Fiber-reinforced resin molded article

Abstract

[Problem] The technical problem of the present invention is to provide a fiber-reinforced resin molded article having excellent dielectric properties, light weight, and high strength. [Solution] This fiber-reinforced resin molded article is provided with polyimide fibers and a resin. The fiber-reinforced resin molded body has a dielectric constant of 4.0 or less at a frequency in the range of 5 GHz to 80 GHz (inclusive), and a dielectric loss tangent of 0.02 or less at the frequency. In addition, the fiber-reinforced resin molded body preferably has a tensile strength in the range of from 0.5 GPa to 2.5 GPa, and preferably has a tensile modulus of elasticity in the range of from 25 GPa to 120 GPa (inclusive).

Description

Technical Field

[0001] The present invention relates to a fiber-reinforced resin molded body having excellent dielectric properties. Background Art

[0002] With the further high-functionality, high-speed and miniaturization of electronic devices such as semiconductor components and mobile communication devices in recent years, the high-speed and high-density wiring of electric signal reception and transmission is developing. As a result, the frequency band of electric signals in electronic components such as semiconductor substrates, printed circuit boards, EMC (Epoxy Molding Compound) and information communication equipment tends to increase. The transmission loss of electric signals is proportional to the dielectric loss tangent of the insulating material and the frequency of the electric signal. Therefore, the higher the frequency of the electric signal, the greater the transmission loss becomes, resulting in attenuation of the electric signal and a reduction in the transmission reliability of the electric signal. In addition, sometimes the transmission loss is converted into heat and caused by heating problems. Therefore, the high-frequency region requires an insulating material with a very small dielectric loss tangent.

[0003] For example, Japanese Patent Publication No. 2016-166347 proposes a prepreg with the problem of providing a high-frequency circuit substrate with excellent dielectric properties. The prepreg has a woven fabric and / or non-woven fabric, and a semi-cured product of a resin composition, wherein the resin composition is filled into the woven fabric and / or non-woven fabric and covers the surface thereof, and the resin composition contains an epoxy resin, a curing agent, and a fluororesin filler. Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent Application Publication No. 2016-166347 Summary of the invention Technical problem to be solved by the invention

[0005] However, in recent years, there has been a demand for further increasing the transmission speed of electric signals, and resin molded bodies have been required to have not only a low dielectric constant but also a dielectric loss tangent for reducing transmission loss.

[0006] The present invention has been made in view of the above background, and an object of the present invention is to provide a fiber-reinforced resin molded body which has excellent dielectric properties, high strength and light weight. Technical means to solve technical problems

[0007] A fiber-reinforced resin molded body according to a first aspect of the present invention comprises polyimide fibers and a resin, and has a dielectric constant of 4.0 or less in a frequency band of 5 GHz to 80 GHz and a dielectric loss tangent of 0.02 or less in the frequency band.

[0008] In the fiber-reinforced resin molded product according to the first aspect of the present invention, it is preferred that the tensile strength be within a range of 0.5 GPa to 2.5 GPa, and the tensile elastic modulus be within a range of 25 GPa to 120 GPa.

[0009] In the fiber-reinforced resin molded article of the first aspect of the present invention, the polyimide fiber is preferably obtained by polymerization reaction of aromatic tetracarboxylic dianhydride and aromatic diamine. In addition, the aromatic tetracarboxylic dianhydride is at least one of pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride, and the aromatic diamine is at least one of 4,4'-diaminodiphenyl ether and p-phenylenediamine.

[0010] In the fiber-reinforced resin molded product according to the first aspect of the present invention, the tensile modulus of the polyimide fiber is preferably within a range of 100 GPa to 170 GPa.

[0011] The prepreg of the second aspect of the present invention is used to manufacture the above-mentioned fiber-reinforced resin molded body. Moreover, the prepreg has polyimide fibers and a resin or a resin precursor. In addition, the "resin precursor" recorded here refers to a monomer composition before curing (including a crosslinking agent, etc.), a polymer precursor, etc. Beneficial Effects

[0012] According to the present invention, it is possible to provide a fiber-reinforced resin molded body which is excellent in dielectric properties, high in strength and light in weight. DETAILED DESCRIPTION

[0013] <Configuration of Fiber-Reinforced Resin Molded Article According to Embodiment of the Invention> The fiber-reinforced resin molded body according to the embodiment of the present invention is mainly composed of polyimide fibers and resin.

