WO2019065663A1 - Curable resin composition and tow prepreg using same - Google Patents

Abstract

Provided is a curable resin composition suitable for use as a matrix resin for a fiber-reinforced composite material having excellent fatigue resistance, the curable resin composition having, low viscosity, minimal increase in viscosity even in a prolonged impregnation step, and good impregnation into reinforcing fibers, and high toughness being obtained in a molded article obtained by curing the curable resin composition. A curable resin composition for a tow prepreg having (A) an epoxy resin, (B) core-shell-type rubber particles, (C) dicyandiamide or a derivative thereof, and (D) a solid aromatic urea compound or a solid imidazole compound as essential components thereof, at least 25% by mass of the epoxy resin (A) being a bisphenol-F-type epoxy resin having a weight per epoxy equivalent of 180 g/eq, the blended amount of the core-shell-type rubber particles (B) being 2-20% by mass with respect to the total amount of components (A) through (D), and the viscosity of the curable resin composition for a tow prepreg at 25°C being in the range of 3 to 45 Pa∙s.

Description

Curable resin composition, and to-prepreg using the same

TECHNICAL FIELD The present invention relates to a curable resin composition for toe prepreg which is excellent in viscosity stability, and toe prepreg using the same.

Fiber-reinforced composite materials are glass fibers, reinforcing fibers such as aramid fibers and carbon fibers, and thermosetting matrices such as unsaturated polyester resins, vinyl ester resins, epoxy resins, epoxy resins, phenol resins, benzoxazine resins, cyanate resins, bismaleimide resins, etc. It is made of resin, is light in weight, and is excellent in mechanical properties such as strength, corrosion resistance and fatigue resistance, so it is widely applied as a structural material for aircraft, automobiles, civil engineering buildings, sports goods and the like.

The method of producing a fiber reinforced composite material includes an autoclave molding method using a prepreg in which a thermosetting matrix resin is impregnated in advance into reinforcing fibers, a press molding method, a step of impregnating reinforcing fibers with a liquid matrix resin, and thermosetting. There are methods such as wet lay-up molding method, pultrusion molding method, filament winding molding method, RTM method and the like including the molding process according to the above.

One of the filament winding methods is a dry method using a tow prepreg in which a reinforcing fiber is impregnated with a resin in advance. Since the dry method is excellent in shortening the winding speed and the stability of the resin ratio, it has an advantage in high productivity and quality stabilization of the fiber reinforced composite material, and is particularly applied as one of the methods for producing a high pressure gas tank. ing.

In the dry method, in order to enhance the to-preg quality, in order to ensure stable impregnation and handling at the time of winding, a matrix resin in a suitable viscosity range and having a small rate of increase in viscosity is used. In addition, a high fracture toughness value is desired to enhance the impact resistance and fatigue resistance of the fiber-reinforced composite material at the time of curing.

There are various methods for enhancing the fracture toughness of the matrix resin, and examples thereof include addition of low elastic modulus rubbery polymer, block copolymer, core-shell type rubber particles, and the like. In the compounding of the core-shell type rubber particles, fracture toughness can be improved by dispersing rubber particles having an average particle diameter of several tens to several hundreds of nm in a matrix resin. Optimization of the compatibility between the matrix resin and the shell layer of the core-shell type rubber particles is important in enhancing the fracture toughness because it affects the dispersibility of the rubber particles.

It is possible to increase fracture toughness by increasing the amount of core-shell rubber particles added, but when the amount is too high, the quality of the prepreg is lowered due to the significant increase in viscosity of the matrix resin, and the low elasticity of the molding It is necessary to pay attention to the components other than the rubber particles in order to reduce the strength and the strength.

Patent documents 1 and 2 propose a resin composition using core-shell type rubber particles. Patent Document 3 proposes a resin composition using core-shell rubber particles and urethane-modified or rubber-modified epoxy. Patent Document 4 proposes a resin composition using core-shell rubber particles and solid bisphenol F-type epoxy resin. In these documents, although the improvement of toughness is seen by using core-shell type rubber particles, it is necessary to pay attention to components other than core-shell type rubber particles for further improvement of toughness, and it mentions about that Absent.

