JPH04266940A - Epoxy resin composition for composite material, intermediate material and composite material - Google Patents

Abstract

PURPOSE:To provide a heat-resistant and flame-retardant composite material having light weight and high rigidity and strength and provide a resin composition for the production of the composite material. CONSTITUTION:The objective epoxy resin composition for a composite material contains an epoxy resin, microballoons, a foaming agent, a flame-retardant and an aromatic diamine.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an epoxy resin composition for composite materials containing micro hollow spheres, a foaming agent, a flame retardant, and an aromatic diamine, an intermediate material formed by molding the same into a sheet shape, and a method for molding the intermediate material. The present invention relates to composite materials obtained by

0002

BACKGROUND OF THE INVENTION In recent years, many high-rise buildings have been constructed, and it is desired to use lightweight materials for interior parts of the high-rise buildings. In addition, as the use of aircraft increases year by year, weight reduction is desired to improve transportation efficiency. Particularly when energy prices are rising as they have been recently, reducing weight can significantly reduce fuel costs, which has a great effect. Conventionally, as the inner core material of laminates, there have been methods such as foaming phenolic resin, rigid polyurethane foam, various vinyl foams, etc. during reaction, or using a foaming agent. Also,
Microscopic hollow spheres dispersed in resin have also been used for various purposes. However, those using foam did not have sufficient strength, rigidity, and heat resistance, and those using microscopic hollow spheres were insufficient for reducing weight.

0003

[Problems to be Solved by the Invention] In view of the above circumstances, the present invention has been made to study how to reduce the weight of interior materials for high-rise buildings, interior materials for aircraft, etc. while maintaining rigidity and strength. , especially resin compositions for materials such as internal core materials,
The purpose of the present invention is to provide sheet-like intermediate materials and composite materials using the same.

0004

[Means for Solving the Problems] As a result of intensive studies in accordance with the above objectives, the present inventors have found that by adding micro hollow spheres, a foaming agent, a flame retardant, and an aromatic diamine to an epoxy resin, a flat plate can be produced. It can be easily laminated even to complex shapes, and can be co-cured with other prepregs.
The present invention has been achieved based on the discovery that it is possible to obtain a composition that is high in strength, high in rigidity, and lightweight. That is, the present invention provides an epoxy resin composition for composite materials containing (A) an epoxy resin, (B) micro hollow spheres, (C) a foaming agent, (D) a flame retardant, and (E) an aromatic diamine. It is something that provides something. The present invention also provides an intermediate material for a composite material in which the above-mentioned epoxy resin composition for a composite material is formed into a sheet, and a composite material obtained by molding the intermediate material.

The present invention will be explained in more detail below. Examples of the epoxy resin (A) used in the present invention include liquid epoxy resins and/or solid epoxy resins, such as bisphenol A epoxy resin, bisphenol F epoxy resin, phenol novolac epoxy resin, and cresol novolac epoxy resin. , glycidyl amine type epoxy resin, glycidyl ester type epoxy resin, alicyclic epoxy resin, tris (glycidyl ether phenyl) methane, terminal carboxylated butadiene-acrylonitrile rubber modified epoxy resin, and various other epoxy resins can be used. A mixture of two or more epoxy resins can be used.

[0006] As bisphenol A type epoxy resins, Epikote 828, Epikote 834, Epikote 827, Epikote 1001 are used.
, 1002, 1004, 1007, 1009 (
(manufactured by Yuka Shell Epoxy Co., Ltd.), Araldite C
Y205, CY230, CY232, CY221
, GY257, GY252, GY255, GY
250, GY260, GY280, 6071, 7071, 7072 (manufactured by Ciba Geigy),
Dowepoxy DER331, DER332, DER
662, DER663U, DER662U (and above,
(manufactured by Dow Chemical Company), Epiclon 840, Epiclon 850, Epiclon 855, Epiclon 860, Epiclon 1050, Epiclon 3050, Epiclon 405
0, Epotote 7050 (manufactured by Dainippon Ink and Chemicals Co., Ltd.), Epotote YD115, Epotote YD115CA, Epotote YD
117, YD121, YD127, YD128,
Same YD128CA, Same YD128S, Same YD134, Same YD001Z, Same YD011, Same YD012, Same YD0
14, YD014ES, YD017, YD0
19, YD020, YD002 (Toto Kasei)
Co., Ltd.), etc.

