Fiber-reinforced resin molding

Abstract

[Problem] To provide a fiber-reinforced resin molded body that excels in dielectric characteristics and product quality and has the same or greater strength and rigidity as that of a fiber-reinforced resin molded body in which a thermosetting resin is used as a matrix resin, even if this fiber-reinforced resin molded body uses a thermoplastic resin as the matrix resin. [Solution] A fiber-reinforced resin molded body comprising an organic long fiber fabric (A) and a thermoplastic resin (B), characterized in that when T (mm) is the thickness of the fiber-reinforced resin molded body and N (sheets) is the number of lamination layers of the organic long fiber fabric (A) constituting the fiber-reinforced resin molded body, the value of T / N is 0.100 or less.

Description

[Technical Field]

[0001] The present invention relates to a fiber-reinforced resin molding comprising an organic long-fiber fabric (A) and a thermoplastic resin (B). [Background technology]

[0002] Fiber-reinforced resin moldings, which are made of a fabric made of reinforcing fibers and a matrix resin, are lightweight and have excellent mechanical properties, and are therefore used in a wide range of fields, such as aircraft materials, vehicle components, electrical and electronic components, and various housings for home appliances, and are effectively used in fields where lightweight, high rigidity, high strength, abrasion resistance, etc. are required. Various reinforcing fibers, such as organic fibers and inorganic fibers, are known for use in fiber-reinforced resin moldings, and typical examples of these include inorganic fibers such as glass fiber and carbon fiber, and organic fibers such as aramid fiber and liquid crystal polyester fiber. Among these, high-strength organic fibers, such as aramid fiber and liquid crystal polyester fiber, are becoming increasingly popular as reinforcing fibers due to their excellent strength and toughness, as well as excellent electrical properties, such as insulation.

[0003] The matrix resins used in fiber-reinforced plastic molded products can be broadly classified into thermosetting resins and thermoplastic resins. Fiber-reinforced plastic molded products that use thermosetting resins as the matrix resin have advantages such as excellent strength, rigidity, and fiber impregnation, but have disadvantages such as long molding cycle times, poor recyclability, and difficulty in quality control of the intermediate substrate. Fiber-reinforced plastic molded products that use thermoplastic resins as the matrix resin have advantages such as short molding cycle times, excellent recyclability, and low production costs, but have disadvantages such as low strength and rigidity, and difficulty in fiber impregnation.

[0004] In the case of fiber-reinforced resin moldings using the above-mentioned thermoplastic resins as matrix resins, a manufacturing method has been investigated to obtain fiber-reinforced resin moldings with high mechanical strength by suppressing the disorder in the orientation of the reinforcing fibers that make up the fiber-reinforced resin molding (Patent Document 1). Furthermore, a method has been studied in which aramid fibers maintained at a specific moisture content are coated with a resin emulsion solution to increase the adhesive strength with thermoplastic resins and enhance the reinforcing effect (Patent Document 2). Additionally, in order to improve shear strength, a thermoplastic composite laminate has been investigated in which the same oligomer as the matrix resin is blended as an adhesive aid into a fabric made of aramid fibers (Patent Document 3).

[0005] Furthermore, with the recent advancement in speed and frequency in computers, mobile devices, and communication infrastructure, there is a growing demand for low-dielectric and ultra-thin film materials with excellent transmission loss in addition to high strength and rigidity. Among these, films or substrates using prepregs containing quartz glass fibers have attracted attention due to their low dielectric constant, dielectric loss, and other properties (Patent Document 4). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-075384 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-145540 [Patent Document 3] Special Publication No. 2019-500241 [Patent Document 4] Japanese Patent Application Publication No. 2019-127492 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a fiber-reinforced resin molding that uses a thermoplastic resin as the matrix resin, but that has strength and rigidity equal to or greater than those of a fiber-reinforced resin molding that uses a thermosetting resin as the matrix resin, and that also has excellent dielectric properties and product quality. [Means for solving the problem]

[0008] As a result of earnest research into achieving the above-mentioned object, the present inventors have found that, when the thickness of a fiber-reinforced resin molding is T (mm) and the number of layers of organic long-fiber fabric constituting the fiber-reinforced resin molding is N (sheets), by controlling the value of T / N within a specific range and, more preferably, by selecting the fibers and resins appropriately, it is possible to provide a fiber-reinforced resin molding that is excellent in strength and rigidity as well as in dielectric properties and product quality, and have arrived at the present invention.

