JPH0213623B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a fiber-reinforced composite material that simultaneously contains carbon fibers and specific wholly aromatic polyamide fibers as reinforcing materials. More specifically, it is a hybrid type that uses a layer of carbon fiber, which is known as a high-performance fiber, and a layer of high-strength fully aromatic polyamide fiber obtained from a fully aromatic copolyamide with a specific chemical structure as a reinforcing material. Concerning high performance fiber reinforced composite materials. [Prior Art] Among fiber-reinforced resin composite materials, so-called high-performance composite materials with high strength and high rigidity have been attracting attention in various fields in recent years because they have the advantage of being lightweight. Particularly in applications such as aircraft, railway vehicles, and automobiles, it is extremely important from the viewpoint of resource and energy conservation. For example, composite materials using carbon fiber, which is a highly rigid fiber, as a reinforcing material have excellent properties and are expected to be representative of so-called high-performance composite materials. However, although such composite materials using carbon fiber as a reinforcing material have the advantages of high strength and high rigidity, they have the disadvantage of being weak against impact. for that,
The lack of impact resistance of such composite materials has always been pointed out as a problem in the above-mentioned high-performance material application fields, and is actually the main cause of various restrictions in the development of composite materials in various fields. As a means to solve the drawback of low impact strength in composite materials reinforced with carbon fibers, attempts have been made to create composite materials reinforced with other high-strength, high-modulus organic fibers. This is a composite material that uses polyparaphenylene terephthalamide fiber as a reinforcing material. However, even if high-performance organic fibers such as polyparaphenylene terephthalamide fibers are used, it is difficult to achieve a high elastic modulus as seen when carbon fibers are used. Therefore, both high-performance fibers are used simultaneously as reinforcing materials with the aim of fully demonstrating the excellent properties that both high-performance fibers inherently possess as described above as constituent elements of composite materials. (For example, see Utility Model Application Publication No. 51-48174). This is a so-called hybrid structure composite material. In other words, the above-mentioned hybrid composite material of carbon fiber and polyparaphenylene terephthalamide fiber can be said to be a composite material that has a high level of balanced properties that cannot be achieved by using each high-performance fiber alone. Recently, it has come to be used as part of aircraft equipment. [Problems to be Solved by the Invention] However, the impact resistance of hybrid composite materials made of carbon fibers and polyparaphenylene terephthalamide fibers as reinforcing materials is still not sufficient. That is, the current reality is that the impact resistance of the actually obtained composite material is lower than the value calculated from the physical properties of the carbon fiber and polyparaphenylene terephthalamide fiber, and does not necessarily exhibit sufficient performance. The main object of the present invention is to solve the problems of conventionally known hybrid composite materials as described above, and to provide a composite material particularly excellent in impact resistance. [Means for Solving the Problems] As a result of intensive research to solve the problems of conventionally known hybrid composite materials, the present inventors have developed a fiber made of a special wholly aromatic copolymerized polyamide having a specific chemical structural unit. By using carbon fiber together with carbon fiber and devising a method for using it, it is possible to create a composite material that has extremely excellent impact resistance and other properties, and can exhibit extremely useful industrial properties. We have discovered this and arrived at the present invention. That is, the present invention provides a fiber-reinforced composite material that includes a layer of wholly aromatic polyamide fiber [A] and a layer of carbon fiber [B] as reinforcing materials, and has a thermosetting or thermosetting resin as a matrix, (A) The fully aromatic polyamide fiber [A] is a copolymerized polyamide consisting of a structural unit represented by the following chemical formula () and a structural unit represented by the following chemical formula () or/and a structural unit represented by the following chemical formula (). It is composed of (However, X in formula () is a halogen atom,
n is an integer of 1 to 3) (a) and the ratio of the content of the fully aromatic polyamide fiber [A] to the content of the carbon fiber [B] in the composite material is 10/90 to 90/90/ by weight. and (c) a layer of the wholly aromatic polyamide fiber [A] is present at least in the vicinity of the outer surface of the composite material. As mentioned above, the hybrid composite material according to the present invention is characterized by the types of fibers used as reinforcing materials, the proportion of each fiber used, and the form in which the fibers (reinforcing materials) are used in the composite material. , each will be explained in detail below. In the composite material according to the present invention, specific wholly aromatic polyamide fibers [A] and carbon fibers [B] are used together as reinforcing materials. Carbon fiber, which is used as a reinforcement in performance composite materials, can be used. That is, polyacrylonitrile (PAN) fibers, carbon fibers made from rayon as a precursor, or high-performance carbon fibers made from petroleum-based or coal-based pitches are preferably used. In the present invention, the wholly aromatic polyamide fiber [A] used as another reinforcing fiber includes the above-mentioned polyamide repeating structural units () and (),
() and (), or () () and ().
