JPH09235397A - Prepreg and fiber-reinforced plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare both a prepreg capable of providing a fiber-reinforced plastic(FRP) capable of affording a high utilization ratio of tensile strength without deteriorating the elastic modulus and heat resistance of a matrix resin and the FRP. SOLUTION: This prepreg comprises (A) reinforcing fibers and (B) a thermosetting resin composition having >=3.0MPa tensile elastic modulus at ambient temperature, >=120 deg.C glass transition point, 0.5-3.0MPa.m<1/2> fracture toughness K1c (MPa.m<1/2> ), 1.5-15% breaking elongation ε (%) and the relationship between K1c and ε of K1c +0.35g>=2.1 in a cured product thereof. A fiber-reinforced composite material is obtained from the prepreg.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a prepreg for producing a fiber-reinforced composite material and a fiber-reinforced plastic thereof.

[0002]

2. Description of the Related Art Fiber reinforced plastics (hereinafter abbreviated as FRP) consisting of reinforced fibers and matrix resins are widely used in sports equipment, aerospace and general industrial applications because they are lightweight and have excellent mechanical properties. . Although various methods are used for manufacturing FRP, a method using a prepreg, which is a sheet-shaped intermediate base material in which reinforcing fibers are impregnated with a matrix resin, is widely used. In this method, a molded product is obtained by laminating a plurality of prepregs and then applying heat and pressure.

The mechanical properties of plastics are dramatically improved by adding reinforcing fibers. Further, in order to further improve the tensile strength of FRP, it is preferable to use a reinforcing fiber having higher strength, but the higher the reinforcing fiber is, the more the original tensile strength of the fiber cannot be utilized. The tensile strength utilization ratio (tensile strength of FRP / (strand strength × volume fiber content) × 100) tends to decrease.

Further, even if the same reinforcing fiber is used, the tensile strength utilization rate varies greatly depending on the matrix resin to be combined. For example, the tensile strength of FRP is increased by increasing the breaking elongation of the resin forming the matrix. In order to increase the breaking elongation of the resin, it is effective to reduce the crosslink density of the resin, but when the crosslink density of the resin is lowered, there is a problem that the elastic modulus of the resin and heat resistance are reduced. .

[0005]

DISCLOSURE OF THE INVENTION The present invention is to provide a prepreg and an FRP that gives an FRP that can obtain a high tensile strength utilization rate without lowering the elastic modulus and heat resistance of the matrix resin. Is.

[0006]

The prepreg of the present invention has the following constitution to achieve the above object. That is,
It is a prepreg consisting of the following components (A) and (B).

(A) Reinforcing fiber (B) The cured product has a tensile modulus of elasticity of 3.0 M at room temperature.
Pa or higher, glass transition point 120 ° C or higher, fracture toughness K _1c
(MPa · m ^1/2 ) is 0.5 to 3.0 MPa · m ^1/2 ,
A thermosetting resin composition having a breaking elongation ε (%) of 1.5 to 15% and a relationship between K _1c and ε being K _1c +0.35 ε ≧ 2.1.

The FRP of the present invention has the following constitution in order to achieve the above object. That is, it is an FRP obtained by curing the prepreg.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A description will be added below for each component.

The element used as the constituent element (A) in the present invention is a reinforcing fiber. Various reinforcing fibers can be used depending on the intended use of the composite material. Specific examples of the reinforcing fiber that can be used in the present invention include carbon fiber, graphite fiber, aramid fiber, silicon carbide fiber, alumina fiber, boron fiber, tungsten carbide fiber, and glass fiber. The reinforcing fiber may be used in combination of plural kinds. Of these, carbon fibers and graphite fibers, which have good specific strength and specific elastic modulus and are recognized to make a great contribution to weight reduction, are preferably used in the present invention. It is possible to use all kinds of carbon fibers and graphite fibers depending on the application, but high-strength carbon fibers having a tensile strength of 4.0 GPa or more and a tensile elongation of 1.5% or more are composite materials. It is suitable for expressing strength. Furthermore, tensile strength 4.5GP
High-strength and high-strength carbon fibers having a or more and a tensile elongation of 1.7% or more are preferable. More preferably, the tensile strength is 4.7 GPa
As described above, the tensile elongation is 2.0% or more.