Although attempts have been made to improve the fracture toughness of moldings by adding core-shell type rubber particles for matrix resins of fiber reinforced composite materials, fracture toughness is further enhanced to improve impact resistance and fatigue resistance of moldings. Is desired.

Unexamined-Japanese-Patent No. 9-227693 WO 2017/099060 JP, 2016-199673, A Unexamined-Japanese-Patent No. 2011-157491

The present invention provides a resin composition used as a matrix resin for tow prepreg which can obtain a fiber-reinforced composite material having high fracture toughness of a molded product obtained by curing and excellent in impact resistance and fatigue resistance. The purpose is to

As a result of investigations to solve the above-mentioned problems, the present inventors have found that a resin composition which gives high fracture toughness to a molded product can be obtained when core-shell type rubber particles and bisphenol F type epoxy resin are used in combination. The present invention has been completed.

That is, the present invention comprises the epoxy resin (A), core-shell type rubber particles (B), dicyandiamide or its derivative (C), a solid aromatic urea compound or a solid imidazole compound (D) as an essential component; A) In 100 parts by mass, 25 parts by mass or more is a bisphenol F-type epoxy resin having an epoxy equivalent of 180 g / eq or less, and the blending amount of the core-shell type rubber particles (B) is the component (A), (B) And 2 to 16 parts by mass with respect to 100 parts by mass of the component (C) and component (D), and the viscosity at 25 ° C. measured with an E-type viscometer is in the range of 3 to 45 Pa · s It is a curable resin composition for toe prepreg characterized by the above.

 
（式中、ｍは０～５の整数である。） The above-mentioned bisphenol F-type epoxy resin is represented by the following general formula (1), and has a dinuclear substance content of 75 area% or more and a trinuclear substance content of 6 area% or less in gel permeation chromatography (GPC) measurement It is preferred to be configured in proportions.

(Wherein, m is an integer of 0 to 5)

The dicyandiamide or its derivative (C) and the solid aromatic urea compound or solid imidazole compound (D) preferably have a D90 particle size of 2 to 8 μm.

In the present invention, the preferred form of tow prepreg is that the reinforcing fibers are blended at a volume content of 48 to 72%.

Another embodiment of the present invention is a fiber-reinforced composite material (molded body) obtained by molding, by filament winding molding method, a tow-preg in which reinforcing fibers are mixed with the above-mentioned resin composition.

In the curable resin composition for tow prepreg of the present invention, a molded product obtained by curing a prepreg using the same exhibits high fracture toughness. In particular, it is suitably used for a fiber reinforced composite material obtained by a filament winding molding method.

The GPC chart of bisphenol F-type epoxy resin YDF-170 is shown. The GPC chart of bisphenol F-type epoxy resin YDF-1500 is shown.

Hereinafter, embodiments of the present invention will be described in detail.
The curable resin composition according to the present invention for epoxy resin (A), core-shell type rubber particles (B), dicyandiamide or derivative thereof (C), solid aromatic urea compound or solid imidazole compound (D) It is an essential ingredient. Hereinafter, epoxy resin (A), core-shell type rubber particles (B), dicyandiamide or its derivative (C), solid aromatic urea compound or solid imidazole compound (D) are respectively component (A) and component (B) It is also referred to as component (C) and component (D). In addition, the curable resin composition for tow prepreg is also referred to as a curable resin composition or a resin composition.

The epoxy resin (A) used by this invention is bisphenol F-type epoxy resin whose epoxy equivalent (g / eq) is 180 or less 25 mass parts or more of the 100 mass parts. If the content of the bisphenol F-type epoxy resin is 25% by mass or more and the epoxy equivalent is not 180 or less, the dispersibility of the core-shell type rubber component of the cured product becomes too uniform, resulting in a decrease in fracture toughness.

