JP7180446B2 - Resin feedstock, preform, and method for producing fiber-reinforced composite material using same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a resin feed material that is excellent in resin-carrying properties, storage stability, and high-cycle moldability, and a method for producing a fiber-reinforced composite material using the resin feed material.

BACKGROUND ART Fiber-reinforced composite materials have excellent specific strength and specific rigidity, and are therefore widely used in applications such as aircraft, automobiles, and sports. Especially for industrial applications such as automobiles and sports, the demand for high-speed molding processes for fiber-reinforced composite materials is increasing.

A high-speed molding method for fiber-reinforced composite materials includes the RTM (resin transfer molding) method. In the RTM method, first, a preform is produced by shaping a dry base material (reinforcing fiber base material that does not contain resin) into a predetermined shape, and this is placed in a mold. It is injected into a mold and cured by heating to form an FRP (fiber reinforced plastic) member. However, since the RTM method requires a resin injection process, auxiliary molding materials such as tubes and pipes used in the injection process are required. In addition, a large amount of wasteful resin remains in the injection path and the like in addition to the resin that forms the molded product, which is a factor in increasing costs. Furthermore, since liquid resin is handled at room temperature, there is a problem that the site is often dirty with resin leaking from containers and pipes.

The molding cycle of fiber-reinforced composite materials is governed by the resin curing speed, and high-cycle molding requires a resin with a high curing speed. However, since fast-curing resins have increased reactivity and shortened curing time, storage stability and quality changes during work often pose problems, and materials with even better stability are desired.

Patent Literatures 1 and 2 propose a method of molding a fiber-reinforced composite material using a resin supply material in which a thermosetting resin that is liquid at room temperature is absorbed into a soft carrier. This method has the advantage that the impregnation distance can be shortened because the resin can be surface-supplied to the dry base material using the resin supply material.

On the other hand, Patent Literature 3 discloses an epoxy resin composition and a prepreg that use a specific aromatic urea as an accelerator and give a cured product having excellent fast curing properties and heat resistance.

Patent Document 4 discloses an epoxy resin composition having an excellent curing speed and a glass transition temperature not exceeding 140°C.

JP-A-2002-234078 International Publication No. 2016/136790 pamphlet Japanese Patent Publication No. 2003-128764 Japanese translation of PCT publication No. 2016-500409

In the resin supply materials disclosed in Patent Documents 1 and 2, the curing speed of the thermosetting resin used for the carrier is not sufficient, and the high cycle moldability is not satisfied.

The epoxy resin composition disclosed in Patent Document 3 has a relatively short curing time and good workability at room temperature. Not in.

The epoxy resin composition disclosed in Patent Document 4 is excellent in rapid curability, but has insufficient storage stability.

Accordingly, an object of the present invention is to provide a resin feed material and a preform that are excellent in resin-carrying properties, storage stability, and high-cycle moldability, and a method for producing a fiber-reinforced composite material using the resin feed material.

A resin supply material (A) used for molding a fiber-reinforced composite material,
The resin feed material (A) has reinforcing fibers (a) and resin (b),
The resin (b) contains the following components [C], [D], [E] and [F] and satisfies the following conditions [c], [d] and [e],
A resin supply material represented by the following formula (I), wherein the reinforcing fiber (a) contained in the resin supply material (A) has a fiber volume content Vfi of 15% or less.
[C]: epoxy resin [D]: dicyandiamide [E]: aromatic urea [F]: borate ester [c]: 0.005≦(mass ratio of component [F]/component [E])≦0. 045
[d]: 0.9 ≤ (number of moles of epoxy groups in component [C]/number of moles of active hydrogen in component [D]) ≤ 1.3
[e]: 12 ≤ (mass ratio of component [C]/component [E]) ≤ 26
Vfi=Va/Vb×100 (%) (I)
Here, Va: fiber volume in resin supply material (mm ³ )
Vb: Volume of resin feed material (mm ³ )
Further, the resin supply material (A) of the present invention is obtained by heating and pressurizing a preform composed of the resin supply material (A) and the base material (B), and transferring the resin (A) from the resin supply material (A) to the base material (B). It can be used in a method for producing a fiber-reinforced composite material in which b) is supplied and molded.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a resin supply material excellent in resin-carrying property, storage stability, and high-cycle moldability, and a method for producing a fiber-reinforced composite material using the resin supply material. According to the present invention, a fiber-reinforced composite material having a low void fraction and high mechanical properties can be easily molded.

1 is a schematic diagram of a preform configuration that is one of the preferred embodiments of the present invention; FIG.

The present invention relates to a resin feedstock (A). The resin feedstock (A) comprises reinforcing fibers (a) and resin (b). The resin supply material (A) may consist of reinforcing fibers (a) and resin (b), that is, may have only reinforcing fibers (a) and resin (b). The resin supply material (A) as used in the present invention means that the resin supported inside is squeezed out by being heated and pressurized in a state adjacent to the fiber base material, and the adjacent fiber base material is impregnated. is possible. That is, in order to supply the resin, the structure is such that the form of the reinforcing fibers constituting the material is not crushed by the resin. Specifically, the composite can be molded by supplying a resin during molding by the method described in <Manufacturing method of carbon fiber composite material> described later.
Examples of reinforcing fibers (a) include carbon fibers. Carbon fiber is preferably used because of its excellent mechanical properties. Carbon fibers may be used in combination with other fibers such as glass fibers, aramid fibers and metal fibers within the scope of the present invention.

The form of the reinforcing fiber (a) having the ability to supply the resin may be a continuous fiber base material or a discontinuous fiber base material. The discontinuous fibers include chopped fibers to make a web, and the web can also be made into a nonwoven fabric. Chopped fibers having an extremely short fiber length and a form in which the single fibers are not bound together are not preferable because the form may be crushed when the resin is supplied. A discontinuous fiber base material is preferred from the viewpoint of resin supply, and a web having voids between fibers for impregnation with a resin is more preferred. There are no restrictions on the form or shape of the web. For example, carbon fibers may be mixed with organic fibers, organic compounds or inorganic compounds, carbon fibers may be held together by other components, or carbon fibers may be bonded to resin components. It's okay to be. From the viewpoint of the resin supply capacity, mechanical properties, and shape followability of the resin supply material (A), a web in which single fibers are bound together with a binder can be exemplified as a preferable form of the reinforcing fibers (a). Among them, it is preferable that the carbon fibers in the web are sufficiently opened.

The mass average fiber length of the reinforcing fibers (a) is preferably 2 to 12 mm, more preferably 3 to 10 mm. The range may be a combination of any of the above upper limits and any of the above lower limits. By setting it as this range, the resin supply capability of a resin supply material, resin carrying property, handleability, and shape followability are excellent.

Further, a form having a mass average fiber length of 2 mm or more is preferable because it is excellent in deformability as a resin supply material.

The mass average fiber length is measured by microscopic observation. For example, a method in which the reinforcing fibers are directly extracted from the reinforcing fiber base material and measured by microscopic observation, the resin is dissolved with a solvent or the like, and the remaining reinforcing fibers are filtered out. There is a method of measuring by microscopic observation, and a method of burning off only the resin in a temperature range where the reinforcing fibers do not decompose and measuring the remaining reinforcing fibers by microscopic observation.

