JP3154516B2 - Prepreg manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a prepreg for a fiber-reinforced composite material, which can impart excellent toughness to a molded product obtained without impairing excellent thermal and mechanical properties of a matrix resin.

[0002]

2. Description of the Related Art Composite materials using high-strength and high-elastic fibers such as carbon fibers as reinforcing materials have been widely used mainly for sports applications, taking advantage of their characteristics of excellent specific strength and specific elasticity. Thermosetting resins such as epoxy resins used as matrix resins have various characteristics, but have a drawback of poor toughness, so that their use has been considerably restricted.

[0003] As a method of improving the disadvantages of the thermosetting resin, a method of adding a rubber component or a thermoplastic resin is generally used. However, in order to obtain a sufficient toughness improving effect, it is necessary to add a large amount. Problems such as a decrease in processability during prepreg production, a decrease in tack level of the prepreg, and a decrease in heat resistance and solvent resistance are caused by an increase in the overall viscosity.

[0004] For example, JP-A-54-3879,
In JP-A-6-115216, JP-A-60-44334 and JP-A-1-110537, short fiber chops, chopped strands, milled fibers and spherical fine particles are localized between layers of the fiber reinforced sheet. In this case, problems such as a significant decrease in prepreg tack, a complicated process, and a complicated quality control arise.

A method of inserting a kind of impact absorbing layer called an interleaf between layers has also been proposed, for example, in US Pat. No. 3,472,730, JP-A-51-58.
No. 484, JP-A-60-63229, JP-A-60-2
No. 31738, however, all of them are not generally used because the thickness of the interlayer is increased, the fiber ratio is lowered, the heat resistance and the handling property are lowered.

On the other hand, the method for producing a prepreg using a fibrous thermoplastic resin according to the present invention has the following advantages: 1) it is possible to arrange a small amount on the surface; 2) it is easy to control the tack level of the prepreg; The prepreg manufacturing process can be used as it is. 4) Quality control is easy. 5) By using fibers obtained by compound spinning, physical properties of the prepreg interface can be controlled with great flexibility. are doing. These are effects that cannot be obtained by conventional techniques, and are effects that can be obtained only by using the prepreg manufacturing method using a fibrous thermoplastic resin in the present invention.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a prepreg for a fiber-reinforced composite material which can impart excellent toughness to a molded product obtained without impairing the excellent thermal and mechanical properties of the matrix resin. It is to provide a manufacturing method.

[0008]

The gist of the present invention is to provide: (A) a reinforcing fiber having an elastic modulus of 200 GPa or more; and (B) an elastic modulus of 1 obtained by composite spinning two or more resins.
When producing a prepreg for a fiber-reinforced composite material from a fibrous thermoplastic resin of 00 GPa or less (C) a thermosetting matrix resin, the thermosetting matrix resin of (C) is heated and melted and applied on release paper. The prepreg is produced by arranging the fibrous thermoplastic resin of (B) and impregnating it by heating.

The elastic modulus (A) of the present invention 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 in the present invention, any resin can be used as long as it is cured by external energy such as heat or light to at least partially form a three-dimensional cured product.

An epoxy resin is used as a thermosetting resin suitable for the present invention. As the epoxy matrix resin (C) in the present invention, an epoxy resin having an amine or phenol as a precursor is preferably used. Specifically, tetraglycidyldiaminodiphenylmethane,
Triglycidyl-p-aminophenol, triglycidyl-m-aminophenol, various isomers of triglycidylaminocresol, bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolak epoxy resin, cresol A novolak type epoxy resin, a mixture of two or more of these, and the like are exemplified, but not limited thereto.

The curing agent for the epoxy resin is not particularly limited, and a compound having a functional group capable of reacting with an epoxy group such as an amino group or an acid anhydride group can be appropriately used. Aromatic amines and dicyandiamide represented by a compound are preferably used. As the matrix resin in the present invention, a resin obtained by adding a thermoplastic resin or an oligomer thereof to the above epoxy resin can be used. As the thermoplastic resin component, those having a skeleton of a so-called engineering plastic such as polyimide, polyetherimide, polysulfone, polyethersulfone, and polyetheretherketone are preferable from the viewpoint of heat resistance, and a functional group capable of reacting with an epoxy resin. Is preferred at the molecular end or in the molecular chain.