[0009] That is, the present invention is as follows. (1) A fiber-reinforced resin molded body made of an organic long-fiber fabric (A) and a thermoplastic resin (B), characterized in that the value of T / N is 0.100 or less, where T (mm) is the thickness of the fiber-reinforced resin molded body and N (sheets) is the number of layers of the organic long-fiber fabric (A) constituting the fiber-reinforced resin molded body. (2) The fiber-reinforced resin molding according to (1), characterized in that the relative dielectric constant at 10 GHz measured by the method described in IEC 62810 of the fiber-reinforced resin molding is 3.0 or less, and / or the dielectric loss tangent measured by the same method is 0.020 or less. (3) The thermoplastic resin (B) has a bending strength of 90 MPa or more as measured by the method described in JIS K7171, and a bending modulus of 2.0 GPa or more as measured by the same method. (1) A fiber-reinforced resin molding according to (2). (4) The fiber-reinforced resin molding according to any one of (1) to (3) above, wherein the thermoplastic resin (B) has a dielectric loss tangent at 10 GHz measured by the method described in IEC 62810 of 0.020 or less. (5) A fiber-reinforced resin molding according to any one of (1) to (4) above, characterized in that the tensile strength of the organic long fiber measured by the method described in JIS L1013 is 10 cN / dtex or more, and the tensile modulus of elasticity measured by the same method is 400 cN / dtex or more. (6) The fiber-reinforced resin molding according to any one of (1) to (5) above, wherein the organic long-fiber fabric (A) has a cover factor (CF) calculated by the following formula (I) of 900 or more: CF = √Dp × Np + √Df × Nf ···(I) Where Dp: warp fineness (dtex) Np: Warp density (threads / 25.4mm) Df: Weft fineness (dtex) Nf: Weft density (count / 25.4mm) (7) The fiber-reinforced resin molding according to any one of (1) to (6), wherein the organic long-fiber fabric (A) is a woven fabric, and the woven fabric density of the warp and weft yarns measured by the method described in JIS L1096 is 15 to 50 yarns / 25.4 mm. (8) The fiber-reinforced resin molding according to any one of (1) to (7) above, wherein the organic long fiber is any one of aramid fiber, polyphenylene sulfide fiber, polyparaphenylene benzobisoxazole fiber, high-strength polyethylene fiber, liquid crystal polyester fiber, and polyarylate fiber, or a combination of two or more thereof. (9) The fiber-reinforced resin molding according to any one of (1) to (8) above, wherein the organic long fiber has a relative dielectric constant of 4.0 or less at 10 GHz as measured by the method described in IEC 62810. [Effects of the Invention]

[0010] According to the present invention, it is possible to obtain a fiber-reinforced resin molding that has rigidity and strength equal to or greater than that of a fiber-reinforced resin molding that uses a thermosetting resin as the matrix resin, and that also has excellent product quality such as dielectric properties and appearance. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing an example of a method for molding a fiber-reinforced resin molded article of the present invention. [Figure 2] 1 is a cross-sectional view showing an example of a fiber-reinforced resin molded article (Example 1) of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail. The fiber-reinforced resin molded product of the present invention is a fiber-reinforced resin molded product comprising an organic long-fiber fabric (A) and a thermoplastic resin (B), characterized in that the value of T / N is 0.100 or less, where T (mm) is the thickness of the fiber-reinforced resin molded product and N (sheets) is the number of layers of the organic long-fiber fabric (A) constituting the fiber-reinforced resin molded product.

[0013] <Organic long fiber fabric (A)> Examples of organic long fibers constituting the organic long-fiber fabric (A) used in the present invention include those selected from aramid (wholly aromatic polyamide) fibers, polyphenylene sulfide fibers, polyimide fibers, polyparaphenylene benzobisoxazole fibers, polyparaphenylene benzobisthiazole fibers, polyether ether ketone fibers, polytetrafluoroethylene fibers, high-strength polyethylene fibers, liquid crystal polyester fibers, polyarylate fibers, etc. These organic long fibers may be used alone or in combination of two or more.

[0014] Among them, the tensile strength measured according to the method described in JIS L1013:2010 "Testing method for chemical fiber filament yarn" is 10 cN / dtex or more and the tensile modulus is 400 cN / dtex. End High-strength organic long fibers having a tensile strength of 15 cN / dtex or more and a tensile modulus of 600 cN / dtex or more are preferred, and those having a tensile strength of 15 cN / dtex or more and a tensile modulus of 600 cN / dtex or more are more preferred. Specifically, aramid (fully aromatic polyamide) fibers, polyparaphenylene benzobisoxazole fibers, high-strength polyethylene fibers, liquid crystal polyester fibers, and polyarylate fibers are preferred. By using organic long fibers having a tensile strength of 10 cN / dtex or more and a tensile modulus of 400 cN / dtex or more, the strength and rigidity of the fiber-reinforced resin molding can be sufficiently achieved. Furthermore, these organic long fibers are preferred because they are non-conductive fibers that do not impair radio wave transparency and also have excellent dielectric properties. Among these, those with low intramolecular polarity or bulky molecular structures have particularly excellent dielectric properties.

[0015] The aramid fiber is not particularly limited as long as it is a fiber having at least one divalent aromatic group, which may be substituted, in the repeating unit of the polymer forming the fiber and has at least one amide bond, and may be what is called a wholly aromatic polyamide fiber or an aramid fiber. The "divalent aromatic group, which may be substituted" means a divalent aromatic group, which may have one or more identical or different substituents. Examples of aramid fibers include para-aramid fibers and meta-aramid fibers, with para-aramid fibers being preferred due to their excellent tensile strength. Such aramid fibers are commercially available, and specific examples of para-aramid fibers include polyparaphenylene terephthalamide fibers (manufactured by DuPont USA, Toray DuPont Co., Ltd., trade name "Kevlar" (registered trademark)) and copolyparaphenylene-3,4'-oxydiphenylene terephthalamide fibers (manufactured by Teijin Limited, trade name "Technora" (registered trademark)). Among these para-aramid fibers, polyparaphenylene terephthalamide fibers are particularly preferred due to their excellent tensile strength.