For the measurement, 400 reinforcing fibers are randomly selected, the length is measured to the nearest 1 μm with an optical microscope, the fiber length and the number ratio are measured, and the mass average fiber length (Lw) is calculated from the measured value. .
Mass average fiber length (Lw) = Σ (Wi × Li) / ΣWi
= Σ (πri ² × Li × ρ × ni × Li) / Σ (πri ² × Li × ρ × ni)
Wi: Mass of reinforcing fiber
Li: Fiber length of reinforcing fiber
ri: Fiber diameter of reinforcing fiber
ρ: Density of reinforcing fibers ni: Number of reinforcing fibers with fiber length Li.

Examples of the binder include thermoplastic resins such as polyvinyl alcohol, polyamide resins, polyester resins, polyacetal resins, polyetherimide resins, polypropylene resins, polyacrylic acid ester resins, and acrylic resins, urethane resins, and melamine resins. , urea resins, thermosetting acrylic resins, phenolic resins, epoxy resins, thermosetting polyesters, and other thermosetting resins are preferably used. From the viewpoint of the mechanical properties of the fiber-reinforced composite material obtained, at least one Resins having functional groups are preferably used. These binders may be used alone or in combination of two or more. The ratio of the adhered binder mass to the reinforcing fiber mass is preferably 0.1 to 15%. By setting the adhered mass of the binder within the range of 0.1% to 15%, it is possible to obtain a resin feeder that is excellent in handleability and shape followability without impairing the resin feedability.
The adhesion mass ratio of the binder can be measured, for example, by the following method. After weighing (W1) the reinforcing fibers, they are left in an electric furnace set at a temperature of 450° C. in a nitrogen stream of 50 liters/minute for 15 minutes to completely thermally decompose the binder. Then, the reinforcing fibers are transferred to a container in a dry nitrogen stream at 20 liters/minute, cooled for 15 minutes, and then weighed (W2) to determine the binder adhesion mass ratio by the following equation.
Binder adhesion mass ratio (%) = (W1-W2) / W1 x 100
The resin (b) used in the present invention contains the following components [C], [D], [E] and [F] and satisfies the following conditions [c], [d] and [e].
[C]: epoxy resin [D]: dicyandiamide [E]: aromatic urea [F]: borate ester [c]: 0.005≦(mass ratio of component [F]/component [E])≦0. 045
[d]: 0.9 ≤ (number of moles of epoxy groups in component [C]/number of moles of active hydrogen in component [D]) ≤ 1.3
[e]: 12 ≤ (mass ratio of component [C]/component [E]) ≤ 26
(Component [C])
Component [C] in the present invention is an epoxy resin. For example, bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, bisphenol S-type epoxy resin, biphenyl-type epoxy resin, naphthalene-type epoxy resin, novolac-type epoxy resin, epoxy resin having a fluorene skeleton, co-polymerization of phenol compound and dicyclopentadiene. Epoxy resins made from polymers, glycidyl ether type epoxy resins such as diglycidylresorcinol, tetrakis(glycidyloxyphenyl)ethane, tris(glycidyloxyphenyl)methane, tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, triglycidylamino Glycidylamine-type epoxy resins such as cresol and tetraglycidylxylenediamine are included. Epoxy resins may be used alone or in combination.

In addition, component [C] is represented by component [C1]: the following formula (II) and/or the following formula (III) from the viewpoint of the balance between fast curing property, storage stability, and bending elastic modulus of the cured product. It preferably contains an epoxy resin. Component [C1] is generally known as a phenol novolak type epoxy resin, a cresol novolak type epoxy resin, or a dicyclopentadiene type epoxy resin, and is commercially available as a mixture of polyfunctional epoxy resins having two or more functionalities. .

When the component [C1] is contained in an amount of 55 to 100 parts by mass in 100 parts by mass of the total epoxy resin contained in the epoxy resin composition, the flexural modulus of the cured resin can be further increased.

(In Formula (II), R ¹ , R ² , and R ³ each independently represent a hydrogen atom or a methyl group, and n represents an integer of 1 or more.)

(In formula (III), n represents an integer of 1 or more).

Commercially available products of component [C1] include "jER (registered trademark)" 152, 154, 180S (manufactured by Mitsubishi Chemical Corporation), "Epiclon (registered trademark)" N-740, N-770, N- 775, N-660, N-665, N-680, N-695, HP7200L, HP7200, HP7200H, HP7200HH, HP7200HHH (manufactured by DIC Corporation), PY307, EPN1179, EPN1180, ECN9511, ECN1273, ECN1285, ECN128 , ECN1299 (manufactured by Huntsman Advanced Materials Co., Ltd.), YDPN638, YDPN638P, YDCN-701, YDCN702, YDCN-703, YDCN-704 (manufactured by Tohto Kasei Co., Ltd.), DEN431, DEN438, DEN439 (manufactured by Dow Chemical Company) and the like.
(Component [D])
Component [D] in the present invention is dicyandiamide. Dicyandiamide is a compound represented by the chemical formula (H2N)2C=N-CN. Dicyandiamide is excellent in that it imparts high mechanical properties and heat resistance to cured resins, and is widely used as a curing agent for epoxy resins. Commercial products of such dicyandiamide include DICY7 and DICY15 (manufactured by Mitsubishi Chemical Corporation).

Incorporation of dicyandiamide [D] as a powder into the epoxy resin composition is preferable from the viewpoint of storage stability at room temperature and viscosity stability during production of the resin supply material. Further, it is preferable to disperse dicyandiamide [D] in a part of the epoxy resin of component [C] in advance using a triple roll or the like, in order to make the epoxy resin composition uniform and to improve the physical properties of the cured product. .

Dicyandiamide [D], when used in combination with component [E] described below, can lower the curing temperature of the resin composition compared to the case where component [D] is blended alone. In the present invention, it is necessary to use component [D] and component [E] together in order to shorten the curing time.
(Component [E])
Component [E] in the present invention is aromatic urea. Component [E] functions as a curing accelerator, and can shorten the curing time when used in combination with component [D].

Specific examples of aromatic urea compounds for component [E] include 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, and phenyldimethylurea. , toluenebisdimethylurea, and the like. In addition, commercially available aromatic urea compounds include DCMU99 (manufactured by Hodogaya Chemical Industry Co., Ltd.), "Omicure (registered trademark)" 24 (manufactured by PTI Japan Co., Ltd.), "Dyhard (registered trademark) )” UR505 (4,4′-methylenebis(phenyldimethylurea, manufactured by CVC) and the like can be used.
(Component [F])
Component [F] in the present invention is a boric acid ester. By using both the component [E] and the component [F], the reaction between the component [D] and the epoxy resin at the storage temperature is suppressed, so that the storage stability of the resin supply material is remarkably improved. Although the mechanism is not clear, since the component [F] has Lewis acidity, the amine compound liberated from the component [E] and the component [F] interact with each other to reduce the reactivity of the amine compound. It is thought that there is no. Specific examples of the boric acid ester of component [F] include trimethyl borate, triethyl borate, tributyl borate, tri-n-octyl borate, tri(triethylene glycol methyl ether) boric acid ester, tricyclohexyl borate, trimenthyl borate, and the like. Alkyl borates, aromatic borates such as tri-o-cresylborate, tri-m-cresylborate, tri-p-cresylborate, triphenylborate, tri(1,3-butanediol)biborate, tri(2 -methyl-2,4-pentanediol) biborate, trioctylene glycol diborate and the like.

