Member for electronic device housing

Abstract

To provide a member for an electronic device housing which is little deformed during molding, and prevents local temperature rise when being used as an electronic device housing.SOLUTION: A member for an electronic device housing has a plate-like component and a thermoplastic resin component which is integrated with at least a part of a peripheral edge region of the plate-like component, in which the plate-like component is a composite material having a fiber-reinforced plastic including at least one or more reinforcement fiber layers containing reinforcement fibers and a resin, and a graphite sheet having thermal conductivity in an in-plane direction of 10 W / (m K) or more and 3,000 W / (m k) or less, and the graphite sheet contained in the plate-like component is arranged in the inner layer of the plate-like component and is not exposed to the surface.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a member for an electronic device housing. [Background technology]

[0002] Fiber-reinforced plastics (FRP), which are made of reinforcing fibers and matrix resin, are widely used in various industrial applications due to their light weight and excellent mechanical properties. Currently, as electrical and electronic devices such as personal computers, office automation equipment, audiovisual equipment, mobile phones, telephones, facsimiles, home appliances, and toys become more portable, there is a demand for them to be smaller and lighter. While electronic devices are becoming smaller, the performance of ICs and CPUs is increasing, which has resulted in an increase in the amount of heat generated per unit volume, and the heat density of electronic devices is rapidly increasing. For example, the thermal conductivity of injection-molded carbon fiber reinforced plastics (CFRP), which was previously used in the housings of personal computers, is 5 W / (m·K) or less, and the thermal conductivity of laminated heat-pressure molded products of carbon fiber woven prepregs is 50 W / (m·K) or less. As a result, the cooling of electronic devices is insufficient, causing the inside to become hot, and problems such as low-temperature burns caused by the heat of the housing are occurring. In order to prevent internal temperature rises and burns in such electronic devices, in addition to the thermal conductivity of the housing itself being high, the thermal conductivity of the housing in the planar direction must be significantly higher than the thermal conductivity in the thickness direction of the housing, so that the heat from the heat-generating components can be instantly spread in the planar direction of the housing rather than in the thickness direction, thereby preventing localized temperature rises. On the other hand, for electronic device casings, the components that make up the device, especially the casing, are required to be thin-walled while achieving high strength and high rigidity so that the casing does not bend significantly when an external load is applied, causing contact with internal parts and resulting in destruction. In molded structures that are made small and lightweight by integrally joining a fiber-reinforced resin structure made of reinforcing fibers and resin with another member, such as a frame member, there is a demand for further thinning without warping and reliable joining strength.

[0003] Patent Document 1 proposes preventing localized temperature increases by laminating graphite prepregs made by impregnating graphite film, which has high thermal conductivity in the in-plane direction, with resin, and then molding the laminated graphite prepregs under heating and pressure to form a housing. This allows the heat from the heat-generating components to be instantly spread in the planar direction of the housing rather than in the thickness direction.

[0004] Patent Document 2 proposes a graphite composite film in which a reinforcing fiber layer is formed on at least one surface of a graphite film, and which is lightweight and has excellent mechanical strength as well as excellent thermal conductivity.

[0005] In Patent Document 3, a fiber-reinforced plastic containing a thermosetting resin is bonded to a different material with good thermal conductivity via a thermoplastic resin layer, which improves not only the light weight and mechanical properties but also the thermal conductivity and heat dissipation properties. An excellent integrally molded product has been proposed.

[0006] Patent Document 4 proposes an integrated molded product that improves thermal conductivity while maintaining the ease of molding plastics (high productivity) by integrating fiber-reinforced plastic with a different material that has excellent thermal conductivity in the in-plane direction, and that is less likely to experience localized temperature increases when in contact with a heat-generating element. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2006-95935 A [Patent Document 2] Patent No. 5107191 [Patent Document 3] Patent No. 4904732 [Patent Document 4] Japanese Patent Application Publication No. 11-179830 Summary of the Invention [Problem to be solved by the invention]

[0008] However, since the electronic device housing produced by the method of Patent Document 1 is made only of a graphite film and a resin, the mechanical strength of the housing is sometimes insufficient for use as a housing for an electronic device.

[0009] The graphite composite film proposed in Patent Document 2 does not adequately suppress the deformation that occurs when the graphite film and fiber-reinforced plastic are integrated, and therefore does not have sufficient dimensional precision for use as an electronic device housing having an electronic device inside. Furthermore, chipping, cracking, and falling off of the graphite sheet may occur during cutting.

[0010] The integrated molded products made of fiber-reinforced plastic and dissimilar materials proposed in Patent Documents 3 and 4 also lack sufficient suppression of deformation that occurs when dissimilar materials are integrated, and the dimensional precision is insufficient for use as an electronic device housing that has an electronic device inside. Furthermore, chipping, cracking, and falling off of the graphite film may occur during cutting.

[0011] The present invention seeks to solve the problems associated with the conventional techniques as described above, and has an object to obtain a component for an electronic device housing having a plate-shaped part having fiber-reinforced plastic and a thermoplastic resin part integrated into at least a part of the peripheral region of the plate-shaped part, which undergoes little deformation during molding and prevents localized temperature increases when used as an electronic device housing. [Means for solving the problem]

