Fiber Reinforced Resin Composite Sheet, Fiber Reinforced Resin Composite Material, and Resin Molded Product Comprising the Same

Abstract

Provided is a fiber-reinforced resin composite sheet that has excellent flame retardant properties, that has favorable moldability, and that has sufficient tensile strength in high temperature conditions. The fiber-reinforced resin composite sheet includes a flame-retardant resin film which is made from a thermoplastic resin composition that has a glass transition temperature Tg of not less than 90°C, and a plurality of reinforcement fibers which are from an opened reinforcement fiber bundle and which are laminated in the flame-retardant resin film so as to be aligned along the same direction. The flammability category of the flame-retardant resin film as determined by the UL94VTM flammability test according to the ASTM D4804 standard is VTM-0. The volume content Vf of the reinforcement fibers is 30-65%. The thickness of the fiber-reinforced resin composite sheet is 20-100 μm. The flammability category of the fiber-reinforced resin composite sheet as determined by the UL94-5V flammability test according to the ASTM D5048 standard is 5V-A or 5V-B.

Description

Technical Field

[0001] The present invention relates to a fiber-reinforced resin composite sheet including a flame-retardant resin film and reinforcing fibers.

Background Art

[0002] Fiber-reinforced resin composites are materials widely used in components for sports and leisure applications, and components for industrial applications such as automobiles and aircraft. Further, fiber-reinforced resin composites are manufactured using an intermediate material, that is, a prepreg, in which a reinforcing material made of long fibers (continuous fibers) such as reinforcing fibers is impregnated with a resin matrix. Specifically, a molded article of a fiber-reinforced resin composite can be obtained by laminating a plurality of prepregs and heating and curing them, or heating and cooling them to solidify them.

[0003] Conventionally, when manufacturing fiber-reinforced resin composites, thermosetting resins have been widely used as the resin used in prepregs from the viewpoint of excellent strength and rigidity (see, for example, Patent Document 1). However, prepregs using thermosetting resins have problems of low impact resistance and difficulty in secondary processing. To solve these problems, prepregs in which reinforcing fibers are impregnated with a thermoplastic resin as the matrix resin have been widely developed. According to such prepregs, since melting by heating and solidification by cooling are easy, the operability during the molding process of the prepregs is excellent, effects such as shortening of the production time are expected, and cost reduction is also achieved.

[0004] Recently, fiber-reinforced resin composites have also been used as materials for the casings and components of smartphones, tablets, notebook computers, video cameras, mobile devices, and other electrical or electronic devices. Casings and components of electrical or electronic devices may catch fire and burn due to heat generation from inside the device or exposure to high-temperature environments. To prevent such accidents, it is necessary for the prepreg of the material to have flame retardancy. Generally, thermosetting resins are excellent in flame retardancy, but thermoplastic resins are inferior in flame retardancy, and there are few thermoplastic resins that have sufficient flame retardancy alone without adding a flame retardant (see, for example, Patent Document 2). Therefore, when manufacturing fiber-reinforced resin composites that require flame retardancy, thermosetting resins are mainly used as the matrix resin.

[0005] However, depending on the type of molded product, for example, the type of casing or component of an electrical or electronic device, good moldability may be required for the fiber-reinforced resin composite (hereinafter also referred to as "fiber-reinforced resin composite sheet") in order to increase the degree of freedom of shape. On the other hand, a fiber-reinforced resin composite sheet using a thermoplastic resin as the matrix resin has excellent moldability compared to a fiber-reinforced resin composite sheet using a thermosetting resin, but has a problem of inferior strength. Depending on the type of casing or component of an electrical or electronic device as described above, strength, for example, tensile strength, may also be required.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

[0007] Therefore, an object of the present invention is to provide a fiber-reinforced resin composite sheet having excellent flame retardancy, good moldability, and sufficient tensile strength under high-temperature conditions.

[0008] The fiber-reinforced resin composite sheet according to the first aspect of the present invention includes a flame-retardant resin film made of a thermoplastic resin composition having a glass transition temperature Tg of 90°C or higher, and a plurality of reinforcing fibers in which a plurality of reinforcing fibers opened from a reinforcing fiber bundle are laminated in a state of being oriented in the same direction on the flame-retardant resin film, and is a fiber-reinforced resin composite sheet, The flammability classification of the flame-retardant resin film determined in the UL94VTM combustion test in accordance with ASTM D4804 standard is VTM-0, The volume content Vf of the reinforcing fiber is 30% or more and 65% or less, The thickness of the fiber-reinforced resin composite sheet is 20 μm or more and 100 μm or less, The flammability classification of the fiber-reinforced resin composite sheet determined in the UL94-5V combustion test in accordance with ASTM D5048 standard is 5V-A or 5V-B.

Brief Description of Drawings

[0009]

Figure 1

Figure 2

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Figure 6

Embodiments for Carrying Out the Invention

[0010] The higher the volume content Vf of the reinforcing fibers in the fiber-reinforced resin composite material, the greater the tensile strength of the fiber-reinforced resin composite material tends to be. However, during the production of the fiber-reinforced resin composite sheet, which is an intermediate material, simply increasing the amount of reinforcing fibers impregnated in the resin matrix will cause the sheet to become thicker, resulting in a decrease in the formability of the fiber-reinforced resin composite sheet. Furthermore, it is predicted that the structure of the reinforcing fibers and the value of the volume content Vf, etc. will also affect the flame retardancy of the fiber-reinforced resin composite sheet and the like. Thus, in a fiber-reinforced resin composite sheet using a thermoplastic resin, it is difficult to adjust so that all of the properties of flame retardancy, formability, and strength are suitable.

[0011] Furthermore, when using a thermoplastic resin for the matrix resin, polyamide 6 resin is often used from the viewpoints of excellent physical properties such as impact resistance, toughness, and flexibility, as well as cost and ease of handling. However, since polyamide 6 resin has a relatively low glass transition temperature Tg, a fiber-reinforced resin composite sheet manufactured using the polyamide 6 resin may have a decrease in strength under high-temperature conditions. Therefore, polyamide 6 resin is not suitable as a material that may be exposed to heat from the inside of the housing or components of electrical or electronic devices.

[0012] Therefore, the present inventors have intensively studied a fiber-reinforced resin composite sheet having excellent flame retardancy, good formability, and sufficient tensile strength under high-temperature conditions. As a result, the present invention has been achieved. Specifically, by selecting a composition of a thermoplastic resin having predetermined properties, constructing a fiber-reinforced resin composite sheet having a predetermined structure, appropriately setting the type and addition amount of an optionally added flame retardant, and appropriately adjusting the volume content Vf of the reinforcing fibers within a predetermined range, it is possible to provide a fiber-reinforced resin composite sheet as described above.

[0013] Hereinafter, embodiments of the present invention will be described in detail. Note that the scope of the present invention is not limited to the embodiments described here, and various modifications can be made without departing from the spirit of the present invention.

[0014] <Fiber Reinforced Resin Composite Sheet> The fiber reinforced resin composite sheet in the present embodiment includes a flame-retardant resin film and a plurality of reinforcing fibers laminated on the flame-retardant resin film. The plurality of reinforcing fibers are laminated on the flame-retardant resin film in a state where the plurality of reinforcing fibers separated from the reinforcing fiber bundle are oriented in the same direction.

[0015] Here, throughout this specification, the phrase "reinforcing fibers are laminated" used in the "flame-retardant resin film" includes meanings such as "laminated after at least a part of the reinforcing fibers are fused to the flame-retardant resin film", "laminated after at least a part of the reinforcing fibers are adhered to the flame-retardant resin film", "laminated after at least a part of the reinforcing fibers are pressure-bonded to the flame-retardant resin film", and "a state where at least approximately half of each reinforcing fiber is impregnated from the surface to the inside of the flame-retardant resin film", depending on the physical property values, shape, type of treatment performed for lamination, and its conditions, etc. of the flame-retardant resin film. More specifically, heating, cooling, and / or pressure treatment may be performed as necessary during "lamination".

[0016] First, each component included in the fiber reinforced resin composite sheet in the present embodiment will be described.

[0017] [Flame-Retardant Resin Film] The flame-retardant resin film is made of a thermoplastic resin composition having a glass transition temperature Tg of 90°C or higher. When the thermoplastic resin contained in the thermoplastic resin composition has flame-retardant properties, the thermoplastic resin composition may consist of the thermoplastic resin alone. Alternatively, when the thermoplastic resin contained in the thermoplastic resin composition does not have flame-retardant properties, the thermoplastic resin composition contains a flame retardant. Furthermore, the thermoplastic resin composition may contain other additives etc. other than the flame retardant as necessary. Hereinafter, each component contained in the thermoplastic resin composition will be described.

