JP2001323046A - Thermosetting resin composition and prepreg - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermosetting resin composition excellent in properties of releasing from and adhering to a honeycomb core, to provide prepreg, and to provide a fiber-reinforced composite material excellent in resistance to moist heat, impact resistance, strength characteristics such as tensile strength and compressive strength. SOLUTION: This thermosetting resin composition gives a grass transition temperature (Tg) of >=150 deg.C to a cured product which is obtained by heating the composition at 180 deg.C for 2 hr, wherein a modulus of rigidity (G'R) in a rubbery plateau area is not more than 10 MPa, when measured at a temperature range not lower than the Tg.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosetting resin composition and a prepreg which can be suitably used for manufacturing a honeycomb sandwich panel for an aircraft.

[0002]

2. Description of the Related Art A fiber-reinforced composite material comprising a reinforcing fiber and a matrix resin has been widely used in aircraft, automobiles and industrial applications because of its excellent mechanical properties. recent years,
With the achievement of its use, the required properties for fiber reinforced composite materials are becoming more and more severe.

In order to sufficiently bring out the mechanical properties and durability of a fiber-reinforced composite material, it is necessary to minimize defects that cause a decrease in strength.

[0004] In the case of aircraft structural materials and interior materials, fiber reinforced composite materials are increasingly used as skin panels for honeycomb sandwich panels from the viewpoint of weight reduction. Here, the honeycomb sandwich panel generally uses an aramid honeycomb, a glass honeycomb, or an aluminum honeycomb as a honeycomb core, and laminates a prepreg for forming a skin panel on both surfaces of the honeycomb core, and simultaneously performs curing of the resin and bonding with the honeycomb core. , So-called cocure molding.

Conventionally, in such cocure molding, a technique of sandwiching and molding a film-like adhesive between a honeycomb core and a prepreg laminate has been frequently used. In recent years, however, a further reduction in the weight of honeycomb sandwich panels has been achieved. From the viewpoint of reducing the molding cost, a so-called self-adhesion technology for directly bonding the honeycomb core and the prepreg is required. However, when an adhesive is not used in this way, the resin contained in the prepreg must be responsible for bonding to the honeycomb core, and it has been difficult to ensure high adhesiveness.

US Pat. No. 4,500,660 discloses a honeycomb molding method for a prepreg and a matrix resin using carbon fiber as a reinforcing fiber, which is specified for the purpose of improving peel adhesion to a honeycomb core and interlaminar shear strength with a skin panel. An epoxy resin composition comprising a reaction product of an epoxy resin to be produced with a butadiene acrylonitrile copolymer having a functional group at both terminals and dicyandiamide as a curing agent is disclosed. Also, Japanese Patent Application Laid-Open No. 58-82755
In order to improve the peel adhesion to the honeycomb core and to reduce defects in the honeycomb sandwich panel surface plate, Japanese Patent Application Laid-Open Publication No. H11-15064 discloses a reaction between a liquid butadiene acrylonitrile copolymer having carboxyl groups at both ends and an epoxy resin. An epoxy resin composition comprising dicyandiamide and diaminodiphenyl sulfone as a product and a curing agent is disclosed.

However, according to these prior arts,
Although the resulting composite material can maintain high strength properties such as wet heat resistance and tensile strength to some extent, it has a drawback of poor peel adhesion between the prepreg and the honeycomb core.

[0008]

The present invention can be suitably used for applications requiring a high degree of physical properties especially in a wet heat environment.
Fiber reinforced composite material with excellent strength properties such as impact resistance, tensile strength, and compression strength, and thermosetting properties with excellent peel adhesion to the honeycomb core, which can be suitably used for the production of the fiber reinforced composite material An object is to provide a resin composition and a prepreg.

[0009]

The present invention has the following structure to solve the above-mentioned problems. That is, at 180 ° C., 2
Glass transition temperature Tg of cured product obtained by heating for hours
Is 150 ° C. or higher, the rubber-like flat portion rigidity G ′ in a temperature range of Tg or higher.
R is a thermosetting resin composition of 10 MPa or less.

The present invention has the following configuration in order to solve the above problems. That is, it is a prepreg containing the reinforcing fibers which are continuous fibers and the resin composition as constituent elements.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive studies, the present inventors have found that the glass transition temperature Tg (hereinafter abbreviated as Tg) of a cured product obtained by heating at 180 ° C. for 2 hours is equal to or higher than a specified temperature. Wherein the rubber-like flat portion rigidity G′R (hereinafter, referred to as “T ′”) in a temperature range equal to or higher than the Tg.
(Abbreviated as G'R) is a thermosetting resin composition having a value of not more than the specified value, and solves the above-mentioned problems at once.

