JP2510093B2 - Prepreg and molded products - 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 producing a molded product which is excellent in impact resistance and has an ability to suppress crack propagation upon impact, and a molded product obtained by molding the prepreg. . More specifically, when a high-strength carbon fiber or the like is used as a reinforcing material, a prepreg and a prepreg for imparting a toughness-imparted molded product without impairing the excellent mechanical properties and thermal properties of the matrix resin, and The present invention relates to the molded product.

[0002]

2. Description of the Related Art In recent years, composite materials using carbon fibers, aromatic polyamide fibers, etc. as reinforcing materials have been widely used as structural materials for aircraft etc. by utilizing their high specific strength and specific rigidity. There is. These composite materials are often actually used from a prepreg, which is an intermediate product in which a reinforcing material is impregnated with a matrix resin, through a molding / processing step such as heating / pressing. As the matrix resin in the prepreg, an epoxy resin known as a thermosetting resin, a bismaleimide resin, an unsaturated polyester resin, a polyimide resin or the like is used, and recently, a thermoplastic resin such as polyether ether ketone is also used. The composite materials have been characterized by excellent heat resistance, mechanical properties, dimensional stability, chemical resistance, and weather resistance regardless of which resin is used. When thermoplastic resin is used as matrix resin, good heat resistance,
It is expected that not only the mechanical properties but also the impact properties of the composite material will be excellent, but the handling property as a prepreg is poor (for example, the drape property is poor), and thus the handling property is poor with the current molding technology. Therefore, it is difficult to apply it to complicated shapes. On the other hand, when a thermosetting resin such as an epoxy resin-based prepreg is used as a matrix resin, it has been confirmed that it exhibits good performance in heat resistance and mechanical properties, but on the other hand, the elongation of the matrix resin is low. ,
It has been pointed out that the toughness and impact resistance of composite materials are inferior due to their brittleness, and their improvement has been demanded. In particular, composite materials made from these prepregs, when used in aircraft primary structural applications, will raise pebbles during takeoff and landing,
Although it is necessary to have the ability to withstand an external impact caused by a tool dropping during maintenance, it has been difficult to improve the impact resistance without lowering the heat resistance. In order to impart impact resistance to these composite materials, the following points have been pointed out as important points and research has been advanced. Improves the elongation of carbon fiber and other reinforcing materials. Increase the toughness of the matrix resin used for prepreg. Optimize the reinforcing fiber / matrix resin interface properties. The composite material has a higher order structure. As a technique for improving the toughness of the matrix resin for prepreg and improving the impact resistance of the composite material, there is disclosed in Japanese Patent Laid-Open No. 58-1.
20639, 61-250021, 62-36
No. 421, No. 62-57417, etc., a prepreg in which a matrix resin is blended with a specific elastomer component, a high molecular weight rubber component, and a thermoplastic resin to improve the toughness (impact resistance) of the composite material. Although a composition has been developed, it has problems such as a low improvement in impact resistance of the composite material and a marked increase in viscosity of the matrix resin. Further, a method of dispersing and mixing a fine powder of a thermoplastic resin in a matrix resin has also been proposed, but in this case, although the viscosity of the matrix resin is small and the impact resistance is improved, the tack of the prepreg in the exposure atmosphere is reduced. There was a problem that it changed over time. Regarding the optimization of the interfacial properties of the reinforcing fiber / matrix resin, researches such as selecting the surface treatment condition of the fiber and the type of sizing agent have been conducted, but it is still in the research stage and the desired effect can be obtained. Not not. As a technique for improving the impact resistance of the composite material by making the composite material a higher-order structure, a method of controlling the material form of the reinforcing fiber, a method of inserting a different material between the laminated layers, and the like are considered. As a method of controlling the material form of the reinforcing fiber, attempts have been made to use a three-dimensional woven fabric as the reinforcing material in order to make it an isotropic material, but at the present time, it is difficult to produce a woven fabric, and it is impregnated with resin. However, there are many problems such as poor control of the fiber volume content and difficulty in controlling the fiber volume content. As for the technique of inserting different materials between the laminated layers of composite materials, as disclosed in JP-A-51-33162 and JP-A-61-135712, a scream.
It is known that a cloth is laminated, but in this case the scream cloth is used for the purpose of reinforcing the prepreg itself, such as preventing lateral cracking of the prepreg and preventing fiber disorder, and has a large toughness. However, no improvement in impact resistance is recognized. As a technique for improving the impact characteristics of a composite material by inserting a different material between the layers of the composite material, JP-A-60-63229 and 63-16273.
There is an interleaf technique as disclosed in Japanese Patent No. As an interleaf material, the thickness is generally 0.03
A thermoplastic resin film having a thickness of 0.01 to 0.05 mm, for example, a film of polyetherimide, polyethersulfone, or polyetheretherketone. Are using. When using an epoxy resin having excellent flexibility in the interleaf material, for example, an epoxy resin layer containing many elastomer components, it is necessary to blend a large amount of the elastomer component in order to improve impact properties. Depending on the type and amount of the elastomer component, the heat resistance and mechanical properties of the composite material may be deteriorated, and the type and amount are limited, so that the sufficient effect cannot be often obtained. When a thermoplastic resin film is inserted between the layers of composite material, the effect of improving the impact resistance of the composite material is recognized, but the resin film completely blocks the space between adjacent layers. However, there is a problem in the tack of the prepreg and the adhesiveness between the matrix resin and the thermoplastic resin film, and there is a drawback that the toughness of the composite material, particularly the strain energy release rate (G _IC ) is low. Also,
Since the resin flow in the interlayer direction is blocked, non-uniform resin flow occurs, resulting in deformation of the molded product, or because the thermoplastic resin film is relatively thick, the ratio of the thermoplastic resin film to the matrix resin is In some cases, it becomes higher, and the performance of the composite material (composite performance) is reduced accordingly.

