JPH11147965A - Fiber-reinforced resin composite and prepreg - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fiber-reinforced resin composite or prepreg which is resistant to ignition, has good mechanical properties after heat exposure, and is suitable for the use in transportation means such as railroad cars. SOLUTION: This composite comprises a fibrous reinforcement and a matrix resin, does not substantially ignite in the ignition test according to the test method No. 81 of the Ministry of Transport, and exhibits a compression strength after impact of 15 kgf/mu<2> or higher and an interlayer shear strength of 7 kgf/mm<2> or higher when measured after heat exposure in a heated oven at 250 deg.C for 10 min. The matrix resin comprises a nonhalogen epoxy resin, a metal oxide, a thermoplastic resin having a glass transition temp. of 120 deg.C or higher, and a curative for an epoxy resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber-reinforced resin composite material having excellent ignition resistance, flame retardancy and impact resistance, and a prepreg for obtaining the fiber-reinforced resin composite material. More specifically, the present invention relates to a fiber-reinforced epoxy resin composite material and a prepreg suitable for use in transportation such as railway vehicles.

[0002]

2. Description of the Related Art Composite materials with carbon fiber-reinforced resins have been used in the fields of sports goods, industrial materials, transportation, etc. due to their excellent mechanical properties. Especially in the fields of aerospace and vehicles, composite materials with matrix resins containing various epoxy resins as main components have been developed. There is a strong demand.

[0003] Conventionally, methods for flame retarding fiber-reinforced composite materials using an epoxy resin as a matrix include: a. Flame-retardant methods for fiber-reinforced composite materials in which a halogenated epoxy resin is blended in a matrix (see, for example,
No. 92775); b. A method for flame retarding a fiber reinforced composite material in which additives such as a halogen compound and a phosphorus compound are blended in a matrix; c. Flame-retardant methods for fiber-reinforced composite materials in which an inorganic filler such as aluminum hydroxide is blended in the matrix (for example,
JP-A-1-197554); and the like.

The object of the flame-retarding methods a to c is a composite material composed of a laminate of a reinforcing fiber and a matrix resin. To stop the supply of oxygen and control the combustion of the composite material.
In addition, this is a method of controlling combustion by reducing an organic component, that is, a combustible component, by adding an inorganic powder component.

[0005]

However, since the composite material is generally a laminate of a thin material, according to the above-described technique of shutting off the laminate and the air, the composite material as an object is exposed to heat. Occasionally, air bubbles are generated between layers near the surface layer of the composite material, and peeled off into thin laminated materials that are each unit before lamination, and as a result, the thin laminated material is ignited, and the surface layer is burned in the early stage of combustion, and then the target object is burned. Halogen gas or water vapor generated from the air causes a phenomenon of shutting off air.

[0006] When the ignition is performed once as described above, a gas barrier due to combustion is generated to achieve the purpose of flame retardation, but the halogen gas and the combustion gas generated at this time have a bad effect on the human body.

[0007] It is important that a material for transportation use is not ignited first, and the Ministry of Transport, Iron Transportation No. 81 also sets a criterion for determining the ignition resistance and seeks the ignition resistance of the material.

Further, as described above, when gas is generated in the laminate by heat exposure at an early stage of a fire, mechanical properties, particularly strength after impact, are extremely reduced, and the object of flame retardancy is achieved. Even if it is performed, there arises a problem that it cannot function as an internal structural material.

Further, in the above a. b. In the method of
As pointed out in, for example, Japanese Patent Application Laid-Open No. 5-92757, there is a problem that it becomes difficult to obtain a resin composition having excellent mechanical properties and heat resistance even before exposure to heat, when the proportion of the bromine-containing epoxy resin is increased.

The above c. According to the method described in
As pointed out in Japanese Patent No. 97554 and the like, when the blending ratio of the inorganic filler such as aluminum hydroxide increases, the thixotropy increases and the moldability deteriorates. In addition, the mechanical properties are greatly reduced. In the method based on the addition of the inorganic component, the mechanical properties are also greatly reduced.

