JPH02151623A - Epoxy resin composition and prepreg - Google Patents

Abstract

PURPOSE:To make the title compsn. curable at a relatively low temp. and to improve storage stability by compounding an epoxy resin, a specified thermoplastic resin, dicyandiamide, a urea compd. and diaminodiphenyl sulfone. CONSTITUTION:The title compsn. is obtd. by compounding 100 pts.wt. (hereinbelow described merely as pts.) epoxy resin (A) contg. 50 pts. or more glydcidylamine epoxy resin, 10-20 pts. thermoplastic resin (B) selected from polyamide, PS, polyether sulfone and polyetherimide with a particle diameter of pref 400mum or smaller and a glass transition temp. of 200 deg.C or higher, 2-10 pts. fine powder of dicyandiamide (C) with a particle diameter of pref. 10mum or smaller, 2-5 pts. urea compd. (D) of the formula (wherein X and Y are each H, Cl or OCH3) and 15-30 pts. diaminodiphenyl sulfone (E). A prepreg is obtd. by impregnating carbon fibers with this compsn.

Description

Detailed Description of the Invention (Technical Field) The present invention provides an epoxy resin composition that can be cured at a relatively low temperature and has excellent storage stability, and a method for applying the resin composition to charcoal W: fibers. It relates to impregnated prepreg. The prepreg of the present invention, in which carbon fibers are impregnated with the resin composition of the present invention, has excellent drape properties and tack properties, and has good handleability. In addition, molded products obtained from the prepreg have excellent heat resistance and mechanical properties, so
The obtained carbon fiber reinforced resin composite material (CFRP composite) reflects the high strength and high elastic modulus of carbon mM, giving a composite with particularly excellent bending strength.
Moreover, it has excellent fracture toughness (impact properties).

[Prior art]

M-fiber reinforced resin composite material has high specific strength and specific modulus, and is used as a lightweight, high-strength material by compounding it with reinforced mta of long fibers and short fibers and various matrix resins, and is used in aerospace, aerospace, etc. It is widely used as a high-performance product in transportation equipment such as ships and vehicles, functional components in cutting-edge industrial fields such as automation equipment, and sports and leisure goods such as fishing rods and golf shafts. Conventionally, unsaturated polyester resin, unsaturated polyester resin,
Thermosetting resins such as epoxy resins and polyimide resins have been used.

When manufacturing a composite, prepreg, which is carbon fiber impregnated with the above-mentioned thermosetting resin, is made as an intermediate product.
A common method is to stack these materials at predetermined dimensions and angles and harden them by heating and pressing to form a molded product.

In the manufacture of composite materials for sports and leisure such as fishing rods and golf shafts, they are often made into composites through the form of prepreg, and the matrix resin is a relatively low temperature of 120 to 130 °C even among extremely thermosetting resins. Epoxy resins are often used because they can be molded at high temperatures and have good mechanical properties.

[Problems with conventional technology]

Epoxy resin compositions that can be molded at relatively low temperatures are mainly compositions that combine an epoxy resin and a dicyandiamide/urea compound curing accelerator, as disclosed in Japanese Patent Publication No. 58-5925. . In this case, the type of main component epoxy resin is a combination of phenol novolac type and bisphenol △ type epoxy resin, so there is a problem that the crosslinking density of the cured resin is low and the elastic modulus is slightly inferior.
In particular, when used as a matrix resin for a composite using high modulus carbon fibers, the apparent 0° bending strength of the flat plate was low, and the performance as a composite could not be fully brought out.

JP-A No. 60-58422 discloses a combination of tetraglycidyldiaminodiphenylmethane/novolac type epoxy resin/dicyandiamide/urea compound curing accelerator, which has high heat resistance, fast curing properties at low temperatures, and storage stability. It offers a good composition. In this case, it is stated that a small amount of diaminodiphenylsulfone may be prepolymerized in order to adjust the viscosity of the resin composition, but this does not sufficiently improve the mechanical properties of the molded product. . Furthermore, in this case, since the rigidity of the matrix resin is high, the mechanical properties such as the 0° bending strength of a flat plate are excellent, but since the resin is hard and brittle, it has the disadvantage that it is inferior to the impact properties of a hunposite.

