JP2007269971A - Binder composition for reinforcing fiber substrate, reinforcing fiber substrate with binder, and method for producing preform and fiber-reinforced composite material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a material system of long term storing without adjusting surroundings, requiring no preliminary work such as measurement and mixing of principal ingredients and a curing agent, excellent in workability, and suitable for RTM (resin transfer molding) molding of fiber-reinforced composite material. <P>SOLUTION: The binder composition for reinforcing fiber substrate comprises a thermoplastic resin (A) and a heterocyclic compound (B) containing nitrogen atom in a molecule and has 50-120°C glass transition temperature, wherein the composition itself has no self curing property but can start curing reaction with an epoxy resin composition (C) at ≥60°C by coming into contact with the epoxy resin (C). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fiber reinforced composite material suitably used for aircraft members, spacecraft members, automobile members, ship members, and the like. More specifically, the present invention relates to a fiber reinforced composite having excellent workability and processability. The present invention relates to a method for producing a material by resin transfer molding, a preform used therefor, a reinforcing fiber substrate with a binder used for producing the preform, and a binder composition for reinforcing fiber substrate.

  Conventionally, fiber reinforced composite materials composed of reinforced fibers such as glass fiber, carbon fiber and aramid fiber and matrix resins such as unsaturated polyester resin, vinyl ester resin, epoxy resin, phenol resin, cyanate resin and bismaleimide resin are lightweight. However, it has excellent mechanical properties such as strength, rigidity, impact resistance and fatigue resistance, as well as excellent corrosion resistance, so it can be used in many applications such as aircraft, spacecraft, automobiles, railway vehicles, ships, civil engineering and sports equipment. Has been applied to the field. Particularly in applications that require high performance, fiber reinforced composite materials using continuous fibers are used as reinforcing fibers, and carbon fibers are preferably used as reinforcing fibers. As the matrix resin, a thermosetting resin, especially an epoxy resin is often used.

  Fiber reinforced composite materials are manufactured by various methods, but since the potential for reducing production costs is high, a liquid thermosetting resin composition is injected into a reinforced fiber base placed in a mold and cured by heating. Resin transfer molding (hereinafter sometimes abbreviated as RTM) for obtaining fiber reinforced composite materials is widely applied.

  When manufacturing a fiber reinforced composite material by RTM, a preform processed into a shape close to the target product of the reinforcing fiber substrate is prepared, the preform is placed in a mold, and a thermosetting resin composition is injected. There are many cases.

  As a thermosetting resin to be used, a so-called “two-component” thermosetting resin composition in which a main component which is a resin component and a curing agent having a function of crosslinking the resin component are measured and mixed immediately before use is used. Is often used (see Patent Documents 1 and 2). The advantage of this “two-component” thermosetting resin composition is that the main agent and the curing agent can be stored separately, so that they can be stored for a long time without adjusting the storage environment. In addition, there is a lot of prior work of RTM, such as defoaming of bubbles generated during mixing, and workability is poor. Also, if the measurement of the main agent and curing agent is wrong, poor curing occurs, and the mechanical properties of the resulting fiber reinforced composite material are significantly reduced. There is a problem of doing.

  As a method for improving the workability of the method for producing a fiber-reinforced composite material using a “two-component” thermosetting resin composition, a so-called “one-component” thermosetting in which a main agent and a curing agent are mixed in advance is used. There is a method using a conductive resin composition (see Patent Documents 3 and 4). However, when a “one-pack type” thermosetting resin composition is used, the storage environment must be adjusted to a low temperature in order to store the thermosetting resin composition because the curing reaction always proceeds. Therefore, it is costly, and even if the environment is adjusted, it is difficult to store for a long period of time like a “two-component” thermosetting resin composition.

  Therefore, in the method of forming a fiber reinforced composite material by RTM, it can be stored for a long period of time without adjusting the storage environment like the “two-component” thermosetting resin composition, Development of a material system having excellent workability such as a thermosetting resin composition of “type” has been desired.

In order to construct such a material system, it is effective to arrange the curing agent component on the reinforcing fiber substrate in advance, but the method for stably arranging the curing agent on the surface of the substrate and the reinforcing fiber strand There was no method to cure evenly, and it was not realized.
US Pat. No. 5,688,877 JP 05-320480 A US Pat. No. 5,369,192 US Pat. No. 5,942,182

  Therefore, in view of the background of the prior art, the object of the present invention is a fiber that can be stored for a long period of time without adjusting the environment, and does not require prior work such as measurement and mixing of the main agent and the curing agent, and has excellent workability. The object is to provide an optimal material system for RTM molding of reinforced composite materials. Specifically, a manufacturing method by resin transfer molding of a fiber reinforced composite material excellent in workability and processability, and a preform used therefor An object of the present invention is to provide a reinforcing fiber substrate with a binder and a binder composition for reinforcing fiber substrate, which are used for producing the preform.

  The present invention employs the following means in order to solve such problems. That is, the binder composition for reinforcing fiber base of the present invention is a resin composition having a glass transition temperature of 50 to 120 ° C. containing a thermoplastic resin (A) and a heterocyclic compound (B) containing a nitrogen atom in the molecule. The resin composition itself is not self-curing, but it can initiate a curing reaction with the epoxy resin composition (C) at a temperature of 60 ° C. or more by contact with the epoxy resin composition (C). It is characterized by.