It is a heat-treated fiber, and in addition to having high strength and high modulus, it has extremely good corrosion resistance and chemical resistance compared to polyparaphenylene terephthalamide fiber, and also has good adhesion to the polymer compound used as a matrix component. It has the advantage of moreover,
A composite material using the wholly aromatic polyamide fiber [A] as a reinforcing material has an extremely high level of impact resistance and exhibits useful properties as a mechanical material or a structural material. That is, the wholly aromatic polyamide fiber [A] used in the present invention is Fully aromatic polyamide fiber with high strength and high elastic modulus made of a copolymerized polyamide consisting of both structural units of
53-33294), or A fully aromatic polyamide fiber with high strength and high elastic modulus made of a copolymerized polyamide consisting of both structural units, and furthermore, Preferred examples include high-strength, high-modulus fibers made of copolyamide consisting of three structural alignments. The latter two fibers have particularly improved modulus of elasticity, and were recently developed by the present inventors and proposed in Japanese Patent Application No. 107749/1982. The copolymerization molar ratio of the above structural units () in these copolyamides is preferably 20 to 80 mol%. In the fiber-reinforced composite material according to the present invention, the carbon fibers and the fully aromatic copolyamide fibers used as reinforcing fibers can each be used as a sheet-like product in which multifilament yarns or rovings are arranged. ,Also,
It can also be used as woven or knitted fabrics with various structures such as plain weave, satin weave, twill weave, and basket weave. The first feature of the fiber-reinforced composite material according to the present invention is that carbon fibers and specific wholly aromatic copolymerized polyamide fibers are used together as reinforcing fibers. The specific wholly aromatic copolyamide fibers used in the present invention cannot be achieved when used in combination with carbon fibers and other wholly aromatic polyamide fibers such as polyparaphenylene terephthalamide fibers. High standard tensile strength,
It is possible to exhibit impact resistance strength etc. in a composite material, and in particular, by devising its usage form, it has become possible to provide a composite material with extremely excellent impact resistance. In the present invention, the ratio of the carbon fibers and the fully aromatic copolyamide fibers used as reinforcing fibers is 90 to 10 parts by weight of the fully aromatic copolyamide fibers to 10 to 90 parts by weight of the carbon fibers. Combinations are preferably applied. The fibers of the wholly aromatic copolyamide consisting of repeating units represented by the above structural formulas () and () or/and () are less than 10 parts by weight (the total amount of the carbon fiber and the wholly aromatic copolyamide fiber) If the total amount is 100 parts by weight), the contribution to improving the impact strength is small, so the balance of properties of the hybrid composite material, which is the object of the present invention, is insufficient. On the other hand, if the amount of the fully aromatic copolyamide used exceeds 90 parts by weight, that is, if the amount of carbon fiber used is less than 10 parts by weight, not only will the high elastic modulus of the composite material be impaired, but the carbon fiber This is not preferable because the advantages of low deflection and low elongation, which are one of the characteristics, are not exhibited, and therefore the dimensional stability of the composite material is impaired. A more preferable usage ratio in the present invention is a combination of 30 to 80% by weight of carbon fiber and 70 to 20% by weight of the fully aromatic copolyamide fiber. Another component of the fiber-reinforced composite material according to the present invention is a resin as a matrix, and various well-known curable resins or thermoplastic resins can be used. Specific examples of such curable resins include epoxy resins, phenolic resins, unsaturated polyester resins, polyimide resins, silicone resins, polyurethane resins, and alkyd resins. Specific examples of thermoplastic resins include polyester, polyamide, polysulfone, polyethersulfone, polyamideimide, polyimide, polyphenylene sulfide, and the like. In order to effectively exhibit the advantages of the fiber-reinforced composite material according to the present invention, it is preferable to use a curable resin as the matrix resin. Particularly suitable matrix resins include epoxy resin, polyimide resin, and unsaturated polyester resin. Such as resin. In the fiber-reinforced composite material according to the present invention, there are no particular restrictions on the proportion of reinforcing fibers and matrix resin used, but if the proportion of reinforcing fibers exceeds about 90% by weight of the whole, The binding or dispersion state of reinforcing fibers becomes non-uniform and voids are likely to occur, which is undesirable. On the other hand, if the proportion of reinforcing fibers used is as small as less than about 20% by weight, it is undesirable because it is difficult to exhibit various properties such as high strength and high rigidity, which are the original objectives.