[0007] As the bisphenol F type epoxy resin, Epotote YDF170 (manufactured by Toto Kasei Co., Ltd.) can be mentioned. Examples of phenol novolac type epoxy resins include Epicote 152, Epicote 154 (manufactured by Yuka Shell Epoxy Co., Ltd.), Araldite EPN1138, Epikote EP
N1139 (manufactured by Ciba-Geigy), Dowepoxy DEN431, DEN438, DEN439 (manufactured by Dow Chemical), EPPN201 (Nippon Kayaku)
Co., Ltd.), Epiclon N740 (Dainippon Ink & Chemicals Co., Ltd.), Epotote YDPN638 (Toto Kasei Co., Ltd.), Tactix785 (Dow Chemical Japan Co., Ltd.)
(manufactured by), etc. Cresol novolac type epoxy resins include ECN1280, ECN1299 (manufactured by Ciba-Geigy), and EOCN102 (Nippon Kayaku).
Co., Ltd.), etc. As the alicyclic epoxy resin, Araldite CY179, Araldite CY178, Araldite CY18
2. CY183 (manufactured by Ciba Geigy), etc. Examples of glycidylamine type epoxy resins include Araldite MY720 (manufactured by Ciba Geigy), Epotote YH434 (manufactured by Toto Kasei Co., Ltd.), ELM120, and EL.
M434 (manufactured by Sumitomo Chemical Co., Ltd.), TETRA
D-C, TETRAD-X (Mitsubishi Gas Chemical Co., Ltd.)
(manufactured by) etc. Tris (glycidyl ether phenyl)
As a methane type epoxy resin, Tac-tix742
(manufactured by Dow Chemical Japan Co., Ltd.). As naphthalene type epoxy resin, HP4032, EXA47
00 (manufactured by Dainippon Ink & Chemicals Co., Ltd.), etc.

Among the above, Araldite MY720, which is a glycidylamine type epoxy resin, and Epotote YH
434, ELM120, ELM434, TETRAD-
C, and TETRAD-X, and T, which is a tris(glycidyl ether phenyl)methane type epoxy resin.
Actix742 and the like are preferred because they improve heat resistance.

Furthermore, in order to improve the toughness of the epoxy resin, various plastics, rubbers, etc. can be added in an amount of usually 5 to 30 parts by weight, preferably 8 to 20 parts by weight, per 100 parts by weight of the epoxy resin. For example, plastics include polycarbonate, polyether sulfone, phenoxy resin, polyvinyl formal, polyvinyl butyral, polyethylene terephthalate, and the like. Rubbers include butadiene-acrylonitrile rubber,
Examples include styrene-butadiene rubber, acrylonitrile-butadiene-styrene resin, and silicone resin. Also,
Further, ultrafine polymer particles may be added to improve toughness. Styrene resin as ultrafine polymer particles,
Divinylbenzene resin, styrene-divinylbenzene resin, benzoguanamine resin, melamine resin, benzoguanamine-melamine cocondensation resin, urea resin, silicone resin, ethylene-acrylic acid copolymer resin, methyl methacrylate resin, n-butyl acrylate resin, acrylic-urethane There are resins, polyamide resins, aromatic polyester resins, etc.

Examples of the micro hollow spheres (B) used in the present invention include inorganic ones such as glass, alumina silicate, ceramic, and carbon, and organic ones such as phenol, epoxy resin, urea resin, and melamine resin. It will be done. Among these, glass microscopic hollow spheres are particularly preferred in terms of strength and weight reduction. The size of the micro hollow spheres is not particularly limited, but is usually 10 to 200 μm,
Preferably, it has a particle size distribution of 80 to 120 μm. Furthermore, it is particularly desirable to use a blend of particles with a particle size distribution of 80 to 120 μm and 20 to 50 μm, since this can improve the strength. For epoxy resin composition films with a thickness of 1 mm or less, glass micro hollow spheres of 5 to 50 μm are preferred.

[0011] Furthermore, when using glass micro hollow spheres,
A silane coupling agent can also be used to increase the interfacial adhesive strength with the matrix resin and improve physical properties. Examples of the silane coupling agent include β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, and the like.

The amount of (B) micro hollow spheres used is usually 5 to 65 parts by weight, preferably 10 to 35 parts by weight per 100 parts by weight of (A) epoxy resin. If the amount used is less than 5 parts by weight, the weight reduction will be insufficient, and if it exceeds 65 parts by weight, the mixability of the resin composition will be insufficient, which is not preferable.