A cyclic boric acid ester having a cyclic structure in the molecule can also be used as the boric acid ester. Cyclic borate esters include tris-o-phenylene bisborate, bis-o-phenylene pyroborate, bis-2,3-dimethylethylene phenylene pyroborate, bis-2,2-dimethyltrimethylene pyroborate, and the like. .

Examples of products containing such borate esters include "Cure Duct (registered trademark)" L-01B (Shikoku Chemical Industry Co., Ltd.), "Cure Duct (registered trademark)" L-07N (Shikoku Chemical Industry Co., Ltd.) ) (a composition containing 5 parts by mass of a boric acid ester compound), and “Cure Duct (registered trademark)” L-07E (Shikoku Kasei Kogyo Co., Ltd.) (a composition containing 5 parts by mass of a boric acid ester compound). .

The resin (b) of the present invention satisfies the following condition [c].
[c]: 0.005 ≤ (mass ratio of component [F]/component [E]) ≤ 0.045
That is, the value represented by the mass ratio of component [F]: borate ester/component [E]: aromatic urea contained in the epoxy resin composition according to the present invention is within the range of 0.005 to 0.045. This gives a resin feedstock with an excellent balance of rapid curing and storage stability. The value represented by the mass ratio of component [F]/component [E] in the epoxy resin composition is preferably in the range of 0.020 to 0.045, and is a resin supply material with an excellent balance between rapid curing and storage stability. is obtained. The range may be a combination of any of the above upper limits and any of the above lower limits. If the mass ratio of component [F]/component [E] is less than 0.005, the storage stability will be insufficient. If the mass ratio of component [F]/component [E] exceeds 0.045, the curing time will be insufficient.

The storage stability of the resin (b) of the present invention is such that the change in glass transition temperature before and after storage at 40° C. and 75% RH for 14 days is 20° C. or less. (A) exhibits excellent storage stability even at room temperature.

The storage stability of the resin (b) of the present invention can be evaluated, for example, by tracking changes in the glass transition temperature using differential scanning calorimetry (DSC). Specifically, the resin (b) is stored for a predetermined period in a constant temperature and humidity bath or the like, and the change in glass transition temperature before and after storage is measured by DSC from -20°C to 150°C at a rate of 5°C/min. It can be determined by

The curing time of the epoxy resin composition of the present invention can be evaluated by using, for example, a vulcanization/curing property tester Curastometer Type V (manufactured by JSR Trading Co., Ltd.). Specifically, a sample of the prepared epoxy resin composition was placed in a die heated to 150°C, and a torsional stress was applied to increase the viscosity of the sample as the sample hardened. The time to reach % is evaluated as the demoldable time. The time to reach 70% of the maximum peak torque is preferably 150 seconds or less, and it can be judged that the rapid curability is excellent.

The resin (b) of the present invention satisfies the following condition [d].
[d]: 0.9 ≤ (number of moles of epoxy groups in component [C]/number of moles of active hydrogen in component [D]) ≤ 1.3
With respect to condition [d], when the number of moles of epoxy groups in component [C]/the number of moles of active hydrogen in component [D] is in the range of 0.9 to 1.3, epoxy with excellent rapid curing properties A resin composition is provided. If the number of moles of epoxy groups in component [C]/the number of moles of active hydrogen in component [D] exceeds 1.3, the curing time will be insufficient. On the other hand, when the number of moles of epoxy groups in component [C]/the number of moles of active hydrogen in component [D] is less than 0.9, the resin flow during thermoforming becomes insufficient.

The number of moles of epoxy groups in component [C] is the sum of the number of moles of epoxy groups in each epoxy resin, and is represented by the following formula.
Number of moles of epoxy groups in component [C] = (mass of resin A/epoxy equivalent of resin A) + (mass of resin B/epoxy equivalent of resin B) + ... + (mass of resin W/epoxy equivalent of resin W) .

The active hydrogen mole number of component [D] is obtained by dividing the dicyandiamide mass by the active hydrogen equivalent of dicyandiamide, and is expressed by the following formula.
Number of moles of active hydrogen in component [D]=mass of dicyandiamide/active hydrogen equivalent of dicyandiamide The resin (b) of the present invention satisfies the following condition [e].
[e]: 12 ≤ (mass ratio of component [C]/component [E]) ≤ 26
The resin (b) of the present invention satisfies the condition [e], that is, the value represented by the mass ratio of component [C]:epoxy resin/component [E]:aromatic urea contained in the resin (b) is 12 When it is in the range of ∼26, it gives an epoxy resin composition which is excellent in fast curing property and storage stability. If the mass ratio of component [C]/component [E] exceeds 26, the curing time will be insufficient. On the other hand, when the mass ratio of component [C]/component [E] is less than 12, storage stability is insufficient.

The resin (b) of the present invention preferably satisfies the following conditions [g] and [h].
[g]: In dynamic viscoelasticity measurement, the temperature at which the resin (b) exhibits the lowest viscosity is 110°C or higher and 140°C or lower while the temperature is raised from 40°C to 250°C at a rate of 5°C/min. When the resin (b) of the invention satisfies the condition [g], the fiber-reinforced composite material using the epoxy resin has a low void fraction. This is because the heating temperature follows the above range during thermoforming of the fiber-reinforced composite material, but the voids in the material are removed by the flow of the resin during thermoforming, while the excess resin is caused by gelation at an appropriate timing. It is speculated that this is because the outflow of

Whether or not the temperature at which the resin (b) of the present invention exhibits the lowest viscosity satisfies the condition [g] can be evaluated by, for example, dynamic viscoelasticity measurement (DMA) and tracking changes in viscosity. Specifically, the epoxy resin composition prepared by the above method was heated from 40°C to 250°C at a rate of 5°C/min using a rheometer (rotational dynamic viscoelasticity measuring device). It can be evaluated by the temperature at which the epoxy resin composition exhibits the lowest viscosity when heated.
[h]: Exothermic start temperature (T ₀ ) and exothermic end temperature (T The difference between ₁ ) is 25° C. or less When the resin (b) of the present invention satisfies the condition [h], it gives an epoxy resin composition having a better balance between rapid curing and storage stability. The difference between _T0 and _T1 represents the sharpness of the DSC peak. Those with a sharp peak have a higher curing initiation temperature than those with a broader peak, even if the temperature of the exothermic peak is the same. This means that it has excellent stability over a wider temperature range. On the other hand, once the curing reaction starts, it progresses rapidly, so rapid curability is not impaired.

The resin (b) of the present invention is used for the purpose of adjusting the viscoelasticity and improving the drape properties of the resin supply material, and for the purpose of enhancing the mechanical properties and toughness of the resin composition, as long as the effects of the present invention are not lost. and may include a thermoplastic resin. As the thermoplastic resin, a thermoplastic resin soluble in epoxy resin, organic particles such as rubber particles and thermoplastic resin particles, inorganic particles such as silica, nanoparticles such as CNT (carbon nanotubes) and graphene, etc. are selected. be able to.