Therefore, the content of reinforcing fibers in the composite material is
20-90% by weight is preferred. When forming the fiber-reinforced composite material of the present invention, when combining a layer of carbon fiber as a reinforcing fiber and a layer of the above-mentioned wholly aromatic copolyamide fiber with a resin as a matrix, the fiber layer is, for example, It can be formed by spraying or impregnating a plurality of fiber bundles aligned in parallel in one direction with a matrix resin or its solution, or it can be formed by forming the fibers into a woven or knitted fabric such as plain weave or satin weave in advance, and then It is also possible to spray or impregnate the matrix resin or its solution. And the arrangement of reinforcing fibers in the composite material is
The layer of the fully aromatic copolyamide fiber [A] (sheet, woven or knitted fabric, etc.) and the layer of carbon fiber [B],
It is preferable that the layer [A] is laminated so that it is arranged at least on the outer surface of the composite material or in the vicinity thereof, and by such an arrangement, it is possible to obtain a composite material with particularly good impact resistance. can. For example, a composite material is produced by alternately arranging and laminating layers of the fully aromatic copolymerized polyamide fiber [A] and carbon fiber [B] so that the layer [A] is at or near the outermost layer. may be formed, and
The layer of carbon fiber [B] may be located in the center (center) of the composite material, and the layer of wholly aromatic copolyamide fiber [A] may be located at or near the outermost layer. On the other hand, if the layer of the wholly aromatic polyamide fiber [A] is present only in the central part (center part) of the laminate, the effect of improving impact resistance may be reduced. When forming the above-mentioned composite material, it is also possible to directly mold the reinforcing fiber obtained as above and the matrix resin by heating (pressurizing if necessary), but in particular, the matrix resin When the resin is a thermosetting resin such as an epoxy resin or an unsaturated polyester resin, the matrix resin impregnated into reinforcing fibers or woven or knitted fabrics arranged in a sheet shape such as so-called prepreg is called "B-stage". After allowing the curing reaction to proceed to an intermediate stage, the molding material is laminated and molded using predetermined heating and pressure conditions.
It is also possible to use a composite material. In the hybrid form, aligned and/or woven or knitted fiber aggregates or "B-stage" layered bodies impregnated with matrix resin are laminated so that the fiber arrangement direction has various angles. It is also possible to do so. The fiber-reinforced composite material according to the present invention can be used to provide useful molded products by various molding methods. A typical molding method is compression molding, which can be performed by mechanical compression using a mold of a predetermined shape, or by applying gas pressure in an autoclave. Other,
The shape of the reinforcing fibers and/or the properties of the matrix resin, such as the commonly used cast molding method, spray method, pandoray up method, lamination method, transfer molding method, injection molding method, pultrusion method, etc. They can be selected together. As mentioned above, the reinforcing fibers for composite materials according to the present invention are characterized by the combination of carbon fibers and specific wholly aromatic copolyamide fibers, but they also include organic and/or inorganic fibers other than the above. It is also possible to use a small proportion as reinforcing fibers. Specific examples of such organic and/or inorganic fibers include organic fibers such as polyarylate, polyester, polyamide, wholly aromatic polyamides other than the above-mentioned wholly aromatic copolyamide specified in the present invention, glass fibers, silica, Examples include inorganic fibers such as silica alumina, silicon carbide, potassium titanate, boron nitride, and silicon nitride. Furthermore, in addition to the reinforcing fibers and matrix resin, additives such as fillers, fillers, and flame retardants can also be used in the composite material according to the present invention.