In the present invention, Tg is a value measured by a differential scanning calorimetry (DSC) as described later, and needs to be 150 ° C. or higher, preferably 160 ° C. or higher, more preferably Is preferably 165 ° C. or higher. In a composite material obtained at a temperature lower than 150 ° C., peeling properties with a honeycomb core (hereinafter simply referred to as peeling adhesion), strength properties such as impact resistance, and heat resistance may decrease.

In the present invention, G′R is a value measured as a rigidity of a rubber-like flat portion in a temperature region equal to or higher than Tg by dynamic viscoelasticity analysis (DMA) as described later, and is 10 MPa. Or less, preferably 9 MPa or less, more preferably 8 MPa
The following should be good. If it exceeds 10 MPa, strength characteristics such as peeling resistance and impact resistance, and heat resistance may be reduced in the obtained composite material.

In the resin composition according to the present invention, as the thermosetting resin, for example, a phenol resin, an amino resin, an unsaturated polyester resin, an epoxy resin and the like can be used. It is preferable to use a resin, and the compounding amount of the epoxy resin is 55% by weight or more based on 100% by weight of the total resin composition,
Preferably 65% by weight or more, more preferably 75% by weight
It is better to do above.

As the epoxy resin, it is preferable to use a bifunctional epoxy resin having two epoxy groups in one molecule, and as the bifunctional epoxy resin, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, A biphenyl-type epoxy resin, a naphthalene-type epoxy resin, a dicyclopentadiene-type epoxy resin, a diphenylfluorene-type epoxy resin, or the like, which has good wet heat resistance and gives a rigid resin, or a mixture thereof can be used.

As the bisphenol A type epoxy resin, for example, Epicoat 827 (epoxy equivalent: 180)
To 190), Epicoat 828 (epoxy equivalent: 184)
194), Epicoat 1001 (epoxy equivalent: 45)
0 to 500), Epicoat 1004 (epoxy equivalent: 8
75 to 975) (registered trademark, Yuka Shell Epoxy)
Co., Ltd.), YD128 (epoxy equivalent: 184-19)
4) (Toto Kasei Co., Ltd.), Epicron 840 (epoxy equivalent: 180-190), Epicron 850 (epoxy equivalent: 184-194), Epicron 855 (epoxy equivalent: 183-193), Epicron 860 (epoxy equivalent: 230-270), Epicron 1050 (epoxy equivalent: 450-500) (registered trademark, manufactured by Dainippon Ink and Chemicals, Inc.), ELA128 (epoxy equivalent:
184-194) (Sumitomo Chemical Co., Ltd.), DER331
(Epoxy equivalent: 184 to 194) (manufactured by Dow Chemical Co., Ltd.) and the like can be used.

As the bisphenol F type epoxy resin, Epicron 830 (epoxy equivalent: 165-18)
5) (registered trademark, manufactured by Dainippon Ink and Chemicals, Inc.), Epicoat 807 (epoxy equivalent: 160 to 175) (registered trademark, manufactured by Yuka Shell Epoxy Co., Ltd.) and the like can be used.

Further, as the biphenyl type epoxy resin, YX4000 (epoxy equivalent: 180-192)
(Manufactured by Yuka Shell Epoxy Co., Ltd.), as a naphthalene type epoxy resin, HP-4032 (epoxy equivalent: 140 to
150) (manufactured by Dainippon Ink and Chemicals, Incorporated), EXA-7200 as a dicyclopentadiene type epoxy resin.
(Epoxy equivalent: 260 to 285) (manufactured by Dainippon Ink and Chemicals, Inc.), EPON HPT1079 (epoxy equivalent: 25) as a diphenylfluorene type epoxy resin.
0 to 260) (trademark, manufactured by Shell Co., Ltd.) and the like.

In the present invention, a trifunctional or more functional epoxy resin having three or more epoxy groups in one molecule can be used as the epoxy resin because the cured product has good wet heat resistance and a rigid cured product. .

Examples of the trifunctional epoxy resin or tetrafunctional epoxy resin include glycidylamine type epoxy resins such as phenol novolak type epoxy resin, cresol novolak type epoxy resin, tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol and triglycidylaminocresol. Resins, glycidyl ether type epoxy resins such as tetrakis (glycidyloxyphenyl) ethane and tris (glycidyloxy) methane, and mixtures thereof can be used.

As the phenol novolak type epoxy resin, Epicoat 152 (epoxy equivalent: 172 to 17)
9), Epicoat 154 (epoxy equivalent: 176-18)
1) (Registered trademark, Yuka Shell Epoxy Co., Ltd.),
DER438 (epoxy equivalent: 176-181) (manufactured by Dow Chemical Company), EPN1138 (epoxy equivalent: 17)
6-181), 1139 (epoxy equivalent: 172-17)
9) (both trademarks, manufactured by Ciba-Geigy) and the like.