Examples of thermoplastic resins soluble in epoxy resins include polyvinyl acetal resins such as polyvinyl formal and polyvinyl butyral, polyvinyl alcohol, phenoxy resins, polyamides, polyimides, polyvinylpyrrolidone, and polysulfones.

Examples of rubber particles include crosslinked rubber particles and core-shell rubber particles obtained by graft-polymerizing a different polymer on the surface of crosslinked rubber particles.

Rapid curing and storage stability of epoxy resins are usually in a trade-off relationship, and cannot be achieved by combining individual technologies. Only when the resin (b) of the present invention satisfies the conditions [c], [d] and [e] at the same time, the trade-off is overcome, and it becomes possible to achieve both rapid curability and storage stability with an extremely high balance. . Any one of [c] to [e] or a combination of the two cannot achieve both rapid curability and storage stability in an extremely high balance.

The resin feedstock (A) of the present invention satisfies condition [f]. That is, the fiber volume content Vfi represented by the following formula is 15% or less. If Vfi exceeds 15%, impregnation of the base material (B) with the resin will be poor, resulting in a fiber-reinforced composite material with many voids. Vfi is preferably 11% or less, more preferably 5% or less. By setting Vfi to 11% or less, a resin supply material (A) having an excellent resin supply capability is obtained, and by setting it to 5% or less, a resin supply material (A) having an even more excellent resin supply capability is obtained. be done. Moreover, the fiber volume content Vfi represented by the following formula of the resin supply material (A) of the present invention is preferably 0.5% or more. By setting the fiber volume content Vfi to 0.5% or more, it is possible to obtain a resin supply material (A) that is more excellent in handleability and shape followability.

The fiber mass content Vfi is determined according to JIS K7075 (testing method for fiber content and void content of carbon fiber reinforced plastics, 1991).

The fiber volume content Vfi of the resin supply material (A) is obtained by taking out only the resin supply material (A) by grinding or cutting a preform containing the resin supply material (A), and measuring it according to JIS K7075 (carbon fiber reinforced It can be determined according to the fiber content rate and void rate test method for plastics, 1991). If it is difficult to measure in an uncured state, you may use what was cured without pressure.
Vfi=Va/Vb×100 (%) (I)
Va: Fiber volume in resin supply material (mm ³ )
Vb: Volume of resin feed (mm ³ ).

The resin supply material (A) of the present invention can be laminated with the substrate (B) to produce a preform, and a fiber-reinforced composite material can be produced from the preform. The base material (B) is a base material having reinforcing fibers and may not be impregnated with a resin. Examples include those using continuous fibers such as wood. Here, the continuous fiber means a reinforcing fiber obtained by arranging a reinforcing fiber bundle in a continuous state without cutting the reinforcing fiber into short fibers. For the purpose of obtaining a fiber-reinforced composite material having excellent mechanical properties, it is preferable to use a substrate made of continuous reinforcing fibers. It is preferable to use a mat base material composed of discontinuous fibers as the base material (B).

The structure of the preform includes a sandwich laminate in which the outermost layer of a laminate obtained by laminating a plurality of resin supply materials (A) is sandwiched between substrates (B), or a laminate in which resin supply materials (A) and substrates (B) are alternately laminated. Alternating laminates and combinations thereof can be exemplified. Among them, the resin feed material (A) and the base material (B) are added in the order of base material (B)/resin feed material (A)/base material (B)/resin feed material (A)/base material (B). Alternating lamination of a plurality of layers is preferable because the impregnation distance of the resin (b) is shortened, and the void fraction of the obtained fiber-reinforced composite material can be greatly reduced. Forming a preform in advance enables rapid and more uniform impregnation of the resin (b) into the substrate (B) in the manufacturing process of the fiber-reinforced composite material containing the substrate (B). It is preferable because it becomes

The preform has a laminated thickness of 5 mm or less, and by satisfying the following formula (IV), the perimeter of the preform base material (free edge) relative to the area of the preform base material is relatively reduced. It is preferable because the void fraction of the resulting fiber-reinforced composite material can be greatly reduced by making it easier to flow in the thickness direction. Here, the perimeter of the substrate refers to the perimeter of a plane perpendicular to the thickness direction. Also, the thickness of the laminated preform is preferably 0.4 mm or more, more preferably 0.9 mm or more. By setting the preform lamination thickness to 0.4 mm or more, the preform is excellent in portability and handleability.

Preform substrate area [x]/preform substrate circumference [y]≧7 [cm] (IV)
Here, it is preferable that the preform substrate area [x]/preform substrate circumference [y]<750 [cm]. .
The preform of the present invention is, for example, heated and pressurized in a closed space, the resin (b) is supplied from the resin supply material (A) to the base material (B), and then the resin (b) is cured to obtain a fiber-reinforced composite. materials can be obtained. From the viewpoint of suppressing the inclusion of voids, press pressure molding and vacuum pressure molding are preferable. The mold may be a double-sided mold such as a rigid closed mold or a single-sided mold. In the latter case, the preform can also be placed between the flexible film and the rigid open mold (in this case, since the pressure between the flexible film and the rigid open mold is lower than the outside, The reform is in a pressurized state). Among them, by applying a pressure of 0.3 to 0.7 MPa with a press, the impregnation of the resin (b) into the base material (B) is improved, and the void fraction of the resulting fiber-reinforced composite material is greatly increased. It is preferable because it can be made small.

The void fraction of the fiber-reinforced composite material of the present invention is preferably 20% or less, more preferably 15% or less, even more preferably 10% or less. A fiber-reinforced composite material with high mechanical properties can be obtained by setting the void fraction to 20% or less.

The void fraction of the fiber-reinforced composite material is determined according to JIS K7075 (testing method for fiber content and void fraction of carbon fiber reinforced plastics, 1991).

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the description of these examples.

The components used in this embodiment are as follows.

<Materials used>
・Reinforcing fiber (a)
A continuous carbon fiber having a total of 12,000 single filaments was obtained by subjecting a copolymer containing PAN as a main component to spinning, baking treatment, and surface oxidation treatment. The properties of this continuous carbon fiber were as follows.

Average fiber diameter: 7 μm
Mass per unit length: 0.8g/m
Specific gravity: 1.8
<Method for producing carbon fiber web>
The reinforcing fibers (a) were cut to a predetermined length with a cartridge cutter to obtain chopped carbon fibers. A dispersion having a concentration of 0.1% by mass consisting of water and a surfactant (polyoxyethylene lauryl ether (trade name), manufactured by Nacalai Tesque Co., Ltd.) was prepared, and this dispersion and the chopped carbon fiber were used. , a papermaking base material was manufactured with a papermaking base material manufacturing apparatus. The manufacturing apparatus includes a cylindrical container with a diameter of 1000 mm having an opening cock at the bottom of the container serving as a dispersing tank, and a linear transport section (tilt angle of 30 degrees) connecting the dispersing tank and the papermaking tank. A stirrer is attached to the opening on the upper surface of the dispersion tank, and the chopped carbon fibers and the dispersion liquid can be introduced through the opening. The papermaking tank is a tank provided with a mesh conveyor having a papermaking surface with a width of 500 mm at the bottom, and a conveyor capable of transporting a carbon fiber base material (papermaking base material) is connected to the mesh conveyor. During papermaking, the mass per unit area was adjusted by adjusting the carbon fiber concentration in the dispersion. If necessary, about 5% by mass of polyvinyl alcohol aqueous solution (Kuraray Poval, manufactured by Kuraray Co., Ltd.) is applied as a binder to the paper-made carbon fiber base material, dried in a drying oven at 140 ° C. for 1 hour, and the following carbon fiber base material is dried. Fiber webs 1-8 were obtained. Each web had a mass per unit area of 50 g/m ² .