Therefore, the present invention does not ignite even by fire exposure, does not generate decomposition gases such as halogen gas and water vapor upon heat exposure, and has good mechanical properties after heat exposure.
An object of the present invention is to provide a carbon fiber reinforced composite material excellent in moldability and a prepreg for obtaining the fiber reinforced resin composite material.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a fiber reinforced resin composite material comprising a fiber reinforced material and a matrix resin. Did not substantially ignite in the ignited test, and had a compressive strength after impact of 1 after the heat exposure test described later.
5 kgf / mm ² or more, interlayer shear strength is 7 kgf / mm
It is a fiber-reinforced resin composite material characterized by being ² or more, and further a prepreg for producing this composite material.

The fiber-reinforced resin composite material of the present invention is intended to suppress the generation of gas itself and to prevent ignition itself. Therefore, the technical concept of the conventional flame-retardant means, that is, halogen gas, water vapor and the like during combustion. The idea itself is different from the technical idea of shutting off the combustion material and the air by generating the gas, thereby achieving the purpose of flame retardancy.

The fiber-reinforced resin composite material of the present invention exerts excellent effects on impact resistance in addition to the above property of not igniting. Such a fiber-reinforced resin composite material is suitable for use as a material for automobiles and a material for railway vehicles.

In the present invention, various tests such as a heat exposure test, an ignition test, an impact resistance test, an interlaminar shear strength test, and a measurement of a glass transition temperature are performed according to the following methods.

Heat exposure test Specimens for compression test after impact and interlaminar shear test were placed in an oven heated to 250 ° C. before measuring mechanical properties.
After leaving still for 0 minutes, the presence or absence of peeling after heat exposure is measured by an ultrasonic flaw detector. The dimensions of the sample used in each test conform to the standards in each test described later.

[0017] performing the ignition test was Junsho to ignition test Ministry of Transport Tetsuun 81 issue. The thickness of the sample is 2 mm.

[0018] The ignition test specified in Tetsu-No-81 consists of the following contents. A sample of B5 size is held at an inclination of 45 °, and the fuel container is placed on a pedestal so that the center of the container is located 25.4 mm below the center of the lower surface of the sample, and 0.5 cc of ethyl alcohol is put in the pedestal. Ignite and leave until fuel burns out. The determination of flammability is divided into during and after burning of alcohol. During burning, the ignition, ignition, smoke state, and flame state are observed, and after combustion, the after-flame, dust, carbonization, and deformation are examined.

If the above observation result is, for example, “ignition”,
There is "flaming", "smoke" is normal, "fire" flame does not exceed the upper end of the test piece, "no residual flame", "no residual dust", "carbonized"
If the deformation / local penetration reaches the “deformed” edge reaching the upper end of the test piece, the determination result is “flame retardant”. If there is no "ignition", no "flame", little "smoke", "carbonization" discoloration of 100 mm or less, and "deformation" surface deformation of 100 mm or less, it is "nonflammable".

Incidentally, Tetsu-kun No. 81 is described in the English-language book "Plastic Flame Retardation-Smoke Reduction and Countermeasures against Hazardous Combustion Gases", Nikkan Kogyo Shimbun (1978) and Nishizawa, "Flame-retardant New Polymers-
"Science and Practical Technology", Taiseisha (1992).

The following vertical combustion test and horizontal combustion test are combustion tests based on UL94 standard for quantitatively evaluating flammability.

Vertical Burning Test The vertical burning test is for quantitatively evaluating the flame retardancy, and is a combustion test conforming to the UL94 standard. The test method is performed as follows.

The sample size is 127 mm × 12.7 mm × 4
mm. 94V-0, 2 if the average time to extinguishing after removing the flame by the Bunsen burner is within 5 seconds.
If within 5 seconds, it will be 94V-1. If there is a flaming drop even if the average time is within 25 seconds, it will be 94V-2. If the test does not pass the vertical combustion test, a horizontal combustion test according to the UL94 standard is performed.

The sample size for the horizontal combustion test is 127 mm × 12.7 mm × 4 mm.
If the burning speed after removing the flame by the Bunsen burner is 38 mm / min or less, it will be 94 HB.

