Prepreg and manufacturing method of the same, and molded body

Abstract

To provide prepreg capable of producing molded bodies with high tensile strength and tensile elastic modulus, methods for manufacturing the prepreg, and molded bodies manufactured using the aforementioned prepreg.SOLUTION: In prepreg comprising a reinforced fiber substrate and a thermoplastic resin, reinforcing fibers contained in the reinforced fiber substrate are reinforcing fibers having a tensile elastic modulus of 420 GPa or more and 940 GPa or less. In a method for manufacturing a prepreg that includes a step of impregnating the thermoplastic resin into the reinforcing fiber substrate, the reinforcing fibers contained in the reinforcing fiber substrate are reinforcing fibers having a tensile elastic modulus of 420 GPa or more and 940 GPa or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a prepreg, a method for producing the same, and a molded body.

Background Art

[0002] Fiber-reinforced plastics (FRP), particularly carbon fiber-reinforced plastics (CFRP) using carbon fibers as a reinforcing material, are lightweight and high-strength, and are widely used in various applications such as sports goods, transportation equipment such as aircraft and automobiles. FRP is manufactured using an intermediate material in which a reinforcing material containing reinforcing fibers is impregnated with a resin, that is, a prepreg.

[0003] Patent Document 1 discloses a unidirectional prepreg composed of high-elastic carbon fibers having a tensile elastic modulus of 350 GPa or more and an epoxy resin.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As a result of investigations by the present inventors, it has been found that a unidirectional prepreg composed of high-elastic carbon fibers and an epoxy resin as in Patent Document 1 has a small elongation at break in the 0° direction (fiber orientation direction), and it is difficult to exhibit the 0° tensile strength of the resulting molded body.

[0006] The main object of the present invention is to provide a prepreg capable of producing a molded body having high tensile strength and tensile elastic modulus, a method for producing the same, and a molded body produced using the prepreg.

Means for Solving the Problems

[0007] The present invention includes the following aspects. [1] A prepreg comprising a reinforcing fiber base material and a thermoplastic resin, wherein the reinforcing fiber base material contains reinforcing fibers having a tensile elastic modulus of 420 GPa or more and 940 GPa or less. [2] The prepreg according to [1], wherein the thermoplastic resin contains at least one selected from the group consisting of polyolefin, polyamide, polyester, polyacetal, polyphenylene sulfide, polyaryl ether ketone, polytetrafluoroethylene, polycarbonate, polymethyl methacrylate, polyvinyl chloride, polystyrene, polyether sulfone, polyether imide, polyether ketone, and polyamide imide. [3] The prepreg according to [1] or [2], wherein the reinforcing fiber base material is a UD material in which the reinforcing fibers are aligned in one direction. [4] The prepreg according to any one of [1] to [3], wherein the reinforcing fibers contain carbon fibers. [5] The prepreg according to [4], wherein the carbon fibers contain pitch-based carbon fibers. [6] The prepreg according to [5], wherein the pitch-based carbon fibers contain mesophase pitch-based carbon fibers. [7] The prepreg according to any one of [1] to [6], wherein the content of the thermoplastic resin is 20% by mass or more and 50% by mass or less based on the total mass of the prepreg. [8] A molded article formed by molding the prepreg according to any one of [1] to [8]. [9] A method for producing a prepreg, comprising a step of impregnating a reinforcing fiber base material with a thermoplastic resin, wherein the reinforcing fiber base material contains reinforcing fibers having a tensile elastic modulus of 420 GPa or more and 940 GPa or less. [Advantages of the Invention]

[0008] According to the present invention, there are provided a prepreg capable of producing a molded article having a high 0° tensile strength and tensile elastic modulus, a method for producing the same, and a molded article produced using the prepreg. [Embodiments for Carrying Out the Invention]

[0009] [Prepreg] The prepreg according to the embodiment includes a reinforcing fiber base material and a thermoplastic resin, and the tensile elastic modulus of the reinforcing fibers contained in the reinforcing fiber base material is 420 GPa or more and 940 GPa or less. By using a prepreg obtained by combining specific reinforcing fibers having a tensile elastic modulus within the above range and a thermoplastic resin, a molded article having a high 0° tensile strength can be manufactured. The prepreg according to the embodiment may further contain components (optional components) other than the reinforcing fiber base material and the thermoplastic resin.