[0018] (Thermoplastic resin) The thermoplastic resin composition is not particularly limited as long as the glass transition temperature Tg is 90°C or higher, and may consist of the thermoplastic resin alone, or may be a composition containing the thermoplastic resin and a flame retardant. Alternatively, commercially available products can also be used. Examples of the type of thermoplastic resin include methacrylic resins such as polymethyl methacrylate resin, polystyrene resins, polystyrene-based resins such as ABS resin and AS resin, polyamide (PA) resins such as PA9T, polycarbonate (PC) resin, polyphenylene sulfide (PPS) resin, modified polyphenylene ether (PPE) resin, polyetherimide (PEI) resin, polysulfone (PSF) resin, polyethersulfone (PES) resin, polyarylate (PAR) resin, polyether nitrile (PEN) resin, polyether ketone (PEK) resin, polyether ether ketone (PEEK) resin, polyether ketone ketone (PEKK) resin, polyimide (PI) resin, polyamideimide (PAI) resin, fluorine (F) resin; liquid crystal polyester resins such as liquid crystal polymer (LCP) resins, or copolymers or modified resins thereof. In the thermoplastic resin composition, these thermoplastic resins may be contained alone or in combination.

[0019] Among these thermoplastic resins, from the viewpoint of excellent various properties such as heat resistance, flame retardancy, and strength, it is preferable to use a high heat-resistant plastic resin called so-called super engineering plastic. That is, the thermoplastic resin composition preferably contains one or more selected from polyphenylene sulfide (PPS) resin, polyether ether ketone (PEEK) resin, polyether ketone ketone (PEKK) resin, polyether imide (PEI) resin, polyether sulfone (PES) resin, and liquid crystal polymer (LCP) resin. Since these thermoplastic resins have excellent flame retardant properties, the thermoplastic resin composition may consist of these thermoplastic resins alone. Specifically, when these resin films satisfy the conditions of the flammability classification described later, and the fiber-reinforced resin composite sheet manufactured using the resin film also satisfies the conditions of the flammability classification described later, a flame retardant may not be included. Furthermore, among these super engineering plastics, from the viewpoint of having a high continuous use temperature, it is more preferable that the thermoplastic resin composition contains one or more selected from polyphenylene sulfide (PPS) resin, polyether ether ketone (PEEK) resin, and polyether ketone ketone (PEKK) resin. For example, the flame retardant resin film made of the thermoplastic resin composition may be made of any one of polyphenylene sulfide (PPS) resin, polyether ether ketone (PEEK) resin, and polyether ketone ketone (PEKK) resin.

[0020] These super engineering plastics may use known commercially available products. Examples of commercially available products of polyphenylene sulfide (PPS) resin include "Torelina (registered trademark)" manufactured by Toray Industries, Inc., "Durafide (registered trademark)" manufactured by Polyplastics Co., Ltd., "Ryton (registered trademark)" manufactured by Solvay, etc. Examples of commercially available products of polyetheretherketone (PEEK) resin include "TORAY TPS (registered trademark) PEEK" manufactured by Toray Industries, Inc., "Vestakeep" manufactured by Daicel - Evonik Co., Ltd., "PEEK Polymer" manufactured by Victrex, etc. Examples of commercially available products of polyetherketoneketone (PEKK) resin include "Kepstan (registered trademark) PEKK" manufactured by Arkema, etc. Examples of commercially available products of polyetherimide (PEI) resin include "Ultem (registered trademark)" manufactured by Sabic, etc. Examples of commercially available products of polyethersulfone (PES) resin include "Sumika Excel PES" manufactured by Sumitomo Chemical Co., Ltd., "Mitsui PES (registered trademark)" manufactured by Mitsui Chemicals Fine Inc., "Ultrason (registered trademark) E" manufactured by BASF, etc. Examples of commercially available products of liquid crystal polymer (LCP) resin include "Sumika Super LCP" manufactured by Sumitomo Chemical Co., Ltd., "Ravelos (registered trademark) LCP" manufactured by Polyplastics Co., Ltd., "UENOLCP (registered trademark)" manufactured by Ueno Fine Chemicals Co., Ltd., etc.

[0021] Alternatively, from the viewpoint of obtaining a fiber - reinforced resin composite sheet with excellent processability, the thermoplastic resin composition preferably contains polycarbonate (PC) resin. When the thermoplastic resin composition contains polycarbonate (PC) resin as the thermoplastic resin, the thermoplastic resin composition preferably further contains one or more flame retardants selected from halogen - based flame retardants, phosphorus - based flame retardants, silicone - based flame retardants, and inorganic - based flame retardants.

[0022] In this embodiment, since the glass transition temperature Tg of the thermoplastic resin composition constituting the flame-retardant resin film is 90°C or higher, it is predicted that characteristics such as tensile strength or flexural strength of the fiber-reinforced resin composite sheet etc. manufactured using the thermoplastic resin composition will not deteriorate even under high-temperature conditions. On the other hand, for example, the glass transition temperature Tg of the polyamide 6 resin matrix widely used as the resin matrix of prepreg is about 50°C (see Comparative Example 1-1 described later). Therefore, it is predicted that characteristics such as strength of the fiber-reinforced resin composite sheet etc. manufactured using the polyamide 6 resin will deteriorate under high-temperature conditions.

[0023] (Flame retardant) The thermoplastic resin composition contains a flame retardant as necessary. In particular, when the thermoplastic resin contained in the thermoplastic resin composition does not have flame-retardant properties, the thermoplastic resin composition contains a flame retardant as an essential component. Even when the thermoplastic resin contained in the thermoplastic resin composition has flame-retardant properties, a flame retardant may be further contained from the viewpoint of improving flame-retardant properties etc.

[0024] The flame retardant is not particularly limited, and examples thereof include halogen-based flame retardants, phosphorus-based flame retardants, silicone-based flame retardants, inorganic-based flame retardants, and other flame retardants. Each will be described below.

[0025] Examples of the halogen-based flame retardants include bromine-based flame retardants and chlorine-based flame retardants.

[0026] Examples of bromine-based flame retardants include, for example, decabromodiphenyl ether; tetrabromobisphenol A, its derivatives such as tetrabromobisphenol A carbonate oligomer, tetrabromobisphenol A epoxy oligomer, etc.; multi-benzenoid ring compound-based bis(pentabromophenyl)ethane, 1,2-bis(2,4,6-tribromophenoxy)ethane, etc.; brominated polystyrene-based brominated polystyrene, polybrominated styrene, etc.; phthalic acid-based ethylene bis(tetrabromophthalimide), etc.; cycloaliphatic-based hexabromocyclododecane, etc.; or other hexabromobenzene, pentabromobenzyl acrylate, etc. Examples of chlorine-based flame retardants include, for example, chlorinated paraffin, dechlorane, chlorendic acid, chlorendic anhydride, etc.

[0027] Examples of phosphorus-based flame retardants include, for example, aromatic phosphate ester-based flame retardants, aromatic condensed phosphate ester-based flame retardants, halogen-containing phosphate ester-based flame retardants, other phosphorus-based flame retardants, etc.

[0028] Examples of aromatic phosphate ester-based flame retardants include, for example, triphenyl phosphate, cresyl phenyl phosphate, tricresyl phosphate, trixylyl phosphate, tris(t-butylated phenyl) phosphate, tris(i-propylated phenyl) phosphate, 2-ethylhexyl diphenyl phosphate, etc. Examples of aromatic condensed phosphate ester-based flame retardants include, for example, 1,3-phenylene bis(diphenyl phosphate), 1,2-phenylene bis(dixylenyl phosphate), etc. Examples of halogen-containing phosphate ester-based flame retardants include, for example, tris(dichloropropyl) phosphate, tris(chloroethyl) phosphate, 2,2-bis(dichloromethyl)trimethylene, bis(2-chloroethyl) phosphate, etc. Examples of other phosphorus-based flame retardants include, for example, red phosphorus, phosphate ester amide, ammonium polyphosphate, etc.

[0029] Examples of silicone flame retardants include polydimethylsiloxane, polymethylethylsiloxane, polymethyloctylsiloxane, polymethylvinylsiloxane, polydimethylphenylsiloxane, polydiphenylsiloxane, polydimethyldiphenylsiloxane, polymethyl(3,3,3-trifluoropropyl)siloxane, and the like.