[0014] The polyimide fiber is preferably obtained by polymerization reaction of aromatic tetracarboxylic dianhydride and aromatic diamine. The aromatic tetracarboxylic dianhydride is preferably at least one of pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride. The aromatic diamine is preferably at least one of 4,4'-diaminodiphenyl ether and p-phenylenediamine.

[0015] In addition, within the scope of not impairing the gist of the present invention, polyimide fibers may also be used in combination with glass fibers, aramid fibers, (liquid crystal) polyester fibers, polyacrylic fibers, carbon fibers, etc. Among them, from the viewpoint of dielectric properties such as dielectric constant and dielectric loss tangent of the fiber-reinforced resin molded body, it is preferred to use only polyimide fibers.

[0016] The tensile elastic modulus of the polyimide fiber is preferably in the range of 100 GPa to 170 GPa, and more preferably in the range of 110 GPa to 150 GPa.

[0017] In addition, in order to improve the strength of the fiber-reinforced resin molded body of the embodiment of the present invention, it is preferred to make the fiber diameter of the polyimide fiber within the range of 10 μm or more and 18 μm or less. By making the fiber diameter of the polyimide fiber within this range, the rigidity of the polyimide fiber can be made good while the manufacturability of the polyimide fiber is well maintained, and its operability can be maintained, so it is preferred. In addition, the volume content of the polyimide fiber in the fiber-reinforced resin molded body is preferably within the range of 40 volume % or more and 70 volume % or less. In the fiber-reinforced resin molded body, by making the volume content of the polyimide fiber within this range, the bonding performance of the resin and the fiber can be well maintained while the high strength and high elasticity of the polyimide fiber can be shown, and the gap can be reduced, so it is preferred. In addition, the volume content of the polyimide fiber is more preferably within the range of 45 volume % or more and 65 volume % or less.

[0018] As the above-mentioned resin, thermosetting resin and thermoplastic resin can be cited, wherein the thermosetting resin is epoxy resin, phenolic resin, polyimide resin, unsaturated polyester resin, polyphenylene ether resin, etc.; the thermoplastic resin is polyimide resin, polyphenylene ether resin, polysulfone resin, fluorine resin, etc., and the fluorine resin is polytetrafluoroethylene resin, perfluoroalkoxy fluorine resin, etc. Among these resins, epoxy resin and polyimide resin have a good balance between electrical properties and adhesiveness, and are more preferred.

[0019] As the epoxy resin, for example, bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolac epoxy resin, bisphenol A novolac epoxy resin, cresol novolac epoxy resin, diaminodiphenylmethane epoxy resin, and epoxy resins flame-retarded by halogenating part of the hydrogen atoms in these epoxy resin structures, etc. In addition, as the curing agent of the epoxy resin, for example, amide curing agents such as dicyandiamide and aliphatic polyamide, amine curing agents such as diaminodiphenylmethane and triethylenediamine, phenol curing agents such as phenol novolac resin and bisphenol A novolac resin, anhydride compounds, thiol compounds, phenolic resins, amino resins, etc. can be mentioned.

[0020] In addition, as the above-mentioned polyimide resin, for example, a polyimide resin composed of an aromatic tetracarboxylic dianhydride and an aromatic diamine can be mentioned. As the aromatic tetracarboxylic dianhydride, pyromellitic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 2,3, 3',4'-Benzophenonetetracarboxylic dianhydride, 3,3',4,4'-Benzophenonetetracarboxylic dianhydride (BTDA), bis(3,4-dicarboxyphenyl)sulfone dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, 2,2-bis[3,4-(dicarboxyphenoxy)phenyl] [1-(4-(6-(1-(4-(2-(2-(4-(2-(2-((2-((2-((2-(((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((( Aromatic tetracarboxylic dianhydrides such as 9,9-bis[4-(3,4'-dicarboxyphenoxy)phenyl]fluorene dianhydride, cyclobutane tetracarboxylic dianhydride, 1,2,3,4-cyclopentane tetracarboxylic dianhydride, 2,3,4,5-tetrahydrofuran tetracarboxylic dianhydride, 1,2,4,5-cyclohexane tetracarboxylic dianhydride, 3,4-dicarboxy-1-cyclohexyl succinic dianhydride, and 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride.Examples of the aromatic diamine include 4,4'-diaminodiphenyl ether, p-phenylenediamine (PPD), m-phenylenediamine (MPDA), 2,5-diaminotoluene, 2,6-diaminotoluene, 4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 2,2-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane (MDA), 2,2-bis-(4-aminophenyl)propane, 3,3'-diaminodiphenyl sulfone (33DDS), 4,4'-diaminodiphenyl sulfone (44DDS), 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl 1,4-bis(4-aminophenoxy)benzene, bis[4-(3-aminophenoxy)phenyl]sulfone (BAPSM), bis[4-(4-aminophenoxy)phenyl]sulfone (BAPS), 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 2,2-bis(3-aminophenyl)1,1,1,3,3,3-hexafluoropropane, 2,2-bis(4-aminophenyl)1,1,1,3,3,3-hexafluoropropane, 9,9-bis(4-aminophenyl)fluorene, etc.