[0016] The liquid crystalline polyester constituting the liquid crystalline polyester fiber is a polyester that can form an anisotropic molten phase (liquid crystallinity) when melted. This property can be confirmed, for example, by placing a sample on a hot stage, heating it under a nitrogen atmosphere, and observing the transmitted light through the sample under polarized light.

[0017] Examples of the liquid crystal polyester include (i) a polymer of an aromatic hydroxycarboxylic acid, (ii) a polymer of an aromatic dicarboxylic acid and a diol selected from an aromatic diol and an aliphatic diol, and (iii) a copolymer of the above (i) and the above (ii), which are produced by a conventionally known method. Among the above (co)polymers, those composed only of aromatic compounds are preferred. (Co)polymers composed only of aromatic compounds exhibit excellent strength and elastic modulus when made into fibers.

[0018] Examples of the aromatic oxycarboxylic acid include hydroxybenzoic acid, hydroxynaphthoic acid, etc., and alkyl, alkoxy, and halogen-substituted derivatives thereof. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, diphenyldicarboxylic acid, naphthalenedicarboxylic acid, diphenyletherdicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenylethanedicarboxylic acid, etc., and alkyl, alkoxy, and halogen-substituted derivatives thereof. Examples of the aromatic diol include hydroquinone, resorcinol, dihydroxybiphenyl, naphthalenediol, etc., and alkyl, alkoxy, and halogen-substituted derivatives thereof. Examples of the aliphatic diol include ethylene glycol, propylene glycol, butanediol, and neopentyl glycol.

[0019] Examples of commercially available liquid crystal polyester fibers include "Zexion (registered trademark)" manufactured by KB Seiren Co., Ltd., "Vectran (registered trademark)" manufactured by Kuraray Co., Ltd., and "Sumikasuper (registered trademark) LCP" manufactured by Sumitomo Chemical Co., Ltd. These liquid crystal polyester fibers can be used alone or in combination of two or more.

[0020] The total fineness of the organic long fibers is not particularly limited, but is usually 50 to 10,000 dtex, preferably 100 to 5,000 dtex, and more preferably 200 to 2,500 dtex. A relatively thin fabric is desirable because it facilitates impregnation of the thermoplastic resin into the fabric and thereby prevents warping of the fabric. To achieve this, it is desirable to use an organic long fiber bundle with a small total fineness. The total fineness of the organic long fibers is more preferably 200 to 500 dtex. Furthermore, long fiber bundles such as air-entangled yarns obtained by subjecting organic long fibers to taslan processing, interlacing, etc.; twisted-heat-set-untwisted yarns (crimped yarns); false-twist textured yarns; and push-textured yarns can also be used, provided that the effects of the present invention are not impaired.

[0021] The moisture content of the organic long fibers is not particularly limited, but is usually less than 15% by mass, preferably less than 10% by mass, and more preferably less than 7% by mass, when the bone dry mass of the entire fiber is taken as 100. If moisture accumulates on the surface of the fibers used to make a composite material, transmission loss may change and dielectric properties may deteriorate. Therefore, to reduce transmission loss in the high frequency band, it is desirable to use organic long fibers with low water absorption. The moisture content of the organic long fibers is more preferably less than 5% by mass.

[0022] The moisture content (mass%) was measured according to the following method: the mass of approximately 5 g of sample was measured, treated at 105°C for 4 hours, left at 24°C and 55% RH for 5 minutes, and then the mass was measured again. The moisture content used here is the dry basis moisture content, calculated by {([mass before drying - mass after drying] / [mass after drying]) × 100}.

[0023] The organic long fibers preferably have a relative dielectric constant of 4.0 or less at 10 GHz measured by the method described in IEC 62810 (cavity resonator perturbation method), more preferably 3.8 or less, and even more preferably 3.6 or less. If the organic long fibers have a relative dielectric constant of 4.0 or less, a fiber-reinforced resin molding with excellent dielectric properties can be obtained.

[0024] The organic long fiber fabric (A) used in the present invention is characterized in that it can give a fiber-reinforced resin molding having excellent strength, rigidity and dielectric properties without any special pretreatment. A pretreatment may be carried out as necessary to improve the adhesion between the organic long fibers constituting the organic long-fiber fabric (A) and the thermoplastic resin (B), thereby improving the properties of the resulting fiber-reinforced resin molding. The pretreatment may be carried out on the entire organic long fibers or fabric, or on only a portion, preferably only the bonding surface.

[0025] Suitable examples of the pretreatment include a method of applying a reactive organic compound together with an oil to the organic long fiber (e.g., Japanese Patent No. 5676337), a treatment of preheating the organic long fiber or fabric, a corona discharge treatment, an electron irradiation treatment, an ultraviolet irradiation treatment, a flame plasma treatment, an atmospheric pressure plasma treatment, or a low pressure plasma treatment. The pretreatment may be performed using known means, such as a corona discharge device, hot air heating, or heating with a heater. These means may be used alone or in combination of two or more means. Such treatments generate a certain number of activation points on the bonding surface of the organic long fiber or fabric, enabling strong bonding with the thermoplastic resin.

[0026] As the organic long-fiber fabric (A), long fibers processed by a known method can be used, and woven fabrics, knitted fabrics, etc. can be preferably used. The thickness of a single fabric is not particularly limited, but from the viewpoint of achieving weight reduction, cost reduction, and performance improvement of the fiber-reinforced resin molded article, it is preferably 0.03 to 0.30 mm, more preferably 0.05 to 0.20 mm, and even more preferably 0.06 to 0.15 mm. By reducing the thickness, it is possible to reduce the crimp of the fabric, and the strength and rigidity of the fiber-reinforced resin molded article can be more easily expressed. The thickness of the organic long-fiber fabric (A) can be measured by the method described in JIS L1096:2020.