[0030] Examples of inorganic flame retardants include antimony compounds such as antimony trioxide, antimony tetroxide, antimony pentoxide, and sodium antimonate; molybdenum compounds such as molybdenum oxide and ammonium molybdate; hydrated metal compounds such as aluminum hydroxide and magnesium hydroxide; nanofillers such as titanium oxide, montmorillonite, and silica; or zinc borate, zinc stannate, zinc sulfide, tin oxide, zirconium oxide, zeolite, low-melting glass, and the like.

[0031] Examples of other flame retardants include nitrogen compounds such as melamine compounds like melamine cyanurate and melamine sulfate, triazine compounds, and guanidine compounds; organometallic compounds such as calcium perfluorobutanesulfonate, potassium perfluorobutanesulfonate, potassium diphenylsulfonate, potassium diphenylsulfone-3-sulfonate, and potassium p-toluenesulfonate; or hindered amine compounds, expanded graphite, and the like.

[0032] Among the above-mentioned flame retardants, halogen-based flame retardants, phosphorus-based flame retardants, hindered amine compounds, and antimony compounds have flame retardancy due to their radical trapping action. Also, hydrated metal compounds and expandable graphite have flame retardancy due to their endothermic action. Phosphorus-based flame retardants, halogen-based flame retardants, nitrogen compounds, hydrated metal compounds, antimony compounds, and ammonium polyphosphate have flame retardancy due to their oxygen barrier action or flammable gas dilution action. Silicone-based flame retardants, low melting point glass, hydrated metal compounds, red phosphorus, ammonium polyphosphate, expandable graphite, and organometallic compounds have flame retardancy due to their heat insulation action. By combining such flame retardants with different actions so as to have the desired flame retardant action, a thermoplastic resin composition having the desired flame retardant action can be obtained.

[0033] The flame retardant may be adjusted and included in an appropriate amount in the thermoplastic resin composition so that the flame-retardant resin film made of the thermoplastic resin composition becomes VTM-0 in the flammability classification determined in the UL94VTM combustion test conforming to the ASTM D4804 standard. The UL94VTM combustion test conforming to the ASTM D4804 standard will be described in detail in the examples described later. Furthermore, the flame retardant needs to be adjusted and included while considering the value of the volume content Vf of the reinforcing fiber so that the fiber-reinforced resin composite sheet produced using the flame-retardant resin film also satisfies the conditions of the flammability classification described later.

[0034] Specifically, for example, in the thermoplastic resin composition, the flame retardant may be included in an amount of about 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin. Alternatively, as described above, when the thermoplastic resin itself contained in the thermoplastic resin composition has suitable flame retardant properties, it may not be necessary to include a flame retardant.

[0035] (Other Additives) The thermoplastic resin composition may contain various known additives as necessary, as long as the effects of the present invention are not impaired. For example, antioxidants, light stabilizers, weather resistance improvers, etc. can be added to improve the storage stability of the thermoplastic resin composition and avoid discoloration or deterioration of the solidified product.

[0036] Specific other additives include, for example, thermosetting elastomers, thermoplastic elastomers, silicone oils, wetting dispersants, defoaming agents, degassing agents, natural waxes, synthetic waxes, metal salts of linear fatty acids, acid amides, esters, mold release agents such as paraffins, crystalline silica, fused silica, calcium silicate, alumina, calcium carbonate, talc, barium sulfate and other powders, inorganic fillers such as metal oxides, metal hydroxides, glass fibers, carbon nanotubes, fullerenes, organic fillers such as carbon fibers, cellulose nanofibers, colorants such as red iron oxide, silane coupling agents, conductive materials, slip agents, leveling agents, polymerization inhibitors such as hydroquinone monomethyl ether, ultraviolet absorbers and the like. These additives can be used singly or in appropriate combinations of two or more.

[0037] In addition, the flame-retardant resin film made of a thermoplastic resin composition can be manufactured by applying any method known to those skilled in the art. The method for manufacturing the film is not particularly limited, and examples include roll coating, reverse coating, comma coating, knife coating, die coating, gravure coating, melt extrusion molding method, solution casting method, T-die method, calendar method and the like. Also, by using a coextrusion method or a lamination method, it is also possible to manufacture a film with a thicker thickness or a laminated resin film with a different resin composition.

[0038] The lower limit of the thickness of the flame-retardant resin film is not particularly limited, but preferably by setting it to 5 μm or more, it is easy to maintain the form of the film well during film forming. Also, the thickness of the flame-retardant resin film is preferably 50 μm or less, more preferably 45 μm or less, still more preferably 40 μm or less, even more preferably 30 μm or less, 25 μm or less, or 20 μm or less. By setting the thickness of the flame-retardant resin film to 50 μm or less, the fiber-reinforced resin composite sheet in this embodiment can also be configured to be thin, and as a result, it can have good moldability.

[0039] The flame-retardant resin film made of such a thermoplastic resin composition is an intermediate material for manufacturing the fiber-reinforced resin composite sheet in the present embodiment. On one or both surfaces of the flame-retardant resin film, a plurality of reinforcing fibers separated from a reinforcing fiber bundle are laminated in a state where they are oriented in the same direction, and by being subjected to heating, cooling, and / or pressurization treatment, the fiber-reinforced resin composite sheet in the present embodiment is obtained. From the viewpoint of obtaining more excellent flame-retardant properties, it is preferable that the plurality of reinforcing fibers are laminated on both surfaces of the flame-retardant resin film.

[0040] [Reinforcing fiber] The reinforcing fibers are laminated on the flame-retardant resin film made of the aforementioned thermoplastic resin composition in a state where a plurality of reinforcing fibers separated from a reinforcing fiber bundle are oriented in the same direction. In the present specification, the "state where a plurality of reinforcing fibers are oriented in the same direction" means a state in which each of the plurality of reinforcing fibers extends in a substantially parallel direction.

[0041] By laminating a plurality of reinforcing fibers on the flame-retardant resin film in such a state (specifically, on the surface of the flame-retardant resin film), the fiber-reinforced resin composite sheet in the present embodiment has very excellent flame retardancy. Specifically, not only does the resin film itself have flame-retardant properties, but also a plurality of non-combustible reinforcing fibers (preferably carbon fibers) are laminated on the flame-retardant resin film in a state where they are exposed without being completely impregnated. Compared with a sheet in which the reinforcing fibers are completely impregnated in the molten resin, the spread of the flame can be suppressed.

[0042] The material of the reinforcing fiber is not particularly limited, but it may be appropriately selected according to the application or the like from fibers that are known as reinforcing fibers constituting the fiber-reinforced resin composite sheet and that satisfy the conditions of the flammability classification to be described in detail later when the sheet is formed. Specific examples include various fibers such as carbon fiber, aramid fiber, glass fiber, boron fiber, alumina fiber, silicon nitride fiber, and basalt fiber. Among these, from the viewpoints of specific strength and specific elasticity, carbon fiber, aramid fiber, glass fiber, boron fiber, and alumina fiber are preferable. Furthermore, since the strength, corrosion resistance, etc. of the molded product using the fiber-reinforced resin composite sheet in the present embodiment can be improved, carbon fiber is more preferable. As the carbon fiber, it is preferable to use PAN (polyacrylonitrile)-based carbon fiber with particularly high strength. When using carbon fiber as the reinforcing fiber, surface treatment with a metal may be performed. In addition, as long as the reinforcing fibers opened from these reinforcing fiber bundles are in an oriented state in the same direction, one type or a combination of two or more types can be appropriately used.

[0043] In the fiber-reinforced resin composite sheet in the present embodiment, the volume content Vf of the reinforcing fiber with respect to the fiber-reinforced resin composite sheet is 30% or more and 65% or less. By setting the volume content Vf of the reinforcing fiber to 30% or more, the fiber-reinforced resin composite sheet is sufficiently reinforced by the reinforcing fiber, and thus has excellent strength, particularly tensile strength. On the other hand, by setting the volume content Vf of the reinforcing fiber to 65% or less, good moldability of the fiber-reinforced resin composite sheet with a thermoplastic resin can be maintained. Furthermore, while considering the type of resin selected and the type and amount of the flame retardant optionally added, by adjusting the volume content Vf of the reinforcing fiber within the range of 30% or more and 65% or less, the fiber-reinforced resin composite sheet can be made to satisfy the conditions of the flammability classification to be described in detail later.

