Carbon fiber reinforced plastic laminate

Abstract

To provide a carbon fiber reinforced plastic laminate having excellent bending durability and flatness.SOLUTION: There is provided a carbon fiber reinforced plastic laminate 1 formed by laminating: a first prepreg layer 30 in which carbon fibers 11 oriented in a first direction P are impregnated with a resin 21; a second prepreg layer 40 in which carbon fibers 12 oriented in a second direction Q different from the first direction P are impregnated with a resin 22; and a third prepreg layer 50 having substantially the same configuration as the first prepreg layer 30, wherein a flexural modulus (Ea1) measured in accordance with JIS K7074 in the first direction P is 10 to 50 GPa, and a flexural modulus (Ea2) in the second direction Q measured in accordance with JIS K7074 is 55 to 95 GPa.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a carbon fiber reinforced plastic laminate formed by laminating a plurality of prepreg layers. [Background technology]

[0002] 2. Description of the Related Art Conventionally, a carbon fiber reinforced plastic laminate has been produced by laminating a plurality of prepreg layers in which carbon fibers are impregnated with a resin.

[0003] As this type of carbon fiber reinforced plastic laminate, a carbon fiber reinforced composite molded product has been proposed in which a plastic film is attached to at least one side of a carbon fiber reinforced resin sheet that is made by impregnating and curing a carbon fiber woven fabric with a resin and processing it into a three-dimensional shape (Patent Document 1). It is said that this carbon fiber reinforced plastic laminate has an excellent surface appearance and can exert a sufficient reinforcing effect. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-098127 A Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, attempts have been made to use carbon fiber reinforced plastic laminates as reinforcing members for screens of smartphones, tablet terminals, and the like. In order to use the carbon fiber reinforced plastic laminate as a reinforcing member, it is necessary to make the carbon fiber reinforced plastic laminate into a thin flat plate. However, when configured in this way, once it is bent, it does not return to its original shape, and there is a risk of reduced bending durability. In addition, due to the thinness of the carbon fiber reinforced plastic laminate, there is a risk of increased warping and loss of flatness.

[0006] In this regard, the carbon fiber reinforced plastic laminate of the above-mentioned Patent Document 1 has a three-dimensional shape and a large thickness, and does not focus on bending durability or flatness.

[0007] In view of the above circumstances, an object of the present invention is to provide a carbon fiber reinforced plastic laminate excellent in bending durability and flatness. [Means for solving the problem]

[0008] The characteristic configuration of the carbon fiber reinforced plastic laminate according to the present invention for solving the above problems is as follows: A carbon fiber reinforced plastic laminate comprising a first prepreg layer in which carbon fibers oriented in a first direction are impregnated with a resin, a second prepreg layer in which carbon fibers oriented in a second direction different from the first direction are impregnated with a resin, and a third prepreg layer having substantially the same configuration as the first prepreg layer, The bending elastic modulus (Ea1) in the first direction measured in accordance with JIS K7074 is 10 to 50 GPa, The flexural modulus (Ea2) in the second direction measured in accordance with JIS K7074 is 55 to 95 GPa.

[0009] According to the carbon fiber reinforced plastic laminate of the present configuration, by laminating the above-mentioned first prepreg layer, second prepreg layer, and third prepreg layer, and setting the flexural modulus in the first direction (Ea1) and the flexural modulus in the second direction (Ea2) within the above-mentioned ranges so that the flexural modulus in the second direction (Ea2) is greater than the flexural modulus in the first direction (Ea1), respectively, the laminate has excellent flexural durability and flatness.

[0010] In the carbon fiber reinforced plastic laminate according to the present invention, It is preferable that the second prepreg layer has a weight per unit area (F2) greater than the weight per unit area (F1) of the first prepreg layer.

[0011] As described above, the third prepreg layer has substantially the same configuration as the first prepreg layer, so when the thread weight (F2) of the second prepreg layer is greater than the thread weight (F1) of the first prepreg layer, the thread weight (F2) of the second prepreg layer will be greater than the thread weight (F3) of the third prepreg layer. In the carbon fiber reinforced plastic laminate of this configuration, by setting the thread weight (F2) of the second prepreg layer larger than the thread weight (F1) of the first prepreg layer (and the thread weight (F3) of the third prepreg layer), it becomes easy to set the flexural modulus in the first direction (Ea1) and the flexural modulus in the second direction (Ea2) within the desired ranges, and therefore it is possible to more reliably improve the flexural durability and flatness.