Impact resistance test (strength test after impact) After quasi-isotropically laminating 32 prepregs and molding them,
A falling weight impact energy of 1000 in-lb / in is applied to the formed plate, and the compressive strength after impact is measured.

Interlaminar shear strength test 14 prepregs are laminated in one direction, and after molding, the interlaminar shear strength (ILSS) is measured according to ASTM D2344.

The glass transition temperature is measured at a heating rate of 20 ° C./min using a TMA penetration mode.

The composite material of the present invention comprises the following [A],
It is preferable to include the components [B] and [C] as constituent elements.

[A]: Epoxy resin containing no halogen [B]: Metal oxide [C]: Thermoplastic resin having a glass transition temperature of 120 ° C. or more The fiber reinforcing material that can be used in the present invention includes carbon Inorganic fibers such as fiber, silicon carbide fiber, glass fiber, alumina fiber, ceramic fiber and the like can be mentioned.

The carbon fibers usable in the present invention include acrylonitrile-based and pitch-based carbon fibers. These carbon fibers can be used in any form of long fiber, short fiber, chop, sheet, woven, knit, mat, or paper.

A halogen-free epoxy resin is used as the component (A). Specifically, examples of the epoxy resin include a glycidylamine type epoxy resin, a novolak type epoxy resin, a bisphenol A type epoxy resin, a urethane modified bisphenol A type epoxy resin, and a single or a mixture of alicyclic epoxy resins.

Examples of the glycidylamine type epoxy resin include Epototo YH434 (trade name, manufactured by Toto Kasei Co., Ltd.) and YDM120 (trade name, manufactured by Toto Kasei Co., Ltd.). Among the novolak-type epoxy resins described above, examples of the phenol novolak-type epoxy resin include Epicoat 152 (trade name) and Epicoat 15 manufactured by Shell Chemical Company.
4 (trade name), Dow Epoxy DEN manufactured by Dow Chemical
431 (trade name), Dow Epoxy DEN43 (trade name), Dow Epoxy DEN 439 (trade name), and E
PPN201 (trade name, manufactured by Nippon Kayaku Co., Ltd.), Epicron N
740 (trade name, manufactured by Dainippon Ink) and cresol novolak type epoxy resins include Araldite ECN1273 (trade name) and Araldite ECN1280 (trade name) manufactured by Ciba Geigy Corporation.

Examples of the bisphenol A type epoxy resin include, for example, Epicoat 827 manufactured by Shell Chemical Company.
(Trade name), Epicoat 828 (trade name), Epicoat 1001 (trade name), Epicoat 1002 (trade name),
Epicoat 1004 (trade name) and the like.

As the urethane-modified bisphenol A type epoxy resin, Adeka Resin EPU manufactured by Asahi Denka Co., Ltd.
-6 (trade name), Adeka Resin EPU-10 (trade name), Adeka Resin EPU-15 (trade name), etc.
Examples of the alicyclic epoxy resin include Araldite CY-179 (trade name), Araldite CY-178 (trade name) and Araldite CY-182 manufactured by Ciba Geigy.
(Trade name), Araldite CY-183 (trade name) and the like.

The epoxy resin (A) in the present invention may be used alone or in combination of two or more.

The curing agent for the epoxy resin is not particularly limited, and examples thereof include aromatic amines, dicyandiamide, boron trifluoride complex salts, acid anhydrides, and imidazoles alone or in a mixture.

Examples of the aromatic amines include metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, and metaxylenediamine.
As the boron trifluoride complex salts, BF3 monoethylamine, B3 benzylamine and the like can be used.

Examples of the acid anhydride include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride and the like. Examples of imidazoles include 2-ethyl-4-imidazole, 2-ethylimidazole, 2,4-dimethylimidazole,
Phenylimidazole and the like can be used.

In addition to the epoxy resin curing agent, for example, 3- (3,4-dichlorophenyl) -1,1-dimethylurea can be used in combination as a curing accelerator.

The metal oxide of the component (B) is not particularly limited, but from the viewpoint of fire resistance, magnesium oxide and aluminum oxide are preferred. Particularly, magnesium oxide having a high thermal conductivity is useful for improving the flame retardancy and is preferred. It is particularly preferable that the magnesium oxide has a 50% particle size in the range of 0.5 to 20 μm.