The tensile strength and tensile elongation of carbon fiber are J
It can be measured according to the resin impregnated strand test method of ISR-7601. In the examples, Bakelite ERL422 made by Union Carbide was used as the resin.
Using 100 parts by weight, 1 part by weight, 3 parts by weight, and 4 parts by weight of acetone, 1,3 fluoromonoethylamine and acetone, respectively, were thoroughly impregnated into carbon fiber,
It was cured at 30 ° C. for 30 minutes to prepare a sample and measure it.

Carbon fibers and graphite fibers may be used by mixing with other reinforcing fibers. The reinforcing fibers are not limited in shape and arrangement, and may be used in a single direction, a random direction, a sheet shape, a mat shape, a woven shape, or a braided shape. In particular, for applications requiring high specific strength and specific elastic modulus, an array in which reinforcing fibers are aligned in a single direction is most suitable, but a cross (woven) array which is easy to handle. Are also suitable for the present invention. In addition to the sheet form, the prepreg includes forms called yarns, strands or rovings. A yarn prepreg is a fiber bundle in which the number of single fibers is usually 1,000 to 50,000 filaments impregnated with a resin, and the reinforcing fibers are arranged in one direction, and the reinforcing fibers are arranged in a direction perpendicular to the arrangement direction of the reinforcing fibers. The width is 15 mm or less. The yarn prepreg is usually wound directly onto the bobbin after the resin impregnation. When used, the yarn prepreg is unwound from a bobbin and subjected to a predetermined molding method. For example, in the case of tubular shaped articles such as automobile propeller shafts, fishing rods, and golf club shafts, they are often manufactured by the filament winding method. In addition, when making a cable made of FRP or a reinforcing bar, usually, a plurality of yarn prepregs in which reinforcing fibers are aligned in one direction are twisted as a strand.
It is obtained by making it into a rope and then curing it. In this case, the obtained FRP is required to have high tensile strength. Braided reinforced fiber forms are often used. The yarn prepreg can be unwound in the pull-through method as well to produce molded articles having various cross-sectional shapes. Since the resin is impregnated in advance, it has advantages that the speed of the molding process can be increased and the resin content can be controlled more accurately as compared with the method of impregnating the reinforcing fibers with the resin in the molding site. The present invention can utilize the excellent tensile strength characteristics even in the form of such a yarn prepreg.

Component (B) used in the present invention
The element used as is a thermosetting resin composition.

The thermosetting resin used in the present invention is usually a resin which is cured by heat, but it may be a resin which is cured by energy other than heat, such as light or electron beam, and is at least partially tertiary. Any resin may be used as long as it is a resin that forms an original cured product.

The thermosetting resin composition used in the present invention has a fracture toughness of 0.5 to 3.0 MPa · m ^1/2 , preferably 0. 6 to 3.0 MPa · m ^1/2 , breaking elongation of 1.5
It is necessary to be -15%, preferably 2.0-15%. Further, the thermosetting resin composition used in the present invention is required to have a tensile elastic modulus at room temperature of a cured product of 3.0 MPa or more, preferably 3.2 MPa or more. In addition, the thermosetting resin composition used in the present invention has a glass transition point (hereinafter,
(Abbreviated as Tg) must be 120 ° C. or higher, preferably 150 ° C. or higher.

Here, the balance between the fracture toughness and the elongation of the cured product of the thermosetting resin composition is controlled, specifically, the fracture toughness K _1c and the fracture elongation ε of the cured product are K _1c + 0.35ε ≧
By satisfying the relationship of 2.1, preferably K _1c + 0.35ε ≧ 3.3, and more preferably the relationship of K _1c + 0.35ε ≧ 3.7, the tensile strength utilization ratio is about 80% or more, preferably Is about 90% or more, more preferably about 95%
It is possible to obtain FRP having high tensile strength.

Here, the tensile elongation and tensile modulus of the cured product of the thermosetting resin composition can be measured as follows.

That is, the test piece is JIS K-711.
A No. 31 type small test piece was prepared and the crosshead speed was measured at 1 mm / min. Further, the calculation of the tensile elastic modulus at room temperature is performed in the range of the strain amount of 0.1 to 0.3%.