[0012] In the carbon fiber reinforced plastic laminate according to the present invention, The first prepreg layer has a thread weight (F1) of 20 to 30 g / m 2 and The second prepreg layer has a thread weight (F2) of 80 to 130 g / m 2 It is preferable that:

[0013] As described above, since the third prepreg layer has substantially the same configuration as the first prepreg layer, the yarn weight (F1) of the first prepreg layer is 20 to 30 g / m 2 In this case, the thread weight (F3) of the third prepreg layer is 20 to 30 g / m 2 It becomes. In the carbon fiber reinforced plastic laminate of this configuration, by setting the thread weight (F2) of the second prepreg layer and the thread weight (F1) of the first prepreg layer (as well as the thread weight (F3) of the third prepreg layer) within the above-mentioned ranges, it becomes easy to set the flexural modulus in the first direction (Ea1) and the flexural modulus in the second direction (Ea2) within the above-mentioned desired ranges, and therefore it is possible to more reliably improve the flexural durability and flatness.

[0014] In the carbon fiber reinforced plastic laminate according to the present invention, The carbon fiber preferably has a tensile modulus of elasticity of 210 to 290 GPa as measured in accordance with JIS R7601.

[0015] In the carbon fiber reinforced plastic laminate of this configuration, by setting the tensile modulus of the carbon fibers within the above range, it becomes easy to set the flexural modulus in the first direction (Ea1) and the flexural modulus in the second direction (Ea2) within the above desired ranges, so that the flexural durability and flatness can be improved more reliably.

[0016] In the carbon fiber reinforced plastic laminate according to the present invention, It is preferable that the angle between the first direction and the second direction is 90°.

[0017] In the carbon fiber reinforced plastic laminate of this configuration, by making the angle between the first direction and the second direction 90°, the direction in which the effect of the flexural modulus in the first direction (Ea1) is exerted and the direction in which the effect of the flexural modulus in the second direction (Ea2) is exerted are the furthest apart, so that the effects of these flexural moduli (Ea1, Ea2) can be exerted most evenly, and the flexural durability and flatness can be improved more evenly. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a perspective view that typically shows a carbon fiber reinforced plastic laminate according to the present invention. [Diagram 2] FIG. 2 is a photograph showing an example of a cross section taken along the line indicated by the arrows AA in FIG. 1, taken with a scanning electron microscope. [Diagram 3] FIG. 3 is a diagram showing an outline of the evaluation method for the examples and comparative examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The carbon fiber reinforced plastic laminate of the present invention will be described with reference to the drawings. However, the layer structure shown in the drawings is appropriately exaggerated or simplified for ease of explanation, and the relationship of thickness and scale of each layer does not necessarily accurately reflect the actual carbon fiber reinforced plastic laminate. In this specification, "laminating the first prepreg layer, the second prepreg layer, and the third prepreg layer in this order" is synonymous with "laminating the third prepreg layer, the second prepreg layer, and the first prepreg layer in this order", and "laminating the flat plate for the first prepreg layer, the flat plate for the second prepreg layer, and the flat plate for the third prepreg layer in this order" is synonymous with "laminating the flat plate for the third prepreg layer, the flat plate for the second prepreg layer, and the flat plate for the first prepreg layer in this order".

[0020] [Carbon fiber reinforced plastic laminate] Fig. 1 is a perspective view showing a carbon fiber reinforced plastic laminate 1 according to the present invention, together with a flat plate 31 for a first prepreg layer 30, a flat plate 41 for a second prepreg layer 40, and a flat plate 51 for a third prepreg layer 50 before lamination. Fig. 2 is a photograph showing an example of a cross section taken by a scanning electron microscope when cut along the arrow AA in Fig. 1.

[0021] The carbon fiber reinforced plastic laminate 1 is formed by laminating a first prepreg layer 30 in which carbon fibers 11 oriented in a first direction P are impregnated with a resin 21, a second prepreg layer 40 in which carbon fibers 12 oriented in a second direction Q different from the first direction P are impregnated with a resin 22, and a third prepreg layer 50 having substantially the same configuration as the first prepreg layer 30. The carbon fiber reinforced plastic laminate 1 is obtained by overlapping a flat plate 31 for the first prepreg layer 30, a flat plate 41 for the second prepreg layer 40, and a flat plate 51 for the third prepreg layer 50 in this order, and hot pressing them.

[0022] [First prepreg layer] The first prepreg layer 30 is formed by impregnating carbon fibers 11 oriented in a first direction P with a resin 21. In the embodiment shown in Fig. 1, the first direction P is set to a direction perpendicular to the upper and lower sides (width direction) of the first prepreg layer 30.