  According to a preferred embodiment of the binder composition for reinforcing fiber substrate of the present invention, the thermoplastic resin is an amorphous thermoplastic resin having a glass transition temperature of 120 to 260 ° C., specifically, polyetherimide or Examples include polyethersulfone. Moreover, the compounding quantity of the said thermoplastic resin (A) is 75 to 95 weight% of the whole.

  Moreover, according to the preferable aspect of the binder composition for reinforcing fiber bases of this invention, an imidazole compound is mentioned as a heterocyclic compound (B) which contains a nitrogen atom in the said molecule | numerator, The heterocyclic compound (B) Is 5 to 25% by weight of the total.

  Furthermore, according to the preferable aspect of the binder composition for reinforcing fiber bases of this invention, the form of the binder composition for reinforcing fiber bases is a particulate form with an average particle diameter of 0.1-200 micrometers. .

The reinforcing fiber substrate with a binder according to the present invention is preferably in the form of a sheet or a tape in which the binder composition for reinforcing fiber substrate is applied at least on one side of the reinforcing fiber substrate, preferably with a basis weight of 1 to 50 g / m ² . According to a preferred embodiment, carbon fiber is used as the reinforcing fiber constituting the reinforcing fiber substrate.

  The preform of the present invention is a preform in which the reinforcing fiber base material with a binder in the form of a sheet or tape is laminated, and the form is fixed by the presence of the binder composition for reinforcing fiber base material between layers. is there.

  Furthermore, the method for producing a fiber-reinforced composite material of the present invention is characterized in that the preform is impregnated with a liquid epoxy resin composition containing no curing agent and cured.

  According to the present invention, a binder composition for a reinforcing fiber substrate that can be stored for a long time without adjusting the environment, and can form a fiber-reinforced composite material by RTM without performing prior work such as weighing and mixing, Reinforced fiber base material and preform can be obtained, and the obtained fiber reinforced composite material is excellent in mechanical properties, so that it can be suitably used for structural members such as aircraft members, spacecraft members, automobile members and ship members. it can.

  The binder composition for reinforcing fiber substrate of the fiber-reinforced composite material of the present invention is a resin composition containing a thermoplastic resin (A) and a heterocyclic compound (B) containing a nitrogen atom in the molecule, the resin composition Resin composition capable of initiating a curing reaction with the epoxy resin composition (C) at a temperature of 60 ° C. or higher by contact with the epoxy resin composition (C) described later, although the product itself is not self-curing Preferably, it is a resin composition capable of initiating a curing reaction at a temperature of 60 ° C. or higher and lower than 100 ° C. When the curing reaction initiated by the contact between the resin composition and the epoxy resin composition (C) is initiated at a temperature of less than 60 ° C., the reactivity is too high, so the epoxy resin composition (C) is preformed. The rate of thickening when injected into the gel is too fast and the use time is shortened. In addition, when the curing reaction is started at a temperature of 100 ° C. or higher, the reactivity is too low, so that the time required for curing becomes long and the cost becomes high, which is not preferable.

  As a method of measuring the curing start temperature, according to JIS K 7123 (1987), a bundle differential scanning calorimeter (in the present invention, Pyris 1 DSC (manufactured by Perkin Elmer Japan, heat flux differential scanning calorimeter)) The specific heat capacity was measured at the time of use, and from the obtained DSC curve, the extrapolated start temperature (a straight line obtained by extending the base line on the low temperature side from the exothermic peak to the high temperature side in accordance with JIS K 0129 (2005), and the low temperature side of the peak There is a method for obtaining the temperature of the intersection of the tangent drawn at the point where the gradient is maximum in the curve of

  The binder composition for reinforcing fiber base of the present invention needs to have a glass transition temperature of 50 to 120 ° C., preferably 60 to 100 ° C., in order to enable processing at a low temperature. Yes, more preferably 65 to 90 ° C.

  When the glass transition temperature of the binder composition for reinforcing fiber substrate of the present invention is lower than 50 ° C., there is a possibility that inconveniences such as particle fusion occur during storage, and the glass of the binder composition of the present invention. When the transition temperature is higher than 120 ° C., the processability at low temperatures and the compressive strength after impact of the fiber-reinforced composite material are lowered.

  In order to set the glass transition temperature of the binder composition for reinforcing fiber base to a preferable value, the blending amount of the thermoplastic resin (A) is preferably 75 to 95% by weight, more preferably 80 to 90% by weight. It is effective that the amount of the heterocyclic compound (B) containing a nitrogen atom in the molecule is preferably 5 to 25% by weight, more preferably 10 to 20% by weight. Moreover, the compounding quantity of these thermoplastic resins (A) and a heterocyclic compound (B) may influence the sclerosis | hardenability of an epoxy resin composition. When the blending amount of the thermoplastic resin (A) is less than 75% by weight and the blending amount of the heterocyclic compound (B) containing a nitrogen atom in the molecule is 25% by weight or more, contact with the epoxy resin composition (C) In this case, the curing reaction rate is too high, so that the viscosity increases rapidly and the low viscosity may not be maintained for the time required for impregnation. When the blending amount of the thermoplastic resin (A) is 95% by weight or more and the blending amount of the heterocyclic compound (B) containing a nitrogen atom in the molecule is less than 5% by weight, the epoxy resin composition (C ) Does not cause a curing reaction and cannot be cured.