The addition amount of the thermoplastic resin to the epoxy resin is preferably 30% by weight or less, more preferably 0 to 15% by weight. If the thermoplastic resin is used in an amount exceeding 30% by weight, the viscosity of the system becomes too high, which may cause impregnation failure during prepreg formation, as well as the tack property of the prepreg,
It also causes a decrease in drape characteristics. It is also possible to mix a small amount of inorganic fine particles such as fine silica powder or an elastomer in an epoxy resin.

The ratio of the reinforcing fiber (A) to the epoxy matrix resin (C) can be appropriately set according to the purpose, but the weight ratio (A) / (C) = 60/40. The range of -75/25 is particularly preferred.

As the fibrous thermoplastic resin having an elastic modulus of 100 GPa or less, obtained by compound spinning two or more resins of (B), polyaramid, polyester, polyacetal,
So-called engineering plastics such as polycarbonate, polyphenylene oxide, polyphenylene sulfide, polyarylate, polybenzimidazole, polyimide, polyetherimide, polysulfone, polyamide, polyamideimide, super engineering plastics, etc. It is preferable to use those that are formed into fibers by composite spinning that discharges from the same nozzle to give a core / sheath structure, side-by-side structure, sea-island structure, etc. Those having a functional group capable of reacting with an epoxy resin such as a phenolic hydroxyl group are particularly preferable.

Examples of such a thermoplastic resin include, in addition to polyamide, polyamideimide, etc., engineering plastics, super-engineering plastics, polyamides, polyamideimides and the like, in which functional groups are introduced into terminals or molecular chains by means such as copolymerization. Engineering plastics, polymer alloys with super engineering plastics and the like are preferably used.

The form of the fibrous thermoplastic resin obtained by composite spinning is preferably 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 (C)
To 100 parts by weight of the epoxy matrix resin.
5-20 parts by weight are preferred. If the amount is less than 0.5 part by weight, a sufficient toughness improving effect cannot be obtained. Conversely, if the amount exceeds 20 parts by weight, the effect of improving the toughness will not only plateau even if a fibrous thermoplastic resin is used, but depending on the type of resin used, properties such as heat resistance and solvent resistance may be significantly reduced in some cases. Yes,
Not desirable.

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. Further, it is more preferable that the fibrous thermoplastic resin is present in a state of being aligned in one direction at equal intervals. The alignment direction is not particularly limited, and may be present at any angle with respect to the reinforcing fiber, but it is easiest in the process to align in the same direction as the reinforcing fiber. The combination form of the composite spun fibrous thermoplastic resin is not limited at all, and may take any combination and form that seems to satisfy the required performance.

A method for producing a prepreg comprising a reinforcing fiber, a matrix resin, and a fibrous thermoplastic resin is, for example, applying a thermosetting resin melted by heating to a release paper to a predetermined thickness with a coater, and then coating the fiber with the fiber. A prepreg for composite material is prepared by arranging and fixing the position of the thermoplastic resin, producing a resin film for prepreg production, and using this to overlap and impregnate reinforcing fibers in a conventional prepreg production facility. Get. It should be noted that there is no problem in using this method as a method for producing a prepreg obtained by arranging a fibrous thermoplastic resin on only one side. The amount of fibrous thermoplastic resin to be used can be easily controlled by adjusting the number (fiber spacing) and denier, and since there is a spacing between fibers, the tack level of the matrix can be directly adjusted to the tack level of the prepreg. Because it is reflected, the tack level of the prepreg can be easily adjusted.

[0020]

The molded product from the prepreg obtained according to the present invention is provided with excellent toughness without impairing the excellent thermal and mechanical properties of the matrix resin, and propagates the generated cracks. Since it has characteristics that are difficult to make, it is suitably used as a structural material for aircraft and the like.

[0021]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

Examples 1 to 3 A matrix resin having a resin composition shown in Table 1 was coated on release paper, and a sheath component was coated with nylon 12 (elastic modulus of about 2 G).
Pa), the core component is polyester (elastic modulus about 15 GPa)
A resin film was prepared in which core-sheath type composite yarns were arranged at a pitch of 3 mm. The composite yarn was a 90 denier 36 filament multifilament of nylon 12 / polyester (8/2 weight ratio).