The cresol novolak type epoxy resin is ESCN220L (epoxy equivalent: 200 to 23).
0) (manufactured by Sumitomo Chemical Co., Ltd.), Epikote 180S6
5 (epoxy equivalent: 205 to 220) (registered trademark, manufactured by Yuka Shell Epoxy Co., Ltd.), ECN1273 (epoxy equivalent: 225) (manufactured by Ciba Geigy) can be used.

Examples of tetraglycidyldiaminodiphenylmethane include ELM434 (manufactured by Sumitomo Chemical Co., Ltd.),
YH434L (manufactured by Toto Kasei Co., Ltd.), Epicoat 604
(Registered trademark, Yuka Shell Epoxy Co., Ltd.) or the like can be used.

As triglycidylaminophenol or triglycidylaminocresol, ELM100
(Manufactured by Sumitomo Chemical Co., Ltd.), MY0510 (manufactured by Ciba-Geigy), Epicoat 630 (registered trademark, manufactured by Yuka Shell Epoxy Co., Ltd.) and the like can be used.

In the present invention, when an epoxy resin is used, it is preferable that the epoxy resin shown in the following (1) or (2) be contained in each weight% with respect to 100% by weight of the total epoxy resin. (1) Trifunctional epoxy resin and / or tetrafunctional epoxy resin 5 to 35% by weight (2) Bifunctional epoxy resin 50 to 95% by weight In the case of the above (1), if less than 5% by weight, a composite material obtained In some cases, the wet heat resistance may decrease, and 35
If the amount exceeds 10% by weight, the tensile strength and the sheet edge peel strength EDS may be reduced in the obtained composite material. From this viewpoint, in the present invention, the component shown in the above (1) is more preferably contained in the range of 5 to 25% by weight.

In the case of the above (2), if the content is less than 50% by weight, the tensile strength and the ED
S may decrease, and if it exceeds 95% by weight, the wet heat resistance of the obtained composite material may decrease. From such a viewpoint, in the present invention, the component shown in the above (2) is more preferably contained in the range of 70 to 95% by weight.

In addition to the above-mentioned polyfunctional epoxy resin, one epoxy group is included in the molecule within a range that does not impair the moist heat resistance.
You may mix and use a small amount of monofunctional epoxy resin having only one.

The curing agent for an epoxy resin used in the present invention is not particularly limited as long as it is a compound having an active group capable of reacting with an epoxy group. Specifically, aromatic amines such as diaminodiphenylmethane and diaminodiphenylsulfone, aliphatic amines, imidazole derivatives, dicyandiamide, tetramethylguanidine, thiourea-added amines, and carboxylic anhydrides such as methylhexahydrophthalic anhydride Carboxylic acid hydrazide, carboxylic acid amide, polyphenol compound, novolak resin, polymercaptan and the like. As the curing catalyst used in combination with the curing agent, for example, a so-called Lewis acid complex such as a boron trifluoride ethylamine complex can be used. In addition, those in which these curing agents are microencapsulated can be suitably used because storage stability of an intermediate substrate such as prepreg is enhanced.

These curing agents can be combined with an appropriate curing accelerator in order to increase the curing activity. Specifically, dicyandiamide is added with 3-
(3,4-dichlorophenyl) -1,1-dimethylurea (D
Examples of combining urea derivatives or imidazole derivatives such as CMU), carboxylic anhydrides and novolak resins,
Examples of the combination of a tertiary amine and the like as a curing accelerator are given.

Incidentally, in order to adjust the viscosity of the resin composition and improve the storage stability, a compound obtained by preliminarily reacting an epoxy resin with a curing agent may be blended in the resin composition.

In the present invention, the bisphenol compound is incorporated in the resin composition in an amount of 1 to 20% by weight, preferably 2 to 10% by weight, based on 100% by weight of the total epoxy resin. If the amount is less than 1% by weight, the peel adhesion and the tensile strength of the obtained composite material may be reduced. If the amount is more than 20% by weight, the tackiness of the prepreg may be reduced, or the heat and moisture resistance of the obtained composite material may be deteriorated. Compressive strength may decrease.

Here, as the bisphenol compound,
Bisphenol A, bisphenol F, bisphenol S, bisphenol AD, bisphenol Z, bisphenol fluorene, dihydroxybiphenyl and the like can be mentioned, and their alkyl-substituted products and halides can also be suitably used. Further, as the bisphenol compound, dihydroxynaphthalene, dihydroxyanthracene, or the like can be used. Among them, bisphenol S is preferable because of its excellent peel adhesion and the effect of enhancing the wet heat resistance and elongation of a cured product obtained by heating the resin composition (hereinafter simply referred to as a cured product).