The fracture toughness of the cured product of the thermosetting resin composition can be measured as follows. That is, the test piece is cut into a thickness of 6 mm and a height of 12.7 mm,
ASTM-D5045 at a span distance of 50.8 mm
It is measured by the SENB method according to the method described in -91.

Further, T of a cured product of the thermosetting resin composition
g can be measured by a conventional method using a differential scanning calorimeter (DSC) at a heating rate of 40 ° C./min.

The thermosetting resin suitable for the present invention is particularly an epoxy resin, which is generally used in combination with a curing agent or a curing catalyst. In particular, an epoxy resin using an amine, a phenol, or a compound having a carbon-carbon double bond as a precursor is preferable. Specifically, as an epoxy resin using amines as a precursor, tetraglycidyldiaminodiphenylmethane, triglycidyl-p-aminophenol, triglycidyl-m-aminophenol, various isomers of triglycidylaminocresol, and pheno- Bisphenol A as an epoxy resin containing a precursor as a precursor
Type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, resorcinol type epoxy resin, compound having carbon-carbon double bond Epoxy resin as a precursor,
Examples thereof include alicyclic epoxy resin. Brominated epoxy resins obtained by bromizing these epoxy resins are also used.

Epoxy resins having an aromatic amine as a precursor, represented by tetraglycidylaminodiphenylmethane, are most suitable for the present invention because they have good heat resistance and good adhesion to reinforcing fibers. Further, in the present invention, the epoxy resin 1
It is preferable that the bifunctional epoxy resin is contained in an amount of 40 parts by weight or more out of 00 parts by weight in order to improve the breaking elongation of the matrix resin. Further, those containing 60 parts by weight or more of the bifunctional epoxy resin are more preferable because their effects are remarkably exhibited.

The epoxy resin is preferably used in combination with an epoxy curing agent. As the curing agent, any compound having an active group capable of reacting with an epoxy group can be used. A compound having an amino group, an acid anhydride group or an azido group is preferable. Specifically, dicyandiamide, various isomers of diaminodiphenyl sulfone, and aminobenzoic acid esters are suitable. More specifically, dicyandiamide is preferably used because it has excellent storage stability in prepreg. Further, various isomers of diaminodiphenyl sulfone are most suitable for the present invention because they give cured products having good heat resistance.

As the aminobenzoic acid esters, trimethylene glycol-di-p-aminobenzoate and neopentyl glycol-di-p-aminobenzoate are preferably used, and are compared with diaminodiphenyl sulfone.
Although it is inferior in heat resistance, it has excellent tensile elongation, so it is selected and used according to the application.

Other thermosetting resins used for the component (B) include maleimide resins, acetylene-terminated resins, nadic acid-terminated resins, cyanate ester-terminated resins, vinyl-terminated resins, Examples thereof include resins having an allyl terminal. These may be appropriately mixed with an epoxy resin or another resin. Also,
A reactive diluent may be used, or a modifier such as a thermoplastic resin or an elastomer may be mixed and used to such an extent that heat resistance is not significantly deteriorated.

Examples of the maleimide resin include N, N'-phenylene bismaleimide, N, N'-hexamethylene bismaleimide, N, N'-methylene-di-p-phenylene bismaleimide, N, N'-oxy-. Di-p-phenylene bismaleimide, N, N'-4,4'-benzophenone bismaleimide, N,
N'-diphenylsulfone bismaleimide, N, N '-(3,3'-
Dimethyl) -methylene-di-p-phenylene bismaleimide, N, N'-4,4'-dicyclohexylmethane bismaleimide, N, N'-m (or p) -xylylene-bismaleimide,
N, N '-(3,3'-diethyl) -methylene-di-p-phenylene bismaleimide, N, N'-metatrilene-di-maleimide and bis (aminophenoxy) benzene bismaleimide, aniline and formalin A reaction product of a mixed polyamine, which is a reaction product of the above, and maleic anhydride. Further, these maleimide resins may be used as a mixture of two or more kinds, and may contain a monomaleimide compound such as N-allylmaleimide, N-propylmaleimide, N-hexylmaleimide or N-phenylmaleimide.