[0044] The volume content Vf of the reinforcing fibers is preferably 35% or more, more preferably 40% or more, and even more preferably 44% or more. Also, the volume content Vf of the reinforcing fibers is preferably 60% or less, more preferably 55% or less, and even more preferably 53% or less. Note that the volume content Vf of the reinforcing fibers in the fiber-reinforced resin composite sheet can be adjusted within the above range by appropriately controlling not only the type and thickness of the reinforcing fibers, the fiber width in which the reinforcing fibers are oriented, the thickness of the flame-retardant resin film, etc., but also the temperature and pressure applied during the production of the fiber-reinforced resin composite sheet. The volume content Vf of the reinforcing fibers can be measured by a combustion method, a nitric acid decomposition method, a sulfuric acid decomposition method, etc., but the volume content Vf of the reinforcing fibers in this specification is taken as the value measured by the same combustion method as in the examples.

[0045] Furthermore, the thickness of the fiber-reinforced resin composite sheet in this embodiment is 20 μm or more and 100 μm or less. The thickness of the fiber-reinforced resin composite sheet is preferably 25 μm or more, more preferably 30 μm or more, even more preferably 35 μm or more, and still more preferably 40 μm or more. Also, the thickness of the fiber-reinforced resin composite sheet is preferably 90 μm or less, more preferably 80 μm or less, even more preferably 70 μm or less, still more preferably 60 μm or less, 55 μm or less, or 50 μm or less.

[0046] Specifically, by making the thickness of the fiber-reinforced resin composite sheet as thin as possible within the above range, the flame-retardant resin film and the reinforcing fibers are laminated after being mostly fused, so that the strength of the reinforcing fibers can be fully exerted. Also, when stress is applied, delamination between the layers of the laminate (fiber-reinforced resin composite material described later) made of the fiber-reinforced composite sheet is less likely to occur, and the fatigue characteristics are also excellent. Furthermore, the moldability when using the fiber-reinforced resin composite sheet can be made more excellent. Note that the thickness of the fiber-reinforced resin composite sheet is also affected by the thickness of the flame-retardant resin film, but it can be made within the above range by appropriately controlling the temperature and pressure applied during the production of the fiber-reinforced resin composite sheet.

[0047] The fiber-reinforced resin composite sheet in this embodiment has a flammability classification of 5V-A or 5V-B as determined in the UL94-5V combustion test in accordance with ASTM D5048 standard. The UL94-5V combustion test in accordance with ASTM D5804 standard will be described in detail in the examples below. Preferably, the flammability classification determined in the UL94-5V combustion test in accordance with ASTM D5048 standard is 5V-A. As described above, the flammability of the fiber-reinforced resin composite sheet can be made to satisfy the conditions of the flammability classification by the type of resin selected, the type and addition amount of the flame retardant optionally added, and the adjustment ratio within the range of 30% or more and 65% or less of the volume content Vf of the reinforcing fiber.

[0048] Thus, the fiber-reinforced resin composite sheet in this embodiment not only has excellent flame retardancy and high heat resistance physical properties, but also has an excellent reinforcing effect and fatigue resistance characteristics due to the volume content Vf of the reinforcing fiber that occupies a sufficient value, and further has excellent moldability due to the relatively thin thickness of the fiber-reinforced resin composite sheet. That is, the fiber-reinforced resin composite sheet in this embodiment is suitably used as a material for manufacturing resin molded products such as the casings and parts of electrical or electronic devices such as smartphones, tablets, and notebook computers, where there is a risk of heat generation, ignition, and combustion from inside the device. Furthermore, according to the fiber-reinforced resin composite sheet in this embodiment, since the fiber-reinforced resin composite sheets can be laminated in multiple layers with as few voids as possible and formed into various shapes at high density, a fiber-reinforced resin composite material and a resin molded product having excellent strength can be manufactured.

[0049] An example of the manufacturing method of the fiber-reinforced resin composite sheet in this embodiment will be described with reference to FIG. 1. In FIG. 1, each reference numeral represents a fiber-reinforced resin composite sheet manufacturing apparatus 1, a heating roller 2, a cooling roller 3, an endless belt 4, a take-out roller 5, a bobbin 6, a fiber-reinforced resin composite sheet S, a flame-retardant resin film R0, a reinforcing fiber bundle F0, and a reinforcing fiber (a reinforcing fiber separated from the reinforcing fiber bundle) F.

[0050] The fiber-reinforced resin composite sheet S can be continuously manufactured, for example, using the fiber-reinforced resin composite sheet manufacturing apparatus 1 shown in FIG. 1. This fiber-reinforced resin composite sheet manufacturing apparatus 1 is an apparatus for continuously manufacturing a fiber-reinforced resin composite sheet S from a flame-retardant resin film R0 composed of a reinforcing fiber bundle F0 and a thermoplastic resin composition.

[0051] Specifically, the fiber-reinforced resin composite sheet manufacturing apparatus 1 includes a plurality of pairs (two pairs in FIG. 1) of heating rollers 2 arranged vertically, a plurality of pairs (two pairs in FIG. 1) of cooling rollers 3 arranged vertically below the heating rollers 2, a pair of endless belts 4 wound between the heating rollers 2 and the cooling rollers 3, a pair of drawing rollers 5 located below the endless belts 4, and a winding bobbin 6 disposed below the drawing rollers 5.

[0052] Although not shown, a fiber opening mechanism for opening and spreading the reinforcing fiber bundle F0 in a band shape is provided near the uppermost heating roller 2. By continuously opening the reinforcing fiber bundle F0, this fiber opening mechanism can form a large number of continuous reinforcing fibers F while spreading them so as to extend in the same direction. As the fiber opening mechanism, any mechanism capable of such processing may be used, and various mechanisms such as a mechanism for hitting and spreading the reinforcing fiber bundle F0, a mechanism for blowing air on the reinforcing fiber bundle F0 to spread it, and a mechanism for applying ultrasonic waves to the reinforcing fiber bundle F0 to spread it can be used.

[0053] In the example of FIG. 1, the fiber opening mechanism has a mechanism for supplying the opened reinforcing fibers F to one surface of the flame-retardant resin film R0 and a mechanism for supplying the opened reinforcing fibers F to the other surface of the flame-retardant resin film R0. The former mechanism is provided to introduce the reinforcing fibers F between one surface of the flame-retardant resin film R0 and the heating roller 2 in contact with that surface, and the latter mechanism is provided to introduce the reinforcing fibers F between the other surface of the flame-retardant resin film R0 and the heating roller 2 in contact with that surface. However, the fiber opening mechanism may supply the reinforcing fibers F only to one surface of the flame-retardant resin film R0.

[0054] The heating roller 2 is a high-temperature roller heated by an electric heater, a heating medium, etc. (e.g., a heating fluid). The two pairs of heating rollers 2 heat the flame-retardant resin film R0 and the reinforcing fibers F introduced on both sides thereof while sandwiching them from both sides via the endless belt 4, thereby continuously laminating the reinforcing fibers F on the flame-retardant resin film R0. The reinforcing fibers F are laminated on the flame-retardant resin film R0 in a state of being oriented in the same direction (aligned in the vertical direction in FIG. 1).

[0055] The cooling roller 3 is a low-temperature roller cooled by a cooling medium, etc. (e.g., a cooling fluid). The cooling roller 3 cools the flame-retardant resin film R0 with the reinforcing fibers F laminated thereon while sandwiching it from both sides via the endless belt 4, thereby fixing the reinforcing fibers F to the flame-retardant resin film R0. Thereby, a fiber-reinforced resin composite sheet S in which the flame-retardant resin film R0 (resin matrix) and the reinforcing fibers F are integrated is formed.

[0056] The take-out roller 5 is a roller that applies tension to the formed fiber-reinforced resin composite sheet S and pulls it downward.

[0057] The winding bobbin 6 is a core material for winding the fiber-reinforced resin composite sheet S. The bobbin 6 is rotationally driven by a drive source such as a motor, and forms a roll-shaped fiber-reinforced resin composite sheet S by sequentially winding the fiber-reinforced resin composite sheet S pulled out by the take-out roller 5.

[0058] Note that it is also possible to manufacture the fiber-reinforced resin composite sheet S by a method of flowing and winding the flame-retardant resin film R0 and the opened reinforcing fibers in the same direction without using the endless belt 4 shown in FIG. 1.

[0059] When laminating the opened reinforcing fibers on one surface of the flame-retardant resin film R0 in a state where the reinforcing fibers are oriented in the same direction, the fiber-reinforced resin composite sheet S in which the reinforcing fibers F are laminated on one surface of the flame-retardant resin film can be obtained by feeding the reinforcing fibers F from one side instead of feeding them from both sides as shown in FIG. 1.

