl lactam), amorphous nylon By using a polyamide such as (also called transparent nylon, which does not cause crystallization of the polymer or has a very low crystallization rate of the polymer), the heat resistance of the obtained composite can be improved.

  The shape of the epoxy resin-insoluble thermoplastic resin is not particularly limited, but is preferably in the form of particles so that the epoxy resin composition is homogeneously blended and the obtained prepreg can maintain good moldability.

  The content of the epoxy resin-insoluble thermoplastic resin contained in the epoxy resin composition [A] is appropriately adjusted according to the viscosity of the primary prepreg. From the viewpoint of workability of the primary prepreg, 5 to 60 parts by mass is preferable with respect to 100 parts by mass of the epoxy resin contained in the epoxy resin composition [A].

  Moreover, 10-45 mass parts is preferable with respect to 100 mass parts of all the epoxy resins contained in epoxy resin composition [A] and epoxy resin composition [B], and 20-45 mass parts is more preferable. When the amount is less than 10 parts by mass, the resulting composite may not have sufficient impact resistance. When it exceeds 45 mass parts, the impregnation property of an epoxy resin composition [A], the drape property of a prepreg, etc. may be reduced.

(2-2-4) Other components The epoxy resin composition [A] of the present invention contains an epoxy resin, a curing agent, and an epoxy resin-soluble thermoplastic resin as essential components. A hardening | curing agent is selected from hardening | curing agents other than the predetermined | prescribed aromatic diamine type hardening | curing agent contained in the epoxy resin composition [B] mentioned later. In addition to the above essential components, it is preferable to further contain an epoxy resin-insoluble thermoplastic resin. In addition, curing acceleration of amine compounds such as tertiary amines and imidazoles, phosphines, phosphorus compounds such as phosphonium, N, N-dimethylurea derivatives, etc., as appropriate, as long as they do not hinder the purpose and effect of the present invention Various additives such as an agent, a reactive diluent, a filler, an antioxidant, a flame retardant, and a pigment may be contained.

(3) Surface layer (epoxy resin composition [B])
The surface layer of the prepreg of the present invention is composed of the epoxy resin composition [B] and is formed on at least one surface of the primary prepreg.

(3-1) Epoxy resin composition [B]
The epoxy resin composition [B] includes at least an epoxy resin, a predetermined aromatic diamine-based curing agent, and an epoxy resin-soluble thermoplastic resin.

(3-1-1) Epoxy resin As the epoxy resin contained in the epoxy resin composition [B], a conventionally known epoxy resin can be used. In order for the resulting composite to exhibit excellent mechanical properties, an epoxy resin containing an aromatic group is preferably used, and an epoxy resin containing either a glycidylamine structure or a glycidyl ether structure is preferred. Moreover, an alicyclic epoxy resin can also be used suitably. These epoxy resins may be used independently and may use 2 or more types together.

In order to adhere the primary prepreg and the surface layer well, it is preferable to use the same epoxy resin as the epoxy resin contained in the epoxy resin composition [A].
(3-1-2) Aromatic diamine-based curing agent The curing agent contained in the epoxy resin composition [B] is an aromatic diamine represented by the following formula (1).

Here, X represents —CH ₂ —, —CH (CH ₃ ) —, —C (CH ₃ ) ₂ —, and Ar—NH ₂ and Ar′—NH ₂ represent the following formulas (2) to ( It represents one of the structures of 9).

R ₁ and R ₂ in the above formulas (2) to (9) each represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. A part of the alkyl group may contain a non-reactive ether group, a non-reactive halogen, or a tertiary amine.

The aromatic diamine-based curing agent preferably contains a methyl group, an ethyl group, and an isopropyl group from the viewpoints of curability of the epoxy resin composition, storage stability, and heat resistance of the cured product. In particular, in the above formula (1), X is —CH ₂ —, and Ar—NH ₂ and Ar′—NH ₂ are preferably formula (3).

  Specifically, diaminodiphenylmethane (DDM), 4,4′-diamino-3,3 ′, 5,5′-tetraethyldiphenylmethane (for example, KAYABODC-300S manufactured by Nippon Kayaku Co., Ltd., M-DEA manufactured by Lonza Japan) 4,4′-diamino-3,3′-diethyl-5,5′-dimethyldiphenylmethane (for example, Cure Hard MED manufactured by Ihara Chemical Industry Co., Ltd.), 4,4′-diamino-3,3 ′, 5,5 '-Tetraisopropyldiphenylmethane (for example, M-DIPA manufactured by Lonza Japan Ltd.) and the like can be mentioned.

  It is preferable that content of this aromatic diamine type hardening | curing agent is 55-85 mass parts with respect to 100 mass parts of epoxy resins contained in an epoxy resin composition [B].

  The total content of curing agents contained in the epoxy resin composition [A] and the epoxy resin composition [B] is the total epoxy resin contained in the epoxy resin composition [A] and the epoxy resin composition [B]. It is sufficient if the amount is sufficient to cure the resin, and is appropriately adjusted depending on the type of epoxy resin or curing agent.