[0021] In the frequency band of 5 GHz or more and 80 GHz or less, the dielectric constant of the fiber-reinforced resin molded body according to the embodiment of the present invention is 4.0 or less, and the dielectric loss tangent is 0.02 or less. In addition, the dielectric constant is preferably in the range of 1.0 or more and 4.0 or less, and the dielectric loss tangent is preferably in the range of 0 or more and 0.02 or less. In addition, the dielectric constant is more preferably in the range of 1.0 or more and 3.5 or less, and the dielectric loss tangent is more preferably in the range of 0 or more and 0.015 or less. This is because the transmission speed can be increased thereby.

[0022] Regarding the fiber-reinforced resin molded body of the embodiment of the present invention, since the dielectric constant and dielectric loss tangent have no frequency dependence even in a wide band above 5 GHz and below 80 GHz, it can be suitably used in the fields of frames or components of satellite mobile phones and next-generation mobile phones (1.0 GHz to 2.5 GHz), frames or components of network-supported terminals (personal computers, mobile phones, portable game consoles, tablets, portable music players), frames or components of wireless LANs (5 GHz to 60 GHz), frames or components of wireless communications: AWA (22 GHz to 45 GHz), etc., without adjusting the dielectric constant, etc.

[0023] In addition, the tensile strength and tensile modulus of the fiber-reinforced resin molded body of the embodiment of the present invention depend on the fiber direction and fiber volume content contained in the fiber-reinforced resin molded body. Therefore, in order to adjust the tensile strength and tensile modulus of the fiber-reinforced resin molded body, it is necessary to appropriately adjust the fiber direction and fiber volume content contained in the fiber-reinforced resin molded body. For example, if the orientation directions of the fibers in the fiber-reinforced resin molded body are all in the same direction, the tensile strength of the fiber-reinforced resin molded body in the fiber direction (the length direction of the fiber) is preferably within the range of 0.5 GPa or more and 2.5 GPa or less, more preferably within the range of 0.75 GPa or more and 2.5 GPa or less, and further preferably within the range of 1.0 GPa or more and 2.5 GPa or less. Under the same conditions, the tensile modulus of the fiber-reinforced resin molded body is preferably within the range of 25 GPa or more and 120 GPa or less, more preferably within the range of 30 GPa or more and 120 GPa or less, and further preferably within the range of 35 GPa or more and 120 GPa or less.

[0024] <Method for Manufacturing Fiber-Reinforced Resin Molded Article According to Embodiment of the Present Invention> The fiber-reinforced resin molded body according to an embodiment of the present invention can be molded by any one of a method via a prepreg and a method without using a prepreg. The polyimide fiber can be a long fiber or a short fiber cut to any length. As the method via a prepreg, for example, a method of laminating a plurality of prepregs and then heating and pressing the laminate to cure it can be cited. Among them, the prepreg is a prepreg in which a resin is impregnated into a fiber base material composed of the above fibers. In this method, as the form of the fiber base material, a so-called UD sheet in which fibers are arranged unidirectionally, or a fiber base material made by weaving or knitting long fiber filaments can be preferably used. As the fabric, for example, multi-axis fabrics such as bi-axial fabrics and tri-axial fabrics can be cited. As the knitted fabric, a knitted fabric knitted by a weft knitting machine such as a circular knitting machine or a warp knitting machine such as a tricot knitting machine, a raschel knitting machine, or a milanese knitting machine can be cited. As the method without using a prepreg, for example, a method of preparing a varnish having the above resin, impregnating the varnish into a fiber base material, and then heating and pressing it to cure it can be cited. Specifically, a hand lay-up method, a filament winding method, a pultrusion method, etc. can be cited.