[0012] [1] A member for an electronic device housing having a plate-shaped part and a thermoplastic resin part integrated with at least a part of a peripheral region of the plate-shaped part, The plate-shaped part includes: A fiber-reinforced plastic including at least one reinforcing fiber layer including reinforcing fibers and a resin; A composite material having a graphite sheet with an in-plane thermal conductivity of 10 W / (m K) or more and 3000 W / (m K) or less, A member for an electronic device housing, wherein the graphite sheet contained in the plate-shaped part is disposed in an inner layer of the plate-shaped part and is not exposed on the surface. [2] The fiber-reinforced plastic contained in the plate-shaped part is A plurality of reinforced fiber layers using reinforced fibers made of continuous fibers oriented in one direction are laminated and integrated, The member for an electronic device casing according to [1], wherein the fiber orientation of the reinforcing fibers constituting one reinforcing fiber layer is oriented in a different direction from the fiber orientation of the reinforcing fibers constituting another reinforcing fiber layer. [3] A member for an electronic device housing according to [2], in which the fiber orientation constituting the reinforcing fiber layer is symmetrically arranged in the thickness direction of the plate-shaped part. [4] The member for an electronic device housing according to [3], wherein the graphite sheets are also arranged symmetrically in the thickness direction of the plate-like part. [5] A member for an electronic device housing according to [1], wherein a reinforcing fiber layer in which the reinforcing fibers are woven is disposed on the surface of the plate-like part or inserted inside the plate-like part. [6] The member for an electronic device housing according to [1], further comprising a thermoplastic resin layer disposed on at least one surface of the plate-like part. [7] The member for an electronic device housing according to [1], wherein the entire circumference of the fiber-reinforced plastic is larger than the entire circumference of the graphite sheet, and the graphite sheet is not exposed from the outer peripheral surface of the plate-shaped part. Effect of the Invention

[0013] According to the present invention, it is possible to obtain a member for an electronic device housing which is less deformed during molding and which prevents localized temperature rise when used as an electronic device housing. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic diagram of an example of an electronic device housing member of the present invention. [Diagram 2] 1 is a schematic cross-sectional view of an example of an electronic device housing member of the present invention. [Diagram 3]FIG. 1 is a schematic cross-sectional view of an example of an electronic device housing member of the present invention using a plate-shaped part having a sandwich structure. [Figure 4] 1 is a schematic cross-sectional view of an example of an electronic device housing member of the present invention, in which a thermoplastic resin part has a rib shape. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments and drawings. The present invention can be carried out with appropriate modifications within the scope of its purpose.

[0016] The electronic device housing member of the present invention is an electronic device housing member having a plate-shaped part and a thermoplastic resin part integrated into at least a part of the peripheral region of the plate-shaped part, wherein the plate-shaped part is a composite material having a fiber-reinforced plastic including at least one reinforcing fiber layer containing reinforcing fibers and resin, and a graphite sheet having an in-plane thermal conductivity of 10 W / (m·K) or more and 3000 W / (m·K) or less, and the graphite sheet included in the plate-shaped part is arranged in an inner layer of the plate-shaped part and is not exposed on the surface.

[0017] An example of the electronic device housing member of the present invention is shown in Fig. 1. In Fig. 1, the electronic device housing member has a plate-like part 1 and a thermoplastic resin part 2 integrated together.

[0018] The term "plate-like" in the context of plate-like parts refers to a generally flat plate, and indicates that the aspect ratio of the long side and thickness of the plate-like part is at least 10. The plate-like part may have unevenness or holes in some parts, an arch shape or a slope, and may have different thicknesses.

[0019] Examples of reinforcing fibers used in the fiber-reinforced plastic include metal fibers such as aluminum, brass, and stainless steel; polyacrylonitrile (PAN), rayon, lignin, and pitch carbon fibers; graphite fibers; insulating fibers such as glass; organic fibers such as aramid, polyparaphenylene benzobisoxazole (PBO), polyphenylene sulfide, polyester, acrylic, nylon, and polyethylene; and inorganic fibers such as silicon carbide and silicon nitride.

[0020] The reinforcing fibers used in the fiber reinforced plastic may be of one type alone or of two or more types in combination.

[0021] The reinforcing fibers used in the fiber-reinforced plastic may be surface-treated, for example, by coating with a metal as a conductor, treatment with a coupling agent, treatment with a sizing agent, treatment with a binder, or treatment with an additive. Among these, from the viewpoint of weight reduction effect, PAN-based, pitch-based, rayon-based and other carbon fibers, which have excellent specific strength and specific rigidity, are preferred, and from the viewpoint of the light weight and strength of the resulting molded product, PAN-based carbon fibers are preferred, while pitch-based carbon fibers are preferred from the viewpoint of rigidity and thermal conductivity.

[0022] The average single fiber diameter of the reinforcing fibers used in the fiber reinforced plastic is preferably 4.0 to 30 μm, more preferably 4.2 to 25 μm, and even more preferably 4.5 to 20 μm. When the average single fiber diameter is 4.0 μm or more, the effort required to obtain the desired reinforcing fiber content is reduced, and the fiber reinforced plastic can be easily produced. When the average single fiber diameter is 30 μm or less, impregnation with a thermosetting resin or a thermoplastic resin becomes easy.

[0023] From the viewpoint of obtaining high strength, the reinforcing fibers used in the fiber reinforced plastic preferably have a tensile strength of 3000 MPa or more, more preferably 3200 MPa or more, and even more preferably 3400 MPa or more.

[0024] From the viewpoint of obtaining a high elastic modulus, the reinforcing fibers used in the fiber reinforced plastic preferably have a tensile modulus of elasticity of 200 GPa or more, more preferably 225 GPa or more, and even more preferably 400 GPa or more.

[0025] In order to obtain high thermal conductivity, the reinforcing fibers used in the fiber reinforced plastic preferably have a thermal conductivity in the fiber direction of 1 W / (m K) or more, more preferably 5 W / (m K) or more, and even more preferably 8 W / (m K) or more.

[0026] From the viewpoint of increasing the electrical conductivity of the resulting molded product, reinforcing fibers coated with a metal such as nickel, copper, or ytterbium can also be used.

[0027] The resin used in the fiber reinforced plastic may be either a thermosetting resin or a thermoplastic resin, or may be used in combination. Examples of the thermosetting resin used in the fiber reinforced plastic include unsaturated polyester resin, vinyl ester resin, epoxy resin, phenol resin, urea resin, melamine resin, polyimide resin, cyanate ester resin, bismaleimide resin, benzoxazine resin, copolymers thereof, modified products thereof, and resins obtained by blending at least two of these resins, etc. Among these, epoxy resins are preferred because of their excellent mechanical properties, heat resistance, and adhesiveness to reinforcing fibers.