  For example, a glycidylamine type epoxy resin and 3,3′-diaminodiphenylsulfone as a curing agent are used for the epoxy resin composition [A], and a glycidylamine type epoxy resin is used for the epoxy resin composition [B]. As a curing agent, 4,4′-diamino-3,3′-diethyl-5,5′-dimethyldiphenylmethane may be used. In this case, it is contained in the epoxy resin composition [A] and the epoxy resin composition [B] with respect to the epoxy equivalent of all the epoxy resins contained in the epoxy resin composition [A] and the epoxy resin composition [B]. The ratio of active hydrogen equivalents (active hydrogen equivalents / epoxy equivalents) of all the curing agents is preferably 0.50 to 0.95, and more preferably 0.60 to 0.90.

  In addition, in said example, Japan Epoxy Resin Epicoat 604 is illustrated as a glycidyl amine type epoxy resin. Examples of 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane include Cure Hard MED manufactured by Ihara Chemical Industry.

(3-1-3) Epoxy resin-soluble thermoplastic resin The epoxy resin-soluble thermoplastic resin contained in the epoxy resin composition [B] is an epoxy resin composition such as polyethersulfone, polysulfone, polyetherimide, and polycarbonate [ Those exemplified as the epoxy resin-soluble thermoplastic resin that can be contained in A] can be similarly used. The same thing as what is contained in an epoxy resin composition [A] may be used, and may differ. These may be used alone or in combination of two or more.

  The content of the epoxy resin-soluble thermoplastic resin contained in the epoxy resin composition [B] is preferably 5 to 50 parts by mass with respect to 100 parts by mass of the epoxy resin contained in the epoxy resin composition [B]. More preferred is 40 parts by weight. When the amount is less than 5 parts by mass, the resulting prepreg and the fiber reinforced composite material may have insufficient impact resistance. When the amount exceeds 50 parts by mass, the viscosity of the prepreg may be remarkably increased and the handleability may be significantly deteriorated.

  Epoxy resin-soluble thermoplastic resins contain reactive groups that are reactive with epoxy resins in terms of dissolution stability during curing, imparting toughness to composite materials, chemical resistance, heat resistance, and moist heat resistance. Is preferred. The reactive group having reactivity with the epoxy resin preferably has a functional group such as a hydroxyl group, a carboxylic acid group, an imino group, and an amino group. Examples of the epoxy resin-soluble thermoplastic resin include polyethersulfone, polysulfone, polyetherimide, and polycarbonate. These may be used alone or in combination of two or more.

  The cured product of the epoxy resin composition [B] that forms the surface layer of the prepreg of the present invention has a sea-island phase separation structure. Preferably, the epoxy resin composition [B] shows a so-called LCST (lower critical solution temperature) phase diagram. In the low temperature region of the LCST phase diagram, the epoxy resin and the epoxy resin-soluble thermoplastic resin are compatible. In the high temperature range, with the increase in the molecular weight of the epoxy resin due to the cross-linking reaction, the two-phase range expands and the compatible range 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 epoxy resin composition [B], and at least inside the surface layer of the prepreg of the present invention, preferably all epoxy contained in the prepreg including the epoxy resin composition [A] By curing the resin composition, a sea-island phase separation structure is formed. Such a sea-island phase separation structure contributes to an improvement in impact resistance of the composite.

  In order to form a sea-island phase separation structure showing an LCST type phase diagram, it is preferable that the epoxy resin-soluble thermoplastic resin forms a hydrogen bond with the epoxy resin. Epoxy resins and curing agents have atoms with large electronegativity such as nitrogen, oxygen, sulfur, and halogen in the molecule. Accordingly, in order to form a hydrogen bond between an epoxy resin or the like and an epoxy resin-soluble thermoplastic resin, the epoxy resin-soluble thermoplastic resin has a functional group that easily forms a hydrogen bond with an atom having a large electronegativity. It is preferable. Through such a functional group, the epoxy resin-soluble thermoplastic resin composition is bonded to a curing agent or an epoxy resin dissolved in the epoxy resin-soluble thermoplastic resin.

  Accordingly, in the present invention, at least the epoxy resin-soluble thermoplastic resin contained in the epoxy resin composition [B] has a functional group such as a hydroxyl group, a carboxylic acid group, an imino group, and an amino group that easily forms a hydrogen bond with the epoxy resin. It preferably has a group, and more preferably has a hydroxyl group. The epoxy resin composition [B] of the present invention easily forms a sea-island phase separation structure showing an LCST type phase diagram by using such an epoxy resin-soluble thermoplastic resin. That is, when a composite material is manufactured with a prepreg using the epoxy resin composition [B], the epoxy resin composition [B] forms a sea-island phase separation structure in the course of its curing reaction. The island component includes a reaction product of an epoxy resin and a curing agent, and the sea component includes an epoxy resin-soluble thermoplastic resin.