[0027] Examples of the woven fabric include a tow sheet in which organic long fibers are oriented in one direction, a unidirectional or bidirectional woven fabric in which organic long fibers are oriented in one or two directions, a triaxial woven fabric in which organic long fibers are oriented in three directions, etc. Examples of the weave include a plain weave, a twill weave, a satin weave, etc. Examples of knitted fabrics include those knitted by weft knitting machines such as circular knitting machines, and warp knitting machines such as tricot knitting machines, raschel knitting machines, and Milanese knitting machines.

[0028] The organic long-fiber fabric (A) preferably has a cover factor (CF) represented by the following formula (I) of 900 to 1,800, more preferably 950 to 1,500. If the cover factor (CF) is 900 or more, there is no risk that the fabric structure will be disturbed by the molten resin when the thermoplastic resin (B) is plasticized and impregnated, resulting in deterioration of the product condition. If the cover factor (CF) exceeds 1,800, it becomes difficult to impregnate the organic long-fiber fabric (A) with the thermoplastic resin (B), and the product thickness may also increase. CF = √Dp × Np + √Df × Nf ···(I) Where Dp: warp fineness (dtex) Np: Warp density (threads / 25.4mm) Df: Weft fineness (dtex) Nf: Weft density (count / 25.4mm)

[0029] The weight per unit area of ​​the organic long fiber fabric (A) is 20 to 200 g / m from the viewpoint of imparting sufficient strength and rigidity while suppressing the thickness of the obtained fiber reinforced resin molding. 2 is preferable, and more preferably 50 to 100 g / m 2 The tensile strength of the fabric measured by the method described in JIS L1096 is preferably 100 to 500 kgf / 25.4 mm, and more preferably 110 to 300 kgf / 25.4 mm, from the viewpoint of imparting sufficient strength and rigidity to the resulting fiber-reinforced resin molding. The basis weight of the organic long-fiber fabric (A) can be measured by the method described in JIS L1096:2020.

[0030] The fabric density (warp and weft density) measured by the method described in JIS L1096:2020 is preferably 15 to 50 threads / 25.4 mm, more preferably 25 to 40 threads / 25.4 mm. If the fabric density is less than 15 threads / 25.4 mm, the fabric structure may be disrupted by the molten resin when the thermoplastic resin (B) is plasticized and impregnated, which may result in a deterioration in the product condition. If the fabric density exceeds 50 threads / 25.4 mm, it may become difficult to plasticize and impregnate the thermoplastic resin (B), resulting in the generation of unimpregnated regions and a decrease in the mechanical strength of the fiber-reinforced resin molding.

[0031] <Thermoplastic resin (B)> The thermoplastic resin (B) used in the present invention can be appropriately selected depending on the purpose, and specific examples include polypropylene resin, polyethylene resin, ABS resin, polycarbonate resin, polyacetal resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyphenylene sulfide resin, polyamide resin, modified polyphenylene ether resin, liquid crystal polyester resin, polyimide resin, syndiotactic polystyrene resin, polycyclohexanedimethylene terephthalate resin, etc. These can be used not only as a single polymer but also as a resin alloyed with two or more types, for example, by compounding.

[0032] Among the above resins, those with excellent material strength and rigidity are preferred, such as polycarbonate resin, polyacetal resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyphenylene sulfide resin, polyamide resin, modified polyphenylene ether resin, liquid crystal polyester resin, polyimide resin, syndiotactic polystyrene resin, polycyclohexanedimethylene terephthalate resin, etc. Furthermore, those with low intramolecular polarity or bulky molecular structure also have excellent dielectric properties.

[0033] The thermoplastic resin (B) may contain additives as needed, provided that the effects of the present invention are not impaired. Examples of additives include heat stabilizers, light stabilizers, UV absorbers, antioxidants, lubricants, nucleating agents, plasticizers, color inhibitors, matting agents, antibacterial agents, deodorizers, flame retardants, antistatic agents, mold release agents, fillers (carbon fiber, glass fiber, glass beads, hollow glass, talc, and other fillers), pigments, and dyes. One or more additives selected from these additives may be blended. The amounts of these additives may be those typically used.

[0034] The thermoplastic resin (B) preferably has a dielectric loss tangent of 0.020 or less, more preferably 0.015 or less, and even more preferably 0.010 or less at 10 GHz, as measured by the method (cavity resonator perturbation method) described in IEC 62810. When the dielectric loss tangent is in this range, a fiber-reinforced resin molding having excellent dielectric properties can be obtained.

[0035] The water absorption of the thermoplastic resin (B) is not particularly limited, but is preferably 0.3% or less, more preferably 0.2% or less, as measured by the method described in JIS K 7209. Since water absorption may change transmission loss and reduce dielectric properties, and may also cause foaming due to heat during molding, resulting in poor appearance, a relatively low water absorption is preferred.

[0036] The thermoplastic resin (B) preferably has a flexural strength of 90 MPa or more and a flexural modulus of 2.0 GPa or more, and more preferably a flexural strength of 95 MPa or more and a flexural modulus of 2.2 GPa or more, as measured by the method described in JIS K 7171. When the flexural strength and flexural modulus are within these ranges, a fiber-reinforced resin molding having excellent strength and rigidity can be obtained.