In the present invention, a thermoplastic resin can be added to the resin composition in order to achieve both physical properties such as toughness required for the cured product and low-pressure moldability by an autoclave or the like. As a thermoplastic resin, carbon-carbon bonds in the main chain,
Thermoplastic resin having a bond selected from amide bond, imide bond (such as polyetherimide), ester bond, ether bond, siloxane bond, carbonate bond, urethane bond, urea bond, thioether bond, sulfone bond, imidazole bond and carbonyl bond Is mentioned. Above all, a thermoplastic resin having a sulfone bond such as polyether sulfone is preferable from the viewpoint of improving the heat and humidity resistance, impact resistance, and adhesion to the reinforcing fiber in the cured product and the obtained composite material.

Incidentally, the thermoplastic resin may be a so-called oligomer. In this case, the number average molecular weight of the oligomer is preferably 10,000 or less, preferably 7000 or less, from the viewpoint of preventing the resin viscosity at the time of molding from being excessively high and impairing the fluidity of the resin. The number average molecular weight of the oligomer is preferably 3,000 or more, and more preferably 4,000 or more, from the viewpoint of maintaining the modification effect by the thermoplastic resin and the impact resistance of the obtained composite material. The oligomer preferably has a functional group that reacts with the thermosetting resin at the terminal or in the molecular chain. Examples of the oligomer of the thermoplastic resin include, for example, polysulfone, polyether sulfone, polyetherimide, polyimide,
Polyamide, polyamide imide, polyphenylene ether and the like having both heat resistance and toughness are exemplified.

Further, the thermoplastic resin is composed of all epoxy resins 1
5 to 20 parts by weight, preferably 8 to 15 parts by weight with respect to 100% by weight
It is good to mix by weight. If the amount is less than 5 parts by weight, the toughness of the cured product may be insufficient, and if it exceeds 20 parts by weight, the fluidity of the resin may be impaired.

In the present invention, resin fine particles can be blended with the resin composition in order to enhance the peel adhesion and the impact resistance of the obtained composite material.

As the resin fine particles, thermoplastic resin fine particles or thermosetting resin fine particles can be used. Examples of thermoplastic resin fine particles include, for example, carbon-carbon bond, amide bond, imide bond, siloxane bond, ester bond, ether bond, siloxane bond, carbonate bond, urethane bond, urea bond, thioether bond, sulfone bond, imidazole bond, carbonyl Examples include a thermoplastic resin having a bond selected from a bond in a main chain.Examples of such a thermoplastic resin include polyamide, polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyester, polyamideimide, and the like. Polyetherimide, polysiloxane, polysulfone, polyethersulfone, polyetheretherketone, polyaramid, polybenzimidazole, polyacrylate, polystyrene, poly Chill methacrylate (PMMA), benzoguanamine / melamine and the like.

The fine resin particles have an average particle diameter of 3 to 70 μm.
m, preferably 10 to 70 μm, more preferably 25 to
The thickness is preferably 60 μm. If it is less than 3 μm, fine particles may enter the gaps between the reinforcing fibers, and the resulting composite material may have reduced impact resistance. If it exceeds 70 μm, the arrangement of the reinforcing fibers may be disturbed, or the resulting prepreg may be laminated. In some cases, the thickness of the layers of the composite material obtained as a result becomes unnecessarily thick, thereby deteriorating the physical properties of the composite material.

As long as a certain thickness is formed between the laminated layers of the composite material, the shape of the resin fine particles may be fine powder obtained by pulverizing the resin, fine particles obtained by a spray drying method, a reprecipitation method, or the like.
A variant shape other than a spherical shape may be used. In addition, it may be porous, fibrous, or acicular.

The resin fine particles are used in an amount of 1 to 15% by weight based on 100% by weight of the total resin composition from the viewpoint of facilitating the mixing with the thermosetting resin and preventing the tack and drape properties of the obtained prepreg from lowering. It is good to have peel adhesion and
From the viewpoint of increasing the compressive strength of the obtained composite material, the content is preferably set to 3 to 12% by weight.

Further, in the present invention, in order to control the rheology of the resin composition, inorganic fine particles such as finely divided silica can be blended with the resin composition within a range that does not impair the toughness and elongation of the cured product. Further, a polymaleimide resin and a resin having a cyanate ester terminal can be blended as long as the toughness of the cured product is not impaired. Further, a suitable reactive diluent such as monofunctional epoxy or acrylate or a modifier such as an elastomer can be blended within a range that does not impair the wet heat resistance of the cured product.