[0023] The first prepreg layer 30 is obtained by preparing a flat plate 31 for the first prepreg layer 30 by impregnating carbon fibers 11 with resin 21, and hot pressing the flat plate 31.

[0024] The thickness of the flat plate 31 for the first prepreg layer 30 and the fiber-attached weight (FAW) of the carbon fibers 11 in the flat plate 31 for the first prepreg layer 30 are appropriately set so that the first prepreg layer 30 in the carbon fiber reinforced plastic laminate 1 has the desired thickness and fiber-attached weight.

[0025] <Carbon fiber> Examples of the carbon fibers 11 include polyacrylonitrile (PAN)-based carbon fibers, pitch-based carbon fibers, etc. In the first prepreg layer 30, the carbon fibers 11 are contained in a state where they are aligned in the first direction P.

[0026] The tensile modulus of the carbon fibers measured in accordance with JIS R7601 is preferably 210 to 300 GPa, more preferably 230 to 290 GPa. By setting the tensile modulus of the carbon fibers 11 within the above range, it becomes easy to set the bending modulus (Ea1) in the first direction P of the carbon fiber reinforced plastic laminate 1 within a desired range described later, so that the bending durability and flatness can be improved more reliably.

[0027] The carbon fiber 11 is treated as a carbon fiber bundle by bundling a plurality of fibers. The carbon fiber bundle of the carbon fiber 11 preferably has 1000 to 30000 fibers, more preferably 3000 to 24000 fibers. By setting the carbon fiber bundle of the carbon fiber 11 within the above range, the tensile strength of the carbon fiber 11 can be made appropriate.

[0028] The fineness (Tex) of the carbon fibers 11 is preferably 66 to 1800 g / 1000 m, and more preferably 200 to 1650 g / 1000 m. By setting the fineness of the carbon fibers 11 within the above range, the tensile strength of the carbon fibers 11 can be made appropriate.

[0029] <Resin> Examples of the resin 21 include thermosetting resins and thermoplastic resins. Among these, thermosetting resins are preferred because they provide excellent strength and thermal stability to the first prepreg layer 30. Thermosetting resins are resins that contain the resin as a main component and are cured by mixing with a curing agent as necessary.

[0030] (thermosetting resin) Examples of the thermosetting resin include phenol resin, urea resin, melamine resin, bismaleimide resin, unsaturated polyester resin, vinyl ester resin, epoxy ester resin, epoxy resin, bismaleimide triazine resin (BT resin), cyanate ester resin, triazine resin, urethane acrylate resin, urethane methacrylate resin, polyimide resin, etc. Among these, epoxy resin is preferred because of its excellent strength, heat resistance, moldability, etc. The thermosetting resin can be used alone or as a mixture of two or more kinds.

[0031] Examples of epoxy resins include bifunctional epoxy resins and trifunctional or higher epoxy resins. Examples of bifunctional epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, biphenyl type epoxy resins, dicyclopentadiene type epoxy resins, and epoxy resins modified from these. Examples of trifunctional or higher epoxy resins include phenol novolac type epoxy resins, cresol novolac type epoxy resins, glycidylamine type epoxy resins such as tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, and tetraglycidylamine, glycidyl ether type epoxy resins such as tetrakis(glycidyloxyphenyl)ethane and tris(glycidyloxymethane), epoxy resins modified from these, and halogenated epoxy resins obtained by halogenating these. From the viewpoint of impregnation, it is preferable that the viscosity of the epoxy resin is low. The epoxy resin can be used alone or as a mixture of two or more types.

[0032] (thermoplastic resin) Examples of the thermoplastic resin include polyamide resin, polypropylene resin, polysulfone resin, polyetherimide resin, polyethersulfone resin, polyetherketone resin, polyetheretherketone resin, aromatic polyamide resin, aromatic polyester resin, polyarylene sulfide resin, aromatic polycarbonate resin, polyarylene oxide resin, thermoplastic polyimide resin, polyamideimide resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyethylene resin, etc. The thermoplastic resin can be used alone or as a mixture of two or more kinds.

[0033] (hardening agent) Examples of the hardener include amines, carboxylic acid anhydrides, phenols (such as novolac resins), mercaptans, Lewis acid amine complexes, onium salts, and imidazoles. Among these, amine-type hardeners are preferred. The hardeners can be used alone or in combination of two or more.

[0034] Examples of the amine-type curing agent include aromatic amines such as diaminodiphenylsulfone, aliphatic amines, imidazole derivatives, dicyandiamide, tetramethylguanidine, thiourea-added amines, etc. Among these, diaminodiphenylsulfone, dicyandiamide, etc. are more preferred in terms of excellent storage stability after curing.