The maleimide resin is preferably used in combination with a curing agent. As the curing agent, any compound having an active group capable of reacting with a maleimide group can be used.
A compound having an amino group, an alkenyl group represented by an allyl group, a benzocyclobutene group, an allyl nadimide group, an isocyanate group, a cyanate group, or an epoxy group is suitable. For example, diaminodiphenylmethane is a typical curing agent having an amino group, and O, O′-diallylbisphenol A and bis (propenylphenoxy) sulfone are examples of a curing agent having an alkenyl group.

The bismaleimide-triazine resin (BT resin) composed of the above-mentioned bismaleimide and cyanate ester is also suitable as the thermosetting resin used in the constituent element (B) of the present invention. As the resin having a cyanate ester terminal, a cyanate ester compound of polyhydric phenol represented by bisphenol A is suitable. A resin obtained by combining a cyanate ester resin and a bismaleimide resin is commercially available as BT resin from Mitsubishi Gas Chemical Co., Inc. and is suitable for the present invention. These are generally used in accordance with the application because they have better heat resistance and water resistance than epoxy resins, but are inferior in toughness and impact resistance. The weight ratio of bismaleimide and cyanate ester is 0 / 100-
Used in the 70/30 range. The case of 0/100 is a triazine resin (also referred to as a cyanate resin), but this is also suitable for the present invention.

Further, a thermosetting polyimide resin having a terminal reactive group is also suitable as the constituent element (B). As the terminal reactive group, a nadiimide group, an acetylene group, a benzocyclobutene group and the like are preferable.

Component (B) of the present invention includes phenol resin, resorcinol resin, unsaturated polyester resin,
Thermosetting resins widely recognized in the industry such as diallyl phthalate resin, urea resin and melamine resin can also be used.

The thermosetting resin composition is preferably mixed with a thermoplastic resin or an elastomer. The thermoplastic resin suitable for the present invention has a carbon-carbon bond, an amide bond, an imide bond, an ester bond, an ether bond in the main chain,
A typical example is a thermoplastic resin having a bond selected from a carbonate bond, a urethane bond, a urea bond, a thioether bond, a sulfone bond, an imidazole bond, and a carbonyl bond. An oligomer thereof may be used as these thermoplastic resins. Specific examples of the thermoplastic resin include polysulfone, polyether sulfone, polyether imide, polyarylate, polyamide imide, polyether ketone, polyvinyl formal, and polyimide. Particularly, the thermoplastic resin having the structure of the following formula (I) Is particularly preferable because it has good heat resistance.

[0032]

Embedded image (R ₁ is any one selected from the following formulas (II) to (V)
, R ₂ is the following formula (V) or (VI), R ₃ is the following formula (V)
Or (VII))

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Embedded image Examples of elastomers suitable for the present invention include butadiene-acrylonitrile copolymer, chloroprene rubber, silicone rubber, polyester-based or polyamide-based thermoplastic elastomers, and the like. These thermoplastic resins and / or elastomers are preferable because they have high toughness and excellent impact resistance. Moreover, you may use these 1 type (s) or 2 or more types.

[0033]

EXAMPLES The present invention will be specifically described below with reference to examples. In the examples, 0 ° tensile strength of FRP was measured as follows.

Six prepregs were laminated in a single direction and cured in an autoclave at a temperature of 180 ° C. and a pressure of 6 kg / cm ² for 2 hours. Hardened plate width 12.7m
m, length 230mm, thickness 1.2m on both ends
A glass-reinforced fiber-plastic tab having a taper of m, a length of 50 mm, and a length of 10 mm was bonded, and tensile measurement was performed at a crosshead speed of 1.27 mm / min.

Example 1 (a) Preparation of Resin Composition The following raw materials were kneaded to obtain a resin composition.

(1) Tetraglycidyldiaminodiphenylmethane (ELM434, manufactured by Sumitomo Chemical Co., Ltd.) 50.0 parts (2) Bisphenol A type epoxy resin (Epicoat 828, manufactured by Yuka Shell Epoxy Co., Ltd.) 20.0 parts (3) Bisphenol A type epoxy resin (Epicoat 1001, manufactured by Yuka Shell Epoxy Co., Ltd.) 30.0 parts (4) 4,4′-diaminodiphenyl sulfone (Sumicure S, manufactured by Sumitomo Chemical Co., Ltd.) 36. 3 parts (b) Physical properties of resin cured product The resin composition prepared in (a) was cured at 180 ° C for 2 hours to prepare a cured resin product, and the physical properties were evaluated. The cured resin has a breaking elongation of 4.2%, a tensile modulus of 3.6 MPa, a fracture toughness of 0.65 MPa · m ^1/2 , and a K _1c +0.35.
ε was 2.12. Also, the glass transition point (Tg)
Was 213 ° C.