・Carbon fiber web 1
Binder adhesion mass: 5%, mass average fiber length: 6.5 mm
・Carbon fiber web 2
Binder adhesion mass: 0%, mass average fiber length: 6.5 mm
・Carbon fiber web 3
Binder adhesion mass: 5%, mass average fiber length: 1.2 mm
・Carbon fiber web 4
Binder adhesion mass: 5%, mass average fiber length: 3.3 mm
・Carbon fiber web 5
Binder adhesion mass: 5%, mass average fiber length: 10.0 mm
・Carbon fiber web 6
Binder adhesion mass: 5%, mass average fiber length: 14.1 mm
・Carbon fiber web 7
Binder adhesion mass: 13%, mass average fiber length: 6.5 mm
・Carbon fiber web 8
Binder adhesion mass: 17%, mass average fiber length: 6.5 mm
<Method for preparing epoxy resin composition>
Predetermined amounts of components other than [D] dicyandiamide, [E] aromatic urea and [F] borate ester were placed in a stainless steel beaker, heated to 60 to 150° C., and kneaded until each component was dissolved. After the temperature was lowered to 60° C., the [F] borate ester component was blended and kneaded to obtain a main ingredient. Separately, predetermined amounts of [C] epoxy resin and [D] dicyandiamide were added to a polyethylene cup, and the mixture was passed through the rolls twice using a triple roll to prepare a dicyandiamide master. The main component prepared above and the dicyandiamide master were kneaded at 60°C or less so as to have a predetermined mixing ratio, and finally [E] aromatic urea was added and kneaded at 60°C for 30 minutes to obtain an epoxy resin composition. got stuff

・Epoxy resin [C]
・ “jER (registered trademark)” 828 (bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation)
・ “jER (registered trademark)” 1001 (bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation)
・ “jER (registered trademark)” 1007FS (bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation)
・ “jER (registered trademark)” 154 (phenol novolak type epoxy resin, manufactured by Mitsubishi Chemical Corporation)
・ “Epiclon (registered trademark)” N-740 (phenol novolak type epoxy resin, manufactured by DIC Corporation)
· "Epiclon (registered trademark)" HP-7200H (dicyclopentadiene type epoxy resin, manufactured by DIC Corporation)
・"Epiclon (registered trademark)" 830 (bisphenol F type epoxy resin, manufactured by DIC Corporation)
・ “Epototo (registered trademark)” YDF-2001 (Bisphenol F type epoxy resin, manufactured by Tohto Kasei Co., Ltd.)
・ “Epotec (registered trademark)” YD136 (bisphenol A type epoxy resin, manufactured by KUKDO)
・"EPON (registered trademark)" 2005 (Bisphenol A type epoxy resin, manufactured by Resolution Performance Products)
・ “Epotec (registered trademark)” YDPN638 (phenol novolak type epoxy resin, manufactured by Tohto Kasei Co., Ltd.)
・Dicyandiamide [D]
・ DICY7 (dicyandiamide, manufactured by Mitsubishi Chemical Corporation)
・Aromatic urea [E]
・ “Omicure (registered trademark)” 24 (4,4′-methylenebis(phenyldimethylurea, manufactured by PTI Japan Co., Ltd.)
・DCMU99 (3-(3,4-dichlorophenyl)-1,1-dimethylurea, manufactured by Hodogaya Chemical Industry Co., Ltd.)
- "Dyhard (registered trademark)" UR505 (4,4'-methylenebis(phenyldimethylurea, manufactured by CVC).

・Boric acid ester [F]
- "Cure Duct (registered trademark)" L-07E (composition containing 5% by mass of a boric acid ester compound, manufactured by Shikoku Kasei Kogyo Co., Ltd.).

・ Thermoplastic resin ・ “Vinylec (registered trademark)” K (polyvinyl formal, manufactured by JNC Co., Ltd.)
・ “Sumika Excel (registered trademark)” PES3600P (polyethersulfone, manufactured by Sumitomo Chemical Co., Ltd.)
- YP-50 (phenoxy resin, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.).

- Other particle components - "Matsumoto Microsphere (registered trademark)" M (manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd.).

<Evaluation method for curing time of epoxy resin composition>
The curing time of the epoxy resin composition was measured using Curastometer Type V (manufactured by JSR Trading Co., Ltd.), placing a sample of the epoxy resin composition obtained by the above method into a die heated to 150° C., and measuring the torsional stress. The torque transmitted to the die was defined as the increase in viscosity as the sample hardened, and the time when 70% of the peak torque was reached was defined as the hardening time.
<Method for evaluating bending elastic modulus of cured resin>
After defoaming the epoxy resin composition in a vacuum, it was cured at a temperature of 150° C. for 2 hours in a mold set to have a thickness of 2 mm with a 2 mm thick “Teflon (registered trademark)” spacer. A 2 mm plate-shaped resin cured product was obtained. A test piece having a width of 10 mm and a length of 60 mm is cut out from this cured resin, and subjected to three-point bending using an Instron universal testing machine (manufactured by Instron) at a span of 32 mm and a crosshead speed of 100 mm/min. and the flexural modulus was measured. The average value of the values measured with the number of samples n=5 was taken as the value of the flexural modulus.
<Evaluation Method for Storage Stability of Epoxy Resin Composition>
8 g of the initial epoxy resin composition obtained by the above method was weighed into an aluminum cup and left to stand in a constant temperature bath for 14 days in an environment of 40 ° C. and 75% RH. Taking the transition temperature as Ts, the amount of change in the glass transition temperature was defined as ΔTg=Te−Ts, and the storage stability of the epoxy resin composition was determined by the value of ΔTg. The glass transition temperature was determined by weighing 3 mg of the epoxy resin composition after storage into a sample pan and using a differential scanning calorimeter (Q-2000: manufactured by TA Instruments Co., Ltd.), from -20 ° C. to 150 ° C. 5 ° C./ The temperature was raised in minutes and measured. The midpoint of the inflection point of the obtained exothermic curve was obtained as the glass transition temperature.
<Method for preparing resin supply material>
Each of the webs obtained in <Method for producing carbon fiber web> was impregnated with each of the epoxy resin compositions of Examples 1 to 23 and Comparative Examples 1 to 8 to prepare a resin supply material. The impregnation process is as follows.
(1) An epoxy resin composition was prepared and coated on release paper using a reverse roll coater to produce a resin film having a mass per unit area of 60 g/m ² or 100 g/m ² .
(2) For each web (size: 10 cm x 10 cm), the epoxy resin film (size: 10 cm x 10 cm) obtained in (1) was two sheets of 60 g/m ² and 100 g/m ² . 5 sheets were laminated.
(3) Heated at 0.1 MPa and 70° C. for about 1.5 hours.
<Method 1 for producing carbon fiber composite material>
On the front and back of the resin supply material (size: 10 cm × 10 cm) prepared in (3), two layers of dry fabrics of the same size (Toray cloth, product number: CO6343B, plain weave, basis weight 198 g / m ² ) are arranged, It was held at 0.1 MPa and 150° C. for 5 minutes in a press to form a composite.
<Method 2 for producing carbon fiber composite material>
A composite is produced in the same manner as the resin supply material production method and carbon fiber composite material production method 1, except that the sizes of the resin supply material and the dry fabric to be produced in (2) are increased (size: 30 cm × 30 cm). Molded.
<Method 3 for producing carbon fiber composite material>
A composite was molded in the same manner as in method 1 for producing a carbon fiber composite material, except that the surface pressure of the press was 0.3 MPa.
<Method 4 for producing carbon fiber composite material>
A composite was molded in the same manner as in carbon fiber composite material production method 1, except that five layers were laminated in the order of dry fabric/resin supply material/dry fabric/resin supply material/dry fabric.
<Method for measuring void fraction of carbon fiber composite material>
The void fraction of the carbon fiber composite material was measured by cutting a part of the carbon fiber composite material obtained by the above method, embedding it in epoxy resin, polishing it so that the cross section along the thickness direction of the outer layer was exposed, and taking a cross-sectional photograph. was photographed using a laser microscope VK-9510 (manufactured by Keyence). A void region was selected from the obtained cross-sectional photograph using image analysis software, and its area was measured. Based on the measured values, (cross-sectional area of void region/cross-sectional area of carbon fiber composite material)×100 was calculated as the void ratio (%).