[0035] These curing agents may be combined with a suitable curing aid to enhance the curing activity. Examples of such combinations include a combination of dicyandiamide as a curing agent and a urea derivative such as 3-phenyl-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, or 2,4-bis(3,3-dimethylureido)toluene as a curing aid; a combination of a carboxylic acid anhydride, a novolac resin, or the like as a curing aid and a tertiary amine or the like; a combination of diaminodiphenylsulfone as a curing agent and an imidazole compound, a urea derivative such as phenyldimethylurea (PDMU), a trifluoride monoethylamine, or an amine complex such as a trichloride amine complex as a curing aid; a combination of dicyandiamide or diaminodiphenylsulfone as a curing agent and the above-mentioned urea derivative as a curing aid; and the like. The curing aid can be used alone or in a mixture of two or more kinds. It is also possible to use a curing assistant instead of the curing agent, without using the curing agent.

[0036] <Other ingredients> In addition to the carbon fibers 11 and resin 21 described above, the first prepreg layer 30 may contain appropriate amounts of additives such as inorganic fine particles such as fine powdered silica, pigments, elastomers, aluminum hydroxide as a flame retardant, bromides as flame retardants, phosphorus-based compounds as flame retardants, defoamers, thermoplastic resins that dissolve in epoxy resins, such as polyvinyl acetal resins and phenoxy resins for the purpose of improving handleability and flexibility, imidazole derivatives that act as catalysts for the curing reaction, metal complex salts, and tertiary amine compounds.

[0037] It is preferable that the unit weight (F1) of the first prepreg layer 30 is set smaller than the unit weight (F2) of the second prepreg layer 40 (i.e., the unit weight (F2) of the second prepreg layer is larger than the unit weight (F1) of the first prepreg layer). By setting the unit weight (F1) of the first prepreg layer 30 smaller than the unit weight (F2) of the second prepreg layer 40, it becomes easy to set the flexural modulus (Ea1) in the first direction P and the flexural modulus (Ea2) in the second direction Q to desired ranges described later, so that the flexural durability and flatness can be more reliably improved.

[0038] The thread weight (F1) of the first prepreg layer 30 is 20 to 30 g / m 2 By setting the thread weight (F1) of the first prepreg layer 30 within the above range, it becomes easy to set the flexural modulus (Ea1) in the first direction P and the flexural modulus (Ea2) in the second direction Q within desired ranges described later, so that the flexural durability and flatness can be improved more reliably.

[0039] As described above, the carbon fibers 11 are treated as carbon fiber bundles. When producing the first prepreg layer 30, it is preferable to carry out a fiber-spreading step in which the carbon fiber bundles are continuously made wide and thin (spread) prior to the resin impregnation. Methods for spreading the carbon fiber bundles include conventionally known methods, such as a method of spreading the carbon fiber bundles by contacting them with a fiber-spreading roller, a vibrating roller, or the like, a method of running the carbon fiber bundles so as to cross the flow of a fluid and bending the carbon fiber bundles to spread them, and a combination of these methods.

[0040] The flat plate 31 for the first prepreg layer 30 can be manufactured by impregnating the carbon fibers 11 with the resin 21. Examples of methods for impregnating the carbon fibers 11 with the resin 21 include a method of applying the uncured resin 21 to a release sheet (not shown) in advance, placing the carbon fibers 11 aligned in one direction on the applied uncured resin 21, and passing the carbon fibers 11 between a pair of rollers (not shown) to impregnate the carbon fibers 11, and a method of applying the uncured resin 21 to the carbon fibers 11 aligned in one direction and then passing the carbon fibers 11 between a pair of rollers (not shown) to impregnate the carbon fibers. In these cases, the thickness of the flat plate 31 for the first prepreg layer 30 can be adjusted by adjusting the nip pressure of the pair of rollers. The pair of rollers may be heated to reduce the viscosity of the resin 21 while impregnating the carbon fibers 11.

[0041] [Second prepreg layer] The second prepreg layer 40 is formed by impregnating the carbon fibers 12 oriented in a second direction Q different from the first direction P with a resin 22. In the embodiment shown in Fig. 1, the second direction Q is set to a direction perpendicular to the left and right sides (width direction) of the second prepreg layer 40.

[0042] The second prepreg layer 40 is obtained by preparing a flat plate 41 for the second prepreg layer 40 by impregnating the carbon fibers 12 with the resin 22, and then hot pressing the flat plate 41.