Examples of such additives include calcium carbonate, calcium silicate, silica, alumina, carbon black, titanium oxide, and the like. [Effects of the Invention] The composite material according to the present invention as described above is a feature of a conventional hybrid composite material that uses wholly aromatic polyamide fiber (polyparaphenylene terephthalamide fiber) and carbon fiber as reinforcement materials. While maintaining the advantages of high strength and high rigidity, the disadvantage of impact resistance is greatly improved. Therefore, this composite material can be widely used in fields where conventional hybrid composite materials were considered difficult to apply. [Examples] Hereinafter, the fiber reinforced composite material of the present invention will be specifically explained with reference to Examples and reference examples regarding the production of specific wholly aromatic copolyamide fibers. However, the present invention is not limited to these examples. In addition, in the following Examples and Reference Examples, "parts" simply represent parts by weight. In addition, in measuring the mechanical properties, a molded product with a thickness of 3 mm was used as a sample unless otherwise specified. That is, the bending properties were measured using a molded piece having the above thickness with a span of 50 mm, and the interlaminar shear strength was measured with a span of 15 mm. Izo impact strength (notched) was measured using a test piece in which a 45° V-notch was cut to a predetermined depth in a molded piece having the above thickness. The molded piece used for measuring compressive strength is width: length: height (fiber direction) =
A 1:1:2 ratio of prisms was used. Further, the intrinsic viscosity of the polymer was measured in concentrated sulfuric acid at a polymer concentration of 0.5 g/dl and a temperature of 30°C. Reference Example 1 10.72 parts of 3,4'-diaminodiphenyl ether and 5.79 parts of paraphenylenediamine were dissolved in 500 parts of N-methylpyrrolidone under a stream of dry nitrogen.
After cooling to 0° C., 21.74 parts of terephthalic acid chloride powder was quickly added while stirring vigorously to carry out polymerization. After about 5 hours, calcium oxide was added to neutralize the by-product hydrochloric acid. The thus obtained polymer is a wholly aromatic copolyamide consisting of the structural units () and () above, and its intrinsic viscosity is 3.02, and the solution viscosity is
It was 100℃ poise. This neutralized solution is filtered, then degassed, and spun using a half-dry, half-wet method. The resulting yarn is washed with water, dried, and then hot-stretched through a hot plate heated to 500°C. The yarn properties of filament yarn (A) are tensile strength of 26.2 g/de, Young's modulus of 630 g/de,
The elongation was 3.9%. Reference Example 2 7.186 parts of 3,4'-diaminodiphenyl ether and 11.942 parts of O-chloroparaphenylenediamine were dissolved in 543.5 parts of N-methylpyrrolidone in a stream of dry nitrogen, and this solution was maintained at 20°C, Terephthalic acid chloride powder 24.310 with vigorous stirring
part was added. Subsequently, when the temperature of the system was maintained at 60°C and stirring was continued, the viscosity of the system gradually increased, and a transparent high-viscosity solution was obtained. After about 1 hour, 8.74 parts of calcium hydroxide was added to neutralize the by-product hydrochloric acid, resulting in a highly viscous transparent solution. A part of this solution is taken out and mixed with water, and the precipitated polymer is isolated, washed with water, and dried. The resulting polymer is a wholly aromatic copolyamide consisting of the structural units () and (') above. It had an intrinsic viscosity of 3.44. After the above-mentioned neutralized solution was filtered and degassed, it was spun using a semi-dry and semi-wet method, and the spun yarn was thoroughly washed in a multi-stage water washing bath, dried, and then spun on a hot plate at 500°C. A multifilament yarn (B) was obtained by hot drawing. The yarn properties of this yarn (B) were strength of 28.0 g/de, Young's modulus of 823 g/de, and elongation of 3.9%. Examples 1 to 3, Comparative Example 1 After drying the fully aromatic copolyamide multifilament yarn (A) (750 denier/500 filaments) obtained in Reference Example 1, an epoxy resin solution ["Epicote" 828 (Siel Chemistry