(Example 1)
[C] 60 parts by mass of "jER (registered trademark)" 828 as epoxy resin, 20 parts by mass of "jER (registered trademark)" 1007FS, 20 parts by mass of "jER (registered trademark)" 154, [D] as dicyandiamide 9.2 parts by mass of DICY7, [E] 4.5 parts by mass of "Omicure (registered trademark)" 24 as an aromatic urea compound, and "Cureduct (registered trademark)" as a mixture containing [F] borate ester Using 3.0 parts by mass of L-07E, an epoxy resin composition was prepared according to the <Method for preparing epoxy resin composition>. In this epoxy resin composition, the mass ratio of component [c] [F]/component [E] is 0.033, and the number of moles of epoxy groups of component [d] [C]/the number of moles of active hydrogen of component [D] is 1. .0, and the mass ratio of [e] component [C]/component [E] was 22.

When this epoxy resin composition was measured according to <Evaluation method for curing time of resin composition>, it was 120 seconds, indicating a good curing time. The temperature at which the epoxy resin composition exhibited the lowest viscosity was 123°C, indicating good resin fluidity. T ₁ -T ₀ was 17° C., indicating good curability.

In addition, when the bending elastic modulus was measured according to <Method for evaluating bending elastic modulus of cured resin>, it was 3.2 GPa.

Furthermore, the ΔTg evaluated according to <Method for Evaluating Storage Stability of Epoxy Resin Composition> was 14° C., indicating good storage stability.

Using the carbon fiber web 1 and the epoxy resin composition, the fiber volume content Vfi of the resin supply material obtained according to <Method for producing resin supply material> is 9.5%, and the substrate form is maintained, Excellent resin supply ability, handleability, and shape followability.

As shown in Table 1, when the cross section of the flat plate obtained according to <Manufacturing method 1 of carbon fiber composite material> was observed, the void ratio was 14%.

(Examples 2 to 14)
An epoxy resin composition, a resin feed material, and a carbon fiber composite material were produced in the same manner as in Example 1, except that the resin composition was changed as shown in Table 1. The resin formulation, resin and fiber reinforced composite properties are summarized in Table 1.

As in Example 1, all of the obtained resin compositions were good in curing time, flexural modulus and storage stability. Further, the fiber volume content Vfi of the obtained resin supply material was 3.0 to 10.3%, and the substrate shape was maintained, and excellent resin supply capability, handleability, and shape followability were obtained. Furthermore, the void fraction of the obtained carbon fiber composite material was 5 to 17%.
(Example 15)
An epoxy resin composition, a resin feed material, and a carbon fiber composite material were produced in the same manner as in Example 1, except that the fiber volume content Vfi of the resin feed material was changed to 10.5%.

The obtained resin feed material maintained the form of the base material and was excellent in resin feed ability, handleability, and shape followability. The void fraction of the carbon fiber composite material was 14%.
(Example 16)
An epoxy resin composition, a resin feed material, and a carbon fiber composite material were produced in the same manner as in Example 1, except that the fiber volume content Vfi of the resin feed material was changed to 12.5%.

At this time, the preform thickness was 3.9 mm, the preform substrate area [x] was 100 cm ² , the preform substrate circumference [y] was 40 cm, and [x]/[y] was 2.0 cm. was 5.
The obtained resin supply material maintained the form of the base material and was excellent in handleability and shape followability. There was some unevenness in the resin supply, but it was within the range of no problem. The void fraction of the carbon fiber composite material was 19%.
(Example 17)
An epoxy resin composition, a resin supply material, and a carbon fiber composite material were produced in the same manner as in Example 1, except that the carbon fiber web for obtaining the resin supply material was changed from carbon fiber web 1 to carbon fiber web 2. .

At this time, the preform thickness was 3.9 mm, the preform substrate area [x] was 100 cm ² , the preform substrate circumference [y] was 40 cm, and [x]/[y] was 2.0 cm. was 5.
The resulting resin feed material was excellent in resin feeding ability. Since the binder was not attached, it was easy to collapse, but the handleability and shape followability were in the range where there was no problem. The fiber volume fraction Vfi of the obtained resin supply material was 9.9%, and the void fraction of the carbon fiber composite material was 18%.
(Example 18)
An epoxy resin composition, a resin supply material, and a carbon fiber composite material were produced in the same manner as in Example 1, except that the carbon fiber web for obtaining the resin supply material was changed from carbon fiber web 1 to carbon fiber web 3. .

At this time, the preform thickness was 3.9 mm, the preform substrate area [x] was 100 cm ² , the preform substrate circumference [y] was 40 cm, and [x]/[y] was 2.0 cm. was 5.
The resulting resin feed material was excellent in resin feeding ability. Due to the short fiber length, it was somewhat difficult to deform, but the handleability and shape followability were in the range where there was no problem. The fiber volume fraction Vfi of the resin feed material was 9.3%, and the void fraction of the carbon fiber composite material was 17%.
(Example 19)
An epoxy resin composition, a resin feed material, and a carbon fiber composite material were produced in the same manner as in Example 1, except that the carbon fiber web for obtaining the resin feed material was changed from carbon fiber web 1 to carbon fiber web 4. .

The obtained resin feed material maintained the form of the base material and was excellent in resin feed ability, handleability, and shape followability. The fiber volume fraction Vfi of the resin feed material was 9.5%, and the void fraction of the carbon fiber composite material was 15%.
(Example 20)
An epoxy resin composition, a resin supply material, and a carbon fiber composite material were produced in the same manner as in Example 1, except that the carbon fiber web for obtaining the resin supply material was changed from carbon fiber web 1 to carbon fiber web 5. .