Preferably, the dinuclear-body content rate in a bisphenol F-type epoxy resin is 75 area% or more, and the trinuclear-body content rate is 6 area% or less. The inclusion of the di-nucleus and the tri-nucleus in the above ratio can further enhance the fracture toughness value without excessively dispersing the core-shell type rubber component.
Here, a binuclear body means a component of m = 0 in the general formula (1), and a trinuclear body means a component of m = 1 in the general formula (1). It is preferable that polynuclear body content rate of tetranuclear body or more is 1 area% or less in GPC measurement. Although a bisphenol F type epoxy resin may also form a tetranuclear body generated by a ring opening reaction of an epoxy group as in a normal epoxy resin, this is not calculated as the above-mentioned tetranuclear body.

The epoxy resin (A) desirably contains 20 to 75 parts by mass, preferably 30 to 70 parts by mass, of bisphenol A epoxy resin having an epoxy equivalent of 195 or less in 100 parts by mass of the epoxy resin (A). It is considered that the dispersibility of the core-shell type rubber component becomes uniform by containing a bisphenol A type epoxy resin having an epoxy equivalent of 195 or less. Moreover, it becomes a composition excellent in the balance of other physical properties, such as resin impregnation property and heat resistance. The viscosity can be optimally controlled by using this bisphenol A epoxy resin in combination with the bisphenol F epoxy resin.
The epoxy resin (A) used in the present invention may be 70 to 90 parts by mass, preferably 75 to 85 parts by mass, of the total 100 parts by mass of the components (A) to (D).

The epoxy resin (A) used in the present invention may contain other epoxy resins (refer to bisphenol F epoxy resin and bisphenol A epoxy resin). The blending amount of the other epoxy resin is 20 parts by mass or less, preferably less than 10 parts by mass, in 100 parts by mass of the component (A).

Other epoxy resins include, for example, bisphenol-type epoxy resins such as bisphenol E-type epoxy resin, bisphenol S-type epoxy resin, bisphenol Z-type epoxy resin, and isophorone bisphenol-type epoxy resin having two or more epoxy groups in one molecule Or a halogen of these bisphenols, an alkyl-substituted product, a hydrogenated product, a polymer having not only a monomer but a plurality of repeating units, a glycidyl ether of an alkylene oxide adduct, a cresol novolac epoxy resin, a bisphenol A novolac Epoxy resins such as epoxy resins, 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate, 3,4-epoxycyclohexylmethyl- Aliphatic epoxy resins such as 2,4-epoxycyclohexanecarboxylate, 1-epoxyethyl-3,4-epoxycyclohexane, and fats such as trimethylolpropane polyglycidyl ether, pentaerythritol polyglycidyl ether, polyoxyalkylene diglycidyl ether Group epoxy resin, phthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, glycidyl ester such as dimer acid glycidyl ester, tetraglycidyl diaminodiphenylmethane, tetraglycidyl diaminodiphenyl sulfone, triglycidyl aminophenol, triglycidyl amino cresol And glycidyl amines such as tetraglycidyl xylylene diamine can be used. Among these epoxy resins, epoxy resins having two epoxy groups in one molecule are preferable from the viewpoint of viscosity increase rate, and polyfunctional epoxy resins are not preferable. One of these may be used alone, or two or more of these may be used in combination.

The compounding amount of the core-shell type rubber particles (B) contained in the curable resin composition of the present invention is 2 with respect to the total amount of 100 parts by mass of the components (A), (B), (C) and (D). 20 parts by mass. Within this range, a fiber-reinforced composite material having enhanced fracture toughness and excellent strength can be obtained without lowering the elastic modulus of the cured product.

The core-shell rubber particle (B) is composed of a core portion and a shell portion forming an outer layer of the core portion. The core portion is preferably made of a polymer having an elastomeric or rubbery polymer as a main component, and the shell portion is preferably made of a polymer grafted to the core portion. The addition of the core-shell type rubber particles has the effect of improving the toughness and improving the tackiness of the prepreg, and the average particle diameter is preferably 1 to 500 nm as volume average particle diameter, and more preferably 3 to 300 nm. .