(C) Preparation of prepreg The resin prepared in (a) was placed on a release paper and the resin weight was 51.8 g.
/ M ² to obtain a resin film. Carbon fibers aligned in one direction (T800H-12K-40
B, manufactured by Toray Industries, Inc., strand tensile strength 5.5 GPa,
Tensile elongation of 1.8%) is sandwiched by resin films from both sides,
The resin was impregnated to prepare a prepreg having a carbon fiber areal weight of 190 g / mm ² .

(D) 0 ° Tensile Strength 0 ° Tensile strength was measured to find that the tensile strength was 2.5 GP.
a. The volume fiber content was 56.5%.

(E) Calculation of tensile strength utilization factor From the tensile strength obtained in (d), the tensile strength utilization factor was calculated to be 80.5%.

(Tensile strength utilization ratio) = (FRP tensile strength) / ((Strand strength) × (Volume fiber content)) ×
100 (Example 2) (a) Preparation of resin composition The following raw materials were kneaded to obtain a resin composition.

(1) Tetraglycidyldiaminodiphenylmethane (ELM434, manufactured by Sumitomo Chemical Co., Ltd.) 20.0 parts (2) Bisphenol A type epoxy resin (Ep828, manufactured by Yuka Shell Epoxy Co., Ltd.) 30.0 parts ( 3) Bisphenol A type epoxy resin (Ep1001, manufactured by Yuka Shell Epoxy Co., Ltd.) 50.0 parts (4) 4,4′-diaminodiphenyl sulfone (Sumicure S, manufactured by Sumitomo Chemical Co., Ltd.) 26.7 parts (B) Physical property measurement of cured resin product The resin prepared in (a) was cured at 180 ° C. for 2 hours to prepare a cured resin product, and the physical properties were evaluated. The cured resin has a breaking elongation of 7.6%, a tensile modulus of 3.3 MPa, a fracture toughness of 0.65 MPa · m ^1/2 , and K _1c + 0.35ε =
It was 3.31. The glass transition point (Tg) was measured and found to be 197 ° C.

(C) Preparation of prepreg The prepared resin was coated on a release paper so as to have a resin areal weight of 51.8 g / m ² to prepare a resin film. Carbon fibers (T800H-12K-40B, manufactured by Toray Industries, Inc., strand tensile strength 5.5 GPa, tensile elongation 1.8%) that are aligned in one direction are sandwiched with resin films from both sides to impregnate the resin with carbon fibers. A prepreg having a basis weight of 190 g / mm ² was produced.

(D) Measurement of 0 ° tensile strength When 0 ° tensile measurement was carried out, the tensile strength was 2.8 GP.
a. The volume fiber content was 56.5%.

(E) Calculation of Tensile Strength Utilization Rate From the tensile strength obtained in (d), the tensile strength utilization rate was calculated to be 90.1%.

(Example 3) (a) Preparation of resin composition The following raw materials were kneaded to obtain a resin composition.

(1) Trifunctional aminophenol epoxy resin (ELM100, manufactured by Sumitomo Chemical Co., Ltd.) 100.0 parts (2) 4,4′-diaminodiphenyl sulfone (Sumicure S, manufactured by Sumitomo Chemical Co., Ltd.) ) 58.5 parts (3) Polyether sulfone (PES5003P, manufactured by Mitsui Toatsu Chemicals, Inc.) 39.6 parts (b) Physical properties of cured resin The resin prepared in (a) is cured at 180 ° C for 2 hours. Then, a resin cured product was produced and the physical properties were evaluated. The fracture elongation of the cured resin product is 2.8%, the tensile modulus is 4.5 MPa, the fracture toughness is 1.22 MPa · m ^1/2 , and K _1c + 0.35ε =
2.2. The glass transition point (Tg) was measured and found to be 233 ° C.