Co., Ltd.), 20 parts of "Epicure" Z (amine-based curing agent made by Ciel Chemical Co., Ltd.), and 12 parts of acetone] to impregnate the resin, and then pour the liquid through the micropores. was held constant and wound onto a large diameter cylindrical drum using the filament winding method. Subsequently, the epoxy resin was kept in a drying oven maintained at 90°C to bring the epoxy resin into a semi-gelled state, so-called "B-stage", to obtain a unidirectionally aligned sheet-like prepreg (C). On the other hand, carbon fiber (600 denier/1000 filament, manufactured by Toho Bethlon Co., Ltd.) was unidirectionally impregnated with Epicoat 828/Epicure Z-based epoxy resin in the same manner as in the case of the fully aromatic copolymerized polyamide fiber multifilament yarn. A rolled sheet prepreg (D) was obtained. The above-mentioned sheet prepreg (C) (wholly aromatic polyamide type) and sheet prepreg (D) (carbon fiber type)
are laminated alternately so that the prepreg (C) is the top layer and the bottom layer, and the volume ratio of carbon fiber and wholly aromatic copolyamide fiber in the composite material is varied within the range shown in Table 1. The composite material was press-molded so that the total fiber content in the composite material was approximately 60%. The properties of the obtained composite material (molded piece) were at an extremely high level as shown in Table 1, and the improvement in impact properties was particularly remarkable. The conditions for press forming are as follows.
The following conditions for preparing molded articles in the present invention were all carried out in accordance with these conditions. [Main curing: 160℃, 80Kg/cm ² (gauge pressure), 20 minutes Post-curing: 160℃, 2 hours

【table】

[Table] Examples 4, 5, Comparative Example 3 Prepreg (C) made from the fully aromatic copolyamide multifilament yarn (A) prepared in Example 1 and prepreg (D) made from carbon fiber, (C)
are located in the top layer and bottom layer, and (D) is located in the middle part, and the carbon fibers shown in Table 2/
They were laminated so that the wholly aromatic polyamide fiber ratio and the total fiber content in the composite material were 66% by weight, and hot pressed to obtain a molded product. The physical properties of the obtained molded piece are shown in Table 2. "Kevlar 49", a commercially available fully aromatic polyamide fiber
(registered trademark of Dupont Co., Ltd.'s polyparaphenylene terephthalamide fiber), the fully aromatic polyamide fiber specified in the present invention has clear superiority in impact strength and interlaminar shear strength. It was confirmed that it shows.

【table】

[Table] Example 6 Using the fully aromatic polyamide multifilament yarn (B) (750 denier/500 filaments) obtained in Reference Example 2, it was woven in the same manner as in Example 1 by the filament winding method. A directionally aligned prepreg (E) was prepared. The thus obtained prepreg (E) and the same carbon fiber prepreg (D) used in Example 1 were laminated in the same manner as in Examples 4 and 5 to obtain a carbon fiber/wholly aromatic polyamide hybrid composite material. Ta. As shown in Table 3, the properties of the molded product obtained by hot pressing the obtained composite material are as follows. Good results were shown in terms of elastic modulus, bending deflection rate, interlaminar shear strength, etc.

【table】

Claims (1)

[Scope of Claims] 1. A fiber-reinforced composite material containing a layer of wholly aromatic polyamide fiber [A] and a layer of carbon fiber [B] as reinforcing materials, and having a thermosetting or thermosetting resin as a matrix. , the fully aromatic polyamide fiber [A] is made of a copolyamide consisting of a structural unit represented by the following chemical formula () and a structural unit represented by the following chemical formula () or/and a structural unit represented by the following chemical formula (). , and the ratio of the content of the fully aromatic polyamide fiber [A] to the content of the carbon fiber [B] in the composite material is within the range of 10/90 to 90/10 in terms of weight ratio, and at least A fiber-reinforced composite material, characterized in that a layer of the fully aromatic polyamide fiber [A] is present near the outer surface of the composite material. (However, X is a halogen atom, n is an integer from 1 to 3)