In the resin composition of the present invention, dicyandiamide or its derivative (C) as a curing agent is used. Dicyandiamide is a curing agent that is solid at room temperature and hardly dissolves in epoxy resin at room temperature, but dissolves when heated to 180 ° C or more, and has excellent storage stability at room temperature, which has the property of reacting with epoxy groups It is a curing agent. Further, as the derivative thereof, N-substituted dicyandiamide derivatives such as N-hexyldicyandiamide described in JP-A-11-119429 can be used. The amount to be used is preferably in the range of 0.2 to 0.8 equivalent (calculated with 1 mole of dicyandiamide as 4 equivalents) to 1 equivalent of the epoxy group of the epoxy resin (A). More preferably, it is 0.2 to 0.5 equivalents. If the amount is less than 0.2 equivalent to the epoxy equivalent, the crosslink density of the cured product becomes low and fracture toughness tends to be low, and if it exceeds 0.8 equivalent, unreacted dicyandiamide tends to remain, so the mechanical properties deteriorate. There is a tendency. From another viewpoint, the range of 0.01 to 7 parts by weight is preferable with respect to 100 parts by weight of the curable resin composition.

In the resin composition of the present invention, a solid aromatic urea compound or a solid imidazole compound (D) as a curing accelerator is blended. The component (D) more desirably has a D90 particle size of 2 to 8 μm. Such a particle size makes it possible to obtain a fiber-reinforced composite material which is excellent in the impregnating property to reinforcing fibers at the time of mixing and has few voids at the time of heat curing. Here, D90 of the particle diameter means a particle diameter corresponding to 90% of the distribution under the integrated sieving. Moreover, it is preferable to set it as the said range also about the particle size of (C) component.

Any method can be adopted as a method for obtaining the above-mentioned small particle diameter. For example, methods such as a method of grinding coarse particles of a curing agent with a jet mill or a mortar, a method of freeze grinding, a method of classifying with a test sieve, and the like can be mentioned, but it is not limited thereto.

As a solid aromatic urea compound or a solid imidazole compound (D), a compound which acts as a curing accelerator and which further satisfies the heat resistance at the time of curing in addition to the impregnating property to the reinforcing fiber at the time of mixing is preferable.
As a solid aromatic urea compound, for example, 3- (3,4-dichlorophenyl) -1,1-dimethylurea, 3- (3,4-dichlorophenyl) -1,1-dimethylurea, N-phenyl-N ' , N'-dimethylurea, N- (4-chlorophenyl) -N ', N'-dimethylurea, N- (3,4-dichlorophenyl) -N', N'-dimethylurea, N- (3-chloro-) 4-Methylphenyl) -N ', N'-dimethylurea, N- (3-chloro-4-ethylphenyl) -N', N'-dimethylurea, N- (3-chloro-4-methoxyphenyl)- N ', N'-dimethylurea, N- (4-methyl-3-nitrophenyl) -N', N'-dimethylurea, 2,4-bis (N ', N'-dimethylureido) toluene, methylene- Bis (p-N ', N'-dimethylurei It can be exemplified phenyl) and the like, among the 3- (3,4-dichlorophenyl) -1,1-dimethylurea, 3- (3,4-dichlorophenyl) -1,1-dimethylurea is preferred.

Further, solid imidazole compounds include 2-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl 6-4 ', 5'-dihydroxymethylimidazole, 1-cyanoethyl-2-ethyl-4methylimidazole, 2-phenyl-4-methyl-5 It is preferable to use an imidazole compound such as -hydroxymethylimidazole.
Furthermore, imidazole compounds containing a triazine ring can also be preferably used, for example, 2,4-diamino-6- [2′-methylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6 -[2'-undecylimidazolyl- (1 ')]-ethyl-s-triazine, 2,4-diamino-6- [2'-ethyl-4'-methylimidazolyl- (1')]-ethyl-S -Triazine isocyanuric acid adduct etc. are mentioned. These may be used alone or in combination of two or more, and are not limited to the above as long as they are chemically stable and do not dissolve in the epoxy resin at normal temperature.
The amount of the solid aromatic urea compound or solid imidazole compound (D) used is preferably 0.01 to 7 parts by mass with respect to 100 parts by mass of the curable resin composition. More preferably, it is 1 to 5 parts by mass. If the amount is more than 7 parts by mass, a powder component is increased, which causes a problem that the number of voids tends to be increased. If the amount is less than 0.01 parts by mass, there arises a problem that fast curing can not be realized.