  In the formed sea-island phase separation structure, the sea component contains an epoxy resin-soluble thermoplastic resin. The composite material obtained by curing the prepreg of the present invention is excellent in impact strength and bending / tensile strength properties, and the low toughness derived from the epoxy resin is remarkably improved.

  The main component of the island component is a reaction product of an epoxy resin and a curing agent. The average particle size of the island component is preferably 0.01 to 10 μm, more preferably 0.01 to 5 μm, still more preferably 0.01 to 1 μm, and particularly preferably 0.01 to 5 μm. 0.6 μm. When the average particle size of the island component is less than 0.01 μm, the viscosity of the epoxy resin composition [B] is increased, which adversely affects processability. On the other hand, when the average particle size of the island component exceeds 10 μm, the viscosity of the resin composition is lowered and the processability is improved, but the mechanical properties, heat resistance, adhesiveness, dimensional stability, and chemical resistance of the cured product are improved. This is not preferable because it is significantly reduced. In the present invention, the average particle size of the island component is a compatibilizer for compatibilizing the epoxy resin and the thermoplastic resin, curing conditions such as the viscosity adjustment of the epoxy resin composition [B], the rate of temperature rise during curing, and the like. It can be controlled by addition.

  Although the kind of compatibilizer is not particularly limited, a compound having a chemical structure close to the monomer unit of the epoxy resin-soluble thermoplastic resin is preferable. Alternatively, it is more preferable to use an epoxy resin curing agent as the compatibilizing agent so that the compatibilizing agent does not remain as an uncured product in the curing of the epoxy resin composition [B].

  The amount of the compatibilizer added to the epoxy resin composition [B] varies depending on the types of the epoxy resin and the epoxy resin-soluble thermoplastic resin, but the epoxy resin composition [A] and the epoxy resin composition contained in the prepreg. It is preferable that it is 0.01-15 mass parts with respect to 100 mass parts of total amounts of [B].

  The compatibilizer added to the epoxy resin composition [B] is also dispersed in the epoxy resin composition [A] due to an increase in fluidity of the resin by heating during the curing reaction. ] Can also act against. The addition amount of the compatibilizer for controlling the average particle size of the island component in the cured product of the epoxy resin composition [B] to 0.01 to 10 μm is approximately 0.05 to 10 parts by mass, and 0.1 -3 mass parts is more preferable. If the addition amount of the compatibilizer is less than 0.01 parts by mass, the epoxy resin and the epoxy resin-soluble thermoplastic resin cannot be sufficiently compatible, and the average particle size of the island component may exceed 10 μm. . When the addition amount of the compatibilizer exceeds 15 parts by mass, the compatibility between the epoxy resin and the epoxy resin-soluble thermoplastic resin becomes too high, and the both are completely compatible, making it impossible to form a sea-island phase separation structure. Therefore, it is not preferable.

  The content of the epoxy resin-soluble thermoplastic resin contained in the epoxy resin composition [B] is appropriately adjusted according to the viscosity of the epoxy resin composition [B]. From the viewpoint of workability of the epoxy resin composition [B], 5 to 50 parts by mass is preferable with respect to 100 parts by mass of the epoxy resin contained in the epoxy resin composition [B].

  Moreover, 5-40 mass parts is preferable and, as for content of the epoxy resin soluble thermoplastic resin with respect to 100 mass parts of all the epoxy resins contained in an epoxy resin composition [A] and an epoxy resin composition [B], 15-35. Part by mass is more preferable. If the amount is less than 5 parts by mass, the resulting fiber-reinforced composite material may have insufficient impact resistance. When it exceeds 40 mass parts, a viscosity may become remarkably high and a handleability may deteriorate remarkably.

  The shape of the epoxy resin-soluble thermoplastic resin blended when producing the epoxy resin composition [B] is not particularly limited, but it is homogeneously blended in the epoxy resin composition, and the resulting prepreg has good moldability. It is preferable that it is a particulate form so that can be exhibited.

  The average particle diameter of the epoxy resin-soluble thermoplastic resin particles is preferably 1 to 50 μm, and more preferably 3 to 30 μm. If it is smaller than 1 μm, the bulk density increases, and the viscosity of the epoxy resin composition may increase significantly, or it may be difficult to add a sufficient amount. When it is larger than 50 μm, it may be difficult to produce a sheet with a uniform thickness when the resulting epoxy resin composition is formed into a sheet shape to be described later.

(3-1-4) Other components The epoxy resin composition [B] of the present invention contains an epoxy resin, a predetermined aromatic diamine-based curing agent, and an epoxy resin-soluble thermoplastic resin as essential components. In addition, curing acceleration of amine compounds such as tertiary amines and imidazoles, phosphines, phosphorus compounds such as phosphonium, N, N-dimethylurea derivatives, etc., as appropriate, as long as they do not hinder the purpose and effect of the present invention Various additives such as an agent, a reactive diluent, a filler, an antioxidant, a flame retardant, and a pigment may be contained.