(C) Preparation of prepreg The prepared resin was coated on a release paper so as to have a resin areal weight of 51.8 g / m ² to prepare a resin film. Carbon fibers (T800H-12K-40B, manufactured by Toray Industries, Inc., strand tensile strength 5.5 GPa, tensile elongation 1.8%) that are aligned in one direction are sandwiched with resin films from both sides to impregnate the resin with carbon fibers. A prepreg having a basis weight of 190 g / mm ² was produced.

(D) Measurement of 0 ° tensile strength When 0 ° tensile measurement was performed, the tensile strength was 2.5 GP.
and the fiber content was 56.5%.

(E) Calculation of tensile strength utilization factor From the tensile strength obtained in (d), the tensile strength utilization factor was calculated to be 80.5%.

Example 4 (a) Preparation of Resin Composition The following raw materials were kneaded to obtain a resin composition.

(1) Trifunctional aminophenol type epoxy resin (ELM100, manufactured by Sumitomo Chemical Co., Ltd.) 25.0 parts (2) Bisphenol F type epoxy resin (Epiclon 830, manufactured by Dainippon Ink and Chemicals, Inc.) 75. 0 parts (3) 4,4'-diaminodiphenyl sulfone (Sumicure S, manufactured by Sumitomo Chemical Co., Ltd.) 41.2 parts (4) Polyether sulfone (PES5003P, manufactured by Mitsui Toatsu Chemicals, Inc.) 35.3 Part (b) Measurement of physical properties of cured resin The resin prepared in (a) was cured at 180 ° C. for 2 hours to prepare a cured resin, and the physical properties were evaluated. The resin cured product had a fracture elongation of 6.3%, a tensile modulus of 3.9 MPa, and a fracture toughness of 1.20 MPa · m ^1/2 . K _1c + 0.35ε =
It was 3.41. The glass transition point (Tg) was measured and found to be 213 ° C.

(C) Preparation of prepreg The resin prepared in (a) was placed on a release paper and the resin weight was 51.8 g.
/ M ² to obtain a resin film. Carbon fibers aligned in one direction (T800H-12K-40
B, manufactured by Toray Industries, Inc., strand tensile strength 5.5 GPa,
Tensile elongation of 1.8%) is sandwiched by resin films from both sides,
The resin was impregnated to prepare a prepreg having a carbon fiber areal weight of 190 g / mm ² .

(D) Measurement of 0 ° tensile strength When 0 ° tensile measurement was performed, the tensile strength was 2.9 GP.
and the fiber content was 56.5%.

(E) Calculation of tensile strength utilization factor From the tensile strength obtained in (d), the tensile strength utilization factor was calculated to be 93.3%.

Example 5 (a) Toughening Agent (Synthesis of Amine-Terminated Siloxane Polyimide Oligomer) A 3000 ml separable flask equipped with a nitrogen inlet, a thermometer, a stirrer and a dehydration trap was replaced with nitrogen. And 392 g (0.91 mol) of bis [4-
(3-Aminophenoxy) phenyl] sulfone (BAP
SM), 39 g (0.11 mol) of 9,9'-bis (4-aminophenyl) fluorene (FDA), 147.
g (0.11 mol) NH ₂ equivalent 650 amino-terminated dimethyl siloxane (Toray Dow Corning Silicone
2000-16 ml of BY-16-853 manufactured by N. Co., Ltd.
It was dissolved in methyl-2-pyrrolidone (NMP) with stirring. Solid biphenyl tetracarboxylic acid dianhydride was added thereto 30
0 g (1.02 mol) was added little by little, the mixture was stirred at room temperature for 3 hours, then heated to 120 ° C. and stirred for 2 hours. The flask was returned to room temperature and 50 ml of triethylamine and 5 parts of toluene were added.
After adding 0 ml, the temperature was raised again and azeotropic dehydration was performed at 160 ° C. to obtain about 30 ml of water. After cooling the reaction mixture, it was diluted with double NMP and slowly poured into 20 ml of acetone to precipitate the amine-terminated siloxane polyimide oligomer as a solid product. Then, the precipitate was vacuum dried at 200 ° C. The number average molecular weight (Mn) of this oligomer was measured by gel permeation chromatography (G) using a dimethylformamide (DMF) solvent.
When measured by PC, polyethylene glycol (PE
It was 5500 in terms of G). The glass transition point was 223 ° C. according to a differential thermal analyzer (DSC). Also,
The introduction of the siloxane skeleton and the amine termination are N
It could be confirmed from the MR spectrum and the IR spectrum.