The polymaleimide resin is, for example, a compound containing at least two maleimide groups at the terminal,
Those produced by a known method by reacting a diamine with an equivalent amount of an unsaturated dicarboxylic anhydride can be used. As the resin having a cyanate ester terminal, a polyhydric phenol cyanate compound represented by bisphenol A can be used.

As the elastomer, butadiene acrylonitrile rubber, styrene butadiene rubber, butyl acrylate and the like can be used.

In the prepreg according to the present invention, it is preferable to use reinforcing fibers composed of continuous fibers. Further, the reinforcing fibers preferably have excellent heat and moisture resistance and tensile strength. Specific examples include carbon fiber, graphite fiber, aramid fiber, silicon carbide fiber, alumina fiber, boron fiber and the like.
Among them, carbon fibers and graphite fibers having good specific strength and specific elastic modulus and greatly contributing to weight reduction of the obtained composite material are preferable. Carbon fiber and graphite fiber have a tensile strength of 4.4 GPa,
Preferably, it is 4.9 GPa, and the tensile elongation is
It is good to be 1.5% or more, preferably 2.0% or more.

The reinforcing fiber made of continuous fiber has a fiber length of 5 cm or more, preferably 7 cm or more. 5cm
If it is less than the above, the strength characteristics of the obtained composite material may be deteriorated.

The form of the reinforcing fibers is preferably unidirectional, random, sheet-like, mat-like, woven, braided, etc., and among them, a composite material having excellent specific strength and specific elastic modulus can be obtained. Although a single direction is preferable, when the skin panel is used as a honeycomb sandwich panel via a prepreg, a woven fabric which is easy to handle and has excellent peel adhesion is preferable.

In the prepreg according to the present invention, the above-mentioned resin fine particles are preferably localized near the surface. This greatly exceeds the peel adhesion expected from the compounding ratio, and the impact resistance of the obtained composite material is improved. The term “localized near the surface” as used herein means that 90% or more of the resin fine particles contained in the resin composition is 20%, preferably 15%, and more preferably the average thickness of the prepreg from the prepreg surface. It means that it is distributed within a depth range of 10%.

A prepreg in which resin fine particles are localized on the surface is disclosed in JP-A-1-26651 and JP-A-63-170.
No. 427, JP-A-63-170428, etc., a method of adhering fine resin particles to the surface of a prepreg, and a method of impregnating a reinforcing fiber with a resin composition containing resin fine particles uniformly. And a method of attaching a resin film containing a high concentration of resin fine particles to the surface of a prepreg.

In the present invention, as the honeycomb core,
A Nomex honeycomb core made of aramid paper impregnated with a phenolic resin is preferable because a light-weight, high-strength structure can be formed. The honeycomb core having a cell size of 3 to 19 mm can be suitably used. In addition, aluminum honeycomb, glass fiber reinforced plastic (GFRP) honeycomb, graphite honeycomb, paper honeycomb, and the like can also be used.

The honeycomb sandwich panel can be formed by a cocure method in which a plurality of prepregs are laminated on both sides of a honeycomb core and the resin is cured and adhered to the honeycomb core. Further, the honeycomb sandwich panel can be formed by vacuum bag molding, autoclave molding using a vacuum bag, press molding, etc.
Autoclave molding is preferred in order to obtain higher quality and higher performance honeycomb sandwich panels.

[0051]

The present invention will be described more specifically with reference to the following examples. In each of Examples and Comparative Examples, preparation of a prepreg, preparation of a composite material, and measurement of various physical properties were performed by the following methods. <Preparation of prepreg> A thermosetting resin composition is coated on release paper to prepare a resin film having a predetermined resin weight. This resin film is stacked on both sides of the reinforcing fiber,
The prepreg is prepared by impregnating the resin composition while heating and pressing.

In the case of a woven prepreg, Toray Industries, Inc.
Carbon fiber "Trayca (registered trademark)" T700G-12K
(12,000 fibers, tensile strength 4.9 GPa, tensile modulus 240 GPa, tensile elongation 2.1%) plain woven fabric CF6273H (woven fabric thickness 0.22 mm, yarn width / yarn thickness ratio 69.2, cover factor 99) 0.7%) or Toray Industries, Inc., carbon fiber “Treca” T300B-3K (3,000 fibers, tensile strength 3.5 GPa, tensile modulus 2)
30GPa, 1.5% tensile elongation) plain woven fabric CO73
73Z (woven fabric thickness 0.27mm, yarn width / yarn thickness ratio 14.
9, the cover factor is 93.3%), and the fiber basis weight is 1
A prepreg having 93 g / m ² and a resin content of 40% by weight is prepared.