  As the thermoplastic resin (A) used in the present invention, an amorphous thermoplastic resin having a glass transition temperature of preferably 120 to 260 ° C, more preferably 130 to 250 ° C can be used. When the glass transition temperature is lower than 120 ° C., the glass transition temperature of the obtained fiber-reinforced composite material becomes low, and it may be difficult to use it suitably as a structural member. Further, when the glass transition temperature exceeds 260 ° C., a temperature of 300 ° C. or higher is required when heating and mixing, which is an inexpensive manufacturing method when manufacturing the resin composition, and nitrogen atoms are introduced into the molecule. The contained heterocyclic compound (B) may be thermally decomposed. Further, there is a method of removing the solvent after dissolving the thermoplastic resin (A) and the heterocyclic compound (B) containing a nitrogen atom in the molecule in an organic solvent, but the cost increases.

  Examples of the amorphous thermoplastic resin used in the present invention include so-called engineering, such as polyimide, polyetherimide, polysulfone, polyethersulfone, polyamide, polyamideimide, polyarylene oxide, polyetherketone and polyetherethersulfone. Resins belonging to plastics are preferably used.

  The amorphous thermoplastic resin preferably has a functional group capable of reacting with an epoxy resin at the terminal or side chain. For example, polyetherimide, polyethersulfone having a terminal hydroxyl group, and the like are preferably used.

  As the heterocyclic compound (B) containing a nitrogen atom in the molecule used in the present invention, for example, piperazine derivatives, triazole derivatives, imidazole derivatives and the like can be preferably used. In particular, imidazole derivatives are cured products having excellent heat resistance. Is preferably used.

  Examples of such imidazole derivatives include imidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1-benzyl-2-methylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1 -Aminoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 1-cyanoethyl-2-ethyl-4-methylimidazolium trime , 1-cyanoethyl-2-undecylimidazolium trimellrate, 2,4-diamino-6- [2'-methylimidazolyl- (1 ')]-ethyl-s-triazine, 2,4-diamino-6 -[2'-undecylimidazolyl- (1 ')]-ethyl-s-triazine, 2,4-diamino-6- [2'-ethyl-4'-methylimidazolyl- (1')]-ethyl-s -Triazine and their epoxy resin addition reaction products are preferably used, especially 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole and their epoxy resin addition reaction A thing etc. are suitable.

  The binder composition for reinforcing fiber substrate of the present invention can further contain other components as optional components. Examples of other components include antioxidants, non-soluble organic particles and inorganic particles. In particular, among the organic particles, crosslinked rubber particles and non-soluble thermoplastic resin particles are effective for improving the toughening effect.

  The preparation of the binder composition for reinforcing fiber substrate of the present invention is not particularly limited because it is thermally stable, and various known methods can be used. The most economical method is a method in which the components constituting the reinforcing fiber base material binder composition are kneaded preferably at a relatively high temperature of about 150 to 260 ° C. using an extruder or a kneader. The obtained binder composition for reinforcing fiber base can be pulverized into particles, or processed into a fibrous or film form by melt extrusion from a die.

  In addition, as a method for preparing the binder composition for reinforcing fiber base of the present invention, an organic solvent solution containing each component is dispersed in water to form an emulsion, the emulsion is heated to volatilize the solvent, and a dispersion (dispersion, In detail, there is a method of preparing a dispersion of solid particles in a liquid. The dispersion can be used as it is for processing of reinforcing fibers that volatilize and remove water from the reinforcing fiber base after the reinforcing fiber base is dipped in the dispersion. It can also be used in a method of applying the particles to the reinforcing fiber substrate.

  As described above, the form of the binder composition for reinforcing fiber substrate of the present invention includes various films such as films, tapes, long fibers, short fibers, spun yarns, woven fabrics, knits, non-woven fabrics, nets, and particles provided with through holes. The thing of the form of can be employ | adopted.

  For example, when the form of the binder composition for a reinforcing fiber substrate is a particulate form, the average particle diameter is 500 times by using a laser analysis / scattering type particle size distribution analyzer (LMS-24 manufactured by Seishin Corporation). When measured by (1), it is preferably 0.1 to 200 μm, more preferably 1 to 150 μm. When the average particle size is smaller than 0.1 μm, the production becomes difficult, and when the average particle size is larger than 200 μm, the reinforced fibers are swelled when formed into a preform, and the mechanical properties of the fiber-reinforced composite material are lowered. In addition, since the particles do not completely dissolve or swell in the epoxy resin composition (C), the curing reaction does not proceed sufficiently in the system, resulting in a problem that heat resistance and chemical resistance are lowered. .

  The binder composition for reinforcing fiber substrate of the present invention is used by being applied to a reinforcing fiber substrate made of reinforcing fibers.

  Examples of the reinforcing fiber used in the present invention include carbon fiber, glass fiber, aramid fiber, metal fiber, and the like. Carbon fiber is preferably used in that a fiber-reinforced composite material having a particularly high performance can be obtained.

  Specific examples of the carbon fiber used in the present invention include acrylic, pitch, and rayon carbon fibers, and acrylic carbon fibers having high tensile strength are particularly preferred. As the form of the carbon fiber, twisted yarn, untwisted yarn, untwisted yarn and the like can be used, but untwisted yarn or untwisted yarn is preferably used because the balance between moldability and strength characteristics of the fiber reinforced composite material is good.