[0010] The prepreg is preferably in the form of a sheet. Further, it is preferably a unidirectional prepreg in which a resin is impregnated into a UD material (unidirectional material) in which the reinforcing fibers contained in the reinforcing fiber base material are aligned in one direction. The thickness of the prepreg is preferably 0.01 mm or more and 0.5 mm or less. If the thickness of the tape is equal to or greater than the lower limit value, the number of steps for laminating to a predetermined thickness can be reduced, and thus a molded article can be manufactured more efficiently. The thickness of the prepreg is more preferably 0.03 mm or more, and even more preferably 0.05 mm or more. If the thickness of the prepreg is equal to or less than the upper limit value, the drapeability of the prepreg is enhanced. The thickness of the prepreg is more preferably 0.4 mm or less, and even more preferably 0.3 mm or less. "Drapeability" refers to the flexibility of the prepreg and indicates the followability to a desired member shape. When the same reinforcing fiber base material and thermoplastic resin are used, the thinner the prepreg, the better the drapeability.

[0011] The width of the unidirectional prepreg, that is, the length in the direction orthogonal to the fiber direction and the thickness direction, is preferably 100 mm or more and 1000 mm or less. If the width of the unidirectional prepreg is equal to or greater than the lower limit value, the manufacturing efficiency of the prepreg is improved, and the applicable member size is expanded. The width of the unidirectional prepreg is more preferably 150 mm or more, and even more preferably 200 mm or more. If the width of the unidirectional prepreg is equal to or less than the upper limit value, the handling and storage of the prepreg become easy. The width of the unidirectional prepreg is more preferably 800 mm or less, and even more preferably 500 mm or less.

[0012] The prepreg according to the embodiment may be a tape with a width of less than 100 mm by slitting it to a predetermined width. It may also be a finely chopped prepreg.

[0013] The density of the prepreg is preferably 1.0 g / cm 3 or more, more preferably 1.2 g / cm 3 or more, and even more preferably 1.5 g / cm 3 or more. On the other hand, the density of the prepreg is preferably 2.0 g / cm 3 or less, preferably 1.95 g / cm 3 or less, and even more preferably 1.9 g / cm 3 or less. The density of the prepreg is the value measured by the method described in the examples.

[0014] (Reinforced fiber substrate) The reinforcing fibers contained in the reinforced fiber substrate include reinforcing fibers having a tensile elastic modulus of 420 GPa or more and 940 GPa or less. By using reinforcing fibers having a tensile elastic modulus within the above range, a molded body having high tensile strength and tensile elastic modulus can be obtained. The tensile elastic modulus of the reinforcing fibers is preferably 500 GPa or more, more preferably 600 GPa or more. Also, the tensile elastic modulus of the reinforcing fibers is preferably 1000 GPa or less, more preferably 950 GPa or less. Note that the tensile elastic modulus (strand elastic modulus) of the reinforcing fibers is the value measured by the method described in the examples.

[0015] The reinforcing fibers are typically used in the form of a bundle of reinforcing fiber bundles in which a plurality of single fibers (filaments) are bundled. The number of filaments of the reinforcing fibers is preferably 1000 to 60000, more preferably 1000 to 50000, and even more preferably 12000 to 48000. If the number of filaments is within the above range, the productivity and mechanical properties of the reinforcing fibers in an industrial scale are excellent.

[0016] The reinforcing fiber may be a long fiber (continuous fiber), for example, a short fiber of 0.01 to 30 cm. From the viewpoints of strength and rigidity, continuous fibers are preferred as the reinforcing fiber. The orientation of the fibers in the reinforcing fiber substrate may be such that the reinforcing fibers are arranged in one direction or arranged in a random direction. Examples of the form of the reinforcing fiber substrate include a woven fabric of reinforcing fibers, a non-woven fabric of reinforcing fibers, a sheet-like UD material in which continuous fibers are aligned in one direction, and the like.

