JP3137671B2 - Prepreg - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a prepreg for a fiber-reinforced composite material capable of imparting excellent toughness to a molded product obtained without impairing excellent thermal and mechanical properties of a matrix resin. The molded product obtained from the prepreg of the present invention is suitably used as an aircraft structural material or the like.

[0002]

2. Description of the Related Art Composite materials using high-strength and high-elasticity fibers such as carbon fibers as reinforcing materials have been widely used mainly in sports applications, taking advantage of their excellent specific strength and specific elasticity. . Thermosetting resins, such as epoxy resins, which are usually used as matrix resins, have various features but have the drawback of poor toughness, so that their use has been considerably restricted.
As a method of improving the disadvantages of this thermosetting resin, a method of adding a rubber component or a thermoplastic resin is generally used, but in order to obtain a sufficient toughness improving effect, it is necessary to add a large amount thereof, heat resistance, As a result, the solvent resistance and the like were reduced.

For example, as proposed in JP-A-63-162732, this can be achieved by adding a thermoplastic resin in a powder form to a matrix resin. When the prepreg is uniformly dispersed or dissolved in the prepreg, problems such as a decrease in processability during prepreg production and a decrease in tack level of the prepreg due to an increase in the viscosity of the entire system cannot be avoided. Further, for example, Japanese Patent Application Laid-Open No. 1-110537 discloses that localization of spherical fine particles from the surface of a prepreg to a depth within 30% of the thickness of the prepreg effectively improves the toughness of the composite material. Is disclosed but in this case,
Not only can a significant decrease in prepreg tack be avoided, but also new problems such as complicated processes and complicated quality control arise. Also, a method of inserting a kind of adhesive layer called an interleaf between layers has been proposed, but it has not been put to practical use because the fiber content cannot be increased.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to impart excellent toughness to a molded article obtained without impairing the excellent thermal and mechanical properties of a matrix resin, and furthermore, to provide a sufficient tack level, drapability, An object of the present invention is to provide a prepreg for a fiber-reinforced composite material, which is characterized by impregnation and excellent in handleability.

[0005]

(A) Modulus of elasticity 200 GP
(B) Fiber made of a thermoplastic resin having a G _IC of 1500 J / m ² or more (C) A prepreg for a fiber-reinforced composite material comprising a thermosetting resin-based matrix resin, wherein (A) , (B),
A prepreg characterized in that the ratio (weight ) of (C) is within the following range and (B) is present on the outer surface thereof. (A) / (C) = 60 / 40-75 / 25 (B) / (C) = 0.5 / 100-20 / 100

In the present invention, the elastic modulus of (A) is 200 GP.
The reinforcing fibers used in ordinary fiber-reinforced composite materials, such as carbon fibers, graphite fibers, and boron fibers, are used as they are as the reinforcing fibers having a tensile strength of 3500 MPa.
The above carbon fibers and graphite fibers are preferably used. Among them, high strength and high elongation carbon fibers and graphite fibers having a tensile strength of 4500 MPa or more and an elongation of 1.7% or more are most preferably used.

As the thermosetting resin-based matrix resin (C) in the present invention, an epoxy resin having an amine or phenol as a precursor or a polyfunctional maleimide resin is preferably used. Specifically, for example, epoxy resins such as tetraglycidyldiaminodiphenylmethane, triglycidyl-p-aminophenol, triglycidyl-m-aminophenol, various isomers of triglycidylaminocresol, bisphenol A epoxy resin, and bisphenol F type An epoxy resin, a bisphenol S type epoxy resin, a phenol novolak type epoxy resin, a cresol novolak type epoxy resin, and a mixture of two or more thereof are exemplified.

Examples of the polyfunctional maleimide-based resin include a resin composition containing 1,2-bismaleimide-dodecane, 1,6-bismaleimide- (2,2,4-trimethyl) hexane as a main component, and the like. However, it is of course not limited to these thermosetting resins, and thermoplastic resin elastomer components, inorganic fine particles, etc. within a range that does not adversely affect the moldability, tackiness, drape characteristics or handleability of the matrix resin of the prepreg. To obtain a matrix resin.

The ratio between (A) and (C) can be appropriately set according to the purpose, but the ratio by weight is (A).
The range of / (C) = 55/45 to 85/15 is appropriate, and the more preferable range is (A) / (C) = 60/40.
７５75/25.

[0010] As the fiber of the component (B), the thermoplastic resin as a raw material has a strain energy release coefficient G _IC of 1500.
J / m ² or more. G _IC is 1500J /
If it is less than m ² , the impact resistance of the composite material is not sufficiently improved, which is not preferable. The evaluation of G _IC was performed using a molded plate of a thermoplastic resin which is a fiber material.
This is performed by the compact tension method or the double torsion method specified in P.99 (type A4).

The form of the fibrous thermoplastic resin is preferably a monofilament or a bundle thereof, but is not necessarily limited thereto. The diameter of the fiber is preferably 100 μm or less, particularly preferably 50 μm or less. The ratio of the fibrous thermoplastic resin is 0.5 to 100 parts by weight of the epoxy matrix resin (C).
-20 parts by weight are preferred. If it is less than 0.5 part by weight, a sufficient toughness improving effect cannot be obtained. Conversely, even if a fibrous thermoplastic resin in an amount of 20 parts by weight or more is used, the effect of improving toughness not only reaches a peak, but also properties such as heat resistance and solvent resistance may be significantly reduced depending on the type of resin used. Not preferred.