[0025] <Examples and Comparative Examples> Hereinafter, examples and comparative examples will be specifically described, but the present invention is not limited to these examples. Example 1

[0026] 1. Production of Polyimide Fiber 136 g of p-phenylenediamine (PPD) and 2224 g of N-methylpyrrolidone were put into a reaction vessel to dissolve PPD in N-methylpyrrolidone. Then, 259.0 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 82.30 g of pyromellitic dianhydride (PMDA) were put into the above reaction vessel, and PMDA and PPD were polymerized at room temperature. As a result, a polyimide precursor solution having a concentration of 17.7% by weight was obtained. Then, a solution in which 21.41 g of 1,3-diazole was dissolved in 40.41 g of N-methylpyrrolidone was added to the polyimide precursor solution to prepare a polyimide precursor solution for spinning. Then, using a spinning ejector, the polyimide precursor solution for spinning was ejected into a coagulation bath mainly composed of water to obtain polyimide precursor fibers. Then, the polyimide precursor fibers were washed with water, stretched, and heated to obtain polyimide fibers.

[0027] The fiber diameter and tensile physical properties of the obtained polyimide fibers were measured by the following methods.

[0028] (1) Fiber diameter The fineness of the polyimide fiber obtained as described above was measured using an automatic vibration fineness measuring instrument DC21 manufactured by SATCH Co., Ltd. The fiber diameter of the polyimide fiber was calculated from the measured fineness and the specific gravity of the polyimide fiber and found to be 14 μm.

[0029] (2) Tensile properties The tensile modulus (cN / dtex) and tensile strength (cN / dtex) of the polyimide fiber obtained as described above were measured by the method according to "JISR7606". Then, the tensile modulus (GPa) of the polyimide fiber was calculated according to the conversion formula of elastic modulus (cN / dtex) × specific gravity ÷ 10. On the other hand, the tensile strength (GPa) of the polyimide fiber was calculated according to the conversion formula of strength (cN / dtex) × specific gravity ÷ 10. As a result, the tensile modulus of the polyimide fiber was 137 GPa and the tensile strength was 3.1 GPa.

[0030] 2. Fabrication of fiber-reinforced resin molded bodies The polyimide fiber obtained as described above was made to have a fiber unit area weight of 56 g / m 2 After being arranged in a specific direction in a manner, an epoxy resin composition obtained by mixing 100% by weight of an epoxy main agent (JER828 manufactured by Mitsubishi Chemikaru Co., Ltd.) and 8% by weight of a curing agent (ADEKA Hardner EH-3636AS manufactured by ADEKA Co., Ltd.) is impregnated into the arranged polyimide fiber, and the polyimide fiber impregnated with the composition is heated at 120°C for 30 minutes in a constant temperature bath to prepare a UD prepreg. Next, the obtained UD prepreg is clamped in a plate-shaped mold for bag molding, and then the UD prepreg is heated and pressurized at 130°C and 6 atmospheres in an autoclave for 90 minutes to obtain a fiber-reinforced resin molded body. In addition, at this time, the heating and cooling rate of the autoclave is 2°C / minute. The thickness of the obtained fiber-reinforced resin molded body is 65μm, and the volume content of the polyimide fiber is 56%.

[0031] In addition, the volume content Vf of the polyimide fiber was determined by the following formula (1). Vf=Faw / ρ / T×100···(1) Here, Faw is the weight per unit area of ​​the polyimide fiber (g / m 2 ), ρ is the density of polyimide fiber (g / cm 3 ), T is the thickness of the fiber-reinforced resin molded body (μm). Here, the density of the polyimide fiber is 1.5 g / cm 3 .

[0032] The dielectric constant, dielectric loss tangent, and tensile properties of the obtained fiber-reinforced resin molded product were measured by the following methods.