(4) Manufacturing method of prepreg The prepreg of this invention is manufactured by integrating the resin composition [B] sheet | seat used as a primary prepreg and a surface layer by hot press, for example.

  FIG. 3 is a conceptual diagram showing an example of the manufacturing process of the prepreg of the present invention. In FIG. 3, the case where the surface layers 16 and 16 are laminated | stacked on both surfaces of the reinforcing fiber sheet 21 is demonstrated. However, the present invention is not limited to this, and the surface layer 16 may be formed only on one side of the reinforcing fiber sheet 21.

  In FIG. 3, 21 is a reinforcing fiber sheet in which carbon fibers are aligned in one direction, and runs in the direction of arrow A. The thickness of the reinforcing fiber sheet 21 is preferably 0.01 to 3 mm, and more preferably 0.1 to 1.5 mm. Resin composition [A] sheets 13 and 13 with release papers 14 and 14 are supplied from film rolls 23 and 23 on both sides of the reinforcing fiber sheet 21 in the thickness direction. The reinforcing fiber sheet 21 and the resin composition [A] sheets 13 and 13 are hot-pressed by a heat roller 40 through release papers 14 and 14. Thereby, the resin composition [A] sheets 13 and 13 are impregnated in the reinforcing fiber sheet 21, and the primary prepreg 10 is manufactured. Thereafter, the release papers 14 and 14 on both sides of the primary prepreg 10 are wound around the rollers 24 and 24. Next, the resin composition [B] sheets 15 and 15 with release paper are supplied from film rolls 25 and 25 to both surfaces of the primary prepreg 10 on which the release papers 14 and 14 are wound. The primary prepreg 10 and the resin composition [B] sheets 15 and 15 are heat-pressed and integrated by heat rollers 41 and 41 through a release paper, and the primary prepreg 10 and the resin composition [B] sheet 15 are integrated. The prepreg 100 of the present invention shown in FIG. 1 is manufactured, which has 15 surface layers 16 and 16. Thereafter, the manufactured prepreg 100 is wound around the roller 101.

(4-1) Production of primary prepreg The primary prepreg is produced by impregnating the epoxy resin composition [A] into a reinforcing fiber sheet. Examples of the impregnation method include a dry method in which the reinforcing fiber layer is impregnated with the epoxy resin composition [A] whose viscosity is reduced by heating. The dry method is preferable because the organic solvent does not remain as compared with the wet method in which the reinforcing fiber layer is impregnated with the resin composition dissolved in the organic solvent and then the organic solvent is removed.

(4-1-1) Production of Epoxy Resin Composition [A] The epoxy resin composition [A] used for the primary prepreg is at least a fragrance represented by the formula (1) with respect to 100 parts by mass of the epoxy resin. It is produced by kneading 30 to 65 parts by mass of a curing agent other than an aliphatic diamine-based curing agent and 5 to 50 parts by mass of an epoxy resin-soluble thermoplastic resin. Furthermore, it is preferable to add 5 to 60 parts by mass of an epoxy resin-insoluble thermoplastic resin.

  The treatment temperature at which the resin is kneaded can be appropriately adjusted depending on the type of epoxy resin and epoxy resin-soluble thermoplastic resin used, taking into account the viscosity, thermal characteristics, curing temperature, etc. of the resin. Preferably, it is 25-100 degreeC.

  The viscosity of epoxy resin composition [A] should just be the viscosity of the resin composition used for a normal prepreg, and heating conditions and content of each component are suitably adjusted according to the viscosity of a kneaded material.

  Kneading may be performed in one stage or in multiple stages. Moreover, the mixing order of each component of a resin composition is not limited. The whole or part of the epoxy resin-soluble thermoplastic resin can be previously dissolved in the epoxy resin and kneaded. Moreover, you may mix as a dispersed particle in an epoxy resin in the state of a powder.

  As the kneading machine apparatus, conventionally known ones such as a roll mill, a planetary mixer, a kneader, an extruder, and a Banbury mixer can be used.

(4-1-2) Impregnation of epoxy resin composition [A] The obtained epoxy resin composition [A] is processed into a sheet shape. In order to process the epoxy resin composition [A] into a sheet, a known method can be used. For example, the melted epoxy resin composition [A] is cast on a support such as release paper or film using a die coater, applicator, reverse roll coater, comma coater, knife coater, etc. to form a sheet. Can be processed. The treatment temperature can be set according to the viscosity of the epoxy resin composition [A]. Usually, the processing temperature is preferably from 100 to 250 ° C, more preferably from 150 to 220 ° C.

  The thickness of the sheet of the epoxy resin composition [A] is preferably about 8 to 350 μm, more preferably 10 to 200 μm.

