JPH04292913A - Manufacture of prepreg - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 prepregs for fiber-reinforced composite materials, which can impart excellent toughness to molded products obtained from the matrix resin without impairing the excellent thermal and mechanical properties of the matrix resin.

0002

BACKGROUND OF THE INVENTION Composite materials using high-strength, high-modulus 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 commonly used as matrix resins, have various features but have the drawback of poor toughness, which has considerably limited their use.

[0003] A common method for improving the drawbacks of thermosetting resins is to add rubber components or thermoplastic resins, but in order to achieve a sufficient effect of improving toughness, it is necessary to add a large amount; This causes problems such as a decrease in process passability during prepreg production due to an increase in overall viscosity, a decrease in the tack level of the prepreg, and a decrease in heat resistance and solvent resistance.

For example, JP-A-54-3879, JP-A-5
6-115216, JP-A-60-44334, and JP-A-1-110537, chopped short fibers, chopped strands, milled fibers, and spherical fine particles are localized between the layers of the fiber-reinforced sheet. In this case, new problems arise such as a significant decrease in prepreg tack, complication of the process, and complication of quality control.

[0005] A method of inserting a type of shock absorbing layer called an interleaf between layers has also been proposed, for example, in US Pat.
No. 484, JP-A-60-63229, JP-A-60-2
No. 31738, etc., but none of them have come into general use because the interlayers become thicker, the fiber ratio becomes lower, and the heat resistance and handleability deteriorate.

On the other hand, the method for producing prepreg using a fibrous thermoplastic resin according to the present invention 1) allows a small amount to be placed on the surface, 2) makes it easy to control the tack level of the prepreg, and 3) makes it easier to control the tack level of the prepreg than the conventional prepreg. It has various features such as the manufacturing process can be used as is 4) quality control is easy. These are effects that cannot be obtained with conventional techniques, and are effects that can only be obtained by using the prepreg manufacturing method using a fibrous thermoplastic resin according to the present invention.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to develop a prepreg for fiber-reinforced composite materials that can impart excellent toughness to molded products obtained from the matrix resin without impairing the excellent thermal and mechanical properties of the matrix resin. The purpose is to provide a manufacturing method.

[0008]

[Means for solving the problems] The gist of the present invention is (A)
Reinforcing fiber (B) with an elastic modulus of 200 GPa or more; fibrous thermoplastic resin (B) with an elastic modulus of 100 GPa or less (
C) When producing a prepreg for fiber-reinforced composite materials from a thermosetting matrix resin, (B
) to produce a prepreg by arranging the fibrous thermoplastic resin and impregnating it with heat.

[0009] The elastic modulus of (A) in the present invention is 200GP
As reinforcing fibers of a or higher, reinforcing fibers used in ordinary fiber-reinforced composite materials such as carbon fibers, graphite fibers, and boron fibers can be used as they are, but carbon fibers and graphite fibers with a tensile strength of 3500 MPa or more are preferably used. . Among them, carbon fibers and graphite fibers with high strength and high elongation, such as 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.

Epoxy resin is used as a thermosetting resin suitable for the present invention. As the epoxy matrix resin (C) in the present invention, epoxy resins using amines or phenols as precursors are preferably used. Specifically, tetraglycidyldiaminodiphenylmethane, triglycidyl-p-aminophenol, triglycidyl-m-aminophenol, various isomers of triglycidyl aminocresol, bisphenol A type epoxy resin,
Bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin,
Examples include, but are not limited to, cresol novolac type epoxy resins and mixtures of two or more thereof.

There are no particular restrictions on the curing agent for epoxy resins, and any compound having a functional group that can react with an epoxy group, such as an amino group or an acid anhydride group, can be used as appropriate. Aromatic amines such as dicyandiamide and dicyandiamide are preferably used. As the matrix resin in the present invention, it is also possible to use the above-mentioned epoxy resin to which a thermoplastic resin or an oligomer thereof is added. As the thermoplastic resin component, those having a so-called engineering plastic skeleton such as polyimide, polyetherimide, polysulfone, polyethersulfone, and polyetheretherketone are preferable from the viewpoint of heat resistance, and those having a functional group that can react with the epoxy resin are preferable. It is preferable to have it at the end of the molecule or in the molecular chain.