[0037] <Fiber-reinforced resin molding> The fiber-reinforced resin molding of the present invention is composed of an organic long-fiber fabric (A) and a thermoplastic resin (B), and the volume content (fiber volume content) of the organic long-fiber fabric (A) in the entire fiber-reinforced resin molding is preferably 30 to 80 volume %, more preferably 30 to 70 volume %, and even more preferably 40 to 60 volume %. If the fiber volume content is less than 30 volume %, the strength and rigidity of the resulting fiber-reinforced resin molding will be insufficient, while if it exceeds 80 volume %, the processing conditions will become strict, and the quality of the product (such as fiber leakage and appearance) may be deteriorated.

[0038] It is important that the fiber-reinforced resin molded body of the present invention has a T / N value of 0.100 or less, preferably 0.090 or less, and more preferably 0.080 or less, where T (mm) is the thickness of the fiber-reinforced resin molded body and N (sheets) is the number of layers of the organic long-fiber fabric (A) constituting the fiber-reinforced resin molded body. If the T / N value exceeds 0.100, the strength or rigidity of the fiber-reinforced resin molded body will be insufficient. By setting the T / N value to 0.100 or less and highly compressing the fabric in the composition to reduce the effect of crimp, the obtained fiber-reinforced resin molded body exhibits excellent strength and rigidity.

[0039] The fiber-reinforced resin molding of the present invention can be obtained by impregnating an organic long-fiber fabric (A) with a thermoplastic resin (B), and the impregnation rate is preferably 95% or more, more preferably 97% or more. The "impregnation rate" used here is defined as the ratio of the area of ​​the region impregnated with the thermoplastic resin (B) to the total area of ​​the exposed cross section when the obtained fiber-reinforced resin molding is cut at any point. If the impregnation rate is less than 95%, the mechanical properties of the obtained fiber-reinforced resin molding may be reduced and the quality may vary greatly.

[0040] The fiber-reinforced resin molding of the present invention preferably has a bending strength of 280 MPa or more, more preferably 300 MPa or more, as measured by the method (three-point bending test) described in JIS K7074. A bending strength of 280 MPa or more ensures sufficient strength of the fiber-reinforced resin molding. The flexural modulus measured by the same method is preferably 18 GPa or more, more preferably 20 GPa or more, and even more preferably 22 GPa or more. A flexural modulus of 18 GPa or more ensures sufficient rigidity of the fiber-reinforced resin molding.

[0041] The fiber-reinforced resin molding of the present invention has excellent dielectric properties. Specifically, the dielectric constant at 10 GHz measured by the method described in IEC 62810 (cavity resonator perturbation method) is 3.0 or less, and / or the dielectric loss tangent measured by the same method is 0.020 or less. The dielectric constant is more preferably 2.9 or less, even more preferably 2.8 or less. The dielectric loss tangent is more preferably 0.019 or less, even more preferably 0.018 or less. It is desirable to satisfy both or either of these requirements, and it is even more desirable to satisfy both. When the dielectric constant is within this range, it becomes easy to apply it to low-dielectric materials suitable for high-frequency applications. Generally, when there is a difference in the dielectric constant at the interface of different materials, refraction and reflection of radio waves occur there, so it is preferable to select a combination of materials with relatively similar dielectric constants. Furthermore, satisfying both requirements not only enables efficient transmission of high-frequency signals, but also has the advantage of suppressing signal degradation caused by the materials.

[0042] In the present invention, the relative dielectric constant refers to the ratio of a property (dielectric constant) that indicates the degree of polarization of electrons when a voltage is applied to an insulator to the dielectric constant of a vacuum. The lower the relative dielectric constant, the smaller the amount of electrostatic energy stored in the insulator, resulting in better insulation. The dielectric loss tangent is a characteristic that indicates the degree of dielectric loss, which occurs when an AC voltage is applied to an insulator, causing a portion of the electrical energy to be lost as heat energy due to polarization. The higher the dielectric loss tangent of a material, the greater the dielectric loss. Furthermore, temperature increases in molded products due to dielectric loss can lead to a decrease in insulation properties and malfunctions in built-in electronic circuits.

[0043] In the fiber-reinforced resin molding of the present invention, the organic long fibers and thermoplastic resin preferably have a molecular structure with low intramolecular polarity or a bulky structure, and more preferably have a molecular structure with low intramolecular polarity and a bulky structure. This allows for the production of a fiber-reinforced resin molding with particularly excellent dielectric properties. Examples of such organic long fibers include aramid fibers, polyparaphenylene benzobisoxazole fibers, and liquid crystal polyester fibers. Examples of thermoplastic resins include polycarbonate resins, polybutylene terephthalate resins, polyphenylene sulfide resins, and liquid crystal polyester resins.

[0044] The method for producing the fiber-reinforced resin molding of the present invention is not particularly limited as long as it can integrate the organic long-fiber fabric (A) and the thermoplastic resin (B). Examples include a method in which the organic long-fiber fabric (A) is laminated with a film made of the thermoplastic resin (B) and then heated and pressed by a heat press or the like; a method in which the organic long-fiber fabric (A) is laminated with a powder made of the thermoplastic resin (B) and then heated and pressed by a heat press or the like; and a method in which the organic long-fiber fabric (A) is melt-impregnated with the thermoplastic resin (B) in advance to prepare a prepreg, and then heated and pressed by a heat press or the like.