[0033] (1) Measurement of dielectric constant and dielectric loss tangent from 5 GHz to 80 GHz Use a vector network analyzer Manufactured by ベクトルネットワークアナライザN5290A), split column resonator (スプリッポストKO Resonator) (manufactured by Kotaku Co., Ltd.) and a separate cylindrical resonator (manufactured by EM Rayman Co., Ltd.) were used to measure fiber-reinforced resin molded articles in the frequency band of 5 GHz to 80 GHz. The dielectric constant (ε) and the dielectric loss tangent are 3.35 at a frequency of 5 GHz, 3.38 at a frequency of 10 GHz, 3.42 at a frequency of 20 GHz, 3.38 at a frequency of 28 GHz, 3.36 at a frequency of 40 GHz, 3.33 at a frequency of 60 GHz, and 3.30 at a frequency of 80 GHz. In addition, the dielectric loss tangent at a frequency of 5 GHz is 0.0123, the dielectric loss tangent at a frequency of 10 GHz is 0.0130, the dielectric loss tangent at a frequency of 20 GHz is 0.0143, the dielectric loss tangent at a frequency of 28 GHz is 0.0137, the dielectric loss tangent at a frequency of 40 GHz is 0.0140, the dielectric loss tangent at a frequency of 60 GHz is 0.0139, and the dielectric loss tangent at a frequency of 80 GHz is 0.0132.

[0034] (2) Tensile properties The fiber-reinforced resin molded body was stretched in the fiber direction (length direction of the fiber) at a tensile speed of 2 mm / min using a precision universal testing machine (AGS-10kNG, manufactured by Shimadzu Corporation), and the tensile modulus and tensile strength of the fiber-reinforced resin molded body were measured. The results showed that the tensile strength of the fiber-reinforced resin molded body was 1.45 GPa, and the tensile modulus was 41.8 GPa. Example 2

[0035] A fiber-reinforced resin molded body was obtained by the same method as described in Example 1 except that the fiber-reinforced resin molded body was produced so that the volume content of the polyimide fiber was 60%.

[0036] The thickness of the obtained fiber-reinforced resin molded body was 62 μm. In addition, the dielectric constant and dielectric loss tangent of the fiber-reinforced resin molded body in the frequency band of 5 GHz to 80 GHz and the tensile properties of the fiber-reinforced resin molded body were measured by the same method as the method described in Example 1. The results showed that the dielectric constant at a frequency of 5 GHz was 3.48, the dielectric constant at a frequency of 10 GHz was 3.48, the dielectric constant at a frequency of 20 GHz was 3.46, the dielectric constant at a frequency of 28 GHz was 3.47, the dielectric constant at a frequency of 40 GHz was 3.42, the dielectric constant at a frequency of 60 GHz was 3.39, and the dielectric constant at a frequency of 80 GHz was 3.38. In addition, the dielectric loss tangent at a frequency of 5 GHz is 0.0120, the dielectric loss tangent at a frequency of 10 GHz is 0.0127, the dielectric loss tangent at a frequency of 20 GHz is 0.0129, the dielectric loss tangent at a frequency of 28 GHz is 0.0125, the dielectric loss tangent at a frequency of 40 GHz is 0.0124, the dielectric loss tangent at a frequency of 60 GHz is 0.0127, and the dielectric loss tangent at a frequency of 80 GHz is 0.0114. In addition, the tensile strength of the fiber-reinforced resin molded body is 1.55 GPa, and the tensile elastic modulus is 44.8 GPa. Example 3

[0037] A fiber-reinforced resin molded body was obtained by the same method as described in Example 1 except that the fiber-reinforced resin molded body was produced so that the volume content of the polyimide fiber was 40%.

[0038] The thickness of the obtained fiber-reinforced resin molded body was 93 μm. In addition, the dielectric constant and dielectric loss tangent of the fiber-reinforced resin molded body in the frequency band of 5 GHz to 80 GHz and the tensile properties of the fiber-reinforced resin molded body were measured by the same method as the method described in Example 1. The results showed that the dielectric constant at 5 GHz was 3.32, the dielectric constant at a frequency of 10 GHz was 3.34, the dielectric constant at a frequency of 20 GHz was 3.31, the dielectric constant at a frequency of 28 GHz was 3.18, the dielectric constant at a frequency of 40 GHz was 3.22, the dielectric constant at a frequency of 60 GHz was 3.20, and the dielectric constant at a frequency of 80 GHz was 3.12. In addition, the dielectric loss tangent at a frequency of 5 GHz is 0.0198, the dielectric loss tangent at a frequency of 10 GHz is 0.0189, the dielectric loss tangent at a frequency of 20 GHz is 0.0197, the dielectric loss tangent at a frequency of 28 GHz is 0.0194, the dielectric loss tangent at a frequency of 40 GHz is 0.0174, the dielectric loss tangent at a frequency of 60 GHz is 0.0165, and the dielectric loss tangent at a frequency of 80 GHz is 0.0194. In addition, the tensile strength of the fiber-reinforced resin molded body is 0.60 GPa, and the tensile elastic modulus is 29.8 GPa. Example 4

[0039] A fiber-reinforced resin molded body was obtained by the same method as described in Example 1 except that the fiber-reinforced resin molded body was produced so that the volume content of the polyimide fiber was 58%.