  The epoxy resin composition [A] sheet is laminated on one side or both sides of the reinforcing fiber base sheet to obtain a first laminate. This first laminate is hot pressed. By performing the heat treatment under pressure, the viscosity of the epoxy resin composition [A] is lowered and impregnated in the voids of the reinforcing fiber sheet.

  The impregnation treatment temperature can be appropriately adjusted in consideration of the viscosity and curing temperature of the epoxy resin composition [A]. Preferably it is 70-160 degreeC, and 90-140 degreeC is more preferable. When the temperature is lower than 70 ° C., the epoxy resin composition [A] has a high viscosity, so that it is difficult to impregnate the reinforcing fiber sheet with the epoxy resin composition [A]. When it exceeds 160 degreeC, an epoxy resin composition [A] becomes easy to harden | cure and the draping property of the obtained prepreg tends to deteriorate.

  The impregnation treatment time is preferably 10 to 300 seconds.

  The pressure condition for the impregnation treatment is appropriately adjusted according to the composition and viscosity of the epoxy resin composition [A], but is preferably 1 to 25 kg / cm, more preferably 2 to 15 kg / cm. is there. When the linear pressure is less than 1 kg / cm, it is difficult to sufficiently impregnate the reinforcing fiber sheet with the epoxy resin composition [A]. When the linear pressure exceeds 25 kg / cm, the reinforcing fiber itself is damaged, and therefore the linear pressure cannot be increased any more.

  The impregnation treatment can be performed by a conventionally known method using a heat roller or the like. The impregnation treatment may be performed once or a plurality of times. In this way, a primary prepreg in which the reinforcing fiber base sheet is impregnated with the epoxy resin composition [A] is produced.

(4-2) Production of Epoxy Resin Composition [B] The epoxy resin composition [B] is at least an aromatic diamine curing agent 55 represented by the formula (1) with respect to 100 parts by mass of the epoxy resin. It is manufactured by kneading 85 parts by mass and 5 to 50 parts by mass of an epoxy resin-soluble thermoplastic resin. The treatment temperature at which the resin is kneaded can be appropriately adjusted depending on the type of epoxy resin and epoxy resin-soluble thermoplastic resin used, taking into account the viscosity, thermal characteristics, curing temperature, etc. of the resin. Preferably, it is 25-100 degreeC.

  The viscosity of epoxy resin composition [B] should just be the viscosity of the resin composition used for manufacture of a normal prepreg, and heating conditions and content of each component are suitably adjusted according to the viscosity of a kneaded material. Kneading may be performed in one stage or in multiple stages. Moreover, the mixing order of each component of a resin composition is not limited. The whole or part of the epoxy resin-soluble thermoplastic resin can be previously dissolved in the epoxy resin and kneaded. Moreover, you may mix as a dispersed particle in an epoxy resin in the state of a powder. A well-known thing can be used for a kneading machine apparatus.

  The obtained epoxy resin composition [B] is processed into a sheet shape for lamination on the surface of the sheet-shaped primary prepreg. As the processing method, a known method such as the method described in the production of the epoxy resin composition [A] sheet can be used.

  2-30 micrometers is preferable and, as for the thickness of the sheet | seat of an epoxy resin composition [B], 5-20 micrometers is especially preferable. When the thickness is less than 2 μm, the tackiness of the obtained prepreg is lowered. When the thickness exceeds 30 μm, the handleability of the obtained prepreg and the molding accuracy of the composite are lowered.

(4-3) Laminate integration of epoxy resin composition [B] The epoxy resin composition [B] sheet is laminated on at least one surface of the obtained primary prepreg to obtain a second laminate. By heating and pressurizing this second laminate, the prepreg of the present invention in which the primary prepreg and the sheet of the epoxy resin composition [B] are integrated is obtained.

  The temperature can be appropriately adjusted in consideration of the viscosity of the epoxy resin composition [B], the curing temperature, and the like. Preferably it is 50-90 degreeC, and 60-80 degreeC is more preferable. When the temperature is lower than 50 ° C., the viscosity of the epoxy resin composition [B] is high, and the process stability of prepreg production may be impaired. When it exceeds 90 ° C., both the epoxy resin composition [B] and the epoxy resin composition [A] used in the primary prepreg are easily melted and mixed, and the curing reaction easily proceeds. As a result, when the obtained prepreg is stored for a long period of time, tackiness and draping properties are likely to be impaired.

  The pressing condition is appropriately adjusted according to the composition and viscosity of the epoxy resin composition [B], but is preferably a linear pressure of 0.1 to 10 kg / cm, more preferably 0.5 to 6 kg / cm. It is. When the linear pressure is less than 0.1 kg / cm, the epoxy resin composition [B] sheet cannot be sufficiently bonded to the primary prepreg. When the linear pressure exceeds 10 kg / cm, the epoxy resin composition [B] sinks into the epoxy resin composition [A] impregnated in the primary prepreg. In this case, the curing agent contained in the epoxy resin composition [B] reacts with the components of the primary prepreg, and the curing reaction easily proceeds. As a result, when stored for a long period of time, tackiness and drapeability are impaired.