[0043] The thickness of the flat plate 41 for the second prepreg layer 40 and the weight per unit area of ​​the carbon fibers 12 in the flat plate 41 for the second prepreg layer 40 are appropriately set so that the second prepreg layer 40 in the carbon fiber reinforced plastic laminate 1 has the desired thickness and weight per unit area.

[0044] The carbon fibers 12 may be the same as the carbon fibers 11 in the first prepreg layer 30. The resin 22 may be the same as the resin 21 in the first prepreg layer 30. The second prepreg layer 40 may contain other components that may be added to the first prepreg layer 30.

[0045] It is preferable that the weight per unit area (F2) of the second prepreg layer 40 is set to be larger than the weight per unit area (F1) of the first prepreg layer 30. In this case, the weight per unit area (F2) of the second prepreg layer 40 is set to be larger than the weight per unit area (F3) of the third prepreg layer 50 described later. By setting the weight per unit area (F2) of the second prepreg layer 40 larger than the weight per unit area (F1) of the first prepreg layer 30 (and the weight per unit area (F3) of the third prepreg layer 50), it becomes easy to set the flexural modulus (Ea1) in the first direction P and the flexural modulus (Ea2) in the second direction Q to the desired ranges described later, so that the bending durability and flatness can be more reliably improved.

[0046] The thread weight (F2) of the second prepreg layer 40 is 80 to 130 g / m 2 By setting the thread weight (F2) of the second prepreg layer 40 within the above range, it becomes easy to set the flexural modulus (Ea1) in the first direction P and the flexural modulus (Ea2) in the second direction Q within desired ranges described below, so that the flexural durability and flatness can be more reliably improved.

[0047] The second prepreg layer 40 can be produced in the same manner as the first prepreg layer 30, by impregnating the carbon fibers 12 with the resin 22.

[0048] [Third prepreg layer] The third prepreg layer 50 has substantially the same configuration as the first prepreg layer 30. Specifically, the third prepreg layer 50 is obtained by impregnating carbon fibers 13 oriented in a first direction P with a resin 23, and uses carbon fibers similar to the carbon fibers 11 of the first prepreg layer 30 as the carbon fibers 13 and uses carbon fibers similar to the resin 21 of the first prepreg layer 30 as the resin 23, so as to have substantially the same configuration as the first prepreg layer 30.

[0049] Here, the statement that the configuration of the third prepreg layer 50 is "substantially the same" as the configuration of the first prepreg layer 30 does not completely exclude cases where the components, content, thread count, etc. of the third prepreg layer 50 are slightly different from the components, content, thread count, etc. of the first prepreg layer 50. Even if at least one of these is slightly different, if there is no substantial effect on the physical properties of the prepreg layer, the configuration of the third prepreg layer 50 will be treated as being substantially the same as the configuration of the first prepreg layer 30.

[0050] The third prepreg layer 50 is obtained by preparing a flat plate 51 for the third prepreg layer 50, which is made by impregnating carbon fibers 13 with resin 23, so as to have the same configuration as the flat plate 31 for the first prepreg layer 30, and hot pressing it.

[0051] When the first prepreg layer 30 contains the other components described above, the third prepreg layer 50 contains the same other components.

[0052] The third prepreg layer 50 has a unit weight (F3) set smaller than the unit weight (F2) of the second prepreg layer 40, similar to the unit weight (F1) of the first prepreg layer 30 (i.e., the unit weight (F2) of the second prepreg layer is larger than the unit weight (F3) of the third prepreg layer). By setting the unit weight (F3) of the third prepreg layer 50 smaller than the unit weight (F2) of the second prepreg layer 40, it becomes easy to set the flexural modulus (Ea1) in the first direction P and the flexural modulus (Ea2) in the second direction Q to desired ranges described later, so that the bending durability and flatness can be more reliably improved.

[0053] The third prepreg layer 50 has a thread weight (F3) of 20 to 30 g / m, similar to the thread weight (F1) of the first prepreg layer 30. 2 By setting the thread weight (F3) of the third prepreg layer 50 within the above range, it becomes easy to set the flexural modulus (Ea1) in the first direction P and the flexural modulus (Ea2) in the second direction Q within desired ranges described later, so that the flexural durability and flatness can be improved more reliably.

[0054] [Characteristics of carbon fiber reinforced plastic laminates] The carbon fiber reinforced plastic laminate 1 is set so that the flexural modulus (Ea1) in the first direction P, measured in accordance with JIS K7074, is 10 to 50 GPa, and the flexural modulus (Ea2) in the second direction Q, measured in accordance with JIS K7074, is 55 to 95 GPa.