In the case of one-way prepreg, Toray Industries, Inc.
Made, carbon fiber "Treca" T800G-12K (1 fiber
2000 pieces, tensile strength 5.9 GPa, tensile modulus 290
GPa, tensile elongation 2.0%), or carbon fiber “Treca” T300B-3K (3,000 fibers, manufactured by Toray Industries, Inc.
Using a tensile strength of 3.5 GPa, a tensile elasticity of 230 GPa and a tensile elongation of 1.5%), a prepreg having a fiber weight of 190 g / m ² and a resin content of 36% by weight is prepared. <Glass transition temperature Tg of cured product> Measured by differential scanning calorimetry (DSC). A cured product obtained by heating the resin composition at 180 ° C. for 2 hours is used as a measurement sample, and the temperature is increased at a rate of 10 ° C./min to obtain a DSC curve.

Next, for this DSC curve, as shown in FIG. 1, the temperature at the intersection of the tangent to the base line and the tangent to the endothermic line and the end-point temperature of the endotherm are determined. I do.

Here, as a measuring device, DSC 2910 (model number) manufactured by TA Instruments was used. <Rubber-like flat portion rigidity G′R of cured product> Measured by dynamic viscoelasticity analysis (DMA). Using a plate-shaped cured product (thickness 2 mm, width 10 mm) obtained by heating the resin composition at 180 ° C. for 2 hours, a span length of 40 mm, and a temperature rising rate of 5 ° C.
/ Min, torsional vibration frequency 0.5 Hz, distortion amount 0.1%, and the temperature is increased to evaluate by DMA. In this evaluation method, as shown in FIG. 2, the torsional rigidity G of the resin is measured in a region from Tg to the rubber-like flat region, and the torsional rigidity G of the rubber-like flat portion appears after the torsional rigidity G is relaxed by the glass transition. Let the rigidity G be G'R.

Here, as a measuring device, Rheometric S
Viscoelasticity measurement system expansion type "ARE" manufactured by cientific
<Tensile fracture strain of cured product> The thermosetting resin composition was poured into a mold that had been subjected to an appropriate release treatment, and was then placed in an oven at 180 ° C.
The mixture is heated and cured at a temperature of 2 ° C. for 2 hours to produce a plate-shaped cured product having a thickness of 2 mm.

Next, JIS K711 was obtained from the cured product.
According to the method described in 3, a test piece was prepared with a dumbbell-type test piece processing machine, a strain gauge was attached to the test piece, and the speed was 1 m.
A tensile test is performed at m / min to determine a tensile breaking strain (%). <0 ° Tensile Strength of Laminate (Composite Material)> Unidirectional prepregs prepared by the above method are aligned in fiber direction, 6-ply laminated, and autoclaved at 180 ° C. for 2 hours.
A laminate is formed by molding at a pressure of 0.59 MPa at a rate of temperature increase of 1.5 ° C./min.

Regarding this laminate, JIS K7073
0 ° tensile strength (MPa) is determined according to <Compressive strength CHW of laminate (composite material)> The unidirectional prepreg laminate produced by the above method was immersed in hot water at 71 ° C. for 2 weeks to sufficiently absorb water, and then JIS K70
According to No. 76, the compressive strength CHW (MPa) is determined by applying a compressive load at 82 ° C. from the fiber direction. <Sheet end peel strength EDS of laminate (composite material)> Ten unidirectional prepregs are quasi-isotropically laminated in a (± 25 ° / ± 25 ° / 90 °) s configuration, and 180 ° C. in an autoclave. For 2 hours under a pressure of 0.59 MPa at a heating rate of 1.5 ° C./min to produce a laminate.

This laminate is described in JIS K7073.
According to the above, when a tensile test is performed, the strength at which board edge peeling occurs is measured and defined as the board edge peel strength EDS (MPa). <Compression strength CAI after impact of laminate (composite material)> 24 unidirectional prepregs are quasi-isotropically laminated in a (+ 45 ° / 0 ° / -45 ° / 90 °) 3s configuration, and autoclaved. 180 ° C
For 2 hours under a pressure of 0.59 MPa and a temperature rising rate of 1.5 ° C.
/ Min to form a laminate.

From this laminate, 150 mm long × 100 mm wide
Is cut out, a falling weight impact of 6.7 J / mm is applied to the center of the sample according to ASTM D695, and the compressive strength CAI (MPa) after the impact is obtained. <Thickness of prepreg> The prepreg is sandwiched between two flat Teflon plates and adhered to each other. The temperature is gradually raised to 150 ° C. over 7 days to gel and harden, and the plate is hardened. Make things.

The cured product is cut from a direction perpendicular to the surface of contact with the Teflon (registered trademark) plate, and the cut surface is polished. To take a photo.