[0045] Fig. 1 shows an example of a method for molding a fiber-reinforced resin molding of the present invention, in which four sheets of organic long-fiber fabric (10) and five sheets of thermoplastic resin film (20) are alternately laminated together, heated and pressurized, and then cooled and pressurized. Fig. 1 shows a method in which organic long-fiber fabric (A) and thermoplastic resin (B) are alternately laminated together, but in the present invention, the method for laminating the organic long-fiber fabric and thermoplastic resin film is not particularly limited as long as the organic long-fiber fabric (A) can be sufficiently impregnated with the thermoplastic resin (B). [Example]

[0046] The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto. In the following examples, "parts by weight" will be abbreviated to "parts" unless otherwise specified. The evaluation methods described in the examples are as follows.

[0047] (1) Fiber volume content of fiber-reinforced resin molding The weight (W) of the organic long fiber in the reinforced fiber resin molding was calculated from the size of the molded product and the number of layers, and the fiber volume content (V) was calculated using the following formula. f ) is found. W f = W / W F × 100 V f = W f × ρ c / ρ f W f : Fiber mass content (%) W : Weight of organic long fiber in fiber-reinforced resin molding (g) W F : Weight of fiber-reinforced resin molding (g) V f : Fiber volume content (%) ρ c : Density of fiber-reinforced resin molding (g / cm 3 ) ρ f : Density of organic long fiber (g / cm 3 )

[0048] (2) Bending strength and bending modulus of fiber-reinforced resin moldings The method (three-point bending test) described in JIS K7074 was followed.

[0049] (3) Thickness of fiber-reinforced resin molding (T) The thickness of the fiber-reinforced resin molding was measured at three arbitrary points using a caliper, and the average value was taken as the thickness (T). The value was measured to two decimal places.

[0050] (4) Flexural strength and flexural modulus of thermoplastic resin The method described in JIS K7171:2016 "Plastics - Determination of bending properties" was followed.

[0051] (5) Fabric thickness, basis weight, fabric density, tensile strength The methods described in JIS L1096:2020 "Testing methods for woven and knitted fabrics" were followed. Fabric thickness was measured according to 8.4 A method, basis weight according to 8.3.2 A method, fabric density according to 8.6.1 A method, and tensile strength according to 8.14.1 A method.

[0052] (6) Fabric distortion The appearance of the obtained fiber reinforced resin molding was evaluated according to the following criteria. 〇: Almost no distortion, good. △: Some distortion can be seen.

[0053] (7) Dielectric constant and dielectric loss tangent of fiber-reinforced resin moldings The method (cavity resonator perturbation method) described in IEC 62810 was followed. A network analyzer (Keysight Technologies) and a cavity resonator (Kanto Electronics Application Development Co., Ltd.) were connected using fiber-reinforced resin moldings, and the relative permittivity and dielectric loss tangent of each molding at a frequency of 10 GHz were measured.

[0054] Table 1 shows the details of the organic long fiber fabrics (A-1) to (A-3) used in the examples.

[0055] [Table 1]

[0056] Details of the thermoplastic resins (B-1) and (B-2) used in the examples are shown in Table 2. The melting point temperature and glass transition temperature are values ​​measured by differential scanning calorimetry.

[0057] [Table 2]

[0058] [Example 1] Four sheets of the organic long-fiber fabric (A-1) shown in Table 1 and five sheets of the thermoplastic resin (B-1) film shown in Table 2 were alternately laminated and heated for 5 minutes in a manual heat press (Toyo Seiki Co., Ltd. "Mini Test Press") at 300 ° C. × 0 MPa (gauge pressure). After the thermoplastic resin (B-1) film was fully plasticized, a pressure of 5 MPa (gauge pressure) was applied for 1 minute while controlling the thickness and fiber volume content of the fiber-reinforced resin molded body. The organic long-fiber fabric (A-1) was impregnated with the thermoplastic resin (B-1). After applying pressure for 1 minute, the material was cooled and solidified in a cooling press at 20 ° C. to obtain a fiber-reinforced resin molded body.

[0059] [Example 2] Five sheets of the organic long-fiber fabric (A-1) shown in Table 1 and six sheets of the thermoplastic resin (B-1) film shown in Table 2 were alternately laminated and heated for 5 minutes in a manual heat press (Toyo Seiki Co., Ltd. "Mini Test Press") at 300 ° C. × 0 MPa (gauge pressure). After the thermoplastic resin (B-1) film was fully plasticized, a pressure of 10 MPa (gauge pressure) was applied for 1 minute while controlling the thickness and fiber volume content of the fiber-reinforced resin molded body. The organic long-fiber fabric (A-1) was impregnated with the thermoplastic resin (B-1). After applying pressure for 1 minute, the material was cooled and solidified in a cooling press at 20 ° C. to obtain a fiber-reinforced resin molded body.