An antifoamer and a leveling agent can be added to the curable resin composition of the present invention as an additive for the purpose of improving surface smoothness. These additives can be blended in an amount of 0.01 to 3 parts by mass, preferably 0.01 to 1 parts by mass, with respect to 100 parts by mass of the resin composition.

The curable resin composition for tow prepreg of the present invention is produced by uniformly mixing the components (A), (B), (C), (D) and the like described above. The obtained resin composition has a viscosity in the range of 3 to 45 Pa · s measured using an E-type viscometer cone plate type at 25 ° C. Within this range, the fiber has a good impregnating property to reinforcing fibers, dripping of resin from the fiber does not occur even after impregnation, good toe prepreg is obtained, and a fiber-reinforced composite material with few voids even at curing is obtained. Be

Moreover, other curable resin can also be mix | blended with the curable resin composition of this invention. As such a curable resin, unsaturated polyester resin, curable acrylic resin, curable amino resin, curable melamine resin, curable urea resin, curable cyanate ester resin, curable urethane resin, curable oxetane resin, Examples thereof include, but are not limited to, curable epoxy / oxetane composite resins.

In the curable resin composition of the present invention, coupling agents, conductive particles such as carbon particles and metal plating organic particles, thermosetting resin particles, or inorganic fillers such as silica gel, nano silica, alumina fibers and clay, A conductive filler can be blended. The conductivity of the cured resin and the fiber-reinforced composite material obtained by using the conductive particles and the conductive filler can be improved.

Examples of the conductive filler include carbon black, carbon nanotubes, fullerenes, metal nanoparticles and the like, which may be used alone or in combination. Among them, it is widely known that the blending of carbon nanotubes not only improves the conductivity but also that the blending strength of less than 1 wt% to the fiber reinforced composite material can enhance the impact strength of the fiber reinforced composite material. It can be used suitably.

The curable resin composition for toe prepreg of the present invention is impregnated into reinforcing fibers or bundles to form toe prepreg. The method of using to-preg may be a known method.
The tow prepreg obtained in this manner is suitably used for a fiber reinforced composite material obtained by a filament winding molding method.

The method for producing a molded article (also referred to as a fiber reinforced composite material) by processing the curable resin composition for tow prepreg of the present invention to tow prepreg is not particularly limited, but it is desirable as a method for producing a pressure vessel by filament winding method. Applied. A tow prepreg is wound around a metal or resin liner and then thermally cured to obtain a molded article in which a layer of a fiber reinforced composite material is formed to cover the liner. After this, the liner may be removed if necessary. In addition, it is desirably applied as a method for producing a circularly cast hollow fiber-reinforced composite material, such as a shaft or roll-shaped molded article, by a filament winding method. A molded article can be obtained by winding and heat-forming a tow prepreg around a metal or resin mandrel, and the mandrel may be removed depending on the application.

Reinforcing fibers used in the toe prepreg of the present invention are selected from glass fibers, aramid fibers, carbon fibers, boron fibers and the like, but carbon fibers are used to obtain a fiber-reinforced composite material excellent in strength. preferable.

The volume content of reinforcing fibers in the tow prepreg composed of the curable resin composition for tow prepreg of the present invention and the reinforcing fibers is preferably 48 to 72%, more preferably 53 to 68%. Since a compact having a small amount of voids and a high volume content of reinforcing fibers can be obtained, a molding material having excellent strength can be obtained.

In the present invention, for a cured product obtained by curing the curable resin composition for toe prepreg at a temperature of 120 ° C. for 2 hours, the flexural modulus measured according to JIS K7171 is 2.0 GPa or more, and ASTM More preferably, the fracture toughness (KIc) at 23 ° C. measured according to D5045 indicates 1.2 MPa · m 0.5 J / m or more.

Next, the present invention will be specifically described based on examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded. The part which shows a compounding quantity is a mass part unless there is particular notice. The unit of epoxy equivalent is g / eq.