Further, JP-A-62-129308 discloses a combination of epoxy resin/polyallyl ether sulfone/dicyandiamide/urea compound type curing accelerator. In this case as well, by mixing polyallylether sulfone into the epoxy resin, the viscosity of the resin composition is adjusted, flow control is performed during molding, and mechanical properties are not deteriorated (in order to improve moldability). This is what I did.

However, in this case, the purpose of increasing the crosslinking density of the cured resin is not to improve the rigidity of the matrix resin and improve the mechanical properties of the composite. The composition was not suitable for fully bringing out the fiber performance.

(Objective of the Invention) The present invention overcomes the above-mentioned drawbacks, can be cured at a relatively low temperature, has excellent storage stability, and reflects the high strength and high modulus of the carbon fiber used. In particular, it is an object of the present invention to provide a resin composition and a prepreg that provide a composite having both bending strength and impact properties.

(Structure and effects of the invention) The present invention is as follows.

(1) Contains the following [A] to [E], has a melt viscosity of 100 to 10,000 voices at 80°C, and 90 to 1
An epoxy resin composition that can be cured at 30°C.

(A) 100 parts by weight of an epoxy resin containing at least 50 parts or more of glycidylamine type epoxy resin (B) At least one selected from polyamide, polysulfone, polyether sulfone, and polyetherimide
10 to 30 parts by weight of thermoplastic resin (C) 2 to 10 parts by weight of dicyandiamide (D) 2 to 5 parts by weight of a urea compound represented by the following formula (where X and Y are the same or different and H, CI, OCH*
represents. ) (E) 15 to 30 parts by weight of diaminodiphenylsulfone (2) A prepreg obtained by impregnating carbon fiber with the epoxy resin composition according to claim (1).

The epoxy resin composition of the present invention is manufactured by uniformly dissolving component (B) in component (A) in advance without using a solvent, and then mixing it with components (C), (D), and (E). In this case, it is possible to provide a relatively uniform hot melt matrix resin composition having a particularly high blending ratio of the thermoplastic resin component. When adding a thermoplastic resin component to a matrix resin, the viscosity of the entire resin composition tends to increase, so the epoxy resin (A) component used is 50 parts by weight or more of a resin with a viscosity of 100 poise or less at 50°C. It is preferable.

The prepreg obtained from the composition of the present invention can be prepared without impairing the mechanical properties and heat resistance of the epoxy resin component.
Composites can be provided with improved toughness and associated impact properties.

In order to exhibit excellent mechanical properties as a composite, the carbon Ill used in the present invention has a tensile strength of 300 kgf/n+*" or more and an elastic modulus of 20 T on/
Carbon fibers of s+n' or more are desirable. In addition, the resin composition of the present invention reflects the high strength and high elastic modulus of carbon fiber, and has a tensile elastic modulus of 40 to 60 T on/
Even for a++n' high modulus carbon fibers, it provides a bending modulus that maintains a contribution rate of 80% or more of the calculated modulus calculated by Keiki assuming additivity, making it suitable for high strength and high modulus carbon fibers. It can be said that it is a resin composition.

Among the matrix resin compositions used in the present invention, the glycidylamine type epoxy resins as component (A) include Araldite MY120 Me'irM-100, E
Examples include LM-434 (manufactured by Sumitomo Chemical Co., Ltd.) and Epicote 604 (manufactured by Shell Chemical Co., Ltd.).

(A) Among the epoxy resins for Jilt, it is necessary to use 50 parts by weight or more of the glycidylamine type epoxy resin. If the crosslinking density is less than 50, the crosslinking density of the cured resin product will not increase as expected, the glass transition temperature will be low, and both heat resistance and mechanical strength will decrease.