[0060] <Fiber Reinforced Resin Composite Material> The fiber reinforced resin composite material in the present embodiment is a fiber reinforced composite material in which a plurality of the fiber reinforced resin composite sheets in the foregoing embodiment are laminated in the thickness direction.

[0061] Here, throughout this specification, the "lamination" used in "the fiber reinforced resin composite sheet (or its chopped material) is laminated" includes meanings of "lamination after being fixed at least in part", "lamination after being bonded at least in part", "lamination after being fused at least in part", "lamination after being adhered at least in part", and "lamination after being pressure-bonded at least in part", depending on physical property values, shapes of the fiber reinforced resin composite sheet (or its chopped material), types of treatments performed for lamination, and conditions thereof. More specifically, heating, cooling, and / or pressure treatment may be performed as necessary during "lamination".

[0062] The fiber reinforced resin composite sheet to be laminated may be shredded or the like as necessary according to the desired shape of the fiber reinforced resin composite material and then laminated. The number of laminated sheets of the fiber reinforced resin composite sheet is not particularly limited and may be appropriately set according to the size of the desired fiber reinforced resin composite material. The fiber reinforced resin composite sheet may be laminated in any state with respect to the fiber direction of the reinforcing fibers, but preferably, the fiber directions of the reinforcing fibers of a plurality of fiber reinforced resin composite sheets are laminated in a state having an angular difference in the two-dimensional direction.

[0063] For example, a plurality of fiber-reinforced resin composite sheets are arranged such that the fiber directions of the reinforcing fibers have an angular difference of approximately 45° in two-dimensional directions. In other words, they have four-axis directions of 0°, 45°, -45°, and 90° (hereinafter also referred to as "four-axis directions with a 45° angular difference") in a two-dimensional plane, and two or more sheets, preferably 4×n sheets (n is an integer of 1 or more), are laminated in the thickness direction. By laminating the fiber-reinforced resin composite sheets in this way, the tensile strength and bending strength along each fiber direction can be improved, and thus the strength of the fiber-reinforced resin composite material as a whole can be effectively improved.

[0064] Alternatively, in another fiber-reinforced resin composite material in the present embodiment, the fiber-reinforced resin composite sheet in the foregoing embodiment may be laminated in the thickness direction in the form of a plurality of chopped materials.

[0065] The chopped materials can be produced in a plurality by, for example, cutting the fiber-reinforced resin composite sheet S shown in FIG. 1 in the foregoing embodiment in the longitudinal direction and the width direction.

[0066] As a specific example, the chopped materials can be produced by the following procedure. The procedure will be described with reference to FIG. 2. In FIG. 2, each reference numeral represents a fiber-reinforced resin composite sheet S, a cut X, a cut Y, a section I, a section II, and a chopped material C. First, as shown in FIG. 2, a cut X extending in the longitudinal direction is formed. That is, while feeding the fiber-reinforced resin composite sheet S in the longitudinal direction, a large number of continuous cuts X in the longitudinal direction are formed in the section I in the middle of the feeding path. The cut X can be formed using, for example, a cutting device including a large number of blades arranged at equal intervals in the width direction of the fiber-reinforced resin composite sheet S.

[0067] Next, in the subsequent section II, a continuous cut Y is formed from one end to the other end in the width direction of the fiber-reinforced resin composite sheet S. The cut Y can be formed using, for example, a rotary cutter or the like. The cut Y is formed each time the fiber-reinforced resin composite sheet S is fed out by a certain distance in the longitudinal direction. As a result, a large number of rectangular chopped materials C having short sides with a length corresponding to the pitch of the cut X and long sides with a length corresponding to the pitch of the cut Y are cut out.

[0068] As described above, the fiber-reinforced resin composite sheet S is a sheet in which a large number of reinforcing fibers F are laminated in the same direction in the longitudinal direction thereof. Therefore, each chopped material C cut out from the fiber-reinforced resin composite sheet S is also laminated with a large number of reinforcing fibers F in the same direction in its longitudinal direction (the direction of the long side). That is, the chopped material C includes a flame-retardant resin film R0 and a large number of reinforcing fibers F laminated on the flame-retardant resin film R0 in the same direction.

[0069] The larger the size of the chopped material C, the higher-strength fiber-reinforced resin composite or resin molded product can be manufactured, but its formability decreases. On the other hand, the smaller the size of the chopped material C, the better its formability, and a fiber-reinforced resin composite or resin molded product with a highly free-form shape can be manufactured, but the strength of the manufactured product decreases. Considering the balance between the formability and mechanical properties due to the size of such a chopped material C, by adjusting the size of the chopped material C and appropriately controlling the balance, characteristics suitable for the use of the molded product can be imparted.

[0070] The length of the short side of the chopped material C is preferably 2 mm or more, more preferably 3 mm or more, still more preferably 4 mm or more, and even more preferably 4.5 mm or more. Also, it is preferably 50 mm or less, more preferably 40 mm or less, still more preferably 30 mm or less, or even more preferably 20 mm or less, 15 mm or less, or 10 mm or less. The length of the long side of the chopped material C is preferably 2 mm or more, more preferably 4 mm or more, still more preferably 6 mm or more, or even more preferably 8 mm or more or 10 mm or more. Also, it is preferably 80 mm or less, more preferably 70 mm or less, still more preferably 60 mm or less, or even more preferably 50 mm or less or 45 mm or less.

[0071] The thickness of the chopped material C is the same as the thickness of the fiber-reinforced resin composite sheet in the above-described embodiment, and is 20 μm or more and 100 μm or less. Regarding the preferred thickness, it is also the same as the thickness of the fiber-reinforced resin composite sheet in the above-described embodiment. That is, similar to the fiber-reinforced resin composite sheet in the above-described embodiment, while minimizing voids due to its thinness, a plurality of sheets can be laminated with a small size as the chopped material C. Therefore, it is possible to manufacture a fiber-reinforced resin composite material having significantly excellent strength and low water absorption with higher density, and a resin molded product using the same. Furthermore, by shaping the chopped material C, the formability is improved, and it is also possible to manufacture a resin molded product having a complex shape.

[0072] In the fiber-reinforced composite material of the present embodiment, such a plurality of chopped materials C may be laminated in any state of the fiber direction of the reinforcing fibers. However, it is preferable that the fiber directions of the reinforcing fibers of the plurality of chopped materials C are laminated in a state of being two-dimensionally random (quasi-isotropic).

[0073] An example of a method for manufacturing such a fiber-reinforced composite material will be described with reference to FIG. 3. In FIG. 3, each reference numeral represents a belt conveyor 7, a release film 8, a heating roller 9, a bobbin 10 for laminated chopped sheets, a chopped material C, section XI, section XII, section XIII, and a laminated chopped sheet CS. First, as shown in FIG. 3, while rotating the belt conveyor 7 arranged substantially horizontally and rotating, a large number of chopped materials C are arranged while being dispersed on its upper surface. For the dispersion arrangement of the chopped material C, for example, a dropping device that drops the chopped material C while vibrating it from above the belt conveyor 7 can be used. Then, by repeating the dropping operation of the chopped material C using such a dropping device, the density and the number of laminated sheets of the chopped material C on the upper surface of the belt conveyor 7 are increased. That is, in a plurality of sections XI, section XII, section XIII,... in the rotation direction of the belt conveyor 7, by repeatedly performing the dropping operation of the chopped material C using the dropping device, the fiber direction of the reinforcing fiber F contained in each chopped material C (in other words, the longitudinal direction of the chopped material C) varies in various directions on the horizontal plane, and a large number of chopped materials C are laminated on the belt conveyor 7 so that a plurality of chopped materials C are stacked in the thickness direction.

[0074] Then, from the end side where a large number of chopped materials C are laminated, the chopped materials C laminated on the upper surface of the belt conveyor 7 are pressurized and heat-treated using a heating roller 9 or a heat-resistant endless belt via a release film 8, and the large number of chopped materials C are integrated. That is, the laminated chopped materials C are bonded to each other by the pressurization and heat-treatment using the heating roller 9. Thus, the dispersion and lamination of the large number of chopped materials C on the upper surface of the belt conveyor 7 and the pressurization and heat-treatment using the heating roller 9 are continuously performed. Thereafter, as a laminated chopped sheet CS in which a plurality of chopped materials C are integrated with each other and laminated, it is continuously formed in a roll shape using a bobbin 10 for the laminated chopped sheet or the like. A partial cross-section of the continuously formed roll-shaped laminated chopped sheet CS is shown in FIG. 4. In FIG. 4, each reference numeral represents a chopped material C, a laminated chopped sheet (fiber-reinforced composite material) CS, and the thickness t of the laminated chopped sheet CS. The thickness t of this laminated chopped sheet CS, that is, the total thickness of the chopped materials C laminated in a plurality of sheets or more, can be set as appropriate.