(B) Preparation of resin composition The following raw materials were kneaded to obtain a resin composition. ((1) to (4) are dissolved in advance and (5) is kneaded) (1) Tetraglycidyldiaminodiphenylmethane (ELM434, manufactured by Sumitomo Chemical Co., Ltd.) 35.0 parts (2) Bisphenol A type epoxy resin ( Epicoat 825, Yuka Shell Epoxy Co., Ltd. 15.0 parts (3) Bisphenol F type epoxy resin (Epiclon 830, Dainippon Ink Co., Ltd.) 50.0 parts (4) Toughening agent ((a 21.1 parts (5) 4,4'-diaminodiphenyl sulfone (Sumicure S, manufactured by Sumitomo Chemical Co., Ltd.) 41.4 parts (c) Physical properties of cured resin prepared in (b) The resin was cured at 180 ° C. for 2 hours to prepare a cured resin product, and the physical properties were evaluated. The cured resin had a breaking elongation of 8.1%, a tensile modulus of 3.7 GPa and a fracture toughness of 0.95 MPa · m ^1/2 . K _1c + 0.35ε
= 3.79. The glass transition point (Tg) was measured and found to be 213 ° C.

(D) Preparation of prepreg The resin prepared in (b) was placed on the release paper to give a resin weight of 51.8 g.
/ M ² to obtain a resin film. Carbon fibers aligned in one direction (T800H-40B-12
K, manufactured by Toray Industries, Inc., strand tensile strength 5.5 GPa,
Tensile elongation of 1.8%) is sandwiched by resin films from both sides,
The resin was impregnated to prepare a prepreg having a carbon fiber areal weight of 190 g / mm ² .

(E) Measurement of 0 ° tensile strength When 0 ° tensile measurement was performed, the tensile strength was 3.0 GP.
The volume fiber content was 56.5%.

(F) Calculation of Tensile Strength Utilization Ratio From the tensile strength obtained in (e), the tensile strength utilization ratio was calculated to be 96.5%.

(Example 6) (a) Preparation of prepreg The resin prepared in Example 5 was applied to a release paper with a resin areal weight of 51.8.
It was applied so as to be g / m ² to prepare a resin film.
Carbon fibers aligned in one direction (T300JC-12K-
50C, Toray Industries, Inc., Strand Tensile Strength 4.3GP
a, a tensile elongation of 1.9%) was sandwiched from both sides with a resin film and impregnated with a resin to prepare a prepreg having a carbon fiber areal weight of 190 g / mm ² .

(B) Measurement of 0 ° tensile strength When 0 ° tensile measurement was carried out, the tensile strength was 2.0 GP.
and the volume fiber content was 56.8%.

(C) Calculation of tensile strength utilization factor From the tensile strength obtained in (b), the tensile strength utilization factor was calculated to be 81.8%.

(Example 7) (a) Preparation of prepreg The resin prepared in Example 5 was applied to a release paper with a resin weight of 51.8.
It was applied so as to be g / m ² to prepare a resin film.
Carbon fibers aligned in one direction (T700SC-12K-
50C, Toray Industries, Inc., Strand Tensile Strength 4.8GP
a, tensile elongation 2.1%) was sandwiched between both sides with a resin film and impregnated with a resin to prepare a prepreg having a carbon fiber areal weight of 190 g / mm ² .

(B) Measurement of 0 ° tensile strength When 0 ° tensile measurement was carried out, the tensile strength was 2.6 GP.
and the volume fiber content was 56.8%.

(C) Calculation of Tensile Strength Utilization Ratio From the tensile strength obtained in (b), the tensile strength utilization ratio was calculated to be 95.4%.

Comparative Example 1 (a) Preparation of Resin Composition The following raw materials were kneaded to obtain a resin composition.

(1) Trifunctional aminophenol type epoxy resin (ELM100, manufactured by Sumitomo Chemical Co., Ltd.) 100.0 parts (2) 4,4′-diaminodiphenyl sulfone (Sumicure S, manufactured by Sumitomo Chemical Co., Ltd.) ) 58.5 parts (b) Measurement of physical properties of cured resin The resin prepared in (a) was cured at 180 ° C for 2 hours to prepare a cured resin, and the physical properties were evaluated. The cured resin product had a breaking elongation of 2.3%, a tensile modulus of 4.7 MPa, and a fracture toughness of 0.55 MPa · m ^1/2 . K _1c + 0.35ε
= 1.36. The glass transition point (Tg) was measured and found to be 245 ° C.