The epoxy resins of component (A) include Epicoat 815, Epicoat 828.1 Bikoat 834, and Epicoat 1 as bisphenol A epoxy resins.
001, Epicote 1002 (manufactured by Shell Chemical Co., Ltd.),
As phenol/novolac type epoxy resins, Epicote 152, Epicote 154 (manufactured by Shell Chemical Co., Ltd.), Dowepoxy DEN 431, DEN 43
8, DEN 439 (manufactured by Dow Chemical Company), EPPN
201 (manufactured by Nippon Kayaku Co., Ltd.), Ebicuron N 74
Araldite E CN 1235, E as a cresol novolak type epoxy resin such as 0 (manufactured by DrC), etc.
CN 1273, E CN 1280 (manufactured by Ciba Geigy), EOCN 102, E OCN
103, εOCN 104 (manufactured by Nippon Kayaku Co., Ltd.), etc. can also be used.

In addition, as an alicyclic epoxy resin, Araldite CY-
179, CY-178, CY-182, C'y'-18
3 (manufactured by Ciba Geigy), etc. can also be used.

7 decal resin EPLI-6, EPU-10, EPU-1 which is urethane modified bisphenol A type epoxy resin
5 (manufactured by Asahi Denka Co., Ltd.) in an amount of about 10 parts by weight, it is possible to provide a resin composition with excellent flexibility and good adhesion to reinforcing fibers.

In order to adjust the viscosity of the entire resin composition, an epoxy resin-based reactive diluent such as polypropylene glycol diglycidyl ether, diglycidyl ether, butanediol glycidyl is added in an amount that does not reduce the heat resistance of the cured resin product. Ether, 2-glycidyl phenyl glycidyl ether, resorcinol diglycidyl ether, alkylphenol glycidyl ether, phenyl glycidyl ether, butyl glycidyl ether, cresol glycidyl ether, styrene oxide, etc. can also be used in combination. In this case, the amount of these ingredients is 1
It is preferably 0 parts by weight or less.

The thermoplastic resin of component (B) includes Elvamide (manufactured by DuPont), which is a thermoplastic polyamide with a melting point of 150"C or higher as a polyamide resin, and Needle Polysulfone P-1, which is a polysulfone resin with a glass transition temperature of 190"C or higher.
700 (manufactured by Union Carbide), Goctrex PE5 (I (manufactured by 1), a polyether sulfone resin with a glass transition temperature of 220°C or higher, glass transition temperature 210
ULTEM (
(manufactured by GE), but from the viewpoint of resin preparation, these thermoplastic resins have a particle size of 400 μm or less, especially 100 μm.
It is preferable that the powder be in the form of a powder having a particle diameter of m or less.

Also, if you consider heat resistance, the glass transition temperature is 200℃.
It is preferable to use the above thermoplastic resins. In particular, the polyether sulfone resin Pictrex PE5 (
manufactured by ICI) and ULTE, a polyetherimide resin.
M (GE Co., Ltd. oxide) Excellent mechanical properties, improved toughness and associated impact properties without sacrificing heat resistance,
As a result, it is possible to obtain moldings that give good composite performance.

These thermoplastic resins need to be used in an amount of 10 to 30 parts by weight based on 100 parts by weight of the epoxy resin. When the amount is less than 10 parts by weight, mechanical strength is good, but the resin tends to be brittle and have poor impact properties. If the amount exceeds 30 parts by weight, the viscosity of the entire resin composition will increase, which may impede workability during prepreg production, and the handleability of the prepreg itself, such as tackiness and drapability, will deteriorate, resulting in poor composite performance. This is not desirable as it has a negative effect on

A commercially available dicyandiamide as component (C) is used, but in consideration of reactivity and moldability, a finely powdered dicyandiamide with a particle size of 10 μm or less is preferable.

By using the dicyandiamide (C) component and the urea compound (D) component together, the
It is possible to provide a resin composition and prepreg that can be completely cured in a curing time of 0 to 120 minutes and have a pot life of 1 month or more at room temperature.

The amount of component (C) used is 2 to 10 parts by weight.

If it is less than 2 parts by weight, it will not function as a curing agent, and if it is more than 10 parts by weight, substances that do not participate in the reaction will remain in the resin composition, adversely affecting the moldability and mechanical properties of the composite. affect

The urea compound of component (D) requires 2 to 5 helical parts. If it is less than 2 parts by weight, it will not function as a curing accelerator and will be too reactive (more than 5 parts by weight), and the reaction will proceed at a relatively low temperature, so the temperature during resin mixing etc. The control conditions become stricter, which impedes workability and shortens the usable life of the prepreg itself.