[0017] Examples of the types of reinforcing fibers include, for example, glass fibers, carbon fibers, aramid fibers, polyester fibers, boron fibers, alumina fibers, silicon nitride fibers, and nylon fibers. Note that "carbon fiber" may include graphite fibers. Also, it may be a reinforcing fiber having a hybrid structure such as carbon fiber coated with a metal. The reinforcing fiber may be used alone or in combination of two or more.

[0018] The prepreg according to the embodiment preferably contains carbon fiber as the reinforcing fiber. Examples of the carbon fiber include, for example, pitch-based carbon fiber, polyacrylonitrile (PAN)-based carbon fiber, rayon-based carbon fiber, lignin-based carbon fiber, and the like. Among them, from the viewpoints of rigidity and thermal conductivity, pitch-based carbon fiber is preferred, and mesophase pitch-based carbon fiber is more preferred.

[0019] The weight per unit area of the reinforcing fiber, that is, the fiber areal weight (FAW), is preferably 10 g / m 2 or more, more preferably 30 g / m 2 or more, and even more preferably 50 g / m 2 or more, since the lamination efficiency of the prepreg is improved. Also, since the formability of the prepreg is improved, the fiber areal weight (FAW) is preferably 500 g / m 2 or less, more preferably 400 g / m 2 or less, and even more preferably 300 g / m 2 or less.

[0020] The volume content (Vf) of the reinforcing fibers in the prepreg is preferably 20 to 75% by volume, more preferably 40 to 70% by volume, and even more preferably 50 to 65% by volume. If the volume content (Vf) of the reinforcing fibers is at least the lower limit value, the reinforcing effect by the reinforcing fibers is more likely to be sufficiently exhibited, and the rigidity and strength of the molded body are further increased. If the volume content (Vf) of the reinforcing fibers is at most the upper limit value, it is easier to sufficiently ensure the adhesiveness between the reinforcing fibers and the thermoplastic resin, and it is easier to obtain a molded body having excellent fatigue characteristics. Note that the volume content (Vf) of the reinforcing fibers is a value measured by a measuring method conforming to ASTM D3171 or JIS K 7075.

[0021] (Thermoplastic resin) As the thermoplastic resin, either a crystalline resin or an amorphous resin can be used. Examples of the crystalline resin include polyolefin, polyamide, polyester, polyacetal, polyphenylene sulfide, polyaryl ether ketone, polytetrafluoroethylene, and the like. Examples of the amorphous resin include polycarbonate, polymethyl methacrylate, polyvinyl chloride, polystyrene, polyether sulfone, polyether imide, polyamide imide, and the like. The thermoplastic resin may be used alone or in combination of two or more.

[0022] When the thermoplastic resin is a crystalline resin, from the viewpoint of heat resistance, the melting point of the crystalline resin is preferably 260°C or higher. The melting point is a value obtained from the peak top of the crystal melting peak obtained when performing a temperature increase measurement using a differential scanning calorimeter (DSC). When the thermoplastic resin is an amorphous resin, from the viewpoint of heat resistance, the glass transition temperature of the amorphous resin is preferably 200°C or higher. The glass transition temperature is a value obtained by a measuring method conforming to ASTM D7028.

[0023] The prepreg according to the embodiment preferably contains at least one selected from the group consisting of polyolefin, polyamide, polyester, polyacetal, polyphenylene sulfide, polyaryl ether ketone, polytetrafluoroethylene, polycarbonate, polymethyl methacrylate, polyvinyl chloride, polystyrene, polyether sulfone, polyether imide, polyether ketone, and polyamide imide as the thermoplastic resin, more preferably contains at least one selected from the group consisting of polyaryl ether ketone, polyether imide, and polyamide, and even more preferably contains at least one of polyaryl ether ketone and polyether imide because it is easy to manufacture a molded body having higher tensile strength and tensile modulus, and particularly preferably contains polyether imide.