[0060] [Example 3] Five sheets of the organic long-fiber fabric (A-1) shown in Table 1 and six sheets of the thermoplastic resin (B-1) film shown in Table 2 were alternately laminated and heated for 5 minutes in a manual heat press (Toyo Seiki Co., Ltd. "Mini Test Press") at 300 ° C. × 0 MPa (gauge pressure). After the thermoplastic resin (B-1) film was fully plasticized, a pressure of 5 MPa (gauge pressure) was applied for 1 minute while controlling the thickness and fiber volume content of the fiber-reinforced resin molded body. The organic long-fiber fabric (A-1) was impregnated with the thermoplastic resin (B-1). After applying pressure for 1 minute, the material was cooled and solidified in a cooling press at 20 ° C. to obtain a fiber-reinforced resin molded body.

[0061] [Example 4] Six sheets of the organic long-fiber fabric (A-2) shown in Table 1 and seven sheets of the thermoplastic resin (B-1) film shown in Table 2 were alternately laminated and heated for 5 minutes in a manual heat press (Toyo Seiki Co., Ltd. "Mini Test Press") at 300 ° C. and 0 MPa (gauge pressure). After the thermoplastic resin (B-1) film was fully plasticized, a pressure of 10 MPa (gauge pressure) was applied for 1 minute while controlling the thickness and fiber volume content of the fiber-reinforced resin molded body. The organic long-fiber fabric (A-2) was impregnated with the thermoplastic resin (B-1). After applying pressure for 1 minute, the material was cooled and solidified in a cooling press at 20 ° C. to obtain a fiber-reinforced resin molded body.

[0062] [Example 5] Five sheets of the organic long-fiber fabric (A-2) shown in Table 1 and six sheets of the thermoplastic resin (B-1) film shown in Table 2 were alternately laminated and heated for 5 minutes in a manual heat press (Toyo Seiki Co., Ltd. "Mini Test Press") at 300 ° C. × 0 MPa (gauge pressure). After the thermoplastic resin (B-1) film was fully plasticized, a pressure of 5 MPa (gauge pressure) was applied for 1 minute while controlling the thickness and fiber volume content of the fiber-reinforced resin molded body. The organic long-fiber fabric (A-2) was impregnated with the thermoplastic resin (B-1). After applying pressure for 1 minute, the material was cooled and solidified in a cooling press at 20 ° C. to obtain a fiber-reinforced resin molded body.

[0063] [Example 6] Molding was carried out under the same conditions as in Example 5, except that the organic long fiber fabric (A-3) shown in Table 1 was used, to obtain a fiber-reinforced resin molding.

[0064] [Example 7] Four sheets of the organic long-fiber fabric (A-1) shown in Table 1 and five sheets of the thermoplastic resin (B-2) film shown in Table 2 were alternately laminated and heated for 5 minutes in a manual heat press (Toyo Seiki Co., Ltd. "Mini Test Press") at 250 ° C. and 0 MPa (gauge pressure). After the thermoplastic resin (B-2) film was fully plasticized, a pressure of 5 MPa (gauge pressure) was applied for 1 minute while controlling the thickness and fiber volume content of the fiber-reinforced resin molded body. The organic long-fiber fabric (A-1) was impregnated with the thermoplastic resin (B-2). After applying pressure for 1 minute, the material was cooled and solidified in a cooling press at 20 ° C. to obtain a fiber-reinforced resin molded body.

[0065] [Comparative Example 1] An organic long-fiber fabric (A-1) shown in Table 1 was impregnated with a one-component curing epoxy resin composition prepared by uniformly mixing 100 parts of jER828 and jER1001 (bisphenol A glycidyl ether (epoxy equivalent: 189) manufactured by Mitsubishi Chemical Corporation) (jER828:jER1001=50:50% by weight), 5 parts of dicyandiamide, and 5 parts of 3-(3,4-dichlorophenyl)-1,1-dimethylurea, to obtain a fabric with a basis weight of 136 g / m. 2 A prepreg with a thickness of 0.13 mm was obtained. Four sheets of the obtained prepreg were stacked and heat-cured in a manual heat press ("Mini Test Press" manufactured by Toyo Seiki Seisaku-sho, Ltd.) under conditions of 120°C x 7 MPa (gauge pressure) x 2 hours while controlling the thickness and fiber volume content of the fiber-reinforced resin molded body, thereby obtaining a fiber-reinforced resin molded body.

[0066] Comparative Example 2 Three sheets of the organic long-fiber fabric (A-1) shown in Table 1 and four sheets of the thermoplastic resin (B-1) film shown in Table 2 were alternately laminated and heated for 5 minutes in a manual heat press (Toyo Seiki Co., Ltd. "Mini Test Press") at 300 ° C. × 0 MPa (gauge pressure). After the thermoplastic resin (B-1) film was fully plasticized, a pressure of 2 MPa (gauge pressure) was applied for 1 minute while controlling the thickness and fiber volume content of the fiber-reinforced resin molded body. The organic long-fiber fabric (A-1) was impregnated with the thermoplastic resin (B-1). After applying pressure for 1 minute, the material was cooled and solidified in a cooling press at 20 ° C. to obtain a fiber-reinforced resin molded body.

[0067] Comparative Example 3 Four sheets of the organic long-fiber fabric (A-1) shown in Table 1 and five sheets of the thermoplastic resin (B-1) film shown in Table 2 were alternately laminated and heated for 5 minutes in a manual heat press (Toyo Seiki Co., Ltd. "Mini Test Press") at 300 ° C. × 0 MPa (gauge pressure). After the thermoplastic resin (B-1) film was fully plasticized, a pressure of 2 MPa (gauge pressure) was applied for 1 minute while controlling the thickness and fiber volume content of the fiber-reinforced resin molded body. The organic long-fiber fabric (A-1) was impregnated with the thermoplastic resin (B-1). After applying pressure for 1 minute, the material was cooled and solidified in a cooling press at 20 ° C. to obtain a fiber-reinforced resin molded body.