The obtained resin feed material maintained the form of the base material and was excellent in resin feed ability, handleability, and shape followability. The fiber volume fraction Vfi of the resin feed material was 9.2%, and the void fraction of the carbon fiber composite material was 15%.
(Example 21)
An epoxy resin composition, a resin feed material, and a carbon fiber composite material were produced in the same manner as in Example 1, except that the carbon fiber web for obtaining the resin feed material was changed from carbon fiber web 1 to carbon fiber web 6. .

At this time, the preform thickness was 3.9 mm, the preform substrate area [x] was 100 cm ² , the preform substrate circumference [y] was 40 cm, and [x]/[y] was 2.0 cm. was 5.
The resulting resin feed material was excellent in resin feeding ability. Although unopened fiber bundles with long fiber lengths were found here and there, the handleability and shape followability were in the range of no problem. The fiber volume fraction Vfi of the resin feed material was 9.7%, and the void fraction of the carbon fiber composite material was 18%.
(Example 22)
An epoxy resin composition, a resin supply material, and a carbon fiber composite material were produced in the same manner as in Example 1, except that the carbon fiber web for obtaining the resin supply material was changed from carbon fiber web 1 to carbon fiber web 7. .

The obtained resin feed material maintained the form of the base material and was excellent in resin feed ability, handleability, and shape followability. The fiber volume fraction Vfi of the resin feed material was 10.8%, and the void fraction of the carbon fiber composite material was 14%.
(Example 23)
An epoxy resin composition, a resin supply material, and a carbon fiber composite material were produced in the same manner as in Example 1, except that the carbon fiber web for obtaining the resin supply material was changed from carbon fiber web 1 to carbon fiber web 8. .

At this time, the preform thickness was 3.9 mm, the preform substrate area [x] was 100 cm ² , the preform substrate circumference [y] was 40 cm, and [x]/[y] was 2.0 cm. was 5.
The obtained resin feed material maintained the form of the base material and was excellent in handleability. It was difficult to deform due to the large amount of binder adhered, but the shape followability was within a range where there was no problem. The fiber volume fraction Vfi of the resin feed material was 13.2%, and the void fraction of the carbon fiber composite material was 19%.
(Example 24)
Epoxy resin composition, resin feed material, and carbon fiber composite material were prepared in the same manner as in Example 16, except that the size of the resin feed material and the dry fabric was 30 cm × 30 cm according to <Production method 2 of carbon fiber composite material>. was made. At this time, the preform thickness was 3.9 mm, the preform base material area [x] was 900 cm ² , the preform base circumference length [y] was 120 cm, and [x]/[y] was 7.0 cm. was 5.
The void fraction of the obtained carbon fiber composite material was 5%.
(Example 25)
Epoxy resin composition, resin feed material, and carbon fiber composite material were prepared in the same manner as in Example 17, except that the size of the resin feed material and dry fabric was 30 cm × 30 cm according to <Production method 2 of carbon fiber composite material>. was made. At this time, the preform thickness was 3.9 mm, the preform base material area [x] was 900 cm ² , the preform base circumference length [y] was 120 cm, and [x]/[y] was 7.0 cm. was 5.

The void fraction of the obtained carbon fiber composite material was 4%.
(Example 26)
Epoxy resin composition, resin feed material, and carbon fiber composite material were prepared in the same manner as in Example 18, except that the size of the resin feed material and dry fabric was 30 cm × 30 cm according to <Carbon fiber composite material manufacturing method 2>. was made. At this time, the preform thickness was 3.9 mm, the preform base material area [x] was 900 cm ² , the preform base circumference length [y] was 120 cm, and [x]/[y] was 7.0 cm. was 5.

The void fraction of the obtained carbon fiber composite material was 4%.
(Example 27)
Epoxy resin composition, resin feed material, and carbon fiber composite material were prepared in the same manner as in Example 21, except that the sizes of the resin feed material and the dry fabric were 30 cm × 30 cm according to <Production method 2 of carbon fiber composite material>. was made. At this time, the preform thickness was 3.9 mm, the preform base material area [x] was 900 cm ² , the preform base circumference length [y] was 120 cm, and [x]/[y] was 7.0 cm. was 5.

The void fraction of the obtained carbon fiber composite material was 4%.
(Example 28)
Epoxy resin composition, resin feed material, and carbon fiber composite material were prepared in the same manner as in Example 23, except that the size of the resin feed material and dry fabric was 30 cm × 30 cm according to <Production method 2 of carbon fiber composite material>. was made. At this time, the preform thickness was 3.9 mm, the preform base material area [x] was 900 cm ² , the preform base circumference length [y] was 120 cm, and [x]/[y] was 7.0 cm. was 5.

The void fraction of the obtained carbon fiber composite material was 5%.
(Example 29)
An epoxy resin composition, a resin supply material, and a carbon fiber composite material were produced in the same manner as in Example 16, except that the press was pressurized to 0.3 MPa according to <Manufacturing Method 3 of Carbon Fiber Composite Material>.

The void fraction of the obtained carbon fiber composite material was 4%.
(Example 30)
An epoxy resin composition and a resin supply material were produced in the same manner as in Example 16, except that the laminate structure was changed according to <Manufacturing Method 4 of Carbon Fiber Composite Material>.

The void fraction of the obtained carbon fiber composite material was 4%.

(Comparative example 1)
An epoxy resin composition, a resin feed material, and a carbon fiber composite material were prepared in the same manner as in Example 1, except that the resin composition was changed as shown in Table 3. The resin composition and evaluation results are shown in Table 3. This epoxy resin composition does not have [F] and does not satisfy the scope of the present invention in that the condition [c] is 0.

Although the obtained resin composition showed rapid curing properties, the storage stability was insufficient, and the void fraction of the carbon fiber composite material was high.
(Comparative example 2)
An epoxy resin composition, a resin feed material, and a carbon fiber composite material were prepared in the same manner as in Example 1, except that the resin composition was changed as shown in Table 3. The resin composition and evaluation results are shown in Table 3. This epoxy resin composition does not meet the scope of the present invention in that condition [d] is 1.7.

Although the obtained epoxy resin composition had good storage stability, the curing time was long and the void fraction of the carbon fiber composite material was high and insufficient.
(Comparative Example 3)
An epoxy resin composition, a resin feed material, and a carbon fiber composite material were prepared in the same manner as in Example 1, except that the resin composition was changed as shown in Table 3. The resin composition and evaluation results are shown in Table 3. This epoxy resin composition does not meet the scope of the present invention in that condition [e] is 33.

Although the obtained epoxy resin composition had good storage stability, the curing time was long and the void fraction of the carbon fiber composite material was high and insufficient.

(Comparative Example 4)
An epoxy resin composition, a resin feed material, and a carbon fiber composite material were prepared in the same manner as in Example 1, except that the resin composition was changed as shown in Table 3. The resin composition and evaluation results are shown in Table 3. This epoxy resin composition does not meet the scope of the present invention in that the condition [d] is 0.8.

The curing time and storage stability of the resulting resin composition were good, but the void fraction of the carbon fiber composite material was high and insufficient.

(Comparative Example 5)
An epoxy resin composition, a resin feed material, and a carbon fiber composite material were prepared in the same manner as in Example 1, except that the resin composition was changed as shown in Table 3. The resin composition and evaluation results are shown in Table 3. This epoxy resin composition does not meet the scope of the present invention in that condition [e] is 9.

The curing time of the obtained resin composition was good, but the storage stability of the epoxy resin composition was insufficient.