[0003]

It is an object of the present invention to provide a molded article which overcomes the above problems and has excellent heat resistance, excellent toughness and impact strength, and the ability to suppress the propagation of cracks at the time of impact. Providing a prepreg and a molded product to be applied to a composite material, when spread, in a prepreg using a thermosetting matrix resin, by mixing fibers made of a thermoplastic resin in the prepreg, tack of the prepreg, It is intended to provide a prepreg for a fiber-reinforced composite material, which has excellent flow characteristics, toughness of the composite material after molding, and impact resistance, and a molded product obtained from the prepreg.

[0004]

The present invention is as follows. (Claim 1) Reinforcing filaments and polyether sulfo
Polyether imide, polyether ether keto
Thermoplastic resin length consisting of polyimide or polyimide alone or in combination
A prepreg obtained by impregnating a base material with fibers with a thermosetting resin composition which is cured at a temperature lower than the melting point or glass transition temperature of the thermoplastic resin filaments. (Claim 2) A molded product obtained by molding the prepreg according to claim 1. Preferred embodiments of the present invention are as follows. The prepreg according to claim 1, wherein the (a) reinforcing material long fibers are carbon fiber long fibers having an elongation of 1.3% or more. The thermoplastic resin filament (b) is a thermoplastic resin fiber having a glass transition temperature or a melting point of 180 ° C. or higher.
The listed prepreg. (C) The length of the single fiber is 1 to 50 μm, and the thermoplastic resin continuous fiber bundle composed of 10 to 10,000 single fibers is preferably 3 to 25% by weight, and more preferably, the reinforcing fiber continuous fiber. The prepreg according to claim 1, wherein the prepreg is uniformly mixed in the prepreg at a ratio of 10 to 20% by weight. The molded article of the present invention is excellent in impact resistance and has characteristics that it is difficult for a generated crack to propagate. The reinforcing filaments used in the present invention are preferably carbon fibers, glass fibers and aromatic polyamide fibers having an elongation of 1.3% or more. Usually, glass fiber and aromatic polyamide fiber have an elongation of 2.5% or more. When carbon fibers having an elongation of less than 1.3% are used, the toughness and impact resistance of the composite material may be slightly insufficient. The carbon fiber is not limited to acrylic carbon fiber, pitch carbon fiber, etc., but in order to improve the mechanical properties of the composite material, tensile strength is 400 Kgf / mm ² or more, elastic modulus is 30 × 10 ^3.
It is preferable to use so-called high-strength medium elastic fibers having a Kgf / mm ² or more. Although filament yarns are generally used as the long fibers, spun yarns of short fibers can also be used. In the present invention, the thermoplastic resin filaments, polyether sulfone, polyether imide,
Polyether ether ketone, polyimide filament
Continuous fibers such as fiber, spun yarn, and blended yarn.
The fibers are used alone or in combination. Including matrix resin
A filament is preferable from the viewpoint of dipping property. Also, these
The fibers are suitable because they have heat resistance. The thickness of the monofilament is 1
It is preferably from 50 to 50 μm and the number of single fibers thereof is from 10 to 10,000, from the viewpoint of the ease of the prepreg production process and the impact resistance of the molded product. These thermoplastic resin continuous fibers have a relationship with the curing temperature of the thermosetting matrix resin so that the thermoplastic resin fibers do not fuse into the matrix resin to form a uniform phase, particularly during prepreg curing (molding). Therefore, it is necessary to select a thermoplastic resin having a glass transition temperature or a melting point higher than the curing temperature. Preferred are thermoplastic resin filaments having a glass transition temperature or melting point of 180 ° C. or higher. Further, these fibers may be subjected to a physical or chemical etching treatment in order to improve the adhesiveness with the matrix resin. The blending ratio of the thermoplastic resin long fibers to the reinforcing long fibers is 3 to 25 from the viewpoint of mechanical properties, heat resistance and impact resistance of the molded product.