Examples of the blowing agent (C) used in the present invention include azobisisobutyronitrile (AIBN),
Azo series such as azodicarbonamide (ADCA), azobisformamide (ABFA), diazoaminobenzene (DAB), N,N'-dinitrosopentamethylenetetramine (DPT), N,N'-dimethyl-N,N' −
Examples include nitroso-based compounds such as dinitrosoterephthalamide, and hydrazide-based compounds such as benzenesulfonylhydrazide (BSH), toluenesulfonylhydrazide (TSH), and p,p'-oxybis(benzenesulfonylhydrazide) (OBSH). Further, during curing, it is also possible to use organic solvents that generate gas when heated or have boiling points near the curing temperature, such as aliphatic hydrocarbons, alcohols, ketones, and halogen compounds. Among them, azodicarbonamide, dinitrosopentamethylenetetramine, and trihydrazinotriazine are preferred from the viewpoint of high-temperature foamability. By using these materials, they can be effectively foamed during curing and a lightweight foamed product can be obtained.

(C) The blowing agent is (A) epoxy resin 10
Usually 0.1 to 25 parts by weight, preferably 2 to 10 parts by weight are added per 0 parts by weight. If the amount added is less than 0.1 parts by weight, the foaming effect will be small, and if it exceeds 25 parts by weight, the amount of foaming will be too large, causing problems in moldability, which are both undesirable.

A foaming aid may also be added for the purpose of adjusting the decomposition temperature, amount of gas generated, foaming speed, etc. of the foaming agent. Examples of the foaming aid include foaming accelerators such as zinc white, zinc nitrate, tribasic lead phosphate, metal soap, borax, oxalic acid, and urea, and foaming inhibitors such as hydroquinone.

The flame retardant (D) used in the present invention includes:
Examples include halogen-based, phosphorus-based, and inorganic metal compound-based materials. Typical halogen flame retardants include, for example, brominated epoxy resins, brominated phenylglycidyl ether, tetrabromobisphenol, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, and tribromo Benzene, tetrabromobenzene, hexabromobenzene, tris(2,3
-dibromopropyl) isocyanurate, 2,2-bis(4-hydroxyethoxy-3,5-dibromophenyl)propane, decabromodiphenyl oxide, chlorinated paraffin, brominated polyphenyl, and the like. Typical phosphorus flame retardants include, for example, ammonium phosphate, tricresyl phosphate, triethyl phosphate, tris (β-chloroethyl) phosphate, tris (β-bromoethyl) phosphate, trischloroethyl phosphate, and tris dichloro. Examples include propyl phosphate, tris-dibromopropyl phosphate, cresyl diphenyl phosphate, xylylene diphenyl phosphate, acidic phosphoric acid ester, and nitrogen-containing phosphorus compounds. Representative examples of inorganic metal compound flame retardants include tin oxide, antimony trioxide,
Examples include barium metaborate, calcium borate, aluminum hydroxide, magnesium hydroxide, red phosphorus, and the like.

(D) Flame retardant is (A) Epoxy resin 1
Usually 5 to 75 parts by weight per 00 parts by weight, preferably 1
It is added in an amount of 0 to 50 parts by weight. If the amount added is less than 5 parts by weight, there is no flame retardant effect, and if it exceeds 75 parts by weight, the viscosity of the resin composition increases and mixing becomes difficult, which is not preferable.

The aromatic diamine (E) used in the present invention includes, for example, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 4,
4'-diaminodiphenylmethane, 4,4'-methylenedi-o-toluidine, 4,4'-methylenedi-2,6-
xylidine, 4,4'-diaminobenzanilide, 4,
4'-methylenedi-2,6-diethylaniline, 4,
Examples include 4'-diamino-3,3'-dimethyldicyclohexylmethane. Particularly when using a solid aromatic diamine, it is preferable that the particle size is 60 μm or less in order to ensure uniform dispersion.

(E) Aromatic diamine is usually added in an amount of 15 to 140 parts by weight, preferably 25 to 65 parts by weight, per 100 parts by weight of (A) epoxy resin. When the amount added is less than 15 parts by weight, a sufficient cured product may not be obtained;
If it exceeds 0 parts by weight, the amount of heat generated is too large and there is a problem with moldability, which is not preferable.