  The elastic modulus of the carbon fiber is preferably in the range of 200 GPa to 400 GPa from the viewpoint of the characteristics and weight of the molded structural member. If the elastic modulus is lower than this range, the rigidity of the structural member may be insufficient and weight reduction may be insufficient. Conversely, if the elastic modulus is higher than this range, the strength of the carbon fiber generally tends to decrease. A more preferable elastic modulus is in the range of 250 GPa to 370 GPa, and more preferably in the range of 290 GPa to 350 GPa.

  The reinforcing fiber substrate made of reinforcing fibers used in the present invention is composed of reinforcing fibers alone or in combination with a plurality of types, and further combined with other chemical fibers as necessary. Woven fabrics, knitted fabrics, braids, mats, etc. can be used, especially in terms of obtaining fiber reinforced composite materials with high mechanical properties and high volume content of reinforcing fibers. A so-called unidirectional fabric in which the fibers are substantially oriented in one direction and fixed with glass fibers or chemical fibers is preferably used.

  Examples of the unidirectional woven fabric include strands made of carbon fibers arranged in parallel in one direction as warps, and wefts made of glass fibers or chemical fibers intersecting with each other to form a plain weave structure. , Consisting of a warp made of carbon fiber strands, an auxiliary warp of a fiber bundle made of glass fibers or chemical fibers arranged parallel to this, and a weft made of glass fibers or chemical fibers arranged so as to be orthogonal thereto, Examples thereof include a non-crimped woven fabric in which carbon fibers are integrally held by the auxiliary warp and the weft intersecting each other to form a woven fabric.

  As a method for applying the binder composition for reinforcing fiber base of the present invention to the reinforcing fiber base composed of reinforcing fibers, the binder composition for reinforcing fiber base of the present invention is applied to the surface of the reinforcing fiber base composed of reinforcing fibers. A method of attaching particles and fixing by heating, a method of winding fibers of the binder composition for reinforcing fiber substrate of the present invention around the surface of a reinforcing fiber substrate made of reinforcing fibers, and the like can be used. The binder composition for reinforcing fiber substrate of the present invention is applied to the reinforcing fiber substrate made of reinforcing fibers, and then a reinforcing fiber substrate with a binder is prepared, and then a preform can be prepared.

  As a method for applying the binder composition for reinforcing fiber base of the present invention to a reinforcing fiber base composed of reinforcing fibers, it can be applied at the time of manufacturing the reinforcing fiber base, and it can be applied to an existing reinforcing fiber base. It can also be given as processing. Moreover, lamination | stacking of a reinforced fiber base material and provision of the binder composition for reinforced fiber base materials of this invention can also be performed alternately at the time of the preform preparation mentioned later.

When the binder composition for reinforcing fiber base of the present invention is applied to the surface of a reinforcing fiber base made of reinforcing fibers, it is preferably attached to at least one side of the reinforcing fiber base with a basis weight of 1 to 50 g / m ^2. . If the basis weight is less than the above range, the effect of fixing the form and increasing the toughness and the reactivity with the epoxy resin composition are low. If the basis weight is large, the apparent volume of the reinforcing fiber strand or the reinforcing fiber base with a binder increases. There may be disadvantages such as difficulty in producing a fiber-reinforced composite material having a large volume content of reinforcing fibers or poor impregnation of the epoxy resin composition.

  A reinforcing fiber substrate with a binder obtained by applying the binder composition for reinforcing fiber substrate of the present invention to a reinforcing fiber substrate composed of reinforcing fibers is cut into a predetermined shape, laminated on a mold, It can be used to make a preform by applying heat and pressure. The pressurizing means can be a press, or a method of bagging and sucking the inside to −90 kPa or less with a vacuum pump and pressurizing with atmospheric pressure. The heating temperature for producing the preform is preferably 60 to 150 ° C.

  In addition to a reinforcing fiber substrate with a binder, a foam core, a honeycomb core, a metal part, and the like can be integrated into the preform.

The preform of the present invention obtained as described above is suitably used for RTM molding.
The method for producing a fiber-reinforced composite material according to the present invention is obtained by injecting and impregnating an epoxy resin composition (C) containing no curing agent into a preform of the present invention placed in a mold and heating it. The fiber base binder composition and the epoxy resin composition undergo a curing reaction to obtain a fiber reinforced composite material.

  In the method for producing a fiber-reinforced composite material of the present invention, a closed mold made of a rigid body may be used as a mold for installing the preform, or a rigid open mold and a flexible film (bag) may be used. . In the latter case, the preform is placed between the rigid open mold and the flexible film.

  As the rigid material, metals such as steel and aluminum, FRP, wood, plaster, and the like can be used. As a material for the flexible film, nylon, fluorine resin, silicone resin, or the like can be used.

  As a specific procedure in the method for producing a fiber-reinforced composite material of the present invention, when a rigid closed mold is used, it can be pressurized and clamped, and the epoxy resin composition (C) can be pressurized and injected. . At this time, a suction port can be provided separately from the injection port and connected to a vacuum pump for suction. Alternatively, the liquid epoxy resin composition (C) can be injected at atmospheric pressure while performing suction without using a pressurizing means.

  Further, when a rigid open mold and a flexible film are used, suction and injection by atmospheric pressure can be usually employed. In order to achieve good impregnation by injection at atmospheric pressure, it is effective to use a resin diffusion medium. It is also preferable to apply a gel coat to the rigid surface prior to installation of the preform. After installing the preform, mold clamping or bagging is performed, and then the epoxy resin composition (C) is injected.