(C) Preparation of prepreg The resin prepared in (a) was placed on a release paper and the resin weight was 51.8 g.
/ M ² to obtain a resin film. Carbon fibers aligned in one direction (T800H-12K-40
B, manufactured by Toray Industries, Inc., strand tensile strength 5.5 GPa,
Tensile elongation of 1.8%) is sandwiched by resin films from both sides,
The resin was impregnated to prepare a prepreg having a carbon fiber areal weight of 190 g / mm ² .

(D) Measurement of 0 ° tensile strength When 0 ° tensile measurement was performed, the tensile strength was 2.1 GPa.
And the volume fiber content was 56.5%.

(E) Calculation of tensile strength utilization factor From the tensile strength obtained in (d), the tensile strength utilization factor was calculated to be 67.6%.

(Comparative Example 2) (a) Preparation of prepreg The resin prepared in Comparative Example 1 was coated on a release paper with a resin weight of 51.8
It was applied so as to be g / m ² to prepare a resin film.
Carbon fibers aligned in one direction (T700SC-12K-
50C, Toray Industries, Inc., Strand Tensile Strength 4.8GP
a, tensile elongation 2.1%) was sandwiched between both sides with a resin film and impregnated with a resin to prepare a prepreg having a carbon fiber areal weight of 190 g / mm ² .

(B) Measurement of 0 ° tensile strength When 0 ° tensile measurement was carried out, the tensile strength was 1.8 GPa.
And the volume fiber content was 56.8%.

(C) Calculation of Tensile Strength Utilization Ratio From the tensile strength obtained in (b), the tensile strength utilization ratio was calculated to be 66.0%.

[0074]

INDUSTRIAL APPLICABILITY The prepreg of the present invention can obtain FRP having high tensile strength without impairing heat resistance by controlling the fracture toughness and fracture elongation after curing of the matrix resin.

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Claims (11)

[Claims] 1. A prepreg comprising the following components (A) and (B): (A) Reinforcing fiber (B) Cured product has a tensile elastic modulus of 3.0 M at room temperature.
Pa or higher, glass transition point 120 ° C or higher, fracture toughness K _1c
(MPa · m ^1/2 ) is 0.5 to 3.0 MPa · m ^1/2 ,
Thermosetting resin composition having a breaking elongation ε (%) of 1.5 to 15% and a relationship between K _1c and ε is K _1c +0.35 ε ≧ 2.1 2. The prepreg according to claim 1, wherein the thermosetting resin composition comprises an epoxy resin and a curing agent. 3. The prepreg according to claim 2, wherein 40 parts by weight or more of a bifunctional epoxy resin is contained in 100 parts by weight of the epoxy resin. 4. The prepreg according to claim 1, wherein the thermosetting resin composition contains an elastomer or a thermoplastic resin. 5. The thermoplastic resin is at least one selected from polysulfone, polyethersulfone, polyetherimide, polyarylate, polyamideimide, polyetherketone, polyvinylformal, polyimide or a compound represented by the following formula (I). The prepreg according to claim 4, wherein: Embedded image (R ₁ is any one selected from the following formulas (II) to (V)
, R ₂ is the following formula (V) or (VI), R ₃ is the following formula (V)
Or (VII)) Embedded image Embedded image Embedded image [Chemical 6] Embedded image 6. The prepreg according to claim 1, wherein the reinforcing fiber (A) is a carbon fiber. 7. The prepreg according to claim 6, wherein the tensile strength of the carbon fiber is 4.4 GPa or more. 8. The prepreg according to claim 6, wherein the carbon fibers are arranged in one direction, and the width of the carbon fibers in the direction perpendicular to the arrangement direction is 15 mm or less. 9. A fiber reinforced plastic obtained by curing the prepreg according to any one of claims 1 to 8. 10. A fiber reinforced plastic obtained by twisting and curing the prepreg according to claim 8. 11. A cable comprising the fiber reinforced plastic according to claim 10.