[0024] Polyaryl ether ketone is a homopolymer or copolymer containing monomer units containing one or more aryl groups, one or more ether groups, and one or more ketone groups, that is, a thermoplastic resin having an aromatic nucleus bond, an ether bond, and a ketone bond in the structural unit. Examples of polyaryl ether ketone include polyether ether ketone, polyether ketone ketone, polyether ketone, polyether ketone ether ketone ketone, polyether ether ketone ketone, polyether diphenyl ether ketone, and copolymers thereof (for example, polyether ketone-polyether diphenyl ether ketone copolymer).

[0025] The viscosity of the polyaryl ether ketone is, for example, 1 to 80 cm 3 / 10 min, or 100 to 200 cm 3 / 10 min, as measured in accordance with ISO1133 under the conditions of a set temperature of 380°C and a load of 5 kg, as the melt volume rate (MVR).

[0026] As the polyaryl ether ketone, polyether ether ketone is preferable because of its excellent heat resistance, mechanical properties, chemical resistance, etc., and polyether ether ketone having a structural unit represented by the following formula (1) (hereinafter, also referred to as "structural unit (1)") is more preferable.

[0027]

Chemical formula

[0028] The proportion of the structural unit (1) in the polyether ether ketone having the structural unit (1) is preferably 70% by mass to 100% by mass, more preferably 80% by mass to 100% by mass, and particularly preferably 90% by mass to 100% by mass.

[0029] As the polyether ether ketone having the structural unit (1), commercially available products can be used. For example, those manufactured by Daicel Evonik Co., Ltd., trade names "VESTAKEEP (registered trademark) 3300G", "VESTAKEEP (registered trademark) J ZV7402", "VESTAKEEP (registered trademark) 1000G", etc. can be mentioned.

[0030] As the polyaryl ether ketone, two or more polyether ether ketones having different viscosities may be used in combination. The polyether ether ketone with an MVR of 1 to 80 cm 3 / 10 minutes and the polyether ether ketone with an MVR of 100 to 200 cm 3 / 10 minutes are preferably used in combination, and the polyether ether ketone having the structural unit (1) with an MVR of 1 to 80 cm 3 / 10 minutes and the polyether ether ketone having the structural unit (1) with an MVR of 100 to 200 cm 3 / 10 minutes are more preferably used in combination. When these two polyether ether ketones having different viscosities are used in combination, the mass ratio of the high-viscosity polyether ether ketone to the low-viscosity polyether ether ketone is preferably 90:10 to 10:90, and more preferably 70:30 to 20:80.

[0031] The polyetherimide is not particularly limited. For example, a polyetherimide having a structural unit represented by the following formula (2) (hereinafter also referred to as "structural unit (2)") and a polyetherimide having a structural unit represented by the following formula (3) (hereinafter also referred to as "structural unit (3)") can be used.

[0032]

Chemical formula

[0033]

Chemical formula

[0034] The proportion of the structural unit (2) in the polyetherimide having the structural unit (2) and the structural unit (3) is preferably 10% by mass to 100% by mass, more preferably 30% by mass to 100% by mass, and particularly preferably 50% by mass to 100% by mass. Examples of the polyetherimide having the structural unit (2) include those manufactured by SABIC and having the trade names "Ultem (registered trademark) 1000" and "Ultem (registered trademark) 1010".

[0035] The proportion of the structural unit (3) in the polyetherimide having the structural unit (3) and the structural unit (2) is preferably 50% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, and particularly preferably 95% by mass to 100% by mass. Examples of the polyetherimide having the structural unit (3) include those manufactured by SABIC and having the trade names "Ultem (registered trademark) CRS5011" and "Ultem (registered trademark) CRS5001", etc.

[0036] As the polyetherimide, in terms of excellent impregnability to carbon fiber, it is preferable to use a polyetherimide having the structural unit (2), and in terms of heat resistance, it is preferable to use a polyetherimide having the structural unit (3). As the polyetherimide, a polyetherimide having the structural unit (3) and a polyetherimide having a structural unit different from the structural unit (3) may be used in combination, and it is preferable to use in combination a polyetherimide having the structural unit (3) and a polyetherimide having the structural unit (2). The mass ratio of the polyetherimide having the structural unit (3) to the polyetherimide having the structural unit (2) is preferably from 20:80 to 100:0, more preferably from 40:60 to 100:0, and even more preferably from 50:50 to 100:0.