[0068] Comparative Example 4 Four sheets of the organic long-fiber fabric (A-1) shown in Table 1 and five sheets of the thermoplastic resin (B-1) film shown in Table 2 were alternately laminated and heated for 5 minutes in a manual heat press (Toyo Seiki Co., Ltd. "Mini Test Press") at 300 ° C. × 0 MPa (gauge pressure). After the thermoplastic resin (B-1) film was fully plasticized, a pressure of 3 MPa (gauge pressure) was applied for 1 minute while controlling the thickness and fiber volume content of the fiber-reinforced resin molded body. The organic long-fiber fabric (A-1) was impregnated with the thermoplastic resin (B-1). After applying pressure for 1 minute, the material was cooled and solidified in a cooling press at 20 ° C. to obtain a fiber-reinforced resin molded body.

[0069] 2 shows a cross-sectional schematic diagram of the fiber-reinforced resin molded body obtained in Example 1. From the thickness (T=0.35 mm) of the obtained fiber-reinforced resin molded body and the number of fabrics (N=4), T / N=0.088.

[0070] The evaluation results of the examples and comparative examples are shown in Table 3.

[0071] [Table 3]

[0072] As shown in Table 3, it is clear that fiber reinforced resin moldings with a T / N value exceeding 0.100 are insufficient in flexural strength or flexural modulus, or both (Comparative Examples 2 to 4). On the other hand, the fiber reinforced resin moldings of the present invention exhibit superior flexural strength to the fiber reinforced resin molding (Comparative Example 1) using a thermosetting resin as the matrix resin, and are also superior in flexural modulus in Examples 1, 2, and 4. Furthermore, Examples 4 to 7 are also superior in appearance.

[0073] As shown in Table 3, it was found that the fiber-reinforced resin molding using a thermoplastic resin as the matrix resin exhibited better dielectric properties than the fiber-reinforced resin molding using a thermosetting resin as the matrix resin (Comparative Example 1), demonstrating the usefulness of the present invention. [Industrial Applicability]

[0074] The fiber-reinforced resin molded product of the present invention has superior strength and rigidity as well as low dielectric properties compared to fiber-reinforced resin molded products using a thermosetting resin as the matrix resin, and therefore can be suitably used for vehicle parts and structural materials, housings for home appliances, bags, protective materials, sporting goods, furniture, musical instruments, household goods, etc., as well as a wide range of other applications including components for electrical and electronic devices, precision machinery, construction materials, automotive components, home appliances, household goods, electronic casings, sporting goods, medical instruments, bags, aircraft and space equipment components, etc. [Explanation of symbols]

[0075] 10 Organic long fiber fabric 20 Thermoplastic resin

Claims

1. A fiber-reinforced resin molding comprising an organic long fiber fabric (A) and a thermoplastic resin (B), The organic long-fiber fabric (A) is a woven fabric having a cover factor (CF) calculated by the following formula (I) of 900 to 1,800, the organic long fiber is any one of para-aramid fiber, polyparaphenylene benzobisoxazole fiber, high-strength polyethylene fiber, liquid crystal polyester fiber, and polyarylate fiber, or a combination of two or more thereof; the thermoplastic resin (B) has a bending strength measured by the method described in JIS K7171 of 90 MPa or more and a bending modulus measured by the same method of 2.0 GPa or more; The fiber reinforced resin molded body has a thickness of T (mm), and the number of layers of the organic long fiber fabric (A) constituting the fiber reinforced resin molded body is N (sheets) (where N is 4 or more). A fiber reinforced resin molded body characterized in that the value of T / N is 0.100 or less. CF = √Dp × Np + √Df × Nf ... (I) where Dp: warp fineness (dtex) Np: Warp density (count / 25.4 mm) Df: Weft fineness (dtex) Nf: Weft density (count / 25.4 mm)

2. The fiber-reinforced resin molding according to claim 1, characterized in that the relative dielectric constant at 10 GHz measured by the method described in IEC 62810 of the fiber-reinforced resin molding is 3.0 or less, and / or the dielectric loss tangent measured by the same method is 0.020 or less.

3. The fiber-reinforced resin molding according to claim 1 or 2, wherein the thermoplastic resin (B) has a dielectric loss tangent at 10 GHz measured by the method described in IEC 62810 of 0.020 or less.

4. The tensile strength of the organic long fiber measured by the method described in JIS L1013 is 10 cN / dtex or more, and the tensile modulus measured by the same method is 400 cN / dtex or more. The fiber-reinforced resin molding according to any one of claims 1 to 3.

5. The organic long fiber fabric (A) is a woven fabric, and the woven density of the warp and weft yarns measured by the method described in JIS L1096 is 15 to 50 yarns / 25.4 mm. The fiber-reinforced resin molded body according to any one of claims 1 to 4.

6. The fiber-reinforced resin molding according to any one of claims 1 to 5, wherein the organic long fiber has a relative dielectric constant of 4.0 or less at 10 GHz as measured by the method described in IEC 62810.

7. A fiber-reinforced resin molding as described in claim 1, characterized in that the para-aramid fiber is polyparaphenylene terephthalamide fiber.

Images