[0020] Other curing agents and curing accelerators may also be added as required. Examples of these include dicyandiamide, BF3 monoethylamine, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, and the like. In the present invention, as other additives, a reactive diluent,
Various fillers, plasticizers, foam stabilizers, thickeners, colorants, etc. can also be mixed.

Next, a method for producing the resin composition for composite materials of the present invention will be explained. Important points in the production of the above resin composition are 1) the order of addition of the blends and 2) the mixing method. When mixing the epoxy resin, hollow microspheres, foaming agent, flame retardant, and aromatic diamine, the epoxy resin is first melted by heating, usually at 80 to 200°C, and after the viscosity has decreased, the hollow microspheres are added. After uniformly mixing and cooling the mixture to usually 60 to 80°C, the blowing agent, flame retardant and aromatic diamine previously mixed with the liquid epoxy resin are quickly added, and then the mixture is extracted and rapidly cooled.

Regarding the mixing method, in the case of solids such as micro hollow spheres that easily break if too much shearing force is applied, it is important to adjust the viscosity and shear rate during mixing. The viscosity during mixing is preferably about 500 to 25,000 cP, preferably 800 to 13,000 cP. At this time, if the viscosity is less than 500 cP, it becomes sticky or fluid when formed into a sheet. Also, the viscosity is 25,
If it is higher than 000 cP, it will be difficult to mix uniformly and the micro hollow spheres will be destroyed, which is not preferable.

Examples of mixers with low shearing force include planetary mixers, twin-screw kneaders, and static mixers. The planetary mixer and kneader are preferably equipped with a transmission. In particular, if the shearing force is large when the viscosity is high, heat generation occurs and the reaction progresses, causing the viscosity of the resin to increase and foaming to occur. When the shearing force is small, the micro hollow spheres, foaming agent, flame retardant and aromatic diamine become non-uniform due to insufficient mixing, and sufficient physical properties cannot be obtained.

The resin composition for composite materials thus obtained is used for producing sheets or films (single intermediate materials) that are intermediate materials for composite materials. There are various manufacturing methods, but typical methods include methods using a calendar coater, reverse roll coater, knife over roll coater, etc. The coating thickness is usually 0.
．． Approximately 1 to 5 mm is preferable. As the material to be coated,
Release paper is commonly used, but films such as plastic can also be used. Furthermore, release paper and films such as polyethylene can be used as the covering material. Furthermore, the above sheet or film as a single intermediate material can be reinforced with glass scrim cloth, glass mat, nonwoven fabric, etc., and used as a reinforcing intermediate material.

[0025] The resin composition for composite materials is made of glass fiber reinforced resin (FRP) or carbon fiber reinforced resin (CFR) by using an extruder, injection machine, etc. heated as it is.
It can also be used for reinforcing purposes by injecting and filling the inside of P) pipes or complex-shaped objects and curing with heat.

[0026] The single intermediate material or reinforcing intermediate material produced as described above can be heated as is and used as a foamed lightweight material. It can be made into a composite material by integrally molding it with a prepreg using polyethylene fiber, alumina fiber, etc., and then heat-curing it. The prepreg used in this case is particularly preferred because it easily co-crosslinks with the epoxy resin. The above intermediate material is usually heat-cured at 150-250°C for 10 minutes or more.
This is achieved by heating for 10 hours, preferably 30 minutes to 3 hours at 170-230°C.

[0027] To create a laminated structure using an intermediate material (single intermediate material or reinforcing intermediate material), a sandwich structure is used in which the intermediate material is the core material, but it is divided into single layer and multilayer according to the number of core material layers. It will be done. Furthermore, it can also be used as a sandwich hybrid structure or an interlayer hybrid structure. Examples of the single-layer sandwich structure include carbon fiber prepreg/intermediate material/carbon fiber prepreg, glass fiber prepreg/intermediate material/glass fiber prepreg, and the like. Examples of the multilayer sandwich structure include carbon fiber prepreg/intermediate material/carbon fiber prepreg/intermediate material/carbon fiber prepreg, glass fiber prepreg/intermediate material/glass fiber prepreg/intermediate material/glass fiber prepreg, and the like. Sandwich hybrids include, for example, carbon fiber prepreg/intermediate material/glass fiber prepreg, aramid fiber prepreg/intermediate material/carbon fiber prepreg, carbon fiber prepreg-aramid prepreg/intermediate material/carbon fiber prepreg-glass fiber prepreg, and the like. Interlayer hybrids include carbon fiber prepreg/intermediate material/glass fiber prepreg/intermediate material/carbon fiber prepreg.

