JP3218075B2 - Prepreg - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention 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 the excellent thermal and mechanical properties of a matrix resin.

[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 characteristics, but have the drawback of poor toughness, so that their use has been considerably restricted. As a method for 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 of the resin, heat resistance, As a result, the solvent resistance and the like were reduced.

For example, as disclosed in Japanese Patent Application Laid-Open No. 63-162732, this can be achieved by adding a thermoplastic resin in a powder form to a matrix resin. When the resin is uniformly dispersed or dissolved in the resin, problems such as a decrease in processability during prepreg production due to an increase in the viscosity of the entire system and a decrease in tack level of the prepreg are not avoided.

Further, for example, Japanese Patent Application Laid-Open No. 1-110537 discloses that the toughness of a composite material is effectively improved by localizing spherical fine particles from the surface of the prepreg to a depth within 30% of the thickness of the prepreg. Is disclosed. However, even in this case, not only can a significant decrease in prepreg tack be avoided, but also problems such as complicated processes and complicated quality control arise. A method of inserting a kind of adhesive layer called an interleaf between layers has also been proposed, but it has not been put to practical use because the fiber content cannot be increased.

[0005]

SUMMARY OF THE INVENTION To summarize the above-mentioned tendency of the prior art, in order to improve the toughness of the composite material, the direction of increasing the toughness of the matrix has been shifted from the direction of increasing the toughness of only the interlayers. . However, in the conventional technology, there are problems such as a decrease in prepreg tack, a complicated manufacturing process, and quality control, and the localization efficiency of the high-toughness resin is not so good because the localization efficiency is not so good. Met.

An object of the present invention is to provide a molded article obtained therefrom with excellent toughness without impairing the excellent thermal and mechanical properties of the matrix resin, and further have a sufficient tack level, drapability and impregnation. It is an object of the present invention to provide a prepreg for a fiber-reinforced composite material, which is characterized by its properties and whose production process and quality control are relatively easy.

[0007]

The present invention relates to a prepreg for a fiber-reinforced composite material comprising (A) a reinforcing fiber, (B) a resin tape and (C) a thermosetting matrix resin, wherein (B) is: When the width of the resin tape is w and the interval is p, the resin tape has a relationship of 2w <p, and the resin tape having a thickness of 50 μm or less is disposed on the surface of the prepreg. The prepreg is characterized in that a layer which is separated from each other is formed.

In the present invention, as the reinforcing fiber of (A), a reinforcing fiber used in ordinary fiber-reinforced composite materials, such as carbon fiber, graphite fiber and boron fiber, is used as it is, but carbon fiber having a tensile strength of 3500 MPa or more is used. And graphite fibers are preferably used. Among them, high-strength, 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, and triglycidyl-m
-Various isomers of aminophenol and triglycidylaminocresol, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, and a mixture of two or more thereof And the like.

Examples of the polyfunctional maleimide-based resin include a resin composition containing 1,2-bismaleimide-dodecane, 1,6-bismaleimide- (2,2,4-trimethyl) hexane or the like as a main component. Although not limited to these thermosetting resins, of course, thermoplastic resins, elastomer components, as long as they do not adversely affect the properties of prepreg such as moldability and tack, drapeability or the handling of matrix resins. It is also possible to add inorganic fine particles or the like to form a matrix resin.

The ratio of (A) to (C) of the prepreg of the present invention can be appropriately set according to the purpose, but (A) / (C) = 55/45 to 85 by weight ratio. / 15
Is more suitable, and the more preferable range is (A) /
(C) = 60/40 to 75/25.

The resin component of the resin tape (B) is preferably a high-toughness thermoplastic resin, but is not limited thereto. For example, a latex-based or other rubber-based material can achieve sufficiently high toughness. However, if a material having low heat resistance is used, the heat resistance of the composite material may be reduced. However, the better the adhesiveness to the matrix, the better, and if the adhesiveness is not sufficient, the effect of the resin tape disposed at all will not be exhibited.

The thickness of the resin tape is 1
It is preferably at most 00 μm, particularly preferably at most 50 μm. When the thickness is 100 μm or more, it considerably penetrates into the fiber layer of (A) and adversely affects the compressive strength and other mechanical strength. There is no particular limitation on the width of the tape. However, when the tape is arranged in one direction at a constant interval, 2w <p, more preferably 2.
It is better that the relationship of 5w <p holds. When 2w ≧ p, when this prepreg is laminated in the same direction, (B)
May be formed, which does not affect the toughness. However, depending on the properties of the resin tape, the interlayer shear strength, heat resistance, and the like may be significantly reduced.