(Comparative Example 6)
An epoxy resin composition, a resin feed material, and a carbon fiber composite material were prepared in the same manner as in Example 1, except that the resin composition was changed as shown in Table 3. The resin composition and evaluation results are shown in Table 3. This epoxy resin composition does not meet the scope of the present invention in that condition [c] is 0.048. The storage stability of the resulting resin composition was good, but the curing time and the void fraction of the carbon fiber composite material were long and unsatisfactory.

(Comparative Example 7)
An epoxy resin composition, a resin feed material, and a carbon fiber composite material were prepared in the same manner as in Example 1, except that the resin composition was changed as shown in Table 3. The resin composition and evaluation results are shown in Table 3. This epoxy resin composition does not meet the scope of the present invention in that condition [c] is zero. The curing time of the obtained resin composition was good, but the storage stability and the void fraction of the carbon fiber composite material were high and insufficient.

(Comparative Example 8)
An epoxy resin composition, a resin feed material, and a carbon fiber composite material were prepared in the same manner as in Example 1, except that the resin composition was changed as shown in Table 3. The resin composition and evaluation results are shown in Table 3. This epoxy resin composition does not satisfy the scope of the present invention in that the condition [c] is 0.050, the condition [d] is 1.8, and the condition [e] is 33.

Although the obtained epoxy resin composition had good storage stability, the curing time and the void fraction of the carbon fiber composite material were insufficient.

(Comparative Example 9)
An epoxy resin composition was produced in the same manner as in Example 1, except that the resin composition was changed as shown in Table 3. The resin composition and evaluation results are shown in Table 3. This epoxy resin composition does not satisfy the scope of the present invention in that the condition [c] is 0, the condition [d] is 2.4, and the condition [e] is 33.

The resulting epoxy resin composition was impregnated into a urethane foam "Moltoprene (registered trademark)" ER-1 manufactured by INOAC CORPORATION to prepare a resin supply material. The mass per unit area of the urethane foam was 175 g/m ² .

The curing time and storage stability of the obtained resin composition and the void fraction of the carbon fiber composite material were high and unsatisfactory.

(Comparative Example 10)
The same epoxy resin composition as in Example 1 was prepared, and carbon fibers "Torayca" (registered trademark) "T700SC-12K" (manufactured by Toray Industries, Inc.) aligned in one direction had a fiber volume content Vfi of 17.5. A prepreg was produced by impregnating the material so as to be 0%. The obtained carbon fiber composite material had an insufficient resin supply capacity and a high void ratio of 34%.

It should be noted that sufficient curing of the epoxy resin composition did not occur when either component [B] dicyandiamide or [C] aromatic urea was not added.

The resin supply material of the present invention and the method for producing a fiber-reinforced composite material using the resin supply material are suitably used for sports applications, general industrial applications, and aerospace applications. More specifically, in general industrial applications, it is suitably used as structural materials for automobiles, ships, wind turbines, etc., electronic device members such as IC trays and notebook computer housings, and repair and reinforcement materials. In aerospace applications, it is suitably used as structural materials for aircraft, rockets, artificial satellites, and the like.

Claims (15)

A resin supply material (A) used for molding a fiber-reinforced composite material,
The resin feed material (A) has reinforcing fibers (a) and resin (b),
The resin (b) contains the following components [C], [D], [E] and [F] and satisfies the following conditions [c], [d] and [e],
A resin supply material represented by the following formula (I), wherein the reinforcing fiber (a) contained in the resin supply material (A) has a fiber volume content Vfi of 15% or less.
[C]: epoxy resin [D]: dicyandiamide [E]: aromatic urea [F]: borate ester [c]: 0.005≦(mass ratio of component [F]/component [E])≦0. 045
[d]: 0.9 ≤ (number of moles of epoxy groups in component [C]/number of moles of active hydrogen in component [D]) ≤ 1.3
[e]: 12 ≤ (mass ratio of component [C]/component [E]) ≤ 26
Vfi=Va/Vb×100 (%) (I)
Here, Va: fiber volume in resin supply material (mm ³ )
Vb: Volume of resin feed material (mm ³ ) The resin feedstock of claim 1, wherein resin (b) satisfies the following conditions [g] and [h].
[g]: In dynamic viscoelasticity measurement, the temperature at which the lowest viscosity is exhibited is 110° C. or higher and 140° C. or lower while the temperature is increased from 40° C. to 250° C. at a rate of 5° C./min [h]: Differential scanning The difference between the exothermic start temperature (T ₀ ) and the exothermic end temperature (T ₁ ) when the temperature is raised from 30° C. to 300° C. at a rate of 5° C./min by a calorimeter is 25° C. or less. 3. The resin feedstock of claim 1 or 2, wherein the change in glass transition temperature of resin (b) before and after storage at 40<0>C, 75% RH for 14 days is no greater than 20<0>C. Claim 1, wherein 55 to 100 parts by mass of at least one epoxy resin [C1] selected from the group consisting of epoxy resins represented by formula (II) or formula (III) is contained in 100 parts by mass of component [C]. 4. The resin feed material according to any one of 1 to 3.

(In Formula (II), R ¹ , R ² , and R ³ each independently represent a hydrogen atom or a methyl group, and n represents an integer of 1 or more.)

(In formula (III), n represents an integer of 1 or more). The resin feed material according to any one of claims 1 to 4, wherein the reinforcing fibers (a) are carbon fibers. The resin feed material according to any one of claims 1 to 5, wherein the reinforcing fibers (a) have a mass average fiber length of 2 to 12 mm. 7. The resin supply material according to any one of claims 1 to 6, wherein the reinforcing fibers (a) are in the form of a web in which single fibers are bound together with a binder. 8. The resin feed material according to claim 7, wherein the weight ratio of the binder to the weight of the reinforcing fibers is 0.1 to 15%. Resin feedstock according to any one of the preceding claims, wherein the fiber volume content Vfi is between 0.5 and 11%. A preform comprising the resin supply material (A) according to any one of claims 1 to 9 and a base material (B) having reinforcing fibers. 11. The preform according to claim 10, wherein the substrate (B) having reinforcing fibers takes at least one form selected from textile substrates, unidirectional substrates and mat substrates. A method for producing a fiber-reinforced composite material, comprising heating and pressurizing the preform according to claim 10 or 11 to supply the resin (b) from the resin supply material (A) to the substrate (B) and molding. By heating and pressurizing the preform according to claim 10 or 11, which has a lamination thickness of 5 mm or less and satisfies the following formula (IV), the resin (b) is transferred from the resin supply material (A) to the base material (B). A method for producing a fiber-reinforced composite material, which supplies and molds.
Preform substrate area [x]/preform substrate circumference [y]≧7 [cm] (IV) A method for producing a fiber-reinforced composite material, wherein the heated preform according to claim 10 or 11 is pressed to 0.3 to 0.7 MPa with a press to obtain a molded article. Substrate (B)/resin feed (A)/substrate (B)/resin feed (A)/substrate (B) in this order, alternating resin feed (A) and substrate (B) A fiber-reinforced composite material that is molded by supplying a resin (b) from a resin supply material (A) to a substrate (B) by heating and pressurizing a plurality of laminated preforms according to claim 10 or 11. manufacturing method.

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