By the same operation, 5 in the horizontal direction of the cross-sectional photograph is obtained.
The distance between the Teflon plates was measured at several locations, and the average value (n =
5) is the thickness of the prepreg. <Presence of Fine Particles in Prepreg> On both surfaces of the prepreg, two lines parallel to the surface of the prepreg are drawn at a depth of 20% of the thickness from the surface of the prepreg.

Next, the total area of the fine particles existing between the surface of the prepreg and the line and the total area of all the fine particles observed over the thickness of the prepreg were determined. Calculate the abundance of fine particles present in a range of a depth of 20% from the surface of the prepreg.

Here, the total area of the fine particles is determined by hollowing out the fine particle portion from the photograph of the cross section and converting from the weight thereof.

When it is difficult to determine the fine particles dispersed in the matrix resin after photographing, means for dyeing the fine particles can be employed. <Amount of Resin Fine Particle> A solvent in which the resin fine particles are not substantially dissolved and the matrix resin is dissolved (here, N
-Methylpyrrolidone) to completely elute only the resin component from the quantified prepreg, and filter the washing liquid with a suitable opening filter to quantify the fine particles to be filtered. Ask for. <Average particle size of resin fine particles>
Then, the resin is immersed in an N-methylpyrrolidone solvent for 24 hours to elute the resin. Next, the eluate is filtered through a filter having an appropriate opening to separate fine particles. Further, a sufficient amount of N-methylpyrrolidone is injected to wash the fine particles. After that, the fine particles were magnified 1000 times or more and photographed with a scanning electron microscope, the fine particles were randomly selected, and the average value (n = 50) of the particle size (equivalent circle diameter) was calculated as the average particle size of the fine particles. I do. <CDP between skin panel / honeycomb core> (1) Lamination of sample Nomex honeycomb SAH1 /
8-8.0 (manufactured by Showa Aircraft Co., Ltd., model number: SAH1 /
8-8.0, thickness 12.7 mm). The prepreg uses the above-described woven prepreg, and has a two-ply symmetric laminated structure of (± 45 °) / (± 45 °) on both the upper and lower sides of the honeycomb core. Here, the dimensions of the honeycomb core and the prepreg are 40 cm (transverse direction) × 50 cm (longitudinal direction), and the prepregs are laminated such that the transversal direction is the ribbon (L) direction of the honeycomb core and the warp direction of the prepreg. I do. (2) Molding of sample The procedure is as follows (a) to (d). (A) An unmolded body obtained by laminating a prepreg on a honeycomb core is subjected to a release agent, for example, “Furicoat 44-NC (THE DE
XTER CORPORATION) on a coated aluminum tool plate. (B) After covering the non-formed body with the nylon film, the inside of the nylon film (hereinafter abbreviated as “system”) is put in an autoclave as it is while keeping a vacuum state. (C) The pressure in the autoclave is increased to 0.15 MPa, then the pressure in the system is returned to normal pressure, and then the pressure in the autoclave is increased to 0.30 MPa, and then the temperature is started. (D) The pressure in the autoclave is 0.30 until the molding is completed.
180 ° C at 1.5 ° C / min
And then left at 180 ° C. for 2 hours to cure the resin and adhere to the honeycomb core.
The temperature is lowered in minutes to obtain a honeycomb cured body, that is, a honeycomb sandwich panel. (3) Measurement of climbing drum peel strength (CDP) A sample was cut out from the above-mentioned molded body and subjected to ASTM D
According to 1781, the CDP between the skin panel on the aluminum tool plate side and the honeycomb core is measured. (Examples 1 to 8, Comparative Examples 1 and 2) In each of Examples and Comparative Examples, the following raw material resins were used. [Raw material resin] ・ Tetraglycidyldiaminodiphenylmethane, MY7
20 (manufactured by Ciba Geigy, model number) Bisphenol A type epoxy resin, Epicoat 825
(Registered trademark of Yuka Shell Epoxy Co., Ltd.) Bisphenol F type epoxy resin, Epicron 830
(Registered trademark, manufactured by Dainippon Ink and Chemicals, Inc.) ・ Biphenyl type epoxy resin, Epicoat YX4000H (registered trademark, manufactured by Yuka Shell Ethoxy Co., Ltd.) ・ Polyether sulfone, Victrex100P
(Registered trademark, manufactured by Sumitomo Chemical Co., Ltd.) Polyetherimide, ULTEM 1000 (registered trademark, manufactured by GE Plastics Shahdani Co., Ltd.) Bisphenol S (manufactured by Konishi Chemical Co., Ltd.) 3,3'-diaminodiphenyl sulfone (Manufactured by Wakayama Seika Kogyo Co., Ltd.) 4,4'-Diaminodiphenylsulfone, Smicure S
(Registered trademark, manufactured by Sumitomo Chemical Co., Ltd.) Dicyandiamide, DICY7 (manufactured by Yuka Shell Epoxy Co., Ltd., model number) 3- (3,4-dichlorophenyl) -1,1-dimethylurea, DCMU99 (Hodogaya Chemical) [Particle]-Crosslinked PMMA fine particles: Techpolymer MBX-20 (average particle size 2)
0 μm), MBX-40 (average particle size 40 μm), MBX-8 (average particle size 8 μm) (model number, manufactured by Sekisui Chemical Co., Ltd.) ・ Benzoguanamine / melamine resin fine particles, eposter
M30 (average particle size: 3 μm) (manufactured by Nippon Shokubai Co., Ltd., model number) The above-mentioned raw resin was kneaded with a composition shown in Table 1 by a kneader to prepare a resin composition. Next, a laminate, a prepreg, and a honeycomb sandwich panel were prepared according to the method described above, and various physical property values were evaluated. The contents of each example and comparative example are summarized in Table 1.