[0037] The melt volume rate (MVR) of the polyetherimide measured under the conditions of a set temperature of 360 ° C and a load of 5 kg in accordance with ISO 1133 is 1 to 30 cm 3 / 10 minutes is preferred. In terms of facilitating the production of the prepreg, the MVR of the polyetherimide having the structural unit (3) is preferably 15 to 30 cm 3 / 10 minutes is preferred. In terms of easily obtaining a molded article with excellent mechanical properties, the MVR of the polyetherimide having the structural unit (3) is 1 to 10 cm 3 / 10 minutes is preferred. In terms of facilitating the production of the prepreg, the MVR of the polyetherimide having the structural unit (2) is preferably 10 to 30 cm 3 / 10 minutes is preferred, and 20 to 30 cm 3 / 10 minutes is more preferred.

[0038] The content of the thermoplastic resin in the prepreg is preferably 20% by mass or more and 50% by mass or less based on the total mass of the prepreg. If the content of the thermoplastic resin is at least the above lower limit value, the dispersibility of the reinforcing fiber base material is increased. The content of the thermoplastic resin is more preferably 20% by mass or more, and even more preferably 25% by mass or more. If the content of the thermoplastic resin is at most the above upper limit value, the mechanical properties of the molded article are improved. The content of the thermoplastic resin is more preferably 45% by mass or less, and even more preferably 40% by mass or less.

[0039] (Optional component) In the thermoplastic resin which is a matrix resin, various additives can be blended as optional components as needed. Examples of the additives include, for example, antioxidants, heat stabilizers, light stabilizers, plasticizers, lubricants, spreading agents, antistatic agents, flame retardants, fillers, matting agents, processing aids, impact resistance aids, antibacterial agents, antifungal agents, foaming agents, mold release agents, colorants, ultraviolet absorbers, and the like. These additives may be used alone or in combination of two or more.

[0040] Examples of the antioxidant include, for example, phenolic antioxidants, sulfur antioxidants, and phosphorus antioxidants. Examples of the heat stabilizer include, for example, hindered phenolic heat stabilizers, sulfur heat stabilizers, and hydrazine heat stabilizers. Examples of the plasticizer include, for example, phthalic esters, phosphoric esters, fatty acid esters, aliphatic dibasic acid esters, oxybenzoic acid esters, epoxy compounds, and polyesters. Examples of the lubricant include, for example, fatty acid esters, fatty acids, metal soaps, fatty acid amides, higher alcohols, and paraffin. Examples of the antistatic agent include, for example, cationic antistatic agents, anionic antistatic agents, nonionic antistatic agents, and amphoteric antistatic agents.

[0041] When blending optional components with the thermoplastic resin, from the viewpoint of durability such as heat stability, the blending ratio of the optional components is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin.

[0042] [Method for producing prepreg] The method for producing a prepreg according to the embodiment includes a step of impregnating a reinforcing fiber base material with a thermoplastic resin, and the reinforcing fiber base material contains a reinforcing fiber having a tensile elastic modulus of 420 GPa or more and 940 GPa or less.

[0043] As a method of impregnating a thermoplastic resin into a reinforcing fiber base material, for example, (i) the thermoplastic resin is formed into a film having a thickness of about 10 to 100 μm, laminated on one or both surfaces of the reinforcing fiber base material, and heated to melt the film and impregnate the reinforcing fiber base material; (ii) the thermoplastic resin is processed into a powder having an average particle size of about 10 to 100 μm and adhered to carbon fibers, and impregnated by heating and melting; (iii) the thermoplastic resin is dissolved in an appropriate solvent and impregnated into the reinforcing fiber base material. Among these, method (i) is preferred because the resin content in the prepreg is more stable.