[0028] The molded product of the laminate can be flat, curved, tubular,
It may be rod-shaped or the like. In the case of tubular and rod-shaped molded products, the skin layer is made of prepreg containing carbon fiber, aramid fiber, glass fiber, etc., and the core material is filled with a single intermediate material in a hollow shape or without any gaps, thereby creating a lightweight molded product. is obtained.

[0029] As another molding method, a pre-cured molded plate made of prepreg containing carbon fibers, aramid fibers, glass fibers, etc. and a single intermediate material may be attached and cured by heating. Furthermore, a reinforced plastic plate containing carbon fibers, aramid fibers, glass fibers, etc. and a cured single intermediate material (composite material) can also be heat-bonded using a film adhesive.

[0030] As described above, the single intermediate material formed into a sheet form from the epoxy resin composition for composite materials can be easily laminated in shapes ranging from flat plates to complex shapes, and can be used as a structural adhesive by co-crosslinking with other prepregs. A composite material that can be used in a similar manner, is easier to handle, and is lighter and stronger is obtained.

Examples of these uses include, in the aircraft industry, core materials for structures, filling complex-shaped objects, repairing holes, depressions, etc., and forming ducts. In the architectural field, there are furniture for upper floors, panels for walls, etc. For vehicles such as automobiles, there are core materials for structural materials, and for electrical equipment, there are housings for devices and equipment.

[0032]

[Examples] The present invention will be specifically explained below with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1 5.5 kg of tetrafunctional glycidylamine type epoxy resin (trade name: Araldite MY720, manufactured by Ciba Geigy)
and bisphenol A type epoxy resin (trade name: Epicote 828, manufactured by Yuka Shell Epoxy Co., Ltd.) 1.5
kg were fed into a planetary mixer and mixed uniformly at 120°C, followed by 1.2 kg of glass micro hollow spheres (trade name: Scotchlite Glass Bubbles B28/750 grade, manufactured by Sumitomo 3M) and three flame retardants. 0.5 kg of antimony oxide and 0.6 kg of tris dibromopropyl phosphate were added and mixed uniformly. After mixing, the contents were cooled to 100°C while stirring,
2.4 kg of 4,4'-diaminodiphenylsulfone as an aromatic diamine and 0.25 kg of azodicarbonamide as a blowing agent were quickly added, stirred for 15 minutes, taken out, and cooled. This blend was remelted at 70°C,
1.3mm thick using calendar roll coater
A sheet-like product (single intermediate material) was obtained. The produced sheet-like material was cut out and cured by heating in an oven at 180°C for 1 hour to obtain a composite material with a thickness of 4 mm. The density of the resulting foam was 0.35 g/cm3.
Furthermore, when the flammability was tested in accordance with JISK6911, self-extinguishing properties were found.

Example 2 Trifunctional glycidylamine type epoxy resin (trade name: Ta
ctix742, manufactured by Dow Chemical Japan Co., Ltd.) 3.0k
g, Bisphenol F type epoxy resin (product name: Epotote YDF170, manufactured by Toto Kasei Co., Ltd.) 1.3 kg
and brominated epoxy resin (product name: Epotote YD
After feeding 1.2 kg of B340 (manufactured by Toto Kasei Co., Ltd.) into a planetary mixer and uniformly mixing it at 130°C,
1.2 kg of glass micro hollow spheres (trade name: Scotchlite Glass Bubbles B28/750 grade) were added and mixed uniformly. Then, while stirring the contents,
After cooling to 0°C, 2.6 kg of 4,4'-diaminodiphenylsulfone as an aromatic diamine and 0.25 kg of dinitrosopentamethylenetetramine as a blowing agent were quickly added, stirred for 10 minutes, taken out, and cooled. This mixture was remelted at 80°C and a sheet of 1.3 mm thick was produced using a calendar roll coater (single intermediate material).
I got it. The produced sheet-like product was cut out and cured by heating in an oven at 180°C for 1 hour, and the density of the resulting foam was 0.35 g/cm 3 . Also, JIS
When the flammability was tested in accordance with K6911, it was found to be self-extinguishing.