(Measurement of molecular weight distribution)
Molecular weight distribution was measured using gel permeation chromatography (GPC). The main body (Tosoh Corporation HLC-8220GPC) with columns (TSKgel G4000HXL, TSKgel G3000HXL, TSKgel G2000 HXL) manufactured in series by Tosoh Corporation is used, the column temperature is set to 40 ° C., and tetrahydrofuran is used as an eluent. The measurement was performed using a RI (differential refractometer) detector as a detector with a flow rate of min, and the binuclear content and trinuclear content were determined from the area% of the peak.

The symbol of each component used in the Example is as follows. The viscosity is a value at 25 ° C. unless otherwise noted, and the unit is mPa · s.
YDF-170: Bisphenol F type epoxy resin (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., viscosity 2600, content of binuclear substance 79.9 area%, content of trinuclear substance 8.5 area%, epoxy equivalent 170)
YDF-1500: Bisphenol F type epoxy resin (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., viscosity 2300, binuclear content 84.1 area%, trinuclear content 4.1 area%, epoxy equivalent 169)
YDF-2001: Bisphenol F type epoxy resin (manufactured by Nippon Steel & Sumikin Chemical, epoxy equivalent 481)
YD-128: Bisphenol A epoxy resin (manufactured by Nippon Steel & Sumikin Chemical, viscosity 12600, epoxy equivalent 186)
MX-154: Bisphenol A epoxy resin containing 40% by weight of core-shell type rubber particles (manufactured by Kaneka, Kaneace MX-154), epoxy equivalent weight 301
MX-154EP: Bisphenol A type epoxy resin component in MX-154, epoxy equivalent 180 to 185
MX-154 CSR: Core-shell rubber particle component in MX-154 DICY: dicyandiamide (D90 particle diameter 6.5 μm)
DCMU: 3- (3,4-Dichlorophenyl) -1,1-dimethylurea (D90 particle size 26.4 μm)
DCMUH: 3- (3,4-Dichlorophenyl) -1,1-dimethylurea (D90 particle size 4.8 μm)
2 MAOK: 2,4-diamino-6- [2′-methylimidazolyl- (1 ′)]-ethyl-s-triazine isocyanuric acid adduct (D90 particle diameter: 4.6 μm)

FIG. 1 shows a GPC chart of YDF-170, and FIG. 2 shows a GPC chart of YDF-1500. In the figure, A is a peak showing a dinuclear body, B is a peak showing a trinuclear body, and C is a peak showing a tetranuclear body formed by ring opening and dimerization of an epoxy group.

Example 1
27 parts of YDF-170 as component (A), 51 parts of YD-128, 7 parts of MX-154EP in MX-154, 5 parts of MX-154 CSR in MX-154 as component (B), (C ) Put 5.7 parts of DICY as the component, 4.5 parts of DCMU as the component (D), and 150 mL of a poly container, and use a vacuum mixer “Awatori Neritaro” (made by Shinky) at room temperature 5 It mixed, stirring for minutes, and curable resin composition was obtained.

(Measurement of viscosity)
The viscosity value at 25 ° C. was measured using an E-type viscometer cone plate type. The curable resin composition was prepared, and 0.8 mL of the composition was used for measurement, and the value after 60 seconds from the start of measurement was taken as the value of viscosity.

(Preparation of molded plate for glass transition temperature, bending test, fracture toughness measurement)
The curable resin composition is poured into a 120 mm long × 120 mm long mold provided with a 4 mm thick spacer hollowed out in a flat plate shape, and cured at 120 ° C. for 2 hours to form a molded plate for measurement; And it was used for measurement of flexural strength, and measurement of fracture toughness.

(Processing to test piece for measuring glass transition temperature, measurement of glass transition temperature)
The resulting molded plate was cut to a size of 3 mm × 3 mm with a table-top band saw, and was further polished to a thickness of approximately 1.2 mm using a belt disc sander. Measured using a differential scanning calorimeter under a nitrogen atmosphere at a temperature elevation rate of 10 ° C./min, from the tangent at the inflection point of the DSC curve and the temperature at which the onset of inflection is seen, ie from the inflection point The point of intersection with the tangent at a temperature range of 20 to 30 ° C. lower is taken as the glass transition temperature Tg.