[0055] By setting the bending modulus of elasticity in the first direction P (Ea1) and the bending modulus of elasticity in the second direction Q (Ea2) within the above ranges so that the bending modulus of elasticity in the second direction Q (Ea2) is greater than the bending modulus of elasticity in the first direction P (Ea1), the carbon fiber reinforced plastic laminate 1 has excellent bending durability and flatness.

[0056] The flexural modulus (Ea1) can be adjusted mainly by adjusting the flexural modulus of the first prepreg layer 30 and the third prepreg layer 50, i.e., by adjusting the type of carbon fibers 11, 13, the type of resins 21, 23, the unit weight, etc. in each of these prepreg layers. The flexural modulus (Ea2) can be adjusted mainly by adjusting the flexural modulus of the second prepreg layer 40, i.e., by adjusting the type of carbon fibers 12, the type of resin 22, the unit weight, etc.

[0057] In the carbon fiber reinforced plastic laminate 1 of this embodiment, it is preferable that the tensile modulus of elasticity (Eb1) measured in accordance with JIS K7073 in the first direction P is 10 to 50 GPa, and the tensile modulus of elasticity (Eb2) measured in accordance with JIS K7073 in the second direction Q is 55 to 90 GPa.

[0058] By setting the tensile modulus of elasticity in the first direction P (Eb1) and the tensile modulus of elasticity in the second direction Q (Eb2) within the above ranges, respectively, it is possible to further improve bending durability and flatness.

[0059] In the carbon fiber reinforced plastic laminate 1 of this embodiment, it is preferable that the compressive modulus (Ec1) measured in accordance with JIS K7018 in the first direction P is 10 to 45 GPa, and the compressive modulus (Ec2) measured in accordance with JIS K7018 in the second direction Q is 50 to 100 GPa.

[0060] By setting the compressive elastic modulus in the first direction P (Ec1) and the compressive elastic modulus in the second direction Q (Ec2) within the above ranges, respectively, it is possible to further improve bending durability and flatness.

[0061] The angle between the first direction P and the second direction Q is not particularly limited, but is preferably 90°.

[0062] By making the angle between the first direction P and the second direction Q 90°, the direction in which the effect of the bending modulus (Ea1) in the first direction P is exerted and the direction in which the effect of the bending modulus (Ea2) in the second direction Q is exerted are the farthest apart, so that the effects of these bending moduli (Ea1, Ea2) can be exerted most evenly, and the bending durability and flatness can be improved more uniformly.

[0063] When the thickness of the carbon fiber reinforced plastic laminate 1 is excessively large, the flexibility may decrease, whereas when the thickness is excessively small, the rigidity (stiffness) may decrease and the flatness may decrease. In consideration of such a viewpoint, the thickness of the carbon fiber reinforced plastic laminate 1 is preferably 0.12 to 0.23 mm, more preferably 0.14 to 0.18 mm. By setting the thickness of the carbon fiber reinforced plastic laminate 1 to the above upper limit or less, the flexibility can be improved, whereas by setting the thickness to the above lower limit or more, the rigidity can be improved and the flatness can be improved. The thicknesses of the first prepreg layer 30 and the third prepreg layer 50 are preferably 0.025 to 0.045 mm, more preferably 0.030 to 0.040 mm. The thickness of the second prepreg layer 40 is preferably 0.070 to 0.140 mm, more preferably 0.080 to 0.120 mm.

[0064] [Manufacturing of carbon fiber reinforced plastic laminates] The carbon fiber reinforced plastic laminate 1 can be produced by overlapping a flat plate 41 for the second prepreg layer 40 on a flat plate 51 for the third prepreg layer 50 such that the orientation direction of the carbon fibers 12 in the flat plate 41 for the second prepreg layer 40 (second direction Q) is at a different angle from the orientation direction of the carbon fibers 13 in the flat plate 51 for the third prepreg layer 50 (first direction P), and overlapping a flat plate 31 for the first prepreg layer 30 on the flat plate 41 for the second prepreg layer 40 such that the orientation direction of the carbon fibers 11 in the flat plate 31 for the first prepreg layer 30 (first direction P) is parallel to the orientation direction of the carbon fibers 13 in the flat plate 51 for the third prepreg layer 50 (first direction P), and then hot pressing (heating and pressurizing). The pressure in the heat press is preferably set to 1 to 2 MPa, the heating temperature is preferably set to 110 to 150° C., and the holding temperature (the time for holding the pressurized and heated states) is preferably set to 100 to 140 minutes. EXAMPLES

[0065] The carbon fiber reinforced plastic laminate of the present invention will be described more specifically below with reference to examples.