The amount of thermoplastic resin added to the epoxy resin is preferably 30% by weight or less, more preferably 0 to 15% by weight. If more than 30% by weight of thermoplastic resin is used, the viscosity of the system becomes too high, which not only causes poor impregnation during prepreg formation, but also reduces the tack properties of the prepreg.
It also causes deterioration of drape characteristics. It is also possible to mix a small amount of inorganic particles such as finely powdered silica or an elastomer with the epoxy resin.

[0013] The ratio of the reinforcing fiber (A) to the epoxy matrix resin (C) can be set as appropriate depending on the purpose, but the weight ratio is (A)/(C) = 60/40. A range of 75/25 is particularly preferred.

The fibrous thermoplastic resin (B) having an elastic modulus of 100 GPa or less includes polyaramid, polyester, polyacetal, polycarbonate, polyphenylene oxide, polyphenylene sulfide, polyarylate, polybenzimidazole, polyimide, polyetherimide, polysulfone, and polyamide. So-called engineering plastics such as polyamide-imide, and super engineering plastics shaped into fibers are preferably used; Particularly preferred are those having the following.

Examples of such thermoplastic resins include polyamides, polyamideimides, etc., as well as engineering plastics, super engineering plastics, polyamides, polyamideimides, etc. in which functional groups are introduced at the ends or into molecular chains by means such as copolymerization. engineering plastics, polymer alloys with super engineering plastics, etc. are suitably used.

The form of the fibrous thermoplastic resin is preferably monofilaments or bundles thereof, but is not necessarily limited thereto. The fiber diameter is preferably 100μ or less, particularly preferably 50μ or less.

The ratio of fibrous thermoplastic resin is (C)
0.0% per 100 parts by weight of epoxy matrix resin.
5 to 20 parts by weight is preferred. If the amount is less than 0.5 parts by weight, a sufficient toughness improvement effect cannot be obtained. On the other hand, if the amount exceeds 20 parts by weight, not only will the toughness improvement effect reach a 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 drop significantly. can be,
Undesirable.

It is important in the present invention that the fibrous thermoplastic resin be present near the outer surface of the prepreg. If it is completely buried in the center of the prepreg, a sufficient toughness improvement effect cannot be obtained. However, it is still undesirable for the fibrous thermoplastic resin to completely protrude from the surface of the prepreg, and it is preferable that most of the fibrous thermoplastic resin be buried in the resin. Further, it is more preferable that the fibrous thermoplastic resin be arranged in one direction at equal intervals. There is no particular restriction on the direction in which the reinforcing fibers are aligned, and they may exist at any angle with respect to the reinforcing fibers, but it is easiest in terms of the process to align them in the same direction as the reinforcing fibers.

[0019] As a method for manufacturing a prepreg made of reinforcing fibers, matrix resin, and fibrous thermoplastic resin, a process as shown in FIG. 1 is used, for example. A prepreg 1 made of reinforcing fibers and a matrix resin is guided to an impregnation table 6, and the fibrous thermoplastic resin 2 is arranged on the prepreg 1 through an alignment comb 3, and heated and pressed by a heating pressure roller 4.
The prepreg is impregnated and fixed in the prepreg to obtain the desired composite material prepreg 5. At this time, when arranging the fibrous thermoplastic resin on the prepreg on both sides of the prepreg, there are two ways to arrange the fibrous thermoplastic resin on both sides of the prepreg: one is to arrange the prepreg on one side through the same process again and arrange it on the opposite side, and the other is to arrange the fibrous thermoplastic resin on both sides of the prepreg at the same time as shown in Figure 2. There are cases in which fibrous thermoplastic resins are arranged from the above, but in either case there is no difference in the performance of the resulting prepreg.