  By performing the predetermined integration treatment, the epoxy resin composition [B] is integrated with the surface of the primary prepreg to form the surface layer of the prepreg of the present invention.

  The method for producing the prepreg of the present invention is not limited to the above. The above production method is a method in which heating and pressurization is performed each time the sheets of the epoxy resin compositions [A] and [B] are laminated, and the epoxy resin composition [ A] sheet, and then the epoxy resin composition [B] sheet on both sides thereof may be sequentially laminated and heated and pressed in one step. In this case, it is preferable to pressurize at 50 to 90 ° C. so that the curing agent contained in the epoxy resin composition [A] does not diffuse into the epoxy resin composition [B].

  The prepreg of the present invention may contain a stabilizer, a release agent, a filler, a colorant, and the like within a range where the effects of the present invention are exhibited.

  The production speed of the prepreg is not particularly limited, but in the case of continuous production, it is preferably 0.1 m / min or more in consideration of productivity, economy and the like. More preferably, it is 1-50 m / min, More preferably, it is 5-20 m / min.

  As a method for producing a fiber reinforced composite material using the prepreg of the present invention, a conventionally known method is applied.

  Hereinafter, the present invention will be described in more detail with reference to examples. The components and test methods used in the examples and comparative examples are as follows.

〔component〕
(Reinforced fiber)
-The tensile strength and elastic modulus of carbon fiber strands manufactured by Toho Tenax Co. are as follows.
・ Tensile strength: 5800 MPa (590 kgf / mm ² )
・ Elastic modulus 310 GPa (32 tf / mm ² )

(Epoxy resin)
・ Glycidylamine type epoxy resin (4 functional groups) (Japan Epoxy Resin Epicoat 604 (trade name)) (JER604)
・ Glycidylamine type epoxy resin (trifunctional group) (Araldite MY0510 (trade name) manufactured by Huntsman Advanced Materials) (MY0510)
・ Glycidylamine type epoxy resin (bifunctional group) (Epicoat 828 (trade name) manufactured by Japan Epoxy Resin) (JER828)

(Epoxy resin soluble thermoplastic resin)
-Polyethersulfone having an average particle diameter of 3 to 40 μm (PES-5003P (trade name) manufactured by Sumitomo Chemical Co., Ltd.)
-Polycarbonate with an average particle size of 10-30 μm (AD5503 (trade name) manufactured by Teijin Chemicals Ltd.)

(Epoxy resin insoluble thermoplastic resin)
・ Grillamide with an average particle size of 5 to 35 μm (TR-55 (trade name) manufactured by Ms. Chemie Japan)

(Aromatic diamine curing agent)
・ 4,4′-diamino-3,3′-diethyl-5,5′-dimethyldiphenylmethane (manufactured by Ihara Chemical Industry Co., Ltd.) (MED)
・ 4,4′-diamino-3,3 ′, 5,5′-tetraethyldiphenylmethane (Lonza Japan) (M-DEA)
・ 4,4′-diamino-3,3 ′, 5,5′-tetraisopropyldiphenylmethane (Lonza Japan) (M-DIPA)

(Curing agents other than aromatic diamine type curing agents)
・ 3,3′-diaminodiphenylsulfone (manufactured by Nippon Synthetic Processing Co., Ltd.) (3,3′-DDS)
・ 4,4′-diaminodiphenylsulfone (Wakayama Seika Co., Ltd.) (4,4′-DDS)

[Water absorption rate]
The prepreg was cut into a square having a side of 100 mm, and the mass (W1) was measured. Thereafter, the prepreg was submerged in a desiccator. The inside of the desiccator was decompressed to 10 KPa or less to replace the air and water inside the prepreg. The prepreg was taken out of the water, the surface water was wiped off, and the mass (W2) of the prepreg was measured. From these measured values, the following formula: water absorption (%) = [(W2-W1) / W1] × 100
W1: Mass of prepreg (g)
W2: Mass of prepreg after water absorption (g)
Was used to calculate the water absorption rate.

  The water absorption is an index indicating the porosity in the prepreg, preferably 2 to 40%, and more preferably 4 to 25%. When the porosity in the prepreg is high, handling during molding becomes difficult. In addition, voids are likely to remain in the fiber-reinforced composite material obtained using this prepreg, which adversely affects its mechanical properties. When the porosity is low, the drapeability becomes low, and thus good moldability cannot be obtained.

[Room temperature storage stability]
After storing the prepreg at a temperature of 25 ° C. and a humidity of 60% for 10 days, the prepreg was cut into a square having a side of 100 mm and evaluated by laminating it on a mold. The mold surface shape was a hemisphere (r = 12.7 mm). The evaluation results were represented by the following criteria (◯, Δ, ×).
○: Even when laminated on a mold, the surface shape of the mold is sufficiently followed, and the handleability is almost the same as that immediately after production.
(Triangle | delta): Although the hardening reaction of a prepreg progresses and tack property and drape property are falling, even if it laminates | stacks on a metal mold | die, it is a level which does not have a problem in use.
X: The curing reaction of the prepreg has progressed, the tackiness and drapeability have been remarkably lowered, and the level of the surface shape cannot be followed when laminated on a mold.