[0075] Alternatively, as another example of the method for manufacturing a fiber-reinforced composite material, when producing a laminated chopped sheet, a large number of chopped materials C may be laminated on a carrier sheet made of a thermoplastic resin composition.

[0076] Specifically, while feeding the carrier sheet in the longitudinal direction like the belt conveyor 7 shown in FIG. 3, a large number of chopped materials C are arranged while being dispersed on the upper surface of the carrier sheet. For the dispersion arrangement of the chopped materials C, for example, the same dropping device as described above can be used from above the carrier sheet. And the dropping operation of the chopped materials C using such a dropping device may also be repeated at a plurality of locations in the feeding direction of the carrier sheet as described above to increase the density and the number of laminated sheets of the chopped materials C on the carrier sheet. That is, a large number of chopped materials C may be laminated on the carrier sheet such that the fiber directions of the reinforcing fibers F contained in each chopped material C vary in various directions on the horizontal plane and a plurality of chopped materials C are stacked in the thickness direction.

[0077] Thereafter, the carrier sheet and the chip material C thereon are subjected to pressure and heat treatment using a heating roller to integrate the carrier sheet and the chip material C with each other. That is, by the pressure and heat treatment using the heating roller, the chip material C is supported on the carrier sheet in a laminated state, and the laminated chip materials C are bonded to each other. By such a method, a laminated chopped sheet CS in which a plurality of chip materials C are laminated on the upper surface of the carrier sheet can be formed.

[0078] As the material of the carrier sheet, basically, the same thermoplastic resin composition as the thermoplastic resin composition of the chip material C, a resin composition containing other thermoplastic resins having flame retardant properties, or a thermoplastic resin composition without flame retardancy can be used. These thermoplastic resin compositions may consist of only the thermoplastic resin without containing additives.

[0079] Although the case of producing the laminated chopped sheet CS by laminating the chip material C only on the upper surface of the carrier sheet has been described, it is of course possible to laminate the chip material C on both surfaces of the carrier sheet. In this case, the operation of laminating the chip material C on the carrier sheet (that is, the operation of randomly arranging the chip material C multiple times and performing heating and pressure treatment) may be performed in order on the upper surface and the lower surface of the carrier sheet. That is, after laminating the chip material C on the upper surface of the carrier sheet, the carrier sheet is turned over so that the lower surface of the carrier sheet comes up, and the operation of laminating the chip material C in that state is repeated in the same manner. As a result, a laminated chopped sheet in which the chip material C is laminated on both surfaces of the carrier sheet can be produced.

[0080] <Resin molded product> The resin molded product in the present embodiment includes the fiber reinforced resin composite material in the foregoing embodiment.

[0081] The resin molded product may be any molded product of any shape that can be manufactured using the fiber-reinforced resin composite material in the above-described embodiment by any molding method known to those skilled in the art. For example, molded products such as housings and parts used in electric or electronic devices such as smartphones, tablets, notebook computers, video cameras, mobile devices, and other household electric appliances can be mentioned.

[0082] The manufacturing method of the resin molded product in the present embodiment is not particularly limited. For example, first, a plurality of plate-shaped laminated chopped sheets CS described in the above-described embodiment cut into a predetermined size are prepared and placed in a mold such as a hot press while stacking them in the thickness direction. Then, the resin molded product can be manufactured by performing heating and / or pressurization treatment and, if necessary, cooling treatment on the plurality of stacked laminated chopped sheets CS.

[0083] According to the manufacturing method as described above, since the flame-retardant resin film R0 made of a heat-resistant thermoplastic resin composition is used, it is possible to obtain a resin molded product in which the physical property values such as the tensile strength and flexural strength of the resin molded product are less likely to decrease even under high-temperature conditions. Furthermore, since the resin molded product is molded using the laminated chopped sheet CS containing a sufficient amount of reinforcing fibers F with the volume content Vf of the reinforcing fibers being 30% or more and 65% or less, an excellent reinforcing effect by the reinforcing fibers F can be obtained, and the strength of the resin molded product can be increased. Furthermore, the laminated chopped sheet CS in which the fiber directions of the reinforcing fibers F of the plurality of chop materials C are randomly two-dimensionally (quasi-isotropic) laminated can reduce the possibility that the reinforcing fibers F are shredded when the laminated chopped sheet CS is press-molded, and can promote the flow of the resin during press-molding to increase the degree of freedom of the shape of the resin molded product. Thereby, various shaped resin molded products can be molded without hindrance while the reinforcing effect by the reinforcing fibers F is exerted isotropically.

[0084] The above is the summary of the present invention. The fiber-reinforced resin composite sheet, fiber-reinforced resin composite material, and resin molded product including the same in the present embodiment are summarized as follows.

[0085] The fiber-reinforced resin composite sheet according to the first aspect of the present invention includes a flame-retardant resin film made of a thermoplastic resin composition having a glass transition temperature Tg of 90°C or higher, and a plurality of reinforcing fibers obtained by opening a reinforcing fiber bundle and laminated on the flame-retardant resin film in a state where the reinforcing fibers are oriented in the same direction. The flammability classification of the flame-retardant resin film determined in the UL94VTM combustion test according to ASTM D4804 standard is VTM-0. The volume content Vf of the reinforcing fiber is 30% or more and 65% or less. The thickness of the fiber-reinforced resin composite sheet is 20 μm or more and 100 μm or less. The flammability classification of the fiber-reinforced resin composite sheet determined in the UL94-5V combustion test according to ASTM D5048 standard is 5V-A or 5V-B.

[0086] The fiber-reinforced resin composite sheet having such a configuration has excellent flame retardancy, good moldability, and sufficient tensile strength under high-temperature conditions.

[0087] The plurality of reinforcing fibers are preferably laminated on one or both surfaces of the flame-retardant resin film.

[0088] The fiber-reinforced resin composite sheet having such a configuration has a plurality of reinforcing fibers laminated on one or both surfaces of the flame-retardant resin film, and thus has extremely excellent flame retardancy compared to a prepreg in which the reinforcing fibers are completely impregnated in the molten resin.

[0089] The plurality of reinforcing fibers are more preferably laminated on both surfaces of the flame-retardant resin film.

[0090] The fiber-reinforced resin composite sheet having such a configuration surely has extremely excellent flame retardancy as compared with a prepreg in which reinforcing fibers are completely impregnated in a molten resin.

[0091] It is more preferable that the thermoplastic resin composition contains a polycarbonate resin and one or more flame retardants selected from a halogen-based flame retardant, a phosphorus-based flame retardant, a silicone-based flame retardant, and an inorganic-based flame retardant.

[0092] The fiber-reinforced resin composite sheet having such a configuration surely has excellent flame retardancy.

[0093] It is particularly preferable that the thermoplastic resin composition contains one or more selected from a polyphenylene sulfide resin, a polyether ether ketone resin, a polyether ketone ketone resin, a polyether imide resin, a polyether sulfone resin, and a liquid crystal polymer resin.

[0094] The fiber-reinforced resin composite sheet having such a configuration surely has excellent flame retardancy.

[0095] It is more preferable that the reinforcing fiber is a carbon fiber.

[0096] The fiber-reinforced resin composite sheet having such a configuration can improve the strength, corrosion resistance, etc. of a molded product using the same, and surely has extremely excellent flame retardancy due to the non-combustible carbon fiber.

[0097] It is even more preferable that the thickness of the flame retardant resin film is 5 μm or more and 50 μm or less.

[0098] The fiber-reinforced resin composite sheet having such a configuration can also be configured to be thin itself, and as a result, can have good moldability.

[0099] The fiber-reinforced resin composite material according to the second aspect of the present invention is a fiber-reinforced composite material in which a plurality of fiber-reinforced resin composite sheets according to the fiber-reinforced resin composite sheet according to the first aspect are laminated in the thickness direction. The fiber-reinforced composite material is laminated in a state where the fiber directions of the reinforcing fibers of the plurality of fiber-reinforced resin composite sheets have an angular difference in a two-dimensional direction.

[0100] The fiber-reinforced resin composite material having such a configuration can effectively improve the strength of the entire fiber-reinforced resin composite material.