Examples of the thermoplastic resin (C) include resins having a glass transition temperature Tg of 120 ° C. or higher, for example, polyamideimide resin (Tg 260 ° C.), polyimide resin (Tg
g259 ° C), polyethersulfone resin (Tg22
3 ° C.), polyetherimide resin (Tg 216 ° C.) and the like. In particular, a polyetherimide resin is desirable because it is useful for improving the impact resistance of an epoxy resin.

The content ratio in the resin composition of the present invention is desirably the following ratio. That is, the metal oxide as the component (B) is 10 to 30 parts by weight based on 100 parts by weight of the component (A).
Parts by weight are preferred. If the amount is less than 10 parts by weight, the flame retardancy is insufficient. If the amount exceeds 30 parts by weight, the mechanical properties are greatly reduced.

The component (C) is preferably used in an amount of 3 to 30 parts by weight based on 100 parts by weight of the component (A). If the amount is less than 3 parts by weight, the impact resistance is insufficient, and if the amount exceeds 30 parts by weight, the melt viscosity becomes high, so that the workability during prepreg production and the moldability of the prepreg become poor, and the laminate tends to have defects. Become.

The amount of the epoxy resin curing agent is not particularly limited. For example, when 4,4'-diaminodiphenyl sulfone is used as the curing agent, the stoichiometric amount is based on 100 parts by weight of the epoxy resin. Required addition amount,
That is, 70 to 90% of (amine equivalent / epoxy equivalent) × 100 parts by weight is blended. When dicyandiamide is used, the epoxy resin is used in an amount of 100 parts by weight.
It is 1 to 10 parts by weight, preferably 3 to 8 parts by weight.

The components [A], [B] and [C] and the respective components of the epoxy resin curing agent are appropriately selected within the range of this content ratio.

The amount of the fiber reinforcing material used varies depending on the application, but as a laminate or a molding material, it can be used up to 400 parts by weight based on 100 parts by weight of the resin composition.

Optional components: The composite material component of the present invention may optionally include the following (1) as long as the object of the present invention is not impaired.
Components (4) to (4) can be added.

(1) Flame retardant aids, for example, antimony trioxide, antimony pentoxide and the like. The amount of these flame retardant aids used is less than 10 parts by weight, preferably less than 5 parts by weight, based on 100 parts by weight of the epoxy resin.

(2) Powdered reinforcing materials, fillers and thixotropic agents, for example, silica, acid clay, bentonite, glass beads, carbon black, zeolite, diatomaceous earth, mica, kaolin, talc and the like. The amount of these reinforcing materials and fillers used is preferably less than 5 parts by weight based on 100 parts by weight of the epoxy resin.

(3) Colorants and pigments such as titanium dioxide, graphite, carbon black and the like. These colorants,
The amount of the pigment used is 5 per 100 parts by weight of the epoxy resin.
Less than parts by weight is desirable.

(4) A curing accelerator, for example, 3- (3,4)
-Dichlorophenyl) -1,1-dimethylurea can be used in combination with the curing agent for epoxy resin. The compounding amount of the curing accelerator to the epoxy resin is as follows.
1 to 5 parts by weight with respect to 00 parts by weight is desirable.

Method for Preparing Resin: The resin composition in the prepreg of the present invention can be prepared, for example, by the following method. That is, each component is supplied to a kneading device and heated and kneaded. The heating temperature at this time is lower than the curing start temperature of the epoxy resin. At this time, the epoxy resin curing agent is preferably kneaded with heat last. Usually 50-100
Prepare at a temperature of ° C.

Production method of prepreg: The production method of the prepreg of the present invention is not particularly limited. For example, a hot melt method or a solvent method can be adopted.

[0054]

EXAMPLES The present invention will be described in more detail with reference to examples. Unless otherwise specified, “%” and “parts” are based on weight.