Thus, for example, in Example 1, the climbing drum peel strength CDP, which is an index of peel adhesion, is improved as compared with each comparative example, and the compression strength CHW, which is an index of 0 ° tensile strength and wet heat resistance, is improved. , Board edge peel strength EDS,
It can be seen that the compression strength CAI after impact is improved.

Further, in Comparative Example 2, the Tg was lower than 150 ° C., the compression strength CHW was significantly lower than those of the respective Examples, and the climbing drum peel strength CDP, 0
° Tensile strength, peel strength at plate edge EDS, compressive strength after impact CA
It turns out that I is also an unsatisfactory value.

[0068]

[Table 1]

[0069]

According to the thermosetting resin composition of the present invention,
According to the present invention, the tensile strength of the cured product is 10% or more, which has excellent elongation, and the tensile strength of the composite material is significantly increased by using this as a matrix resin of the composite material. Impact resistance, which can be suitably used especially for applications requiring high physical properties in a wet heat environment,
A fiber-reinforced composite material excellent in various strength properties such as tensile strength and compression strength, and a thermosetting resin composition excellent in peel adhesion with a honeycomb core, which can be suitably used for the production of the fiber-reinforced composite material, and A prepreg can be provided.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of Tg measurement by DSC.

FIG. 2 is a conceptual diagram of G′R measurement by DMA.

[Explanation of symbols]

 1: heat absorption direction 2: heat generation direction 3: glass transition temperature Tg 4: temperature 5: rigidity G 6: glassy region 7: glass transition region 8: rubbery region 9: rubbery flat portion rigidity G'R 10: temperature

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 63/00 C08L 63/00 C 87/00 87/00 F term (Reference) 4F072 AA04 AB06 AB08 AB10 AB28 AD14 AD23 AD28 AD38 AE01 AE02 AF14 AF25 AG03 AH21 AH25 AJ04 AL02 4J002 AA021 CC031 CC131 CD002 CD041 CD051 CF211 DA016 DA026 DE146 DJ006 DK006 EJ037 FA046 FD016 FD140 FD157 GF00 4J036 AD01 AD08 AJ02 AJ03 DB05

Claims (9)

[Claims] 1. A thermosetting resin composition in which a cured product obtained by heating at 180 ° C. for 2 hours has a glass transition temperature Tg of 150 ° C. or higher, and a rubber-like flat portion rigidity in a temperature range of the Tg or higher. A thermosetting resin composition having a rate G′R of 10 MPa or less. 2. The thermosetting resin composition according to claim 1, wherein the epoxy resin is contained in an amount of 55% by weight or more based on 100% by weight of the total resin composition. 3. The method according to claim 1, wherein 3% of the total epoxy resin is 100% by weight.
When the functional epoxy resin and / or the tetrafunctional epoxy resin
The thermosetting resin composition according to claim 2, which is contained in an amount of from 35 to 35% by weight. 4. The method according to claim 1, wherein 100% by weight of the total epoxy resin
The thermosetting resin composition according to claim 2 or 3, wherein the functional epoxy resin is contained in an amount of 50 to 95% by weight. 5. The thermosetting resin composition according to claim 2, wherein the bisphenol compound is contained in an amount of 1 to 20% by weight based on 100% by weight of the total epoxy resin. 6. A reinforcing fiber which is a continuous fiber;
A prepreg comprising the resin composition according to any one of the above as a constituent element. 7. The prepreg according to claim 6, wherein the reinforcing fibers are carbon fibers. 8. The reinforcing fiber in a woven form.
The prepreg described. 9. A prepreg containing resin fine particles having an average particle diameter of 3 to 70 μm, wherein 90% or more of the fine particles are within a depth of 20% of the average thickness of the prepreg from the surface of the prepreg. The prepreg according to any one of claims 6 to 8, which is contained.