[0101] Alternatively, the fiber-reinforced resin composite material according to the second aspect of the present invention is a fiber-reinforced composite material in which the fiber-reinforced resin composite sheet according to the first aspect is laminated in the thickness direction in the form of a plurality of chopped materials, The chopped material is formed such that the fiber-reinforced resin composite sheet exhibits a rectangle with a short side length of 2 mm or more and 50 mm or less and a long side length of 2 mm or more and 80 mm or less, The fiber-reinforced composite material is laminated in a state where the fiber directions of the reinforcing fibers of the plurality of chopped materials are two-dimensionally random.

[0102] The fiber-reinforced resin composite material having such a configuration can mold resin molded products of various shapes without hindrance while isotropically exhibiting the reinforcing effect by the reinforcing fibers.

[0103] The resin molded product according to the third aspect of the present invention includes the fiber-reinforced resin composite material according to the second aspect.

[0104] The resin molded product having such a configuration has excellent flame retardancy and sufficient tensile strength under high temperature conditions.

Examples

[0105] Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited by the examples at all.

[0106] Test pieces of the fiber-reinforced resin composite sheets and fiber-reinforced composite materials of Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-5 were produced as follows.

[0107] (Example 1-1) To produce a fiber-reinforced resin composite sheet, a flame-retardant resin film made of a thermoplastic resin composition was prepared. In Example 1-1, a flame-retardant resin film made of a thermoplastic resin composition containing a polycarbonate resin and added with a non-bromine-based and non-phosphorus-based flame retardant was used. The glass transition temperature Tg of this thermoplastic resin composition is 148°C to 150°C. Also, the thickness of the flame-retardant resin film is 20 μm.

[0108] This flame-retardant resin film and carbon fiber (manufactured by Toray Industries, Inc., "TORAYCA", grade: T-700 (PAN-based carbon fiber), fiber diameter: 7 μm, number of filaments: 12K, fineness: 800 tex) as the reinforcing fiber were used, and the fiber-reinforced resin composite sheet in the above-described embodiment was obtained while opening the carbon fiber bundle by the manufacturing apparatus shown in FIG. 1. At this time, the pressing force was 0.5 MPa, the roll temperature (the temperature of the heating roller 2 shown in FIG. 1) was 270°C, and the feeding speed was 10 m / min. In the obtained fiber-reinforced resin composite sheet, the opened carbon fiber bundles are laminated on both sides of the flame-retardant resin film. The volume content Vf of carbon fiber in the fiber-reinforced resin composite sheet is 53%, and the thickness of the fiber-reinforced resin composite sheet was 40 μm to 50 μm.

[0109] The obtained fiber-reinforced resin composite sheets were laminated 40 sheets so that the opened carbon fibers were in the direction with an angular difference of 0°. The laminated fiber-reinforced resin composite sheets were put into a mold, and were pressed while heating at 300°C and 2 MPa for 15 minutes, and then were pressed while cooling at room temperature and 3 MPa for 10 minutes. A fiber-reinforced resin composite material of 300 mm × 300 mm × 2 mm (thickness) was taken out from the mold, and the fiber-reinforced resin composite material was cut out to obtain a test piece of a fiber-reinforced resin composite material of 150 mm × 150 mm × 2 mm (thickness). The volume content Vf of carbon fiber in the test piece was also 53%.

[0110] (Example 1-2) In Example 1-2, instead of the thermoplastic resin composition containing the polycarbonate resin added with the flame retardant of Example 1-1, a thermoplastic resin composition consisting only of polyphenylene sulfide (PPS) resin (manufactured by Solvay, "Ryton® QC200N") having flame retardant properties was used. The glass transition temperature Tg of the thermoplastic resin composition made of polyphenylene sulfide (PPS) resin is 90 °C. Pellets of polyphenylene sulfide (PPS) resin were set under the condition of a molding temperature of 280 °C using an extruder equipped with a T-die, and a flame-retardant resin film made of polyphenylene sulfide (PPS) resin with a thickness of 25 μm was produced.

[0111] Using this flame-retardant resin film and the carbon fiber described in Example 1-1, a fiber-reinforced resin composite sheet was obtained by the manufacturing apparatus shown in Fig. 1 while opening the carbon fiber bundle. At this time, the pressing pressure was 0.5 MPa, the roll temperature (the temperature of the heating roller 2 shown in Fig. 1) was 280 °C, the feeding speed was 20 m / min, and a fiber-reinforced resin composite sheet having the same shape as in Example 1-1 was obtained. The volume content Vf of the carbon fiber in the fiber-reinforced resin composite sheet was 44.7%, and the thickness of the fiber-reinforced resin composite sheet was 50 μm.

[0112] Using the obtained fiber-reinforced resin composite sheet, a test piece of a fiber-reinforced resin composite material with dimensions of 150 mm × 150 mm × 2 mm (thickness) was obtained in the same manner as in Example 1-1 described above. The volume content Vf of the carbon fiber in the test piece was also 44.7%.

[0113] (Example 1-3) When laminating the carbon fiber fiber-reinforced resin composite sheet so that the volume content Vf of the carbon fiber in the fiber-reinforced resin composite sheet becomes 35%, except that a film made of polyphenylene sulfide (PPS) resin with a thickness of 25 μm was further added, a fiber-reinforced resin composite sheet with a thickness of 50 μm and a test piece of a fiber-reinforced resin composite material with dimensions of 150 mm × 150 mm × 2 mm (thickness) were obtained in the same manner as in Example 1-2 described above.

[0114] (Example 1-4) Instead of the flame-retardant resin film made of polyphenylene sulfide (PPS) resin with a thickness of 25 μm prepared in Example 1-2, a polyether ether ketone (PEEK) resin film (manufactured by Mitsubishi Chemical Corporation, "Sperio UT (registered trademark) αKN-type") having flame-retardant properties and a thickness of 20 μm was used. The glass transition temperature Tg of the thermoplastic resin composition made of polyether ether ketone (PEEK) resin is 143°C to 147°C.

[0115] Using this flame-retardant resin film and the carbon fiber described in Example 1-1, a fiber-reinforced resin composite sheet was obtained by the manufacturing apparatus shown in FIG. 1 while opening the carbon fiber bundle. At this time, the pressing pressure was 0.5 MPa, the roll temperature (the temperature of the heating roller 2 shown in FIG. 1) was 360°C, the feeding speed was 10 m / min, and a fiber-reinforced resin composite sheet having the same shape as in Example 1-1 was obtained. The volume content Vf of the carbon fiber in the fiber-reinforced resin composite sheet was 53%, and the thickness of the fiber-reinforced resin composite sheet was 40 μm.

[0116] Using the obtained fiber-reinforced resin composite sheet, a test piece of a fiber-reinforced resin composite material with dimensions of 150 mm × 150 mm × 2 mm (thickness) was obtained by the same method as in Example 1-1 described above. The volume content Vf of the carbon fiber in the test piece was also 53%.

[0117] (Comparative Example 1-1) As Comparative Example 1-1, a commercially available fiber-reinforced resin composite sheet (manufactured by TCAC Co., "TC910") having a polyamide 6 resin matrix in which the carbon fiber bundle was not opened and was impregnated as it was in the molten resin was used. The glass transition temperature Tg of the polyamide 6 resin matrix is about 50°C (reference value). The volume content Vf of the carbon fiber in the fiber-reinforced resin composite sheet was 48%, and the thickness of the fiber-reinforced resin composite sheet was 180 μm.

[0118] Fourteen fiber-reinforced resin composite sheets were laminated such that the carbon fiber bundles were in a direction with an angular difference of approximately 0°. Thereafter, a test piece of a fiber-reinforced resin composite material with dimensions of 150 mm × 150 mm × 2 mm (thickness) was obtained in the same manner as in Example 1-1 described above. The volume fraction Vf of carbon fibers in the test piece was also 48%.

[0119] (Comparative Example 1-2) In Comparative Example 1-2, except for reducing the amount of carbon fibers laminated on both sides of a flame-retardant resin film containing a polycarbonate resin with a flame retardant added so that the volume fraction Vf of carbon fibers with respect to the fiber-reinforced resin composite sheet was 25%, a fiber-reinforced resin composite sheet with a thickness of 30 μm was obtained in the same manner as in Example 1-1 described above.

[0120] The obtained fiber-reinforced resin composite sheets were laminated 74 sheets such that the opened carbon fibers were in a direction with an angular difference of 0°. Thereafter, a test piece of a fiber-reinforced resin composite material with dimensions of 150 mm × 150 mm × 2 mm (thickness) was obtained in the same manner as in Example 1-1 described above. The volume fraction Vf of carbon fibers in the test piece was also 25%.