[0028] Examples of the thermoplastic resin used in the fiber reinforced plastic include styrene resins, polyoxymethylene resins, vinyl chloride resins, olefin resins, thermoplastic elastomers, polyacrylate resins, polyether ether ketone resins, polyarylene sulfide resins, cellulose derivatives such as cellulose acetate, cellulose acetate butyrate, and ethyl cellulose, liquid crystal resins, polyethylene resins, polypropylene resins, polyvinyl chloride resins, polyvinylidene chloride resins, ABS resins, polystyrene resins, acrylonitrile styrene (AS) resins, methacrylic resins, and polyvinylidene chloride resins. Examples of such resins include alcohol resins, ethylene-vinyl acetate copolymer (EVA) resins, cellulose-based resins, polyamide resins, polyacetal resins, polycarbonate resins, modified polyphenylene ether resins, thermoplastic polyester resins, polytetrafluoroethylene resins, fluorine-based resins, polyphenylene sulfide resins, polysulfone resins, amorphous polyarylate resins, polyetherimide resins, polyethersulfone resins, polyetherketone resins, liquid crystal polyester resins, polyamideimide resins, polyimide resins, polyanyl ether nitrile resins, polybenzimidazole resins, etc. Among these, polyethylene resins, polypropylene resins, ABS resins, polystyrene resins, AS resins, polyamide resins, polyacetal resins, polyphenylene sulfide resins, and modified materials thereof or blends of two or more thereof are preferred because of the good mechanical properties of the injection molded products.

[0029] The resin used in the fiber-reinforced plastic may contain other fillers and additives according to the required characteristics, within the scope of the present invention, such as inorganic fillers, flame retardants, conductivity imparting agents, crystal nucleating agents, ultraviolet absorbers, antioxidants, vibration dampers, antibacterial agents, insect repellents, deodorants, coloring inhibitors, heat stabilizers, release agents, antistatic agents, plasticizers, lubricants, colorants, pigments, dyes, foaming agents, foam control agents, coupling agents, etc.

[0030] The graphite sheet of the present invention has anisotropic thermal conductivity, and the thermal conductivity in the direction showing good thermal conductivity is sufficient to be 10 W / (m·K) or more and 3000 W / (m·K) or less, preferably 100 W / (m·K) or more and 3000 W / (m·K) or less, and more preferably 500 W / (m·K) or more and 3000 W / (m·K) or less. If the thermal conductivity is 10 W / (m·K) or more, even when it is integrated with a reinforcing fiber layer to form a plate-shaped part, it has good thermal conductivity and can prevent localized temperature rises. The density of the graphite sheet of the present invention is 1.0 g / cm 3 More than 2.7g / cm 3 It is sufficient if the density is less than 1.2 g / cm 3 More than 2.5g / cm 3 More preferably, 1.5 g / cm 3 More than 2.3g / cm 3 The density is 1.0 g / cm 3 If the density is 2.7g / cm or more, there will be no air space inside the graphite and high thermal conductivity will be achieved. 3 If it is less than 2.70g / cm3, it is aluminum (density: 2.70g / cm3). 3 ) and copper (density: 8.96g / cm 3 ) and the like, it is therefore lighter when integrated with fiber-reinforced plastics; and when compared to products of the same size and weight, it is possible to improve their heat dissipation properties and enhance their heat dissipation performance.

[0031] The thickness of the graphite sheet is 1 μm to 1 mm, preferably 5 μm to 500 μm, and more preferably 10 μm to 300 μm. If the thickness is 1 μm or more, even if it is integrated with a reinforcing fiber layer to form a plate-shaped part, it has good thermal conductivity and can prevent local temperature rise. If the thickness is 1 mm or less, it can be integrated with a reinforcing fiber layer to form a plate-shaped part while maintaining a sufficient thinness.

[0032] The graphite sheet of the present invention may be produced by any method as long as it has the desired thermal conductivity and density. In addition, it is preferable to subject the graphite to a surface treatment in order to improve adhesion to fiber-reinforced plastics.

[0033] One example of a method for producing a plate-shaped part is a method in which a prepreg containing uncured thermosetting resin, or thermoplastic resin, or a mixture of thermoplastic resin and thermosetting resin, and reinforcing fibers is laminated with a graphite sheet, and the laminate is heated and pressurized, or heated and then cooled under pressure to form a cured fiber-reinforced resin.

[0034] A prepreg containing uncured thermosetting resin, thermoplastic resin, or a mixture of thermoplastic resin and thermosetting resin, and reinforcing fibers can be produced, for example, by impregnating a reinforcing fiber bundle in which reinforcing fibers are arranged in one direction, or a woven fabric of reinforcing fibers, with uncured thermosetting resin, thermoplastic resin, or a mixture of thermoplastic resin and thermosetting resin, by a known method. Also, such prepregs may be commercially available.

[0035] The molding method for forming plate-shaped parts is not particularly limited, but from the viewpoint of mass production, press molding in which uncured materials are laminated and then pressed with a press to obtain plate-shaped parts is preferred.

[0036] The electronic device housing member of the present invention is formed by integrating a thermoplastic resin part with at least a part of the peripheral region of a plate-like part. Here, the thermoplastic resin part preferably contains reinforcing fibers.

[0037] As the reinforcing fibers, the reinforcing fibers used in the fiber-reinforced plastics described above can be used. Among them, glass fiber and carbon fiber are preferred because they provide good mechanical properties of the injection molded product. The reinforcing fibers may contain a plurality of reinforcing fibers depending on the purpose. In addition, from the viewpoints of detailed filling and impact strength after the thermoplastic resin part containing the reinforcing fibers is integrally molded with the plate-shaped part, it is also preferred that at least a part of the reinforcing fibers is not dispersed to single yarns but exists in the form of a converging part composed of a plurality of single yarns.