[Tackiness]
The tackiness of the prepreg was measured by the following method using a tacking test apparatus TAC-II (manufactured by RHESCA CO., LTD.). As a test method, the maximum was obtained when a prepreg was set on a test stage held at 27 ° C., an initial load of 100 gf was applied with a φ5 tack probe held at 27 ° C., and the test stage was pulled out at a test speed of 10 mm / sec. The load of was determined.

A tack probe test was performed on the prepreg immediately after production and the prepreg stored at a temperature of 26 ° C. and a humidity of 55% for 10 days. The prepreg tack stored for 10 days when the prepreg tack immediately after production was taken as 100% was taken as the tack retention. The evaluation results were represented by the following criteria (◯, Δ, ×).
○: The load immediately after production is 200 gf or more, and the tack retention after storage for 10 days is 100% to 50%.
(Triangle | delta): The load immediately after manufacture is 200 gf or more, and the tack retention after 10 days storage is 50%-25%
X: The load immediately after manufacture is 200 gf or more, and the tack retention after storage for 10 days is 25% to 0%.

[Drapability]
The prepreg drapeability was evaluated by the following test in accordance with ASTM D1388. The prepreg was cut into a square having a side of 100 mm in a 90 ° direction with respect to the 0 ° fiber direction, and the draping property (flexural rigidity, mg · cm) with respect to an inclination having an inclination angle of 41.5 ° was evaluated. This evaluation was performed immediately after the production of the prepreg and after storage for a predetermined period at a temperature of 26 ° C. and a humidity of 55%. The evaluation results were represented by the following criteria (◯, Δ, ×).
○: Even after 20 days from the manufacture, the drapeability is the same as that immediately after the manufacture.
(Triangle | delta): Drapability is not different from immediately after manufacture for 10 days after manufacture, but after 10 days, a slight decrease in drape was observed.
X: After 10 days from the production, the drapeability was lower than that immediately after the production, which was a problematic level for use.

[Examples 1-7]
First, each component shown in Table 1 was mixed with a stirrer at 80 ° C. for 30 minutes to prepare an epoxy resin composition [A] and an epoxy resin composition [B], respectively. The epoxy resin composition [A] and the epoxy resin composition [B] were applied on a release film using a film coater, respectively, and an epoxy resin composition [A] sheet having a thickness of 0.048 mm and a thickness of 0 were used. A 0.15 mm epoxy resin composition [B] sheet was produced.

Next, between two epoxy resin composition [A] sheets, carbon fiber strands are uniformly arranged and supplied in one direction with a basis weight (190 g / m ² ), and are fed at 130 ° C. using a roller at 60 ° C. A primary prepreg was obtained by applying pressure and heating at a linear pressure of 8 kg / cm for 2 seconds.

  Subsequently, the obtained primary prepreg is supplied between two sheets of the epoxy resin composition [B], and the roller is pressed and heated at 70 ° C. for 20 seconds at a linear pressure of 2 kg / cm to form a roll. It wound up and obtained the prepreg of this invention. The production speed of the prepreg was 3 m / min.

  The resin content relative to the entire prepreg was 35% by mass. Various performances of the obtained prepreg are shown in Table 1.

[Comparative Examples 1-6]
Each component shown in Table 1 was mixed with a stirrer at 80 ° C. for 15 minutes to prepare an epoxy resin composition [A] and an epoxy resin composition [B], respectively. The epoxy resin composition [A] and the epoxy resin composition [B] were applied on a release film using a film coater, respectively, and an epoxy resin composition [A] sheet having a thickness of 0.048 mm and a thickness of 0 were used. A 0.15 mm epoxy resin composition [B] sheet was produced.

Next, between the obtained epoxy resin composition [A] sheet and the epoxy resin composition [B] sheet, the carbon fiber strands are uniformly arranged with a basis weight (190 g / m ² ) in one direction and supplied. Then, using a roller, it was pressed and heated at 70 ° C. for 20 seconds with a linear pressure of 2 kg / cm, and wound up on a roll to obtain a prepreg. The production speed of the prepreg was 3 m / min.

  The resin content relative to the entire prepreg was 35% by mass. Various performances of the obtained prepreg are shown in Table 1.

DESCRIPTION OF SYMBOLS 100 ... Prepreg 10 ... Primary prepreg 10a .... Surface of primary prepreg 11 ... Reinforcement fiber 12 ... Reinforcement fiber sheet 13 ... Epoxy resin composition [A] sheet 14 ... Separation Paper pattern 15 ... Epoxy resin composition [B] sheet 16 ... Surface layer 21 ... Reinforcing fiber sheet 23 ... Epoxy resin composition [A] sheet roll 24 ... Release paper take-up roll 25... Epoxy resin composition [B] sheet roll 40, 41... Hot roller 101.