[Examples 1 to 8 and Comparative Examples 1 to 7] [A]
The components [C] to [C] were mixed at the composition ratios shown in Table 1 below, and 10 parts by weight of a curing agent and 3 parts by weight of a curing accelerator were further added. Each flame-retardant epoxy resin composition was obtained. Each resin film was produced from each of these resin compositions using a film coater. Each of these resin films is pressed from both sides of aligned carbon fiber Vesfight IM-400 (registered trademark, manufactured by Toho Rayon Co., Ltd., tensile strength 4510 MPa, tensile modulus 294 GPa), and the carbon fiber weight is 150 g / m ^2. The unidirectional prepregs of Examples 1 to 8 and Comparative Examples 1 to 7 having a resin content of 34% were obtained.

Each of these prepregs was heated at 125 ° C. for 5 k
Autoclave molding was performed under the conditions of g / cm ² and 2 hours, and the following items were evaluated by the test method described above.

Flammability after forced ignition: UL94 standard Thermal stability assuming heat exposure in the early stage of fire: Presence or absence of blistering after heat exposure Mechanical properties after heat exposure : Compressive strength after impact (CAI), Interlaminar shear strength (ILSS) These results are shown in Table 1 (Examples 1 to 8) and Table 2 (Comparative Examples 1 to 7) below.

[0058]

[Table 1]

[0059]

[Table 2]

* 1 Epicoat 834: Bisphenol A diglycidyl ether type epoxy resin (manufactured by Yuka Shell Epoxy) * 2 Epicoat 1002: Bisphenol A diglycidyl ether type epoxy resin (manufactured by Yuka Shell Epoxy) * 3 Epicoat 604: N, N, N ', N'-tetraglycidyldiaminodiphenylmethane (manufactured by Yuka Shell Epoxy) * 4 EPU-6: urethane-modified epoxy resin (manufactured by Asahi Denka Kogyo) * 5 PEI Ultem 1000: polyether imide resin (manufactured by Nippon GE Plastics) * 6 PES 5003P: polyether sulfone resin (manufactured by Sumitomo Chemical Co., Ltd.) * 7 DDS: 4,4'-diaminodiphenyl sulfone * 8 DCMU: 3- (3,4-dichlorophenyl)-
1,1-dimethylurea * 9 PPS T-4: polyphenylene sulfide (manufactured by Topren Co., Ltd.) * 10 Fiber volume content of ignitable test piece * 11 Inspection with ultrasonic flaw detector after exposure to heat at 250 ° C. for 10 minutes * 12 1000 in-l after exposure to heat at 250 ° C for 10 minutes
Compressive strength is measured after applying b / in impact energy. * 13 Measured after heat exposure at 250 ° C x 10 minutes. * 14 Measurement not possible due to swelling after heat exposure.

According to Tables 1 and 2, it is understood that the examples of the present invention have the following effects as compared with the comparative examples.

As is apparent from comparison between Example 1 and Comparative Example 1, magnesium oxide and [C] were used as the component [B].
By blending polyetherimide as a component, it is possible to improve the compressive strength after impact (CAI), ignition resistance and flame retardancy after heat exposure.

As is clear from the comparison between Example 1, Comparative Example 2 and Comparative Example 3, when there is no component [B], the ignition resistance is insufficient. The compressive strength after impact after exposure is greatly reduced.

As is clear from comparison between Example 1, Example 2, and Comparative Example 3, the compressive strength after impact after heat exposure increases with an increase in the amount of the polyetherimide of the component [C].

As is apparent from comparison of Examples 1, 3 and 4, when the magnesium oxide component (B) is 12 parts by weight, the flame retardancy is slightly low. The impact resistance and mechanical properties after exposure are slightly reduced.

As is clear from comparison between Example 1 and Comparative Example 4, when a PPS resin having a glass transition temperature of 120 ° C. or lower (Tg of 85 ° C.) is used, the flame retardancy is slightly reduced.

As is clear from comparison between Example 5 and Comparative Example 1, aluminum oxide and [C] were used as the component [B].
By blending polyetherimide as a component, it is possible to improve the compressive strength after impact after heat exposure, ignition resistance, and flame retardancy.