[0040] The thickness of the obtained fiber-reinforced resin molded body was 64 μm. In addition, the dielectric constant and dielectric loss tangent of the fiber-reinforced resin molded body in the frequency band of 5 GHz to 80 GHz and the tensile properties of the fiber-reinforced resin molded body were measured by the same method as the method described in Example 1. The results showed that the dielectric constant at a frequency of 5 GHz was 3.47, the dielectric constant at a frequency of 10 GHz was 3.46, the dielectric constant at a frequency of 20 GHz was 3.45, the dielectric constant at a frequency of 28 GHz was 3.45, the dielectric constant at a frequency of 40 GHz was 3.43, the dielectric constant at a frequency of 60 GHz was 3.40, and the dielectric constant at a frequency of 80 GHz was 3.39. In addition, the dielectric loss tangent at a frequency of 5 GHz is 0.0137, the dielectric loss tangent at a frequency of 10 GHz is 0.0138, the dielectric loss tangent at a frequency of 20 GHz is 0.0138, the dielectric loss tangent at a frequency of 28 GHz is 0.0134, the dielectric loss tangent at a frequency of 40 GHz is 0.0137, the dielectric loss tangent at a frequency of 60 GHz is 0.0155, and the dielectric loss tangent at a frequency of 80 GHz is 0.0133. In addition, the tensile strength of the fiber-reinforced resin molded body is 1.50 GPa, and the tensile elastic modulus is 43.1 GPa. Example 5

[0041] A fiber-reinforced resin molded body was obtained by the same method as described in Example 1 except that the fiber-reinforced resin molded body was produced so that the volume content of the polyimide fiber was 45%.

[0042] The thickness of the obtained fiber-reinforced resin molded body was 83 μm. In addition, the dielectric constant and dielectric loss tangent of the fiber-reinforced resin molded body in the frequency band of 5 GHz to 80 GHz and the tensile properties of the fiber-reinforced resin molded body were measured by the same method as the method described in Example 1. The results showed that the dielectric constant at a frequency of 5 GHz was 3.34, the dielectric constant at a frequency of 10 GHz was 3.33, the dielectric constant at a frequency of 20 GHz was 3.35, the dielectric constant at a frequency of 28 GHz was 3.25, the dielectric constant at a frequency of 40 GHz was 3.27, the dielectric constant at a frequency of 60 GHz was 3.25, and the dielectric constant at a frequency of 80 GHz was 3.19. In addition, the dielectric loss tangent at a frequency of 5 GHz is 0.0193, the dielectric loss tangent at a frequency of 10 GHz is 0.0195, the dielectric loss tangent at a frequency of 20 GHz is 0.0182, the dielectric loss tangent at a frequency of 28 GHz is 0.0179, the dielectric loss tangent at a frequency of 40 GHz is 0.0190, the dielectric loss tangent at a frequency of 60 GHz is 0.0154, and the dielectric loss tangent at a frequency of 80 GHz is 0.0169. In addition, the tensile strength of the fiber-reinforced resin molded body is 0.75 GPa, and the tensile elastic modulus is 32.1 GPa.

[0043] (Comparative Example 1) The polyimide fibers were replaced with aramid fibers (Kebla (registered trademark) 49 manufactured by Toray Dupon Co., Ltd., fiber diameter: 12 μm, tensile strength: 3.0 GPa, tensile modulus: 112 GPa) and the fiber weight per unit area was adjusted to 54 g / m 2 The same method as described in Example 1 was used to obtain a fiber-reinforced resin molded body except for the above.