[0038] The method for forming the convergent portion is not limited, but for example, a thermoplastic resin having a melting point sufficiently higher than that of the injected resin, fiber reinforced plastic pieces obtained by crushing fiber reinforced plastic made of a thermosetting resin, or fiber reinforced plastic pieces crushed, classified, and heat-treated as recycling may be mixed during molding of the thermoplastic resin. From the viewpoint of reducing waste to be landfilled, recycled fiber reinforced plastic obtained by crushing, classifying, and heat-treating waste fiber reinforced plastic using a thermosetting resin is preferable. In terms of good physical properties of the reinforcing fiber bundle, it is also preferable that the recycled fiber reinforced plastic is CFRP using carbon fiber. The method for obtaining the recycled fiber reinforced plastic is not limited.

[0039] The number of single yarns constituting the converging portion is preferably 2 or more, more preferably 5 or more, and even more preferably 10 or more. The upper limit of the number of single yarns constituting the converging portion E is not particularly limited, but is preferably 100,000 or less, more preferably 80,000 or less, and even more preferably 60,000 or less. If the number of single yarns constituting the converging portion E is 2 or more, the impact resistance of the resulting molded product when dropped can be improved. In addition, if the number of single yarns constituting the converging portion is 100,000 or less, the fluidity during integral molding is improved, and the detailed filling property is easily improved.

[0040] The length of the long side of the converging portion is preferably 0.5 to 20 mm, more preferably 0.8 to 15 mm, and even more preferably 1.0 to 10 mm. When the length of the long side of the converging portion is 0.5 mm or more, the physical properties of the molded product tend to be improved. When the length of the long side of the converging portion is 20 mm or less, the flowability during integral molding is improved, and the ability to fill small areas tends to be improved.

[0041] The length of the long side of the convergence portion refers to the length of the longest single yarn among the single yarns that make up the convergence portion. The convergence portion may contain single yarns that are shorter than 0.5 mm.

[0042] Here, the term "randomly existing convergent portions" means that the convergent portions are not aligned in a specific direction. The acute angle formed by the long side of a convergent portion and the long side of another convergent portion that is not in contact with the convergent portion is preferably 20° or more, more preferably 25° or more, and even more preferably 30° or more.

[0043] The average fiber length of the reinforcing fibers contained in the thermoplastic resin part is preferably 10 μm to 20 mm or less, more preferably 12 μm to 15 mm, and even more preferably 15 μm to 10 mm. When the average fiber length of the reinforcing fibers is 10 μm or more, the physical properties of the molded product tend to improve. Also, when the average fiber length of the reinforcing fibers is 20 mm or less, the flowability during integral molding is improved, and the fine filling property tends to improve.

[0044] The content of reinforcing fibers in 100% by mass of a thermoplastic resin part is preferably 1 to 50% by mass. The content of reinforcing fibers is more preferably 1 to 45% by mass, and even more preferably 1 to 40% by mass. When the content of reinforcing fibers is 1% by mass or more, the physical properties of a molded product obtained by using the reinforcing fibers tend to be improved. When the content is 50% by mass or less, the flowability during molding is improved, and the ability to fill small areas tends to be improved.

[0045] The thermoplastic resin used in the thermoplastic resin part of the present invention is not particularly limited, and the thermoplastic resin used in the fiber reinforced plastic described above can be used. Among them, from the viewpoint of various good mechanical properties of the injection molded product, polyethylene resin, polypropylene resin, ABS resin, polystyrene resin, AS resin, polyamide resin, polyacetal resin, polycarbonate resin, modified polyphenylene ether resin, thermoplastic polyester resin, polyphenylene sulfide resin are preferred, and polyamide resin, polycarbonate resin, and ABS resin are more preferred. These thermoplastic resins may be used alone or in the form of a mixture or copolymer. In the case of a mixture, a compatibilizer may be used in combination.

[0046] The thermoplastic resin may contain additives such as a flame retardant, and can be used appropriately according to the desired purpose.

[0047] The method of producing thermoplastic resin parts is not limited as long as the desired physical properties and shape can be obtained. Commercially available thermoplastic resin pellets may be used, or a molding material mixture may be prepared by melt kneading, dry blending, or other methods. Among these, dry blending is preferred because it allows easy adjustment of the content of reinforcing fibers in the molded product. Here, dry blending is different from melt kneading in that multiple materials are stirred and mixed at a temperature at which the resin components do not melt, resulting in a substantially uniform state, and is preferably used when using pellet-shaped molding materials, such as injection molding and extrusion molding. Thermoplastic resin pellets without reinforcing fibers may be mixed to achieve the desired fiber content, or additives such as flame retardants may be added depending on the purpose.

[0048] The electronic device housing member of the present invention has a thermoplastic resin part integrated with at least a part of the peripheral region of a plate-shaped part. Here, "integration" refers to melting the thermoplastic resin part, the plate-shaped part, or both, and then cooling and bonding them. The peripheral region is the outer periphery of the plate-shaped part, but in order to increase the adhesive strength with the thermoplastic resin part, it is also preferable to integrate the thermoplastic resin part so that a part of the peripheral region overlaps the plate-shaped part.

[0049] The method for producing the electronic device housing member of the present invention is not particularly limited, but examples include (i) a method in which a plate-shaped part and a thermoplastic resin part are molded separately in advance and then the two are joined together, and (ii) a method in which a plate-shaped part is molded in advance, and then the thermoplastic resin part is molded and then the two are joined together at the same time.

[0050] As a specific example of (i), a plate-shaped part is press-molded, and a thermoplastic resin part is press-molded or injection-molded, and the respective parts thus produced are joined by a known welding means such as hot plate welding, vibration welding, ultrasonic welding, laser welding, resistance welding, or induction heating welding.