(Processing of bending test pieces, measurement of bending elastic modulus and bending strength)
The obtained molded plate was cut to a size of 80 mm × 10 mm with a table-top band saw, and a bending test piece was subjected to a bending test at a temperature of 23 ° C by a method according to JIS 7171 to calculate bending elastic modulus and bending strength .
(Processing of fracture toughness test pieces, measurement of fracture toughness)
The obtained molded plate was cut to a size of 80 mm × 10 mm with a table-top band saw, processed into a test piece in accordance with ASTM 5045, and a fracture toughness test was conducted under a temperature condition of 23 ° C. to calculate a fracture toughness value. .

T700SC-12000-50C in a groove of 28 mm in width formed by holding an aluminum disc with an inner diameter of 140 mm and a width of 28 mm between the left and right sides with an aluminum disc of 160 mm in inner diameter and 4 mm in height Every 270 cm of (Toray Industries, Ltd., fineness 0.8 g / m), 1 g of the curable resin composition obtained in Example 1 is applied and impregnated into carbon fibers to manufacture a to-re-ply, thereby making an aluminum disk After winding on a plate, repeating this 12 times without cutting carbon fiber, curing at 120 ° C. for 2 hours and then removing aluminum disc on both sides, weight about 38 g, carbon fiber volume ratio about 60 %, A hoop-like carbon fiber reinforced composite material (molded body) having a thickness of about 2 mm was obtained.

The obtained hoop-like carbon fiber reinforced composite material was cut into a size of inner arc length 100 mm × width 14 mm with a table-top band saw, and the actual density was measured by the Archimedes method. Further, the theoretical density was calculated by the following equation with the density of the cured epoxy resin being 1.2 and the density of carbon fibers being 1.8.
Theoretical density = weight of cut-out carbon fiber reinforced composite material / (application weight of resin / density of cured epoxy resin + wound weight of carbon fiber / density of carbon fiber)
Furthermore, the porosity was calculated from the following equation using the measured actual density and the calculated theoretical density value.
Porosity = 100 × (1-actual density / theoretical density)

Examples 2 to 10, Comparative Examples 1 to 6
A curable resin composition was produced in the same manner as in Example 1 except that the raw materials were used in the compositions described in Tables 1 and 2 as the components (A) to (D).
A carbon fiber reinforced composite material is formed by using this curable resin composition and heat curing followed by obtaining in the same manner as in Example 1 to form a carbon fiber reinforced composite material. The test, the molding plate for fracture toughness measurement, and the porosity were measured.

The raw materials, the amounts used (parts by mass) and the results of the tests are shown in Tables 1 and 2, respectively.

 

 

   

 

Industrial Applicability

From the curable resin composition for tow prepreg of the present invention, a fiber-reinforced composite material exhibiting high fracture toughness can be obtained.

A peak showing a binuclear body A peak showing a trinuclear body

Claims (5)

Epoxy resin (A), core-shell rubber particles (B), dicyandiamide or derivative thereof (C), solid aromatic urea compound or solid imidazole compound (D) as an essential component, 100 parts by mass of the epoxy resin (A) Among them, a bisphenol F-type epoxy resin having an epoxy equivalent weight of 180 g / eq or less and 25 parts by mass or more of the core-shell type rubber particles (B) is contained in the above (A), (B), (C), and 2 to 20 parts by mass with respect to a total of 100 parts by mass of D), and the viscosity at 25 ° C. measured by an E-type viscometer is in the range of 3 to 45 Pa · s. object. The above bisphenol F-type epoxy resin is represented by the following general formula (1), and the ratio of the dinuclear substance content is 75 area% or more and the trinuclear substance content is 6 area% or less in the measurement by gel permeation chromatography The curable resin composition for toe prepreg according to claim 1.

(Wherein, m represents an integer of 0 to 5) 2. The curable resin for toe prepreg according to claim 1, wherein the D90 particle size of both dicyandiamide or its derivative (C) and the solid aromatic urea compound or solid imidazole compound (D) is 2 to 8 μm. Composition. A tow-preg comprising a curable resin composition for tow-preg according to any one of claims 1 to 3 and reinforcing fibers so as to have a volume content of 48 to 72%. The molded object obtained by shape | molding the tow prepreg of Claim 4 by the filament winding molding method.

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