[0066] [Raw materials used] Carbon Fiber Torayca T700-SC-12000 (manufactured by Toray Industries, Inc.) Carbon fiber bundle: 12,000 strands, fineness (Tex): 800g / 1000m, Tensile strength: 4900MPa, Tensile modulus: 230GPa, Elongation: 2.1% Torayca M40-JB-12000 (manufactured by Toray Industries, Inc.) Carbon fiber bundle: 12,000 strands, fineness (Tex): 450g / 1000m, Tensile strength: 4400MPa, Tensile modulus: 377GPa, Elongation: 1.2% Pyrofil TR 30S 3L (Mitsubishi Chemical Corporation) Carbon fiber bundle: 3000 pieces, fineness (Tex): 200g / 1000m, Tensile strength: 4120MPa, Tensile modulus: 235GPa, Elongation: 1.8% ·resin Base resin: A mixture of bisphenol A type epoxy resins jER828 and jER1001 (both manufactured by Mitsubishi Chemical Corporation) in a mass ratio of 18:22 Hardener: Phenyl-1,1-dimethylurea (DCMU99, manufactured by Hodogaya Chemical Co., Ltd.)

[0067] [Examples 1 to 3, Comparative Examples 1 to 3] A base agent and a curing agent were mixed so as to obtain the layer structure shown in Tables 1-2, and the mixture was impregnated into the carbon fibers oriented in one direction, to obtain rectangular flat plates for the first and third prepreg layers and a rectangular flat plate for the second prepreg layer. In each flat plate, the orientation direction of the carbon fibers was set to be parallel to a pair of opposing edges of the flat plate. The flat plate for the first prepreg layer, the flat plate for the second prepreg layer, and the flat plate for the third prepreg layer were laminated in this order so that the orientation direction of the carbon fibers in the flat plate for the first prepreg layer (first direction) and the orientation direction of the carbon fibers in the flat plate for the second prepreg layer (first direction) were 90° (i.e., perpendicular), and the orientation direction of the carbon fibers in the flat plate for the first prepreg layer (first direction) and the orientation direction of the carbon fibers in the flat plate for the third prepreg layer (first direction) were 0° (i.e., parallel), to obtain a laminate that was a flat plate. Next, the laminate was press molded using a hot press under conditions of a pressure of 1.5 MPa, a temperature of 130°C, and a holding time of 120 minutes to obtain carbon fiber reinforced plastic laminates in which a first prepreg layer, a second prepreg layer, and a third prepreg layer were laminated in this order in Examples 1 to 3 and Comparative Examples 1 to 3. The thicknesses of the first prepreg layer, the second prepreg layer, and the third prepreg layer in the carbon fiber reinforced plastic laminates were set to the values ​​shown in Tables 1 and 2.

[0068] The resulting carbon fiber reinforced plastic laminate was measured for flexural modulus, tensile modulus, and compressive modulus by the measurement methods described below, and evaluated for bending durability and flatness (degree of warpage) by the evaluation methods described below. The results are shown in Tables 1 and 2.

[0069] <Flexural modulus> In accordance with JIS K7074, the flexural modulus Ea1 in a first direction (set at 0°) and the flexural modulus Ea2 in a second direction (set at 90°) of the carbon fiber reinforced plastic laminate were measured.

[0070] <Tensile modulus> In accordance with JIS K7073, the tensile modulus Eb1 in a first direction (set at 0°) and the tensile modulus Eb2 in a second direction (set at 90°) of the carbon fiber reinforced plastic laminate were measured.

[0071] <Compressive elastic modulus> In accordance with JIS K7018, the compressive elastic modulus Ec1 in a first direction (set at 0°) and the compressive elastic modulus Ec2 in a second direction (set at 90°) of the carbon fiber reinforced plastic laminate were measured.