[0051] On the other hand, a specific example of (ii) is a method in which a plate-shaped part obtained by press molding is placed in an injection molding die, a material for forming a thermoplastic resin part is insert injection molded or outsert injection molded into the die, and the thermoplastic resin part, which is an injection-molded body, is joined to the plate-shaped part.

[0052] From the viewpoint of mass production of integrally molded products, the method (ii) is preferred. In the injection molding of thermoplastic resin parts, the desired shape may be obtained in one molding, or the injection molding may be performed in multiple separate steps. However, in order to reduce the amount of deformation due to cure shrinkage after molding, it is preferable to perform the injection molding in multiple separate steps.

[0053] As an example, below, a method for integrating a plate-shaped part and a thermoplastic resin part by injection molding to produce a component for an electronic device housing of the present invention is shown, but as long as it falls within the scope of the present invention, the integration method can be selected according to the purpose and is not limited.

[0054] The plate-shaped part is set in an injection mold, the mold is closed, and then the molding material mixture prepared above is injection molded into the peripheral portion of the plate-shaped part to form an electronic device housing member having an integrated thermoplastic resin part. When setting the plate-shaped part in the injection mold, it may be processed into a predetermined shape and size before use.

[0055] It is also important that the entire perimeter of the fiber reinforced plastic is larger than the entire perimeter of the graphite sheet, and that the graphite sheet is not exposed from the outer periphery of the plate-shaped part.

[0056] As shown in Fig. 4, when the plate-shaped part is viewed from above, it is preferable that the surface area of ​​the fiber-reinforced plastic is larger than the surface area of ​​the graphite sheet. When stacked in this manner, the entire circumference of the graphite sheet is covered with the fiber-reinforced plastic. In this case, if ribs are formed on the ends of the fiber-reinforced plastic, the fiber-reinforced plastics will be directly bonded to each other. For this reason, heat accumulated in the graphite sheet is less likely to be dissipated from the outer peripheral surface of the plate-shaped part. Heat is less likely to be transferred to the thermoplastic resin part integrated with at least a part of the peripheral region of the plate-shaped part.

[0057] Furthermore, in the present invention, the fiber-reinforced plastic contained in the plate-shaped part is formed by laminating and integrating a plurality of reinforcing fiber layers using reinforcing fibers consisting of continuous fibers oriented in one direction, and it is preferable that the fiber orientation of the reinforcing fibers constituting one reinforcing fiber layer and the fiber orientation of the reinforcing fibers constituting another reinforcing fiber layer are arranged in different directions.

[0058] When continuous reinforcing fibers are used, it is also preferable to laminate multiple layers so that the orientation directions of the reinforcing fibers are different in order to obtain high strength. By different directions, it is preferable that the angle between the orientation direction of a large number of reinforcing fibers in one layer and the orientation direction of a large number of reinforcing fibers in another layer is 20° or more, more preferably 25° or more, and even more preferably 30° or more.

[0059] When multiple reinforcing fiber layers are laminated, it is preferable to laminate them symmetrically in the thickness direction in order to reduce warping caused by differences in deformation during molding. In order to prevent cracks along the reinforcing fibers and protrusion of the reinforcing fibers during cutting, it is preferable that the outer layer of the plate-shaped part has two or more reinforcing fiber layers with different orientation directions. In order to suppress warping, it is preferable to laminate them so that the fiber orientations are perpendicular to each other. It is also preferred to have a woven fabric.

[0060] In FIG. 2, the outermost layer is a reinforcing fiber layer 3, and the inner layer is a reinforcing fiber layer 4, a graphite sheet 5, another reinforcing fiber layer 4, and another reinforcing fiber layer 3 are laminated in this order.

[0061] Here, the fiber orientation of the reinforcing fiber layer arranged in the outermost layer is perpendicular to the fiber orientation of the reinforcing fiber layer arranged in the inner layer. In this case, the plate-shaped part as a whole becomes quasi-isotropic, and anisotropy is not expressed, and a plate-shaped part without warping can be obtained.

[0062] In the present invention, it is also preferable that the graphite sheets are arranged symmetrically in the thickness direction of the plate-shaped part.

[0063] When the fiber orientation of the reinforcing fiber layer is quasi-isotropic, warping is less likely to occur and strength can be isotropically developed, as described above. Furthermore, when the interlayer adhesive layers and graphite sheets constituting the plate-shaped part are also symmetrically arranged, the plate-shaped part as a whole becomes quasi-isotropic, so that warping is even less likely to occur and strength can be isotropically developed.

[0064] In the present invention, it is also preferable that a reinforcing fiber layer in which the reinforcing fibers are woven is disposed on the surface of the plate-shaped component or inserted inside the plate-shaped component.

[0065] Apart from the reinforcing fiber layers using unidirectional reinforcing fibers being symmetrically arranged, it is preferable that a woven reinforcing fiber layer is inserted between the reinforcing fiber layers using unidirectional reinforcing fibers on the surface of the plate-shaped component or inside the plate-shaped component.

[0066] In the present invention, it is preferable to further dispose a thermoplastic resin layer on at least one surface of the plate-like part.

[0067] By providing a thermoplastic resin layer, it is expected that the adhesion between the plate-shaped part and the thermoplastic part can be improved. The thermoplastic resin layer can be the thermoplastic resin exemplified as the plate-shaped part. When using a thermoplastic resin, the same thermoplastic resin may be used, or a different thermoplastic resin may be used. The plate-shaped part may contain a different material such as a metal depending on the purpose.

[0068] In the present invention, it is also preferable that the entire perimeter of the fiber reinforced plastic is larger than the entire perimeter of the graphite sheet, and that the graphite sheet is not exposed from the outer circumferential surface of the plate-shaped part.