The blending ratio of component (C) and component (D) can be arbitrarily determined in consideration of the intended use, molding method, molding conditions, etc.

As the component (E), diaminodiphenylsulfone, a commercially available one may be used. The blending amount is 15 to 30 parts by weight, but in the resin system of the present invention, component (C) and (
Even though it is possible to completely cure the system by using component D), the purpose of using component (E) is to add component (E) to this system, knowing that the amine component will be in excess. By adding it, the mechanical strength of the composite can be further improved. In particular, when high modulus carbon fibers are used, the high modulus of elasticity of carbon IIH can be efficiently reflected in the composite.

That is, by the combination of component (C)/component [D]/component (E), complete curing is possible at a temperature of 90 to 130°C in a curing time of 30 to 120 minutes, and the carbon fiber used has high strength. We were able to provide a composite that reflected the high modulus of elasticity and had particularly excellent bending strength. In this case, the glycidylamine type epoxy resin used in an amount of 50 parts by weight or more as component [A) is also important when used in combination with component (E), and further improves the elastic modulus of the cured resin and improves the mechanical properties of the composite. It has the role of increasing In particular, the effect is more pronounced when a preliminary reaction, which will be described later, is carried out.

The blending ratio of component (E) is 15 to 30 parts by weight, but if it is less than 15 parts by weight, the effect of the blending will be insufficient, and if it is more than 30 parts by weight, the moisture absorption properties of the molded product will deteriorate. This is not desirable because it causes

A small amount of (E) from 15 to 30 parts by weight of component (E)
The component may be extracted and preliminarily reacted with a portion or portion of component (A). In this case, the preliminary reaction conditions are 60 to 120 minutes at a temperature of 120 to 140 °C (
It is preferable that component (E) has 15 or less weights compared to 10 weights of component A).

In addition, as a curing accelerator for epoxy resin, a small amount of
BF1 heptanoethylamine, BF3 benzylamine, 2-
Ethyl-4methylimidazole, 2-ethylimidazole, 2,4-dimethylimidazole, 2-phenylimidazole, Go(II) acetylacetonate, etc. can also be used in combination.

In the present invention, component (B) does not mix uniformly with the epoxy resin and may destroy a proper phase separation structure, but it is preferable because it tends to improve the impact properties of the composite.

Among the prepreg resin compositions used in the present invention,
In addition to the above-mentioned essential components, a small amount of rubber components (e.g. carboxyl-terminated butadiene-acrylonitrile copolymer, nitrile rubber, epoxy-modified polybutadiene rubber, etc.) that does not reduce heat resistance, and prepreg handling properties. Filler (for example, silica powder) to the extent that it does not deteriorate the
Flame retardants such as antimony trioxide or coloring agents may be added.

The prepreg resin composition of the present invention can be prepared, for example, by the following method.

That is, each component is supplied to a mixing device and heated and kneaded, preferably under an inert gas atmosphere. The heating temperature at this time is lower than the humidity at which the epoxy resin starts curing. Alternatively, after dissolving component (8) in component (A), components (C), (D), and (E) may be added and kneaded. Component (B) is dissolved in component (A) usually at a temperature of 20 to 200°C, particularly preferably at a temperature of 100 to 150°C. In this case, from the viewpoint of resin preparation, component (B) is preferably in the form of a fine powder of 100 μm or less in order to speed up dissolution.

By this operation, it is possible to prepare an epoxy resin composition containing as much as 30 parts by weight of a thermoplastic resin.
The viscosity of the composition becomes very high, making crosstalk difficult.
Undesirable.

The mechanical properties of the resulting composite will also be adversely affected.

When carbon fibers are impregnated with the resin composition for prepreg of the present invention to form a prepreg, the so-called hot melt method, which is already known, can be used.