The prepared resin film and high-strength medium elastic carbon fiber (Mitsubishi Rayon, MR60P, tensile strength 5600)
(MPa, elastic modulus 310 GPa, elongation 1.9%), a unidirectional prepreg was prepared by a hot melt method. The prepreg has a basis weight of 190 g / m ² and a resin content of 34% by weight.
Met. 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).

Using this test piece, SACMA (Sup
pliers of Advanced Compos
item Materials Associate
n) Recommended Method SRM2
The compressive strength after 270 lb-in impact was measured according to -88, and the results shown in Table 1 were obtained.

Example 4 A prepreg was produced in the same manner as in Example 1 except that a multifilament having a nylon / polyester spinning form of 1/1 side-by-side was used, and the compressive strength after impact was measured. The obtained compressive strength after impact is 327MP.
a.

Example 5 A nylon 12 / polyester (8/2) was prepared in the same manner as in Example 1 except that the composite yarn was such that polyester islands were scattered in the nylon sea when the cross section of the yarn was observed.
A prepreg was manufactured using multifilaments of 90 denier and 36 filaments (weight ratio), and the compressive strength after impact was measured. The resulting compressive strength after impact is 320M
Pa.

Example 6 In the same manner as in Example 1, except that the sheath of the fiber component was a prepreg using a multifilament consisting of polybutylene terephthalate (elasticity: about 2.5 GPa) and the core of polypropylene (elasticity: about 1 GPa). Was manufactured, and the compressive strength after impact was measured. However, the composite yarn was polybutylene terephthalate / polypropylene (5/5 weight ratio). The obtained compressive strength after impact was 313 MPa.

Comparative Examples 1 to 3 Unidirectional prepregs were produced in the same manner as in Examples 1 to 3, except that a resin film in which the resin content of the prepreg was 36% by weight was used. Using this prepreg, evaluation was made in the same manner as in Example 1 without attaching fibers. The results are shown in Table 1.

[0029]

[Table 1] YH434L: Tetraglycidylamine type epoxy resin (manufactured by Toho Kasei Co., Ltd.) ELM-100: Triglycidylamine type epoxy resin (manufactured by Sumitomo Chemical Co., Ltd.) Epicoat 828: Bisphenol A type epoxy resin (manufactured by Yuka Shell Co., Ltd.)

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Kato 4-160 Sunadabashi, Higashi-ku, Nagoya City, Aichi Prefecture Mitsubishi Rayon Co., Ltd. Product Development Research Center (72) Inventor Kazuya Goto 4-chome Sunadabashi, Higashi-ku, Nagoya City, Aichi Prefecture No. 1-60 Mitsubishi Rayon Co., Ltd. Product Development Research Center (72) Inventor Shigenji Hayashi 4-160 Sunadabashi, Higashi-ku, Nagoya City, Aichi Prefecture Mitsubishi Rayon Co., Ltd. Product Development Research Laboratory (72) Inventor Takashi Akita Nagoya Aichi Prefecture Hiroki Amano, Examiner, 4-160 Sunadabashi, Higashi-ku, Mitsubishi Mitsubishi Rayon Co., Ltd. (56) References Patent 3065685 (JP, B2) Patent 3065687 (JP, B2) Patent 3065689 (JP, B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08J 5/04-5/10 C08J 5/24 B29B 11/16 B29B 15/10

Claims (2)

(57) [Claims] (A) a reinforcing fiber having an elastic modulus of 200 GPa or more; (B) an elastic modulus obtained by compound spinning two or more resins.
When producing a prepreg for a fiber-reinforced composite material from a fibrous thermoplastic resin of 00 GPa or less (C) a thermosetting matrix resin,
After the thermosetting matrix resin of (C) is heated and melted and applied on release paper, the fibrous thermoplastic resin of (B) is arranged and fixed, and then the reinforcing fibers of (A) are overlapped and impregnated. A prepreg manufacturing method characterized by the following: 2. The method according to claim 1, wherein the fibrous thermoplastic resin is localized on the surface of the prepreg.