[0069] As shown in FIG. 4, in the cross-sectional view of the plate-shaped part, it is preferable that the graphite sheet does not protrude onto the outer peripheral surface of the plate-shaped part. In other words, when the plate-shaped part is viewed from above, it is preferable that the surface area of ​​the fiber-reinforced plastic is larger than the surface area of ​​the graphite sheet. When laminated in this manner, the entire circumference of the graphite sheet is covered with the fiber-reinforced plastic, and the ends of the fiber-reinforced plastic are directly bonded to each other. For this reason, heat accumulated in the graphite sheet is difficult to dissipate from the outer peripheral surface of the plate-shaped part. It is difficult to transfer heat to the thermoplastic resin part integrated into at least a part of the peripheral region of the plate-shaped part. EXAMPLES

[0070] Next, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

[0071] First, the evaluation method used in the present embodiment will be described.

[0072] (1) Thickness of plate-like parts (hereinafter, simply referred to as "thickness") The thickness of the plate-like part is measured at a total of nine points, including the four corners, two centers of the long sides, and two centers of the short sides, using a micrometer MDC-25SX manufactured by Mitutoyo Corporation, and the average value is the thickness of the plate-like part.

[0073] (2) Heat dissipation measurement The molded plate-shaped part was cut into a rectangle measuring 280mm x 150mm, and a ceramic heater MC2525 manufactured by Sakaguchi Electric Heating Co., Ltd. was attached to the center of the back surface. A load of 3W was applied to the heater, and the part was left for 15 minutes. The surface temperature of the side of the plate-shaped part opposite the side where the heater was attached, and the surface temperature of the heater used for heating were measured with a contact thermometer. The highest temperatures measured were taken as the surface temperature and heater temperature, respectively. Materials with good heat dissipation had lower temperatures, and the surface temperatures obtained were evaluated according to the following criteria. A and B were pass, and C was fail. A: Surface temperature is less than 40℃ B: Surface temperature is between 40℃ and 50℃ C: Surface temperature is 50℃ or higher Furthermore, the heater surface temperature was evaluated according to the following criteria: A and B are pass, and C is fail. A: Heater temperature is less than 85℃ B: Heater temperature is between 85℃ and 95℃ C: Heater temperature is 95℃ or higher (3) Warpage measurement The warpage of each side of the plate-shaped part was measured using the following method. The molded plate-shaped part was cut into a rectangle of 280 mm x 150 mm, and the plate-shaped part was placed on a flat surface with the design surface facing up. A gap gauge was used to measure the gap between the center of each side and the flat surface on which it was placed. The gauge thickness that entered the gap and the gauge thickness that did not enter the gap were measured to the nearest 0.05 mm, and the maximum value of the gauge thickness that entered the gap was taken as the warpage value.

[0074] For example, a 0.2 mm feeler gauge fits into the gap, and a 0.25 mm feeler gauge fits into the gap. If not, the gap warp was set to 0.2 mm.

[0075] Furthermore, the warpage was evaluated according to the following criteria: A and B are acceptable, and C is unacceptable. A: Less than 0.2 mm B: 0.2mm or more and less than 1.0mm C:1.0mm or more (4) Quality of machined end surface After machining a total of 20 through holes, each 1 mm wide and 10 mm long rectangular, in two rows of 10 holes spaced 1 mm apart, the machined end faces were visually inspected and cracks in the plate-like parts, protruding reinforcing fibers, and peeling between layers were deemed defective. The obtained surface temperatures were evaluated according to the following criteria: A and B are acceptable, and C is unacceptable. A: The number of defects is one or less, and no single defect exceeds 10 mm. B: Less than 5 defective items C: 5 or more defective items (5) Material costs Two layers of carbon fiber unidirectional prepreg ("TORAYCA" (registered trademark) prepreg) P3052S-10 (carbon fiber: T700SC, epoxy resin 33% by mass in 100% by mass of the entire prepreg, average single yarn diameter: 7.0 μm) manufactured by Toray Industries, Inc. were laminated, and then a graphite sheet SQ-H1070 manufactured by GuangDong Suqun New Material Co., Ltd. was laminated, and two layers of P3052S-10 were laminated again so that the laminate was symmetrical in the thickness direction. When the longitudinal direction of the fiber-reinforced plastic molded product was set to 0°, the lamination configuration in which the orientation direction of the carbon fiber is shown in parentheses was laminated in the order of prepreg (0°) / prepreg (90°) / graphite sheet / prepreg (90°) / prepreg (0°) from the outermost layer. The material price when the size of this laminate was set to 280 mm x 150 mm was used as a comparison subject, and the evaluation was based on the increase rate of material price when compared at the same size. The evaluation results were evaluated according to the following criteria: A and B are pass, and C is fail. A: The increase rate is less than 5% B: Increase rate is between 5% and 10% C: Increase rate is 10% or more Example 1 (Method of forming plate-shaped parts) Two layers of carbon fiber unidirectional prepreg ("TORAYCA" (registered trademark) prepreg) P3052S-10 (carbon fiber: T700SC, epoxy resin content of 33 mass% in 100 mass% of the total prepreg, average single fiber diameter: 7.0 μm) manufactured by Toray Industries, Inc. were laminated, and then a graphite sheet SQ-H1070 (in-plane thermal conductivity 1200 W / (m·K)) manufactured by GuangDong Suqun New Material Co., Ltd. was laminated, and two layers of P3052S-10 were laminated again so that the laminate was symmetrical in the thickness direction. When the longitudinal direction of the fiber-reinforced plastic molded product is 0°, the laminate configuration in which the orientation direction of the carbon fiber is shown in parentheses was prepreg (0°) / prepreg (90°) / graphite sheet / prepreg (90°) / prepreg (0°) in order from the outermost layer. This laminate was sandwiched between release films and press molded (mold temperature 150°C, pressure 1.5 MPa, curing time 30 minutes, target thickness after pressing 0.4 mm) to obtain two plate-shaped parts. At this time, the graphite sheet was not exposed from the surface of the plate-shaped parts.