As is clear from the comparison between Example 1 and Comparative Example 5, when aluminum hydroxide was used as the flame retardant, the laminate was swelled during the heat exposure test, and the strength could not be measured. Can no longer function as

As is clear from comparison between Examples 1, 6 and 7, when the fiber volume content is 56%,
When the flame retardancy is slightly low, and when it is 64%, the mechanical properties after heat exposure are slightly reduced.

As is clear from comparison of Example 1, Comparative Examples 6 and 7, when the fiber volume content is 50%,
When the ignition resistance and the flame retardancy are low, and when it is 72%, the mechanical properties after heat exposure are reduced.

As is clear from comparison between Example 8 and Comparative Example 1, magnesium oxide and [C] were used as the component [B].
By blending polyether sulfone as an ingredient,
It is possible to improve compressive strength after impact after heat exposure, ignition resistance and flame retardancy.

From the above results, it was found that Examples 1 to 8 and especially Examples 1, 2, 5, and 8 exhibited ignition resistance, flame retardancy, thermal stability, and the like as compared with Comparative Examples 1 to 7. It can be seen that the composite material has an excellent balance in mechanical properties after heat exposure.

[0073]

The fiber reinforced resin composite material produced by using the prepreg of the present invention has ignition resistance, and does not generate decomposition gases such as halogen gas and water vapor even when exposed to heat. No decrease in mechanical strength after exposure. The fiber reinforced resin composite material of the present invention has passed the test of the Ministry of Transportation, Iron Transportation No. 81, and can be used for railway vehicles.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // C08L 63:00

Claims (11)

[Claims] 1. A fiber-reinforced resin composite material comprising a fiber-reinforced material and a matrix resin, which does not substantially ignite in an ignition test according to the Ministry of Transport, Iron Transport No. 81, and has a temperature of 250 ° C.
A fiber reinforced resin composite having a compressive strength after impact of 15 kgf / mm ² or more and an interlayer shear strength of 7 kgf / mm ² or more after a heat exposure test left standing in an oven heated for 10 minutes. material. 2. The fiber-reinforced resin composite material according to claim 1, wherein substantially no decomposition gas is generated in the heat exposure test. 3. The compression strength after impact is 18 kgf / mm.
^2. The fiber-reinforced resin composite material according to claim 1, wherein the shear strength is ² kg or more and the shear strength between layers is 9 kgf / mm ² or more. 4. The fiber-reinforced resin composite material according to claim 1, wherein said fiber-reinforced material is carbon fiber. 5. The volume fraction of the reinforcing fibers is 55 to 65.
%. The fiber reinforced resin composite material according to claim 1. 6. The method according to claim 1, wherein the matrix resin comprises the following [A]:
2. The fiber-reinforced resin composite material according to claim 1, which contains [B] and [C] components and a curing agent for an epoxy resin as essential components: [A]: an epoxy resin containing no halogen; [B]: a metal oxide; C]: a thermoplastic resin having a glass transition temperature of 120 ° C. or higher. 7. The halogen-free epoxy resin is a halogen selected from glycidylamine type epoxy resin, novolak type epoxy resin, pisphenol A type epoxy resin, urethane modified bisphenol A type epoxy resin and alicyclic epoxy resin. 7. The fiber-reinforced resin composite material according to claim 6, which is a single epoxy resin or a mixture of two or more epoxy resins. 8. The thermoplastic resin is a polyamide-imide resin, a polyimide resin, a polyether sulfone resin,
The fiber-reinforced resin composite material according to claim 6, which is a thermoplastic resin selected from a polyetherimide resin alone or a mixture of two or more. 9. The fiber-reinforced resin composite material according to claim 6, wherein the metal oxide is a single material or a mixture of two materials selected from magnesium oxide and aluminum oxide. 10. The fiber-reinforced resin composite material according to claim 6, wherein the component weight ratio of the components [A], [B] and [C] is as follows: [A]: 100 parts by weight; ]: 10 to 30 parts by weight; [C]: 3 to 30 parts by weight. 11. A prepreg obtained by impregnating a fiber reinforcement with a matrix resin essentially containing the following components [A], [B], [C] and a curing agent for an epoxy resin: [A]: halogen [B]: metal oxide; [C]: a thermoplastic resin having a glass transition temperature of 120 ° C. or higher.