[0044] In addition, as an impregnation method other than methods (1) to (3), there is a method of dispersing thermoplastic resin particles in water to process them into a slurry and impregnating the reinforcing fiber base material. In this case, first, the reinforcing fiber base material is introduced into a dispersion liquid in which the thermoplastic resin particles are dispersed, and the dispersion liquid is circulated to uniformly adhere the resin particles to the reinforcing fiber base material. Subsequently, the reinforcing fiber base material is taken out from the dispersion liquid and dried, for example, in an infrared heating furnace to remove water. Subsequently, the dried reinforcing fiber base material to which the resin particles are adhered is heated to melt the resin particles and impregnate the reinforcing fiber base material. The reinforcing fiber base material impregnated with the thermoplastic resin may be pressurized as necessary.

[0045] [Molded article] The molded article according to the embodiment is a molded article formed by molding the prepreg according to the foregoing embodiment. The molded article according to the embodiment may be a molded article formed by molding only one sheet of the prepreg according to the foregoing embodiment, or may be a molded article in which a laminate of two or more sheets laminated is formed. The molded article according to the embodiment may be a molded article in which a laminate is formed by combining and laminating the prepreg according to the foregoing embodiment and another prepreg other than the prepreg according to the foregoing embodiment.

[0046] The lamination structure of the prepregs in the laminate is not particularly limited. The number of prepreg laminations in the laminate can be appropriately set according to the thickness of the prepreg and the required thickness of the molded body. When using unidirectional prepregs, the fiber direction of the reinforcing fibers contained in each unidirectional prepreg to be laminated can be appropriately set according to the physical properties required for the molded body.

[0047] The use of the molded body according to the embodiment is not particularly limited. However, since it has high tensile strength and tensile modulus of elasticity, excellent heat resistance, is difficult to absorb water, and has low volatility, it is particularly useful for space applications. In addition, the molded body according to the embodiment can also be used for applications such as sports goods and transportation equipment such as aircraft and automobiles.

[0048] The manufacturing method of the molded body is not particularly limited except for using the prepreg according to the above-described embodiment, and a known molding method can be adopted. When laminating two or more prepregs to form a laminate, examples of the prepreg lamination method include an automatic lamination method utilizing a robot. Examples of the prepreg molding method include molding by a die pressing method, an autoclave method, a hot / cold pressing method, etc.

Examples

[0049] Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to the following description as long as it does not exceed the gist thereof. The values of various manufacturing conditions and evaluation results in the following examples have the meaning as preferable values of the upper limit or lower limit in the embodiment modes of the present invention, and the preferable range may be a range defined by a combination of the above-mentioned upper limit or lower limit values and the values of the following examples or the values between the examples.

[0050] [Measurement of Tensile Modulus of Elasticity of Reinforcing Fibers] The tensile modulus of elasticity of the reinforcing fibers was calculated by Method A by conducting a tensile test on the reinforcing fibers in accordance with JIS R 7608:2007.

[0051] [Example 1] (Prepreg Production) As the thermoplastic resin, polyetherimide (manufactured by Sabic, Ultem 1000, glass transition temperature: 217 °C, density: 1.27 g / cm 3 ) was extruded into a film form to obtain a film with a thickness of about 23 μm. As the reinforcing fiber, carbon fiber (manufactured by Mitsubishi Chemical Corporation, product name "K63712", 2.0 tex, 12,000 strands, tensile modulus of elasticity: 640 GPa, density: 2.12 g / cm 3 ) was used to obtain a unidirectional (UD) material with a carbon fiber areal density of 150 g / m 2 in which continuous carbon fibers were oriented in one direction. The film was overlaid on the UD material, and the film was heated and melted to impregnate the UD material, thereby producing a unidirectional prepreg. The width of the obtained unidirectional prepreg was about 200 mm.

[0052] (Density measurement) Three points were randomly selected in the width direction of the obtained unidirectional prepreg, and a prepreg for density measurement was sampled. Using an automatic specific gravity meter (manufactured by Toyo Seiki, D-H100), the density was measured by a method compliant with JIS K7112, and the average value of the three points was taken as the density of the unidirectional prepreg. The density measurement was carried out in a thermostatic chamber at 23 °C using pure water. The density of the unidirectional prepreg was 1.77 g / cm 3 .