[0076] One of the obtained plate-like parts was cut into a rectangle of 280 mm x 150 mm, and the heat dissipation properties were measured. For another plate-shaped part, after measuring the thickness and warpage, a Roland MDX-540 cutting machine was used to cut rectangular through holes, 10 of which were cut at 1mm intervals in two rows, for a total of 20 through holes, each 1mm wide and 10mm long. When the cut end surface was observed, it was in good condition, with no peeling between layers, cracks starting from the end surface, or protruding fibers.

[0077] (Integrated molding with thermoplastic resin parts) The molded plate-like part was processed to a size of 318 mm x 211 mm, set in an injection molding die, and then clamped. Polycarbonate resin (Teijin Chemical Co., Ltd., "Panlite" (registered trademark) GXV-3540UI, glass fiber content 40% by weight, polycarbonate resin) was injection molded into the peripheral part of the plate-like part as a thermoplastic resin member to produce a composite molded product.

[0078] The measurement results of the laminated structure, thickness, heat dissipation, amount of warpage, and machined end surface are shown in Table 1. The properties of the plate-shaped parts are summarized in Table 1.

[0079] Example 2 The graphite sheet of the plate-shaped part was changed to a graphite sheet SQ-H1017 (in-plane thermal conductivity 2000 W / (m K)) manufactured by GuangDong Suqun New Material Co., Ltd., and the laminated structure was changed to two layers, with the top layer being prepreg (0°) / prepreg (90°) / graphite sheet / prepreg (90°) / graphite sheet / prepreg (90°) / prepreg (0°). The plate-shaped part was molded in the same manner as in Example 1, except that the thickness, warpage, and heat dissipation were measured, and through-holes were machined by cutting. A composite molded product was then manufactured by injection molding a thermoplastic resin member on the periphery. The properties of the plate-shaped part are summarized in Table 1.

[0080] Example 3 A foamed core layer made of foamed polypropylene (RC2008W, manufactured by Furukawa Electric Co., Ltd.) was arranged in the center of the thickness direction of the plate-shaped part, and a laminated structure made of a graphite sheet, a prepreg, and a core layer was laminated in the order of prepreg (0°) / prepreg (90°) / graphite sheet / prepreg (90°) / foamed core layer / prepreg (90°) / graphite sheet / prepreg (90°) / prepreg (0°) from the outermost layer, and then this laminate was sandwiched between release films and placed on a press molding lower die. A 1.3 mm spacer was inserted into the outer periphery of the press molding lower die. After setting the press molding upper die, it was placed on a plate surface with a plate surface temperature of 150° C., and the plate surface was closed and hot pressed at a surface pressure of 1.5 MPa. After 30 minutes had passed since the pressurization, the plate surface was opened and cooled at room temperature. After cooling, two plate-shaped parts with a thickness of 1.6 mm were obtained. The heat dissipation, thickness and warpage were measured in the same manner as in Example 1, and then through-holes were machined. A composite molded product was then manufactured by injection molding a thermoplastic resin member on the periphery. The properties of the plate-shaped parts are summarized in Table 1.

[0081] Example 4 As a porous substrate, a discontinuous fiber core layer was prepared, which was made of discontinuous fibers (T700S, manufactured by Toray Industries, Inc., carbon fiber number average fiber length 5 mm) and thermoplastic resin (polypropylene), with a discontinuous fiber weight content of 30 wt %.

[0082] The discontinuous fiber core layer was arranged in the center of the thickness direction of the plate-shaped part, and the laminated structure consisting of the graphite sheet, prepreg, and core layer was prepreg (0 °) / prepreg (90 °) / graphite sheet / prepreg (90 °) / discontinuous fiber core layer / prepreg (90 °) / graphite sheet / prepreg (90 °) / prepreg (0 °) from the outermost layer. Then, as in Example 4, this laminate was sandwiched between release films and placed on the press molding lower die. A 1.4 mm spacer was inserted into the outer periphery of the press molding lower die. After setting the press molding upper die, it was placed on a plate surface with a plate surface temperature of 150 ° C., and the plate surface was closed and hot pressed at a surface pressure of 1.5 MPa. After 30 minutes from pressurization, the plate surface was opened and cooled at room temperature. After cooling, two plate-shaped parts with a thickness of 1.4 mm were obtained. The heat dissipation, thickness and warpage were measured in the same manner as in Example 1, and then through-holes were machined. A composite molded product was then manufactured by injection molding a thermoplastic resin member on the periphery. The properties of the plate-shaped parts are summarized in Table 1.

[0083] Example 5 The size of the prepreg was 300 x 170 mm, the size of the graphite sheet was 260 mm x 130 mm, and they were stacked so as not to place the graphite sheet in the area where the through holes were to be drilled. Two plate-shaped parts were then obtained using the same molding method as in Example 1.

[0084] One of the obtained plate-like parts was cut into a 280 mm x 150 mm rectangle so that each side of the graphite sheet was approximately 10 mm inward from each side of the outermost prepreg layer, and the heat dissipation properties of the plate-like part with the graphite sheet not exposed at the cut end surfaces were measured. For another plate-shaped part, the thickness and warpage were measured, and then the thickness, warpage, and heat dissipation were measured in the same manner as in Example 1, after which through-holes were machined. A composite molded product was then manufactured by injection molding a thermoplastic resin member on the periphery. The properties of the plate-shaped part are summarized in Table 1.

[0085] Comparative Example 1 A plate-shaped part was molded in the same manner as in Example 1, except that no graphite sheet was used and the laminated structure was prepreg (0°) / prepreg (90°) / prepreg (90°) / prepreg (0°) from the outermost layer. After measuring the thickness, warpage and heat dissipation, through-holes were machined. A composite molded product was then manufactured by injection molding a thermoplastic resin member on the periphery. The properties of the plate-shaped part are summarized in Table 1.