[0072] <Bending durability> The carbon fiber reinforced plastic laminate was cut into a rectangular shape with a length of 10 mm in the first direction and 15 mm in the second direction to obtain a test piece for evaluation. As shown in FIG. 3(a), the test piece was first placed upright so that the second direction was oriented vertically (set at 0°) in a bending tester (TCDM111LH, manufactured by Yuasa System Co., Ltd.), and fixed between a pair of cylindrical support members with a diameter (φ) of 1 mm at a position 50 mm from the upper end. Next, the upper end was bent toward one side (+ direction) with respect to the vertical direction until it was 135° from the vertical direction, and then bent toward the other side (- direction) until it was 135° from the vertical direction, and each of these bendings was counted as one bending (i.e., a round trip was counted as two bendings). These bendings are called bending in the second direction because the carbon fibers in the first and third prepreg layers (first direction) do not bend, while the carbon fibers in the second prepreg layer (second direction) are bent. These bending cycles were repeated at a rate of 60 times per minute up to a maximum of 200,000 times, and the number of times when damage such as peeling or tearing occurred was counted. If no damage occurred after 200,000 repetitions, it was evaluated as "200,000 times or more."

[0073] <Flatness (degree of warping)> The carbon fiber reinforced plastic laminate was cut into a rectangular shape of 10 mm in the first direction and 15 mm in the second direction to obtain a test specimen for evaluation. As shown in Fig. 3(b), the test specimen was placed on a flat surface, and the height of each side (four sides) of the test specimen raised above the flat surface was measured. The maximum value of the four side measurements was taken as the degree of warping (mm), which is an index of flatness.

[0074] [Table 1]

[0075] [Table 2]

[0076] As shown in Table 1, the carbon fiber reinforced plastic laminates of Examples 1 to 3, which are formed by laminating a first prepreg layer in which carbon fibers oriented in a first direction are impregnated with resin, a second prepreg layer in which carbon fibers oriented in a second direction different from the first direction are impregnated with resin, and a third prepreg layer having substantially the same configuration as the first prepreg layer, and which have a flexural modulus in the first direction (Ea1) of 10 to 50 GPa and a flexural modulus in the second direction (Ea2) of 55 to 95 GPa, are excellent in bending durability and also excellent in flatness (warping is suppressed).

[0077] As can be seen from Table 2, the carbon fiber reinforced plastic laminate of Comparative Example 1, which is configured so that the flexural modulus in the second direction (Ea2) is greater than the flexural modulus in the first direction (Ea1) and which has a flexural modulus (Ea1) of 10 to 50 GPa but a flexural modulus (Ea2) of 55 to 95 GPa, experienced peeling after 100,000 flexes, indicating that it had inferior flexural durability compared to the carbon fiber reinforced plastic laminates of Examples 1 to 3.

[0078] The carbon fiber reinforced plastic laminates of Comparative Examples 2 and 3, which were configured so that the bending modulus in the second direction (Ea2) was smaller than the bending modulus in the first direction (Ea1), and in which the bending modulus (Ea1) did not satisfy the range of 10 to 50 GPa and the bending modulus (Ea2) did not satisfy the range of 55 to 95 GPa, had a warp degree of 1.5 mm and were shown to be inferior in flatness compared to the carbon fiber reinforced plastic laminates of Examples 1 to 3. [Industrial Applicability]

[0079] The carbon fiber reinforced plastic laminate of the present invention can be suitably used, for example, as a reinforcing member for the displays of notebook computers, tablets, and smartphones. [Explanation of symbols]

[0080] 1 Carbon fiber reinforced plastic laminate 11, 12, 13 Carbon fiber 21, 22, 23 Resin 30 First prepreg layer 40 Second prepreg layer 50 Third prepreg layer P First direction Q Second Direction

Claims

1. A carbon fiber reinforced plastic laminate comprising a first prepreg layer in which carbon fibers oriented in a first direction are impregnated with a resin, a second prepreg layer in which carbon fibers oriented in a second direction different from the first direction are impregnated with a resin, and a third prepreg layer having substantially the same configuration as the first prepreg layer, The flexural modulus (Ea1) in the first direction measured in accordance with JIS K7074 is 10 to 50 GPa, A carbon fiber reinforced plastic laminate having a flexural modulus (Ea2) of 55 to 95 GPa measured in the second direction in accordance with JIS K7074.

2. The carbon fiber reinforced plastic laminate according to claim 1, wherein the second prepreg layer is configured so that its basis weight (F2) is greater than the basis weight (F1) of the first prepreg layer.

3. The first prepreg layer has a basis weight (F1) of 20 to 30 g / m ２ and The second prepreg layer has a thread weight (F2) of 80 to 130 g / m ２ 3. The carbon fiber reinforced plastic laminate according to claim 2,

4. The carbon fiber reinforced plastic laminate according to any one of claims 1 to 3, wherein the carbon fiber has a tensile modulus of elasticity of 210 to 290 GPa as measured in accordance with JIS R7601.

5. The carbon fiber reinforced plastic laminate according to any one of claims 1 to 3, wherein the angle between the first direction and the second direction is 90°.

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