  In the present invention, the epoxy resin composition (C) includes an epoxy resin having two or more epoxy groups in the molecule, and the epoxy resin can be used alone or in a mixture of plural kinds.

  Examples of such an epoxy resin include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, tetrabromobisphenol A diglycidyl ether, bisphenol AD diglycidyl ether, 2,2 ′, 6,6′-tetramethyl-4,4. '-Biphenol diglycidyl ether, N, N, O-triglycidyl-m-aminophenol, N, N, O-triglycidyl-p-aminophenol, N, N, O-triglycidyl-4-amino-3- Methylphenol, N, N-diglycidylaniline, N, N-diglycidyl-o-toluidine, N, N, N ′, N′-tetraglycidyl-4,4′-methylenedianiline, N, N, N ′, N′-tetraglycidyl-2,2′-diethyl-4,4′-methylenedianiline, , N, N ′, N′-tetraglycidyl-m-xylylenediamine, 1,3-bis (diglycidylaminomethyl) cyclohexane, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, hexamethylene glycol diglycidyl ether, Neopentyl glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, diglycidyl phthalate, diglycidyl terephthalate, diglycidyl ether of 1,6-dihydroxynaphthalene, 9,9- Diglycidyl ether of bis (4-hydroxyphenyl) fluorene, triglycidyl ether of tris (p-hydroxyphenyl) methane, tetrakis ( -Hydroxyphenyl) ethane tetraglycidyl ether, phenol novolac glycidyl ether, cresol novolac glycidyl ether, glycidyl ether of a condensate of phenol and dicyclopentadiene, glycidyl ether of phenol aralkyl resin, triglycidyl isocyanurate, N-glycidyl phthalimide, 5 -Ethyl-1,3-diglycidyl-5-methylhydantoin, 1,3-diglycidyl-5,5-dimethylhydantoin, oxazolidone type epoxy resin obtained by addition of bisphenol A diglycidyl ether and tolylene isocyanate, and phenol aralkyl type Epoxy or the like can be used.

  In particular, bisphenol A diglycidyl ether and bisphenol F diglycidyl ether are suitable in that a cured product having well-balanced mechanical properties and chemical resistance can be obtained, and N, N, O-triglycidyl- By using p-aminophenol or N, N, N ′, N′-tetraglycidyl-4,4′-methylenedianiline, the heat resistance of the resulting cured product can be improved.

  The epoxy resin composition (C) can be appropriately mixed with other components such as a plasticizer, a dye, an organic pigment, an inorganic filler, a polymer compound, a coupling agent, and a surfactant.

  While injecting the epoxy resin composition (C), the mold composition is heated to a temperature of about 30 to 90 ° C. so that the binder composition for reinforcing fiber substrate of the present invention and the subsequent curing are smoothly performed. An injection can be performed.

  Heat-curing is performed after injection | pouring of an epoxy resin composition (C). The mold temperature at the time of heat curing may be the same as the mold temperature at the time of injection of the epoxy resin composition (C), but in the case of curing at a low temperature, the fiber reinforced composite material is not deformed at the time of demolding. Since it may take time to advance curing until rigidity is obtained, it is preferable to select a temperature higher than the temperature of the mold at the time of injection, for example, a temperature in the range of 80 to 180 ° C is preferable. The heat curing time is preferably in the range of 1 to 20 hours.

  In the process of heat curing, it is preferable that the binder composition for reinforcing fiber substrate of the present invention is once dissolved in the epoxy resin composition (C) or swollen with the epoxy resin composition (C). By doing in this way, the heterocyclic compound (B) which contains a nitrogen atom in the molecule | numerator which is one of the components of the binder composition for reinforcing fiber bases of this invention, and an epoxy resin composition (C) contact, Initiate the curing reaction. Since the curing reaction proceeds by anionic polymerization, even if the heterocyclic compound (B) containing a nitrogen atom in the molecule is not uniformly dispersed in the epoxy resin composition (C), the toughness of the fiber-reinforced composite material, etc. The physical properties, heat resistance, chemical resistance, and the like can be improved.

  As described above, the mode in which the binder composition is once dissolved or swollen before heat-curing is the shape of the binder composition for reinforcing fiber base, and the epoxy in the binder composition for reinforcing fiber base and the epoxy resin composition. It is achieved by appropriately selecting the combination with the resin, the thermoplastic resin (A) in the binder composition for reinforcing fiber substrate, or the heating temperature condition.

  After heat curing, the mold is removed and the fiber reinforced composite material is taken out.

  In the present invention, after that, so-called post-curing may be performed in which the fiber-reinforced composite material is heated at a temperature higher than the curing temperature. The post-curing temperature is preferably 90 to 200 ° C., and the time is preferably 1 to 4 hours.

  The binder composition for reinforcing fiber base of the present invention is particularly suitable for the RTM method, but can also be suitably used for molding methods other than the RTM method. For example, when the shape of the reinforcing fiber substrate to which the binder composition for reinforcing fiber substrate of the present invention is applied is a strand or a tape, it is also suitable for the filament winding method, the pultrusion method, the prepreg method, etc. When the shape of the reinforcing fiber base is a sheet, it is suitable for a hand layup method, a prepreg method, and the like.