Comparative Example 1 Except that no blowing agent and glass micro hollow spheres were used.
A sheet with a thickness of 1.7 mm was obtained in the same manner as in Example 1. The density of the cured product obtained by further curing at 180° C. for 1 hour was 1.3 g/cm 3 .

Comparative Example 2 A sheet-like product with a thickness of 1.7 mm was obtained in the same manner as in Example 1, except that no blowing agent was used. Furthermore, 1 at 180℃
The density of the cured product obtained by time curing is 0.65 g/cm
It was 3.

Comparative Example 3 A sheet with a thickness of 1.7 mm was obtained in the same manner as in Example 1, except that glass micro hollow spheres were not used. Further, the density of the cured product obtained by curing at 180° C. for 1 hour was 0.65 g/cm 3 .

Example 3 Two 300 x 300 mm square carbon fiber cloth prepregs were laminated on a 301 x 301 mm square, 3.5 mm thick stainless steel mold, and on top of that, 30 pieces of carbon fiber cloth prepreg obtained in Example 1 were laminated.
Attach one piece of uncured intermediate material of 0 x 300 mm square,
Furthermore, two sheets of carbon fiber cloth prepreg measuring 300 x 300 mm were laminated. Release films were applied to the upper and lower surfaces of these, and a stainless steel backing plate was placed on the outside of the release film, and the pieces were sandwiched in a hot press. This was heated from room temperature to 180°C at a rate of 2.5°C/min, and then held at 180°C for 1 hour to cure. The thickness of the molded plate of the obtained laminate was 3.5
mm, the density was 0.5 g/cm3, and it was extremely lightweight regardless of the thickness. Next, a rectangular test plate with a length of 20 cm and a width of 1.5 cm was cut from this molded plate, and a 4-point bending test was conducted under the conditions of a length/thickness ratio between fulcrums of 30 and a measurement temperature of 120°C in accordance with ASTM C393. As a result, the bending strength was 14 kg/mm2, and the bending rigidity was 2.9 ton/mm2.

Example 4 Two carbon fiber cloth prepregs of 300 x 300 mm square were placed in a stainless steel mold of 301 x 301 mm square and 3 mm thick.
300× obtained in Example 1
Two sheets of uncured single intermediate material of 300 mm square were attached, and two sheets of carbon fiber cloth prepreg of 300 x 300 mm square were further laminated. Release films were applied to the upper and lower surfaces of these, and a stainless steel backing plate was placed on the outside of the release film, and the pieces were sandwiched in a hot press. 1 from room temperature at a rate of 2.5°C/min.
After heating to 80°C, it was held at 180°C for 1 hour to foam and harden. The thickness of the obtained molded plate was 3.0 mm, and the density was 0.
．． It was 5g/cm3 and was extremely lightweight regardless of its thickness. In addition, the bending strength at 120℃ is 14kg.
/mm2, and the bending rigidity was 2.9 ton/mm2.

Example 5 The uncured single intermediate material obtained in Example 2 was
It is cut into 1 mm square pieces, rolled into a rod shape with an outer diameter of about 10 mm, and wrapped with a 0.12 mm thick, 200 x 72 mm square unidirectional carbon fiber prepreg, and then wrapped with a 0.1 mm thick unidirectional carbon fiber prepreg.
Wrap a release film of 0.05 mm, 220 x 40 mm square,
Both ends were sealed with heat-resistant tape. This has an inner diameter of 12.5m
After putting it into a 200 mm long iron pipe, both ends were closed with caps. Put this in the oven and let it rise from room temperature to 1
The temperature was raised to 80°C at a rate of 3°C/min, and then the temperature was increased to 18°C.
The foam was cured by heating at 0° C. for 1 hour. As a result, a cylindrical molded body was obtained.

Comparative Example 4 Two 300 x 300 mm square carbon fiber cloth prepregs were laminated on a 301 x 301 mm square, 3.5 mm thick stainless steel mold, and on top of that, 30 pieces of carbon fiber cloth prepreg obtained in Comparative Example 2 were laminated.
Attach one uncured sheet of 0 x 300 mm square,
Furthermore, two sheets of carbon fiber cloth prepreg measuring 300 x 300 mm were laminated. Release films were applied to the upper and lower surfaces of these, and a stainless steel backing plate was placed on the outside of the release film, and the pieces were sandwiched in a hot press. After heating from room temperature to 185°C at a rate of 2.5°C/min, it was held at 185°C for 1 hour to cure. The thickness of the molded plate of the obtained laminate was 3.5 mm,
The density was 0.95 g/cm3, which was about twice the density of Example 3 in which a blowing agent was added. Bending strength at 120℃ is 14kg/mm2, bending rigidity is 3.2ton/m
It was m2.