It is important that the fibrous thermoplastic resin in the present invention exists near the outer surface of the prepreg. In the state of being completely buried in the center of the prepreg, a sufficient toughness improving effect cannot be obtained. However, it is not preferable that the fibrous thermoplastic resin is completely raised from the prepreg surface, and it is preferable that most of the fibrous thermoplastic resin is buried in the resin.

The direction of alignment is not particularly limited and may be at any angle with respect to the reinforcing fibers, but it is easiest in the process to align in the same direction as the reinforcing fibers. There is no particular limitation on the method for producing such a prepreg from the reinforcing fiber and the matrix resin and the fibrous thermoplastic resin, and the resin film and the reinforcing fiber impregnated with the fibrous thermoplastic resin in advance and impregnated are usually used. The prepreg can be produced by various methods, such as a method of forming a prepreg by the same method as that for producing a prepreg, and a method of aligning and integrating a fibrous thermoplastic resin with a prepreg produced by a usual method.

[0014]

The molded article obtained from the prepreg of the present invention is provided with excellent toughness without impairing the excellent thermal and mechanical properties of the matrix resin, and is less likely to propagate cracks generated. Since it has properties, it is suitably used as a structural material for aircraft and the like. Furthermore, the prepreg of the present invention has a sufficient tack level, drape property, impregnation property, and is excellent in handleability. It is expensive.

[0015]

The present invention will be described below in detail with reference to examples. Examples 1 and 2 A unidirectional prepreg was hot-melt-processed from the resin compositions shown in Table 1 and high-strength medium-elastic carbon fibers (manufactured by Mitsubishi Rayon, MR60P, tensile strength 5600 MPa, elastic modulus 310 GPa, elongation 1.9%). Manufactured by. The prepreg had a basis weight of 190 g / m ² and a resin content of 34 wt%.
A multifilament (90 ^d / 36f) of polyamideimide (Toron 4000T manufactured by Amoco) was added to this prepreg.
il, an elastic modulus of about 2 GPa) was wound on both sides of the prepreg at a pitch of 3 mm by a filament winding method to produce a prepreg of the present invention. A small piece of a predetermined size was cut out from this prepreg, and after lamination, a test piece for measuring compressive strength after impact was formed by autoclave molding (curing conditions:
180 ° C x 2 hr, test method SACMA SRM2-8
8, 270 lb-in). The polyamide imide is press-molded into a resin plate, and then subjected to ASTM E399.
The G _IC value measured by the compact tension method based on the above was 2350 J / m ² . Table 1 shows the measurement results.
Shown in Comparative Examples 1 and 2 In the same manner as in Examples 1 and 2, except that the polyamideimide filament was replaced with a polystyrene-based filament (95 ^d /
36fil, elastic modulus of about 4 GPa),
A prepreg was prepared, molded, and evaluated in the same manner as in Example 2. When G _IC was similarly evaluated, it was 1380 J / m ² .
The results are shown in Table 1 together with the results. As is clear from Table 1,
It can be seen that the molded article obtained from the prepreg of the present invention has a higher compressive strength after impact than the comparative example and is excellent in impact resistance.

[Table 1]

Continued on the front page (72) Inventor Masahiro Sugimori 4-1-1-60 Sunadabashi, Higashi-ku, Nagoya-shi, Aichi Prefecture Mitsubishi Rayon Co., Ltd. Product Development Research Center (72) Inventor Takeshi Kato 4-6-160 Sunadabashi, Higashi-ku, Nagoya-shi, Aichi Prefecture Mitsubishi Rayon Co., Ltd. Product Development Research Center (72) Inventor Takashi Murata 4-60, Sunadabashi, Higashi-ku, Nagoya City, Aichi Pref. No. 1-60 Investigator, Mitsubishi Rayon Co., Ltd. Product Development Research Laboratory Hiroki Amano (56) References Patent 3065683 (JP, B2) Patent 3065684 (JP, B2) Patent 3065686 (JP, B2) (58) Fields investigated (Int) .Cl. ⁷ , DB name) C08J 5/04-5/10 C08J 5/24

Claims (4)

(57) [Claims] (A) a reinforcing fiber having an elastic modulus of 200 GPa or more; (B) a fiber made of a thermoplastic resin having a G _IC of 1500 J / m ² or more; and (C) a fiber made of a thermosetting resin-based matrix resin. In the prepreg for a reinforced composite material, (A), (B),
(C) A prepreg characterized in that the ratio (weight ) of each component is within the following range and (B) is present on its outer surface. (A) / (C) = 60 / 40-75 / 25 (B) / (C) = 0.5 / 100-20 / 100 2. The prepreg according to claim 1, wherein (A) is a carbon fiber or a graphite fiber having a tensile strength of 3500 MPa or more. 3. The prepreg according to claim 1, wherein (B) is a mono- or multi-filament of a thermoplastic resin. 4. The prepreg according to claim 1, wherein the fibrous thermoplastic resin (B) is embedded in the outer surface thereof at a certain interval in one direction.