  The material system for producing the fiber-reinforced composite material of the present invention is superior in storage stability and workability compared to conventional material systems, and is manufactured using the binder composition for reinforcing fiber substrate of the present invention. The fiber reinforced composite material has excellent toughness, aircraft parts such as fuselage, main wing, tail wing, moving wing, fairing, cowl, door, seat and interior material, spacecraft parts such as motor case and main wing, structure and It can be suitably used for many structural materials such as artificial satellite members such as antennas, outer plates, chassis, automobile members such as aerodynamic members and seats, railway vehicle members such as structures and seats, and ship members such as hulls and seats.

Hereinafter, the present invention will be described in more detail with reference to examples.
The reinforcing fiber substrate made of carbon fiber used in each example was produced as follows. Carbon fiber T800S-24K-10C (manufactured by Toray Industries, Inc.), which is a non-twisted yarn, is used as warp yarns, and glass fiber ECE225 1/0 1Z (manufactured by Nittobo Co., Ltd.) is used as weft yarns. A plain woven fabric arranged in one direction was produced. The warp yarn density was 7.2 yarns / 25 mm, and the weft yarn density was 7.5 yarns / 25 mm. The carbon fiber basis weight of the woven fabric was 190 g / m ² .

<Preparation of epoxy resin composition (C)>
The epoxy resin composition (C) used in each example is prepared by mixing the following components. The following composition is a composition ratio in the mixed solution, and the unit is parts by weight.
-"Araldite" (registered trademark) MY-721 (manufactured by Huntsman Advanced Materials, glycidylamine type epoxy resin): 40 parts-"Epicoat" (registered trademark) 630 (manufactured by Japan Epoxy Resin Co., Ltd., aminophenol type) Epoxy resin): 15 parts, “Epicoat” (registered trademark) 825 (manufactured by Japan Epoxy Resin Co., Ltd., bisphenol A type epoxy resin): 30 parts, “Epicoat” (registered trademark) 1750 (manufactured by Japan Epoxy Resin Co., Ltd.) Bisphenol F type epoxy resin): 15 parts <Measurement of glass transition temperature of binder composition for reinforcing fiber substrate and its raw material>
5-10 mg of the thermoplastic resin that is the raw material of the binder composition for reinforcing fiber base used in each example or 5-10 mg of the binder composition for reinforcing fiber base obtained in each example is collected and in accordance with JIS K7121 (1987). The midpoint glass transition temperature (T _mg ) was measured. For the measurement, Pyris 1 DSC (manufactured by PerkinElmer Japan Co., Ltd., heat flux differential scanning calorimeter) was used, and the number of samples was 2.

<Measurement of curing start temperature (extrapolation start temperature)>
10 parts of the binder composition for reinforcing fiber substrate obtained in each Example and 90 parts of the epoxy resin composition (C) obtained by the above method were mixed, and 5 to 10 mg was sampled from the obtained mixture. Then, the specific heat capacity was measured according to JIS K 7123 (1987), and the extrapolated onset temperature (the straight line obtained by extending the base line on the lower temperature side than the exothermic peak to the higher temperature side) from the obtained DSC curve according to JIS K 0129 (2005) The temperature of the intersection with the tangent line drawn at the point where the slope is maximum on the curve on the low temperature side of the peak was determined. For the measurement, Pyris 1 DSC (manufactured by PerkinElmer Japan Co., Ltd., heat flux differential scanning calorimeter) was used, and the number of samples was 2.

<Manufacture of specimens of fiber reinforced composite materials>
The fiber reinforced composite material used in each example is manufactured by RTM. In the reinforcing fiber substrate with binder to which the binder composition for reinforcing fiber substrate produced in each Example and Comparative Example was applied, the reinforcing fiber substrate with the longitudinal direction of the carbon fiber being 0 ° was [+ 45 ° / 0 ° / -45 [deg.] / 90 [deg.]] Are repeated three times and laminated symmetrically to produce a preform. The obtained preform was impregnated with the epoxy resin composition (C) at a temperature of 70 ° C., and then heated to a temperature of 130 ° C. at a rate of 1.5 ° C. per minute. Pre-cure for hours. The pre-cured product was taken out of the RTM mold and then cured in a hot air oven at a temperature of 180 ° C. for 2 hours to obtain a fiber reinforced composite material of a test specimen.

<Measurement of glass transition temperature of fiber reinforced composite material>
A sample having a weight of 20 mg was cut out from the fiber-reinforced composite material obtained by the above production method, and the midpoint glass transition temperature (T _mg ) was measured according to JIS k7121 (1987). For the measurement, Pyris 1 DSC (manufactured by PerkinElmer Japan Co., Ltd., heat flux differential scanning calorimeter) was used, and the number of samples was 2.

<Measurement of compressive strength after impact of fiber reinforced composite material>
From the fiber reinforced composite material obtained by the above production method, a rectangular test piece having a length of 150 mm and a width of 100 mm was cut out with a carbon fiber orientation angle of 0 ° as a longitudinal direction of the test piece, and JIS K 7089 was formed at the center of the rectangular test piece. After applying a falling weight impact of 20 J per 1 mm thickness of the test piece according to (1996), the residual compressive strength (CAI) was measured according to JIS K 7089 (1996). The number of samples was 5.