% By weight, preferably 10 to 20% by weight. A prepreg using these fibers as a base material is one-way aligned and impregnated with an uncured thermosetting resin composition between fibers of a base material such as a unidirectional woven fabric or a woven fabric. The thermosetting resin composition as the matrix resin is a resin composition that cures at a temperature lower than the glass transition temperature or the melting point of the thermoplastic resin filaments of the base material. Specifically, epoxy resin, bismaleimide resin, unsaturated polyester resin, phenol resin,
The content of the entire resin composition (including the thermoplastic resin filaments) which is a polyimide resin in the prepreg is preferably 20 to 60% by weight, more preferably 25 to 45% by weight.
Is appropriate. When the elongation of the matrix resin is improved due to the modification of the resin and the like, the molded product has the property of making it difficult for the generated cracks to propagate. A molded product made of such a prepreg is a molded product which is excellent in toughness and impact resistance and does not easily peel off. The prepreg of the present invention can be prepared as a prepreg by a solvent method or a hot melt method by preparing a substrate by a generally known method, but when the solvent method is used, a solvent that does not dissolve the thermoplastic resin filaments is used. Need to use. When introducing the reinforcing material long fibers and the thermoplastic resin long fibers into the prepreg producing apparatus, they may be individually carried out or may be entangled (commingle, combined yarn) in advance. For example, it can be manufactured by the following method. First, using the prepared thermosetting resin, a uniform resin film is produced by a film coater or the like. Then, by a hot melt method or the like, the reinforcing material long fibers and the thermoplastic resin long fibers are uniformly arranged in one direction on the resin film, heated by a plate, a roller, etc., pressurized and impregnated to obtain a prepreg. .

[0005]

Example 1 Using a resin composition having the following composition, a resin film was produced with a film coater. Next, using the hot melt method, the carbon fibers and the thermoplastic resin fibers uniformly arranged in one direction were passed through a hot roller at 100 ° C. to impregnate the uncured thermosetting resin between the fibers to form a prepreg. Was produced. 1) Tetraglycidylaminodiphenylmethane (manufactured by Ciba-Geigy, MY-720) 50 parts by weight 2) Phenol novolac epoxy resin (manufactured by Dow Chemical Co., TACTIX485) 20 parts by weight 3 ) Bisphenol A type epoxy resin (Yukaka Shell Epoxy Co., Ep. 828) ... 30 parts by weight 4) 4,4'diaminodiphenyl sulfone (Sumitomo Chemical Co., Ltd., Sumikyua) ...... 40 parts by weight The carbon fiber (CF) used is Besfite IM-600.
(Manufactured by Toho Rayon Co., Ltd., tensile strength 580 Kgf / mm ² ,
The elastic modulus is 30 × 10 ³ Kgf / mm ² ). Further, the thermoplastic resin fiber has a single fiber thickness of 20 μm, and the filamentary polyetherimide fiber (abbreviated as PEI fiber: glass transition temperature 216) having 150 single fibers.
C) was used. CF basis weight of prepreg is 150g /
m ² , the weight of PEI fiber was 15 g / m ² , and the resin content (including PEI fiber) of the entire prepreg was 32% by weight. The obtained prepreg has C in the matrix resin.
The F and PEI fibers were uniformly mixed, and had good tack and drape properties. From this prepreg,
Small pieces of a predetermined size and number were cut, laminated, and cured by autoclave molding under a curing condition of a heating rate of 2 ° C./minute and 180 ° C. for 2 hours to prepare a molded plate. Thus, the test piece was cut out, and the glass transition temperature (Tg), G _IC ,
1500 in-lb / in, compressive strength after impact (CA
I: 32ply pseudo isotropic laminate)
g is 190 ° C., GIC is 480 J / m ² , CAI is 35
It was Kgf / mm ² .