[0053] (Measurement of resin weight fraction) Three points were randomly selected from the width direction of the unidirectional prepreg, and a prepreg for resin weight fraction measurement was sampled. For the sampled prepreg, the weight fraction of the resin was measured by a method compliant with JIS K7075, and the average value of the three points was taken as the resin weight fraction of the unidirectional prepreg. The resin weight fraction of the unidirectional prepreg was 0.28.

[0054] (Manufacture of molded body) Fifteen pieces of the unidirectional prepreg cut into dimensions of 178 mm × 328 mm were prepared and laminated so that the fiber directions all faced the 0° direction to form a laminate with a thickness of 2 mm. The obtained laminate was placed in the lower die of a titanium mold, and the upper die was closed. Using a heating and cooling two-stage press (manufactured by Shindo Metal Industries Co., Ltd., product name "50-ton press") which is a 50t press machine, in a press machine set at 380°C, the mold was preheated to 380°C in about 10 minutes, and then compression molding was performed for 30 minutes under a molding condition of 5 MPa. Thereafter, the mold was transferred to a press platen adjusted to 80°C, cooled down to 100°C in about 3 minutes, and a molded body (thickness 2 mm) of 180 mm × 330 mm was obtained.

[0055] [Comparative Example 1] As a unidirectional prepreg, a thermosetting pitch CF prepreg (manufactured by Mitsubishi Chemical Corporation, product name "HyE J34M65PD", tensile elastic modulus of carbon fiber: 760 GPa, matrix resin: epoxy resin) was used, and a molded body was manufactured in the same manner as in Example 1 except that autoclave molding was performed at a heating temperature of 200°C, a pressing pressure of 1 MPa, and a heating and pressing time of 720 minutes.

[0056] [Evaluation of Mechanical Properties: 0° Tensile] Test pieces having a width of 12.7 mm and a length of 230 mm were obtained from the molded bodies obtained in each example, and in accordance with ASTM D3039, using a universal testing machine (manufactured by INSTRON, product name "INSTRON 5882"), the 0° tensile strength and 0° tensile elastic modulus were measured under the condition of a crosshead speed = 1.27 mm / min). The results are shown in Table 1.

[0057]

Table 1

[0058] As shown in Table 1, the molded body of Example 1 using a prepreg combining a reinforcing fiber and a thermoplastic resin satisfying the provisions of the present invention had a higher 0° tensile strength and 0° tensile elastic modulus than the molded body of Comparative Example 1 in which the matrix resin was a thermosetting resin.

Claims

1. A prepreg comprising a reinforcing fiber base material and a thermoplastic resin, wherein the reinforcing fiber base material contains reinforcing fibers having a tensile elastic modulus of 420 GPa or more and 940 GPa or less.

2. The prepreg according to Claim 1, wherein the thermoplastic resin contains at least one selected from the group consisting of polyolefin, polyamide, polyester, polyacetal, polyphenylene sulfide, polyaryl ether ketone, polytetrafluoroethylene, polycarbonate, polymethyl methacrylate, polyvinyl chloride, polystyrene, polyether sulfone, polyether imide, polyether ketone, and polyamide imide.

3. The prepreg according to Claim 1, wherein the reinforcing fiber base material is a UD material in which the reinforcing fibers are aligned in one direction.

4. The prepreg according to Claim 1, wherein the reinforcing fibers include carbon fibers.

5. The prepreg according to Claim 4, wherein the carbon fibers include pitch-based carbon fibers.

6. The prepreg according to Claim 5, wherein the pitch-based carbon fibers include mesophase pitch-based carbon fibers.

7. The prepreg according to Claim 1, wherein the content of the thermoplastic resin is 20% by mass or more and 50% by mass or less based on the total mass of the prepreg.

8. A molded article formed by molding the prepreg according to any one of Claims 1 to 7.

9. A method for producing a prepreg, comprising a step of impregnating a reinforcing fiber base material with a thermoplastic resin, wherein the reinforcing fiber base material contains reinforcing fibers having a tensile elastic modulus of 420 GPa or more and 940 GPa or less.

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