<Example 1>
80 parts of polyetherimide (“Ultem” (registered trademark) 1000, manufactured by GE Plastics, glass transition temperature: 213 ° C.) and 1-benzyl-2-methylimidazole (“Curazole” (registered trademark) 1B2MZ, Shikoku Chemical Industries ( 20 parts) was dissolved in 400 parts of methylene chloride to obtain a solution. While stirring this solution at about 5000 rpm with a homomixer at room temperature, 600 parts of an aqueous solution in which 1% by weight of higher alcohol sulfate soda ("Monogen" (registered trademark) Y-100, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was dissolved. Was added dropwise over 10 minutes to obtain an emulsion solution. While stirring the obtained emulsion solution at 50 rpm, the temperature was raised to 60 ° C. at 5 ° C. per minute, and methylene chloride was evaporated at 60 ° C. for 2 hours to obtain a dispersion solution. The obtained dispersion solution is allowed to cool to a temperature of 25 ° C., and then the powder obtained by repeating filtration and washing three times is vacuum-dried at a temperature of 50 ° C. for 24 hours to form a particulate reinforcing fiber substrate. A binder composition was obtained.

  It was 87 degreeC when the glass transition temperature of the obtained binder composition for particulate reinforcing fiber base materials was measured by the said method. Moreover, it was 6 micrometers when the average particle diameter was measured using the laser diffraction and scattering type particle size distribution measuring device (LMS-24, Seisin Enterprise Co., Ltd.).

  Moreover, it was 85 degreeC when the hardening start temperature was measured by the said method.

After dispersing the obtained binder composition for reinforcing fiber base material on one side of the fiber base material made of carbon fiber with a basis weight of 25 g / m ² , the surface temperature becomes 160 ° C. It heated using the far red heater, the particulate binder composition for reinforcement fiber base materials was fused, and the reinforcement fiber base material which provided the binder composition for reinforcement fiber base materials was obtained. Using the obtained reinforcing fiber base material to which the binder composition for reinforcing fiber base material is applied, the volume content of the reinforcing fiber (carbon fiber) is 58.1% and the thickness is 4. A 43 mm fiber reinforced composite material was obtained.

When the obtained fiber reinforced composite material glass transition temperature was measured by the above method, it was 185 ° C., and it was confirmed that it was normally cured. Moreover, as a result of giving impact energy of 20 J per 1 mm thickness according to the said method to the obtained fiber reinforced composite material and measuring compressive strength after impact (CAI), it was as high as 220 MPa.
<Example 2>
75 parts of a powder obtained by freeze-pulverizing polyethersulfone (“Sumika Excel” (registered trademark) PES5003P, manufactured by Sumitomo Chemical Co., Ltd., glass transition temperature: 227 ° C.) and 1-benzyl-2-phenylimidazole (“Cureazole”) 25 parts of “(registered trademark) 1B2PZ, manufactured by Shikoku Kasei Kogyo Co., Ltd.” were kneaded at a temperature of 210 ° C. by a twin screw extruder to obtain particulate pellets of a binder composition for a reinforcing fiber substrate. It was 72 degreeC when the glass transition temperature of the pellet of the obtained binder composition for reinforcing fiber base materials was measured by the said method. Moreover, it was 98 micrometers when the average particle diameter of the obtained particulate pellet was measured using the laser diffraction / scattering type particle size distribution measuring device (LMS-24, Seisin Enterprise Co., Ltd.).

  Moreover, it was 93 degreeC when the hardening start temperature was measured by the said method.

After the obtained particulate binder composition for reinforcing fiber base material is sprayed on one side of the fiber base material made of carbon fiber with a basis weight of 27 g / m ² , the surface temperature is 160 ° C. so that the surface temperature becomes 160 ° C. It heated using the red heater, the particulate binder composition for reinforcing fiber bases was fused, and the reinforcing fiber base material which provided the binder composition for reinforcing fiber bases was obtained.

  Using the obtained reinforcing fiber base material to which the binder composition for reinforcing fiber base material is applied, the fiber content of reinforcing fiber is 58.6% and the thickness is 4.39 mm by the above manufacturing method. A composite material was obtained.

  When the obtained fiber reinforced composite material glass transition temperature was measured by the above-mentioned method, it was 192 ° C., and it was confirmed that it was normally cured. In addition, as a result of applying impact energy of 20 J per 1 mm thickness to the obtained fiber-reinforced composite material according to the above method and measuring the compressive strength after impact (CAI), it was a high value of 227 MPa.

<Comparative Example 1>
Polyetherimide (“Ultem” (registered trademark) 1000, manufactured by GE Plastics, glass transition temperature: 213 ° C.) 98 parts and 1-benzyl-2-methylimidazole (“Cureazole” (registered trademark) 1B2MZ, Shikoku Chemical Industries ( 2 parts) was dissolved in 400 parts of methylene chloride to obtain a solution. While stirring this solution at about 5000 rpm with a homomixer at room temperature, 600 parts of an aqueous solution in which 1% by weight of higher alcohol sulfate soda ("Monogen" (registered trademark) Y-100, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was dissolved. Was added dropwise over 10 minutes to obtain an emulsion solution. While stirring the obtained emulsion solution at 50 rpm, the temperature was raised to 60 ° C. at 5 ° C. per minute, and methylene chloride was evaporated at 60 ° C. for 2 hours to obtain a dispersion solution. The obtained dispersion solution is allowed to cool to a temperature of 25 ° C., and then the powder obtained by repeating filtration and washing three times is vacuum-dried at a temperature of 50 ° C. for 24 hours to form a particulate reinforcing fiber substrate. A binder composition was obtained.