Example 2 The weight of the PEI fiber shown in Example 1 was 7 g.
/ M ² and the same procedure as in Example 1 was repeated. The obtained prepreg was one in which CF and PEI fibers were uniformly mixed in the matrix resin, and had good tack and drape properties. A molded product obtained by curing this prepreg in the same manner as in Example 1 had a Tg of 188 ° C. and a G _IC of 410 J /
m ² and CAI were 31 Kgf / mm ² .

Example 3 Instead of the PEI fiber shown in Example 1,
Polyether sulfone fiber (abbreviation PES fiber: Tg2)
23 ° C.) and the basis weight of PES fiber was 15 g / m ^2, and the same procedure as in Example 1 was repeated. The obtained prepreg was one in which CF and PES fibers were uniformly mixed in the matrix resin, and had good tack and drape properties. A molded article obtained by curing this prepreg in the same manner as in Example 1 had a Tg of 191 ° C. and a G _IC of 420 J /
m ² and CAI were 34 Kgf / mm ² .

[Example 4] The thickness of the PEI fiber shown in Example 1 is 40μ.
m, the monofilament was changed to 70 monofilaments, the weight of the PEI fiber was changed to 15 g / m ^2, and the same procedure as in Example 1 was repeated. The obtained prepreg was one in which CF and PEI fibers were uniformly mixed in the matrix resin, and had good tack and drape properties. The molded product obtained by curing this prepreg in the same manner as in Example 1 had a Tg of 190.
℃, G _IC is 450 J / m ² , CAI is 32 Kgf / m
It was m ² .

[0006]

Comparative Example 1 A prepreg was produced by the same procedure as in Example 1 without adding thermoplastic resin fibers. The obtained prepreg had a CF areal weight of 150 g / m ² , a resin content of 32% by weight, and had good tack and drapability. This prepreg was cured as in Example 1. T of this molding
g is 191 ° C., G _IC is 190 J / m ² , CAI is 14
It was Kgf / mm ² .

[Comparative Example 2] A prepreg was produced by the same procedure as in Example 1 except that the thermoplastic resin fiber was not added. A 20 μm-thick polyetherimide film was placed on one surface of the obtained prepreg and passed through a hot roller at 80 ° C. to press them together. The CF weight of the obtained prepreg is 150 g / m.
^{2. The} resin content was 33% by weight. This prepreg had a good drape property, but the side to which the film was pressure bonded had no tack. This prepreg was cured as in Example 1. The Tg of this molding is 190
℃, G _IC is 130 J / m ² , CAI is 31 Kgf / m
It was m ² .

[0007]

[Table 1] The measurement results are summarized in Table 1. Compared to Comparative Example 1, Examples 1 to 4 show no difference in Tg, but CAI,
It was revealed that the G _IC was high, and the impact resistance and toughness were excellent. Further, even when compared with Comparative Example 2 in which a polyetherimide film was placed between the prepreg layers, it was confirmed that the Tg and CAI were the same but the G _IC was very excellent.

[0008]

According to the present invention, it is possible to easily manufacture a prepreg in which reinforcing fiber long fibers and thermoplastic resin long fibers are mixed in an arbitrary ratio. The molded product molded using the prepreg of the present invention does not form a homogeneous phase in which the thermoplastic resin filaments are fused to the matrix resin in the molded product, and a heterogeneous phase exists because it exists in a fibrous state. Form.
Moreover, unlike the case where the thermoplastic resin film is interposed, the layers are not blocked. For this reason, the obtained prepreg and molded product have excellent mechanical properties and thermal properties, as well as toughness and impact resistance, and have properties that make it difficult for cracks that occur to propagate. It is preferably used for materials and space structure materials.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a prepreg of the present invention.

[Explanation of symbols]

 1 long-fiber thermoplastic resin 2 long-fiber reinforcing material 3 uncured thermosetting resin

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display area B29K 271: 00 B29K 271: 00 286: 00 286: 00

Claims (2)

(57) [Claims] 1. Reinforcement filaments and polyether sulfo.
Polyether imide, polyether ether keto
Thermoplastic resin length consisting of polyimide or polyimide alone or in combination
A prepreg obtained by impregnating a base material with fibers with a thermosetting resin composition which is cured at a temperature lower than the melting point or glass transition temperature of the thermoplastic resin filaments. 2. A molded product obtained by molding the prepreg according to claim 1.