[0086] Comparative Example 2 A plate-shaped part was molded in the same manner as in Example 1, except that a graphite sheet was placed on the outermost layer and the laminated structure was graphite sheet / prepreg (0°) / prepreg (90°) / prepreg (90°) / prepreg (0°) from the outermost layer. After measuring the thickness, warpage, and heat dissipation, through-holes were machined. A composite molded product was then manufactured by injection molding a thermoplastic resin member on the periphery. The properties of the plate-shaped part are summarized in Table 1.

[0087] Comparative Example 3 Without stacking graphite sheets, the layer structure is prepreg (0°) / prepreg (90°) / prepreg (90°) / foam core / prepreg (90°) / prepreg (90°) / prepreg (0°) from the outermost layer. After laminating so that the laminate was formed as described above, the laminate was sandwiched between release films and placed on the press molding lower die in the same manner as in Example 4. A spacer of 1.3 mm was inserted into the press molding lower die on the outer periphery. After setting the press molding upper die, it was placed on a plate surface with a plate surface temperature of 150°C, the plate surface was closed, and hot-pressed at a surface pressure of 1.5 MPa. After 30 minutes had passed since pressing, the plate surface was opened and cooled at room temperature. After cooling, two plate-shaped parts with a thickness of 1.3 mm were obtained. After measuring the heat dissipation property, the thickness and the amount of warping were measured in the same manner as in Example 1, through-hole processing was performed by cutting. Then, a composite molded product was manufactured by injection molding a thermoplastic resin member on the periphery. The characteristics of the plate-shaped parts are summarized in Table 1.

[0088] Comparative Example 4 Without laminating the graphite sheet, the laminate was laminated so that the laminate structure was prepreg (0 °) / prepreg (90 °) / prepreg (90 °) / discontinuous fiber core layer / prepreg (90 °) / prepreg (90 °) / prepreg (0 °) from the outermost layer, and then, as in Example 4, this laminate was sandwiched between release films and placed on the press molding lower die. A 1.4 mm spacer was inserted into the outer periphery of the press molding lower die. After setting the press molding upper die, it was placed on a plate surface with a plate surface temperature of 150 ° C., and the plate surface was closed and hot pressed at a surface pressure of 1.5 MPa. After 30 minutes from the pressurization, the plate surface was opened and cooled at room temperature. After cooling, two plate-shaped parts with a thickness of 1.4 mm were obtained. After measuring the heat dissipation property, the thickness and the amount of warping were measured in the same manner as in Example 1, and through-hole processing was performed by cutting. Then, a composite molded product was manufactured by injection molding a thermoplastic resin member on the periphery. The properties of the plate parts are summarized in Table 1.

[0089] (Reference example 1) Polyester resin (Hytrel® 4057, manufactured by DuPont-Toray Co., Ltd.) was fed from the hopper of a twin-screw extruder, melt-kneaded in the extruder, and then extruded from a T-die. The resin was then taken up on a chill roll at 60°C to cool and solidify, yielding a polyester resin film with a thickness of 0.05 mm. This was used as the interlayer adhesive layer.

[0090] A plate-shaped part was molded in the same manner as in Example 1, except that the interlayer adhesive layer was arranged between the graphite sheet and the reinforcing fiber layer, and the laminated structure was prepreg (0°) / prepreg (90°) / interlayer adhesive layer / graphite sheet / interlayer adhesive layer / prepreg (90°) / prepreg (0°) from the outermost layer. After measuring the thickness, warpage, and heat dissipation, through-holes were machined by cutting. Then, a composite molded product was manufactured by injection molding a thermoplastic resin member on the periphery. The properties of the plate-shaped part are summarized in Table 1.

[0091] [Table 1] [Industrial Applicability]

[0092] According to the present invention, it is possible to obtain a component for an electronic device housing having good heat dissipation properties and dimensional accuracy as an electronic device housing, and the component can be widely used for parts and housings of electric and electronic devices such as personal computers, office automation equipment, audiovisual equipment, and home appliances, but the range of applications is not limited to these. [Explanation of symbols]

[0093] 1 Plate-shaped parts 2 Thermoplastic resin parts 3 Reinforced fiber layer (unidirectional) 4 Reinforced fiber layer (unidirectional) 5. Graphite Sheet 6 Core Material 7 Region where the reinforcing fiber layers are integrated

Claims

1. A member for an electronic device housing having a plate-shaped part and a thermoplastic resin part integrated with at least a part of a peripheral region of the plate-shaped part, The plate-shaped part includes: A fiber-reinforced plastic including at least one reinforcing fiber layer including reinforcing fibers and a resin; A composite material having a graphite sheet with an in-plane thermal conductivity of 10 W / (m K) or more and 3000 W / (m K) or less, A member for an electronic device housing, wherein the graphite sheet contained in the plate-shaped part is disposed in an inner layer of the plate-shaped part and is not exposed on the surface.

2. The fiber reinforced plastic contained in the plate-shaped part is A plurality of reinforced fiber layers using reinforced fibers made of continuous fibers oriented in one direction are laminated and integrated, 2. The electronic device housing member according to claim 1, wherein the fiber orientation of the reinforcing fibers constituting one reinforcing fiber layer is oriented in a direction different from the fiber orientation of the reinforcing fibers constituting another reinforcing fiber layer.

3. The electronic device housing member according to claim 2 , wherein the fibers constituting the reinforcing fiber layer are oriented symmetrically in a thickness direction of the plate-like part.

4. 4. The electronic device housing member according to claim 3, wherein the graphite sheets are also disposed symmetrically in a thickness direction of the plate-like part.

5. 2. The electronic device housing member according to claim 1, wherein a reinforcing fiber layer in which the reinforcing fibers are woven is disposed on a surface of the plate-like component or inserted inside the plate-like component.

6. 2. The electronic device housing member according to claim 1, further comprising a thermoplastic resin layer disposed on at least one surface of the plate-like component.

7. 2. The electronic device housing member according to claim 1, wherein the entire circumference of the fiber reinforced plastic is larger than the entire circumference of the graphite sheet, and the graphite sheet is not exposed from the outer circumferential surface of the plate-like part.

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