Claims (11)

A primary prepreg obtained by impregnating a sheet-like reinforcing fiber base material with an epoxy resin composition [A], and at least one surface of the primary prepreg has the following formula (1)

(In Formula (1), X represents —CH ₂ —, —CH (CH ₃ ) —, —C (CH ₃ ) ₂ —, and Ar—NH ₂ and Ar′—NH ₂ represent the following formulas ( Represents any one of the structures of 2) to (9).

(R ₁ and R ₂ in the above formulas (2) to (9) each represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.)
A prepreg having a surface layer made of an epoxy resin composition [B] containing an aromatic diamine-based curing agent represented by:
The epoxy resin composition [A] is at least 5 to 50 parts by mass of an epoxy resin-soluble thermoplastic resin with respect to 100 parts by mass of the epoxy resin, and a curing agent other than the curing agent represented by the above formula (1) 30 to 30 parts. 65 parts by mass of the epoxy resin composition, and the epoxy resin composition [B] is at least an aromatic diamine-based curing agent represented by the above formula (1) with respect to 100 parts by mass of the epoxy resin. A prepreg which is an epoxy resin composition containing 55 to 85 parts by mass and 5 to 50 parts by mass of an epoxy resin-soluble thermoplastic resin.   The prepreg according to claim 1, wherein the curing agent contained in the epoxy resin composition [A] is 4,4'-diaminodiphenylsulfone and / or 3,3'-diaminodiphenylsulfone.   The prepreg according to claim 1 or 2, wherein the epoxy resin composition [B] contains the same epoxy resin as the epoxy resin contained in the epoxy resin composition [A]. At least the cured product of the epoxy resin composition [B] has a sea-island phase separation structure,
The sea-island phase separation structure includes an epoxy resin-soluble thermoplastic resin in which a sea component is contained in the epoxy resin composition [B], and an epoxy resin contained in at least the epoxy resin composition [B] as an island component. The prepreg according to any one of claims 1 to 3, which contains a reaction product of a curing agent and a curing agent.   The prepreg according to claim 4, wherein the island component has an average particle size of 0.01 to 10 μm.   The prepreg according to any one of claims 1 to 5, wherein the epoxy resin-soluble thermoplastic resin contained in at least the epoxy resin composition [B] has a functional group capable of forming a hydrogen bond with the epoxy resin.   The prepreg according to any one of claims 1 to 6, wherein the epoxy resin-soluble thermoplastic resin contained in at least the epoxy resin composition [B] has a hydroxyl group, a carboxylic acid group, an imino group, or an amino group. .   The prepreg according to any one of claims 1 to 7, wherein the epoxy resin composition [A] further contains 5 to 60 parts by mass of an epoxy resin insoluble thermoplastic resin with respect to 100 parts by mass of the epoxy resin.   The prepreg according to claim 8, wherein the epoxy resin-insoluble thermoplastic resin is made of any one of amorphous nylon, nylon 6, nylon 12, and amorphous polyimide.   An epoxy resin composition [A] and an epoxy resin composition [B] contained in a prepreg are used as a compatibilizing agent for compatibilizing an epoxy resin and an epoxy resin-soluble thermoplastic resin in the epoxy resin composition [B]. The prepreg according to any one of claims 1 to 9, which is contained in an amount of 0.01 to 15 parts by mass with respect to 100 parts by mass of the total amount. At least one surface of a reinforcing fiber layer formed by forming a reinforcing fiber substrate into a sheet shape, with respect to 100 parts by mass of the epoxy resin, at least 5 to 50 parts by mass of an epoxy resin-soluble thermoplastic resin, and the following formula (1)

(In Formula (1), X represents —CH ₂ —, —CH (CH ₃ ) —, —C (CH ₃ ) ₂ —, and Ar—NH ₂ and Ar′—NH ₂ represent the following formulas ( Represents any one of the structures of 2) to (9).

(R ₁ and R ₂ in the above formulas (2) to (9) each represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.)
The reinforcing fiber layer is obtained by laminating 30 to 65 parts by mass of a curing agent other than the curing agent represented by the above and laminating an epoxy resin composition [A] sheet, and heating and pressing the obtained first laminate. A primary prepreg manufacturing process for obtaining a primary prepreg by impregnating the epoxy resin composition [A] therein;
On at least one surface of the primary prepreg, with respect to 100 parts by mass of the epoxy resin, at least 55 to 85 parts by mass of the aromatic diamine-based curing agent represented by the above formula (1) and the epoxy resin-soluble thermoplastic resin 5 The said epoxy resin composition [B] sheet | seat containing -50 mass parts is laminated | stacked, and the process which heat-presses the obtained 2nd laminated body is described in any one of Claim 1 thru | or 10 A method for producing a prepreg.

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