[0020]

[Effects of the Invention] The molded product made from the prepreg obtained in the present invention is endowed with excellent toughness without impairing the excellent thermal properties and mechanical properties of the matrix resin, and is free from cracks that occur. Since it has the property of being difficult to propagate, it is suitably used as a structural material for aircraft, etc.

[0021]

[Examples] The present invention will be explained in detail with reference to Examples below. Examples 1 to 3 Unidirectional prepregs made of the resin compositions shown in Table 1 and high-strength and medium-elasticity carbon fibers (manufactured by Mitsubishi Rayon, MR60P, tensile strength 5600 MPa, elastic modulus 300 GPa) were produced by a hot melt method, and As shown in the figure, a multifilament of nylon 12 (90d/36fil, elastic modulus of about 2GPa) with an apparent thickness of about 20μ was added to this prepreg by about 3.
A prepreg arrayed on both sides with a pitch of mm was manufactured. The CF basis weight of this prepreg was 190 g/m2, and the resin content was 34% by weight. Small pieces of predetermined dimensions were cut out from this prepreg, and after lamination, test pieces for measuring compressive strength after impact were molded in an autoclave (curing conditions: 1
80°C x 2 hours). Using this test piece, SACMA (
Suppliers of Advanced
Composite Materials Ass
recommendation) Recommended Met
270 lb- according to hod SRM2-88
The compressive strength after in-impact was measured, and the results shown in Table 1 were obtained.

Comparative Examples 1 to 3 Unidirectional prepregs were produced in the same manner as Examples 1 to 3, except that a resin film was used such that the resin content of the prepreg was 36% by weight. This prepreg was evaluated in the same manner as in Example 1 without attaching nylon 12 fibers. The results are also shown in Table 1.

As is clear from the results in Table 1, the molded articles obtained from the prepregs of the present invention have higher compressive strength after impact than the comparative examples, and are superior in impact resistance.

Example 4 Instead of the nylon 12 multifilament, a nylon 612 monofilament (90 d, elastic modulus approximately 2 GPa) was used.
) A prepreg was produced in the same manner as in Example 1, except that
The compressive strength after impact was measured. The obtained compressive strength after impact was 330 MPa.

Example 5 A prepreg was produced in the same manner as in Example 1, except that the pitch of the nylon 12 multifilament was changed as shown in Table 2, and the compressive strength after impact was measured. The results obtained are shown in Table 2.

Example 6 Polyetherimide multifilament (100d/10fil, elastic modulus approximately 4GPa) was used instead of nylon 12.
) A prepreg was produced in the same manner as in Example 1, except that
The compressive strength after impact was measured. The obtained compressive strength after impact was 310 MPa.

[0027]

[Table 1]

[0028]

[Table 2]

[Brief explanation of drawings]

[Figure 1],

FIG. 2 shows a manufacturing process diagram of a prepreg suitable for carrying out the present invention.

[Explanation of symbols]

1, 11 Prepreg made of reinforcing fibers and matrix resin 2, 12 Fibrous thermoplastic resin 3, 13 Comb 4, 14 Heated pressure rollers 5, 15 Prepreg 6 Impregnation table 17 Release pattern 18 Supply release paper

Claims (2)

[Claims] Claim 1: When producing a prepreg for fiber reinforced composite material from (A) reinforcing fiber with an elastic modulus of 200 GPa or more, (B) a fibrous thermoplastic resin with an elastic modulus of 100 GPa or less, and (C) a thermosetting matrix resin,
(B) on a unidirectional prepreg obtained by a conventional method from the reinforcing fibers of (A) and the thermosetting matrix resin of (C).
A prepreg manufacturing method characterized by arranging fibrous thermoplastic resin and impregnating it with heat. 2. The method according to claim 1, wherein the fibrous thermoplastic resin is localized on the prepreg surface.