In the present invention, since the resin tape (B) is arranged in a tape form, localization of the molded product between layers can be relatively easily achieved even after the prepreg is cured.
Its localization efficiency is extremely high, and toughness can be achieved with a very small amount. Therefore, the influence on the other mechanical strength, heat resistance and the like by the resin tape arrangement is extremely small. Further, by adjusting the interval between the resin tapes, it is possible to maintain an appropriate tack level. If it is desired to further improve the tack level, the matrix resin (C) may be applied to the surface of the resin tape before curing.

The arrangement direction of (B) is not particularly limited, and it may exist at any angle with respect to the reinforcing fiber (A). However, it is easiest in the process to arrange the reinforcing fiber in the same direction as the reinforcing fiber. There are no restrictions on the placement method,
(A) may be arranged after being arranged on (C) previously formed into a film, or (B) may be arranged on an intermediate material impregnated with (C) in (A). These means are appropriately determined based on simplicity in process, preparation of tack, and the like.

[0017]

The present invention will be described below with reference to examples. (Examples 1 and 2) Resin compositions shown in Table 1 and high-strength medium-elastic carbon fibers (trade name: MR60, manufactured by Mitsubishi Rayon Co., Ltd.)
P, tensile strength 5600 MPa, elastic modulus 310 GPs, elongation 1.9%) to produce a unidirectional prepreg by a hot melt method. The basis weight of CF of this prepreg is 190 g / m.
^{2. The} resin content was 34% by weight. A nylon 12 tape having a thickness of 10 μm and a width of 2 mm was arranged on the prepreg in the same direction as carbon fibers (hereinafter abbreviated as CF) at intervals of 5 mm to produce a prepreg. A small piece of a predetermined size was cut out from the prepreg, and after lamination, a test piece for measuring compressive strength after impact was formed by autoclave molding (curing condition: 180 ° C. × 2 hours).

Comparative Examples 1 and 2 Unidirectional prepregs were produced in the same manner as in Examples 1 and 2, except that a resin film having a resin content of 36% by weight was used.
Using this prepreg, evaluation was made in the same manner as in the example without attaching a nylon 12 tape. Table 1 summarizes the above results.

[0019]

[Table 1]

[0020]

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 furthermore, the cracks generated can be propagated. Since it has difficult properties, it is particularly suitably used as a structural material for aircraft and the like.
Further, the prepreg of the present invention has a relatively easy manufacturing process,
It can be manufactured under quality control, has a sufficient tack level, drapability, etc., and is excellent in handling, so it can be used for lamination with an auto lay-up device and has extremely high industrial utility. It is.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI C08L 101: 00 C08L 101: 00 (72) Inventor Masahiro Sugimori 4- 60 Sunadabashi, Higashi-ku, Nagoya City, Aichi Prefecture Mitsubishi Rayon Co., Ltd. Inside the Research Laboratory (72) Inventor Takeshi Kato 4-1-160 Sunadabashi, Higashi-ku, Nagoya City, Aichi Prefecture Mitsubishi Rayon Co., Ltd. No. Mitsubishi Rayon Co., Ltd. Product Development Laboratory (72) Inventor Katsuyuki 4-60 Sunadabashi, Higashi-ku, Nagoya City, Aichi Prefecture Mitsubishi Rayon Co., Ltd. Product Development Laboratory (56) References JP-A-1-135584 ( JP, A) JP-A-62-45629 (JP, A) JP-A-63-97635 (JP, A) JP-A-1-320146 (JP, A A) JP-A-2-235938 (JP, A) JP-A-4-189541 (JP, A) JP-A-1-90360 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) ) C08J 5/24 B29B 11/16 B29B 15/08 B32B 7/02

Claims (1)

(57) [Claims] 1. A prepreg for a fiber-reinforced composite material comprising (A) a reinforcing fiber, (B) a resin tape, and (C) a thermosetting matrix resin, wherein (B) is provided on the surface of the prepreg, When width is w and interval is p, 2w <
A prepreg, wherein a resin tape having a relationship of p and having a thickness of 50 μm or less is disposed, and a layer substantially separated from (C) is formed even after curing.