Comparative Example 5 2.8 kg of bisphenol A type epoxy resin (trade name: Epicote 828, manufactured by Yuka Shell Epoxy Co., Ltd.) and phenol novolak type epoxy resin (trade name: Epicote 154, manufactured by Yuka Shell Epoxy Co., Ltd.) manufactured by) 5.2
kg into a planetary mixer and mixed uniformly at 120°C, 1.2 kg of glass micro hollow spheres (trade name: Scotchlite Glass Bubbles B28/750 grade, manufactured by Sumitomo 3M) and Tris (β- 1.2 kg of (bromoethyl) phosphate and 0.4 kg of antimony trioxide were added and mixed uniformly. After mixing, the contents were cooled to 70°C while stirring, and further added 0.24 kg of dicyandiamide as a hardening agent, 0.32 kg of 3-p-chlorophenyl-1,1-dimethylurea as a hardening accelerator, and azodicarbonamide as a blowing agent. 0
．． 24 kg was quickly added, stirred for 5 minutes, removed and cooled. This blend was remelted at 70°C, and a sheet-like product with a thickness of 1.3 mm was obtained using a calendar roll coater. Next, two sheets of 300 x 300 mm square carbon fiber cloth prepreg were laminated on a 301 x 301 mm square, 3 mm thick stainless steel mold, and on top of that, the 300 x 300 mm square, 1.3 mm thick sheet obtained by the above method was laminated. One sheet-like material was attached, and two 300 x 300 mm square carbon fiber cloth prepregs were further laminated. Release films were applied to the upper and lower surfaces of these, and a stainless steel backing plate was placed on the outside of the release film, and the pieces were sandwiched in a hot press. and 2.5℃/m
After heating from room temperature to 130° C. at a speed of 100° C., the film was cured by holding at 130° C. for 1 hour. The thickness of the molded plate of the obtained laminate was 3.0 mm, the density was 0.5 g/cm3,
Despite its thickness, it was extremely lightweight. Also, 120
The bending strength at ℃ is 8 kg/mm2, and the bending rigidity is 1.
It was 8 tons/mm2.

The difference between Examples 3 and 4 and Comparative Example 5 is that in Examples 3 and 4, curing was carried out at 180°C, whereas in Comparative Example 5, a low temperature curing resin was used. , and is cured at 130°C. When a low-temperature curing resin is used in this manner, the glass transition temperature (Tg) becomes low, resulting in poor heat resistance, for example, bending properties at 120°C. Furthermore, it can be seen that Examples 3 and 4 have the same bending properties as Comparative Example 4 in which no blowing agent is used, and the density is about 1/2 lower.

[0044]

Effects of the Invention According to the present invention, a composite material containing a foam that is flame retardant, heat resistant, lightweight, strong and rigid is obtained from an easy-to-handle resin sheet or film for composite material. be able to.

Claims (6)

[Claims] 1. An epoxy resin composition for a composite material, comprising (A) an epoxy resin, (B) micro hollow spheres, (C) a foaming agent, (D) a flame retardant, and (E) an aromatic diamine. thing. 2. (A) 100 parts by weight of epoxy resin, (B) 5 to 65 parts by weight of micro hollow spheres, (C) 0.1 to 25 parts by weight of blowing agent, and (D) 5 to 75 parts by weight of flame retardant. 2. The epoxy resin composition for composite materials according to claim 1, wherein the amount of the aromatic diamine (E) is 15 to 140 parts by weight. 3. A single intermediate material, characterized in that the epoxy resin composition for composite materials according to claim 1 or 2 is molded into a sheet or a film. 4. A composite material obtained by foaming and curing the single intermediate material according to claim 3. 5. A reinforcing intermediate material comprising the single intermediate material according to claim 3 and a reinforcing material for reinforcing the single intermediate material. 6. A composite material obtained by foaming and curing the reinforcing intermediate material according to claim 5.