The resin composition of the present invention has an epoxy resin as a component (A) and a component (B).
), it is possible to manufacture prepregs using the hot melt method because the thermoplastic resin of the component is dissolved, and there is no influence of residual solvent, and the epoxy resin has excellent heat resistance and the thermoplastic resin has excellent toughness and impact strength. This provides an excellent prepreg resin composition that has the following properties.

Further, due to solubility problems, component (B) may precipitate as a phase of 50 μm or less, but even in this case, there is no problem in producing prepreg by the hot melt method.

The unidirectional or woven prepreg obtained by such an operation is of good quality.

[Examples and comparative examples]

Examples 1 to 6 and Comparative Examples 1 to 7 The main components (A) and (B) were weighed and placed in a beaker so that the types and blending ratios were as shown in Table 1. This was heated at 130° C. for 1 hour with stirring to obtain a uniform resin mixture. Next, in roll mill mixing, the first
Add ingredients (C), (D), and (E) in the proportions shown in the table, and
Mixing was carried out at 0°C for 30 minutes to obtain a resin composition for prepreg, and the gel time of the resin composition at 130°C and the viscosity at 80°C were measured.

A resin film was prepared from this composition using a film coater, and carbon fiber (CF) Besphite l-IMs-46X (manufactured by Toho Rayon Co., Ltd., tensile strength 380 kg f/mm', elastic modulus 46T1) was coated on the resin film.
01') were arranged, heated and impregnated, and the CF area weight was 140o.
/II', a unidirectional bobble leg with a resin content of 34% by weight was obtained. The pot life of the prepreg was defined as the time until the prepreg loses its drapability after being left in a temperature-controlled room at 23°C.

From this prepreg, a predetermined number of sheets of prepreg were cut and laminated, and a test piece was cut out from a molded plate that was heat-cured by autoclave molding at a heating rate of 2°C/min and 130°C for 90 minutes, and the glass transition Moisture content, O' layer tm shear strength, O° bending strength, and ±45° Charpy impact value were measured.

Furthermore, the contribution ratio (Er /f-cxloo) of the actually measured bending elastic modulus Er to the bending elastic modulus EC of the composite calculated from the elastic modulus of carbon fibers assuming additivity was calculated. The results are shown in Table 1.

In addition, as comparative examples, systems containing less than 50 parts by weight of glycidylamine type epoxy resin in the component (A), systems with a small amount of the (B) component, systems with a large amount of the (B) component, systems with a small amount of the (C) component, For systems with a small amount of component (D) and systems without component (E), prepregs were prepared and molded under the same conditions as in the example,
Physical properties were measured. The results obtained are shown in Table 2.

From the above results, it has become clear that Examples 1 to 6 can be cured at a relatively low temperature and have excellent composite performance compared to Comparative Examples.

Example 7 Components (A) and (B), which are the main components, were weighed and placed in a beaker so that the types and blending ratios were as shown in Table 1. This was heated at 130° C. for 1 hour with stirring to obtain a uniform resin mixture. Next, add 10 parts by weight of component (E),
A reaction with 120 molecules was carried out at 130°C. Next, in roll mill mixing, (C) (D) with the blending ratio shown in Table 1.
10 parts by weight of components ) and I'E) were added and mixed at 80°C for 30 minutes to obtain a prepreg resin composition.The gel time of the resin composition at 130°C and the viscosity at 80°C were measured.

Claims (2)

[Claims] (1) Contains the following [A] to [E], has a melt viscosity of 100 to 10,000 poise at 80°C, and 90 to 1
An epoxy resin composition that can be cured at 30°C. (A) 100 parts by weight of an epoxy resin containing at least 50 parts by weight of a glycidylamine type epoxy resin (B) 10 parts by weight of at least one thermoplastic resin selected from polyamide, polysulfone, polyethersulfone, and polyetherimide ~30 parts by weight (C) 2 to 10 parts by weight of dicyandiamide (D) 2 to 5 parts by weight of a urea compound represented by the formula below ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ (However, X and Y may be the same or different and H ,Cl,OCH_
Represents 3. ) (E) 15 to 30 parts by weight of diaminodiphenylsulfone (2) A prepreg obtained by impregnating carbon fiber with the epoxy resin composition according to claim (1).