  It was 206 degreeC when the glass transition temperature of the obtained binder composition for particulate reinforcing fiber base materials was measured by the said method. Moreover, it was 7 micrometers when the average particle diameter was measured using the laser diffraction and scattering type particle size distribution measuring device (LMS-24, Seisin Enterprise Co., Ltd.).

  Further, when the curing start temperature was measured by the above method, a clear curing start temperature was not obtained.

The resulting particulate reinforcing fiber base binder composition was applied at a basis weight of 25 g / m ² on one surface of the fibrous base material consisting of the carbon fiber, so that the surface temperature becomes a temperature of 160 ° C. far Although heating was performed using a red heater, the particulate binder composition for reinforcing fiber base material could not be fused. Using the reinforcing fiber substrate sprinkled with the obtained binder composition for reinforcing fiber substrate, an attempt was made to form a fiber-reinforced composite material by the above production method, but the resin was not cured and a fiber-reinforced composite material could not be obtained. It was.
<Comparative example 2>
50 parts of powder obtained by freeze-pulverizing polyethersulfone (“Sumika Excel” (registered trademark) PES5003P, manufactured by Sumitomo Chemical Co., Ltd., glass transition temperature: 227 ° C.) and 1-benzyl-2-phenylimidazole (“Cureazole”) 50 parts of “(registered trademark) 1B2PZ, manufactured by Shikoku Kasei Kogyo Co., Ltd.” were kneaded at a temperature of 210 ° C. by a twin screw extruder to obtain pellets of a binder composition for a reinforcing fiber substrate. It was 53 degreeC when the glass transition temperature of the pellet of the obtained binder composition for reinforcing fiber base materials was measured by the said method. Moreover, it was 86 micrometers when the average particle diameter of the obtained particulate pellet was measured using the laser diffraction and scattering type particle size distribution measuring device (LMS-24, Seisin Enterprise Co., Ltd.).

  Moreover, it was 50 degreeC when the hardening start temperature was measured by the said method.

After the obtained particulate binder composition for reinforcing fiber base material is sprayed on one side of the fiber base material made of carbon fiber with a basis weight of 27 g / m ² , the surface temperature is 160 ° C. so that the surface temperature becomes 160 ° C. It heated using the red heater, the particulate binder composition for reinforcing fiber bases was fused, and the reinforcing fiber base material which provided the binder composition for reinforcing fiber bases was obtained.

  Using the reinforcing fiber substrate to which the obtained binder composition for reinforcing fiber substrate was applied, an attempt was made to form a fiber-reinforced composite material by the above-described production method, but the viscosity increased during the injection of the epoxy resin composition (C). Thus, the fiber-reinforced composite material could not be obtained because of complete impregnation.

  The binder composition for reinforcing fiber substrate of the present invention is suitable for a fiber reinforced composite material molded by RTM, and the obtained fiber reinforced composite material is a structural material for aircraft, spacecraft, rail vehicles, automobiles, ships, etc. However, the present invention is useful because it can be applied to other fields such as leisure industries such as tennis rackets, golf shafts and fishing rods, and construction.

Claims (12)

  A resin composition having a glass transition temperature of 50 to 120 ° C. containing a thermoplastic resin (A) and a heterocyclic compound (B) containing a nitrogen atom in the molecule, and the resin composition itself is not self-curing. Is capable of initiating a curing reaction with the epoxy resin composition (C) at a temperature of 60 ° C. or more by contact with the epoxy resin composition (C).   The binder composition for reinforcing fiber substrate according to claim 1, wherein the thermoplastic resin (A) is an amorphous thermoplastic resin having a glass transition temperature of 120 to 260 ° C.   The binder composition for reinforcing fiber base according to claim 1 or 2, wherein the thermoplastic resin (A) is polyetherimide or polyethersulfone.   The binder composition for a reinforcing fiber substrate according to any one of claims 1 to 3, wherein the blending amount of the thermoplastic resin (A) is 75 to 95% by weight of the whole.   The binder composition for reinforcing fiber substrate according to any one of claims 1 to 4, wherein the heterocyclic compound (B) containing a nitrogen atom in the molecule is an imidazole compound.   6. The binder composition for reinforcing fiber base according to claim 1, wherein the amount of the heterocyclic compound (B) containing a nitrogen atom in the molecule is 5 to 25% by weight of the whole. .   The binder composition for reinforcing fiber substrate according to any one of claims 1 to 6, wherein the binder composition is in a particulate form having an average particle diameter of 0.1 to 200 µm.   A reinforcing fiber substrate with a binder, wherein the reinforcing fiber substrate binder composition according to any one of claims 1 to 7 is applied to the surface of the reinforcing fiber substrate. The reinforcing fiber base binder composition according to claim 1, reinforced with a binder, characterized by comprising imparted by basis weight one side of 1 to 50 g / m ² of at least reinforcing fiber substrate Fiber substrate.   The reinforcing fiber substrate with a binder according to claim 8 or 9, wherein the reinforcing fiber constituting the reinforcing fiber substrate is a carbon fiber.   A reinforcing fiber substrate with a binder according to any one of claims 8 to 10 is laminated, and the form is formed by causing the binder composition for reinforcing fiber substrate according to any one of claims 1 to 7 to exist between layers. Preform characterized by being fixed.   A method for producing a fiber-reinforced composite material, wherein the preform according to claim 10 is impregnated with an epoxy resin composition containing no curing agent and thermally cured.