[0044] The thickness of the obtained fiber-reinforced resin molded body is 62 μm, and the volume content of the aramid fiber is 56.3%. In addition, the dielectric constant and dielectric loss tangent of the fiber-reinforced resin molded body in the frequency band of 5 GHz to 80 GHz and the tensile properties of the fiber-reinforced resin molded body were measured by the same method as the method described in Example 1. The result is that the dielectric constant at a frequency of 5 GHz is 3.63, the dielectric constant at a frequency of 10 GHz is 3.63, the dielectric constant at a frequency of 20 GHz is 3.58, and the dielectric constant at a frequency of 28 GHz is 3.56. In addition, the dielectric loss tangent at a frequency of 5 GHz is 0.0201, the dielectric loss tangent at a frequency of 10 GHz is 0.0210, the dielectric loss tangent at a frequency of 20 GHz is 0.0226, and the dielectric loss tangent at a frequency of 28 GHz is 0.0223. In addition, the dielectric constant and dielectric loss tangent in the frequency band above 40 GHz cannot be measured due to large losses. The fiber-reinforced resin molded body had a tensile strength of 1.53 GPa and a tensile elastic modulus of 54.1 GPa.

[0045] (Comparative Example 2) A fiber-reinforced resin molded body was obtained in the same manner as in Example 1 except that the polyimide fiber was replaced with a glass fiber (ECG150 1 / 0 manufactured by Nitto Bosei Co., Ltd.).

[0046] The obtained fiber-reinforced resin molded body had a thickness of 70 μm and a volume content of glass fiber of 55.7%. In addition, the dielectric constant and dielectric loss tangent of the fiber-reinforced resin molded body in the frequency band of 5 GHz to 80 GHz and the tensile properties of the fiber-reinforced resin molded body were measured by the same method as described in Example 1. The results showed that the dielectric constant at a frequency of 5 GHz was 4.85, the dielectric constant at a frequency of 10 GHz was 5.03, the dielectric constant at a frequency of 20 GHz was 4.77, the dielectric constant at a frequency of 28 GHz was 4.78, and the dielectric constant at a frequency of 40 GHz was 4.74. In addition, the dielectric loss tangent at a frequency of 5 GHz is 0.0148, the dielectric loss tangent at a frequency of 10 GHz is 0.0162, the dielectric loss tangent at a frequency of 20 GHz is 0.0199, the dielectric loss tangent at a frequency of 28 GHz is 0.0238, and the dielectric loss tangent at a frequency of 40 GHz is 0.0221. In addition, the dielectric constant and dielectric loss tangent in the frequency band above 60 GHz are not measured due to the large loss. In addition, the tensile strength of the fiber reinforced resin molded body is 1.42 GPa, and the tensile elastic modulus is 33.2 GPa.

[0047] (Comparative Example 3) A fiber-reinforced resin molded body was obtained in the same manner as in Example 1 except that the UD prepreg was replaced with a unidirectional carbon fiber prepreg (P3252S-10 manufactured by Toray Industries, Inc.).

[0048] The thickness of the obtained fiber-reinforced resin molded body was 94 μm, and the volume content of carbon fiber was 59%. In addition, an attempt was made to measure the dielectric constant and dielectric loss tangent of the fiber-reinforced resin molded body in the frequency band of 5 GHz to 80 GHz by the same method as described in Example 1, but since the fiber-reinforced resin molded body is a conductor, the dielectric constant and dielectric loss tangent could not be measured. In addition, the tensile properties of the fiber-reinforced resin molded body were measured by the same method as described in Example 1, and the results were that the tensile strength was 2.46 GPa and the tensile elastic modulus was 117.2 GPa.

Claims

1. A fiber-reinforced resin molded body, wherein: The fiber-reinforced resin molded body comprises polyimide fibers and resin. The dielectric constant in the frequency band from 5 GHz to 80 GHz is 4.0 or less. The dielectric loss tangent in the frequency band is 0.02 or less.

2. The fiber-reinforced resin molded body according to claim 1, wherein The tensile strength is within the range of 0.5 GPa or more and 2.5 GPa. The tensile elastic modulus is within a range of 25 GPa to 120 GPa.

3. The fiber-reinforced resin molded body according to claim 1 or 2, wherein: The polyimide fiber is obtained by polymerization reaction of aromatic tetracarboxylic dianhydride and aromatic diamine. The aromatic tetracarboxylic dianhydride is at least one of pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride. The aromatic diamine is at least one of 4,4'-diaminodiphenyl ether and p-phenylenediamine.

4. The fiber-reinforced resin molded body according to claim 1 or 2, wherein: The polyimide fiber has a tensile elastic modulus in a range of 100 GPa to 170 GPa.

5. A prepreg, wherein: The prepreg is a prepreg for producing the fiber-reinforced resin molded body according to claim 1 or 2, and comprises polyimide fibers and a resin or a resin precursor.