[0121] (Comparative Example 1-3) In Comparative Example 1-3, except for increasing the amount of carbon fibers laminated on both sides of a flame-retardant resin film containing a polycarbonate resin with a flame retardant added so that the volume fraction Vf of carbon fibers with respect to the fiber-reinforced resin composite sheet was 70%, a fiber-reinforced resin composite sheet with a thickness of 70 μm was obtained in the same manner as in Example 1-1 described above.

[0122] Attempts were made to fabricate a test piece of a fiber-reinforced resin composite material with dimensions of 150 mm × 150 mm × 2 mm (thickness) in the same manner as in Example 1-1 described above using the obtained fiber-reinforced resin composite sheets, but the impregnation property between the fibers and the resin was poor, and the test piece could not be molded.

[0123] (Comparative Example 1-4) In Comparative Examples 1-4, except that the amount of carbon fibers laminated on both sides of the flame-retardant resin film made of polyphenylene sulfide (PPS) resin was decreased so that the volume content Vf of carbon fibers in the fiber-reinforced resin composite sheet became 25%, a fiber-reinforced resin composite sheet with a thickness of 35 μm was obtained in the same manner as in Examples 1-2 described above.

[0124] The obtained fiber-reinforced resin composite sheets were laminated 64 sheets so that the direction of the opened carbon fibers was at an angular difference of 0°. Thereafter, a test piece of a fiber-reinforced resin composite material having a size of 150 mm × 150 mm × 2 mm (thickness) was obtained in the same manner as in Examples 1-2 described above. The volume content Vf of carbon fibers in the test piece was also 25%.

[0125] (Comparative Example 1-5) In Comparative Example 1-5, except that the amount of carbon fibers laminated on both sides of the flame-retardant resin film made of polyphenylene sulfide (PPS) resin was increased so that the volume content Vf of carbon fibers in the fiber-reinforced resin composite sheet became 70%, a fiber-reinforced resin composite sheet with a thickness of 85 μm was obtained in the same manner as in Examples 1-2 described above.

[0126] Using the obtained fiber-reinforced resin composite sheet, a test piece of a fiber-reinforced resin composite material having a size of 150 mm × 150 mm × 2 mm (thickness) was attempted to be produced in the same manner as in Examples 1-2 described above. However, the impregnation property between the fibers and the resin was poor, and the test piece could not be molded.

[0127] The volume content Vf of the reinforcing fibers in the fiber-reinforced resin composite sheet and the fiber-reinforced resin composite material was measured by a combustion method. The glass transition temperature Tg of each thermoplastic resin composition or the thermoplastic resin itself was the temperature measured by a differential scanning calorimeter (DSC).

[0128] <Flame Retardancy Evaluation of Thermoplastic Resin Film or Resin Matrix> For the resin films produced in Examples 1-1 to 1-4 and Comparative Examples 1-2 to 1-5, and the polyamide 6 resin matrix used in Comparative Example 1-1, their flammability was determined by the UL94VTM combustion test in accordance with ASTM D4804 standard. Specifically, the test piece (dimensions: 200 ± 5 mm × 50 ± 1 mm × t mm) was wound into a cylindrical shape, vertically attached to a clamp, and indirect flame application with a 20 mm flame for 3 seconds was performed twice, and the combustion behavior was used to determine "VTM-0", "VTM-1", "VTM-2" or "Not". Note that t was set to 20 to 25 μm. The specific judgment criteria are shown in Table 1 below.

[0129]

Table 1

[0130] <Flammability evaluation of fiber-reinforced resin composite sheet> For the test pieces of the fiber-reinforced resin composite sheets produced in Examples 1-1 to 1-4 and Comparative Examples 1-1, 1-2 and 1-4, their flammability was determined by the UL94-5V combustion test in accordance with ASTM D5048 standard. Specifically, a strip-shaped test piece (dimensions: 125 ± 5 mm × 13 ± 0.5 × t mm) was vertically attached to a clamp, and indirect flame application with a 125 mm flame for 5 seconds was performed 5 times. Further, a flat plate test piece (dimensions: 150 ± 5 mm × 150 ± 5 × t mm) was held horizontally, and indirect flame application with a 125 mm flame for 5 seconds was performed 5 times from below. Based on these combustion behaviors, judgments of "5V-B", "5V-A" or "Not" were made. Note that t was set to 2 mm. The specific judgment criteria are shown in Table 2 below. In Comparative Examples 1-3 and 1-5, the test pieces of the fiber-reinforced resin composite sheets had poor impregnation between the fibers and the resin, so the tests could not be performed.

[0131]

Table 2

[0132] <Evaluation of tensile strength (MPa) of test pieces of fiber-reinforced resin composites> For the test pieces of the fiber-reinforced resin composites of Examples 1-1 to 1-4 and Comparative Examples 1-1, 1-2, and 1-4, the tensile strength was measured in accordance with JIS K 7165:2008. In Comparative Examples 1-3 and 1-5, as described above, test pieces of the fiber-reinforced resin composite could not be molded, so the tests could not be conducted.

[0133] The properties and evaluation results of the thermoplastic resin films or resin matrices and fiber-reinforced resin composite sheets in Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-5 are summarized in Tables 3 and 4 below.

[0134] [Table 3]

[0135] [Table 4]

[0136] As is clear from the results in Table 3 above, the resin films of Examples 1-1 to 1-4 and their fiber-reinforced resin composite sheets had excellent flame retardancy compared to the polyamide 6 resin matrix of Comparative Example 1-1 and its fiber-reinforced resin composite sheet.

[0137] Furthermore, compared with the fiber-reinforced resin composite sheet of Comparative Example 1-1 produced by impregnating a resin matrix without opening the carbon fiber bundles, the fiber-reinforced resin composite sheets of Examples 1-1 to 1-4 could be formed with a significantly reduced thickness. In addition, although the test pieces of the fiber-reinforced resin composites of Examples 1-2 and 1-3 had a smaller volume fraction Vf of reinforcing fibers compared to the test pieces of the fiber-reinforced resin composite of Comparative Example 1-1, contrary to the normally predicted results, they had high tensile strength. This is presumably because the fiber-reinforced resin composite sheets of Examples 1-1 to 1-4 are composed of multiple thin fiber-reinforced resin composite sheets stacked on top of each other, resulting in good dispersibility of the reinforcing fibers and the resin. Therefore, compared to the laminate in Comparative Example 1-1 composed of thick layers, delamination between layers is less likely to occur, and the inherent strength of the fibers is exhibited. Thus, the fiber-reinforced resin composite sheets of Examples 1-1 to 1-4 were excellent in formability as an intermediate material and also had excellent tensile strength of the fiber-reinforced resin composites produced from the sheets.

[0138] Furthermore, as can be seen from the results of Comparative Examples 1-2 and 1-4 in Table 4 above, when the volume fraction Vf of the reinforcing fibers was reduced to 25%, the tensile strength of the fiber-reinforced resin composite significantly decreased. Also, as can be seen from the results of Comparative Examples 1-3 and 1-5 in Table 4 above, when the volume fraction Vf of the reinforcing fibers was increased to 70%, the impregnation property between the fibers and the resin in the obtained fiber-reinforced resin composite sheet deteriorated, and as a result, the formability deteriorated, so that the fiber-reinforced resin composite could not be formed. From these results, it can be understood that if the volume fraction Vf of the reinforcing fibers is not adjusted to a value within the specific range defined for the fiber-reinforced resin composite sheet of the present embodiment, it is impossible to obtain a fiber-reinforced resin composite sheet that combines good formability and sufficient tensile strength under high-temperature conditions.

[0139] The glass transition temperature Tg of the resin films (thermoplastic resin compositions or thermoplastic resins) used in Examples 1-1 to 1-4 is significantly higher than the glass transition temperature Tg of the polyamide 6 resin matrix used in Comparative Example 1-1. Therefore, the fiber-reinforced resin composite sheets of Examples 1-1 to 1-4 and the fiber-reinforced resin composites produced therefrom are assumed to have heat resistance and good strength, such as tensile strength (or flexural strength), even under high-temperature conditions. Furthermore, it is assumed that the thermoplastic resins (polyetherketoneketone (PEKK) resin, polyetherimide (PEI) resin, polyethersulfone (PES) resin, and liquid crystal polymer (LCP) resin) of Reference Examples 1 to 4, which have a high glass transition temperature Tg and high flammability as shown in Table 5 below, also exhibit the same effects as the present invention.

[0140]

Table 5

[0141] Furthermore, additional experiments on the flame retardancy evaluation of the fiber-reinforced resin composite sheets were conducted. Specifically, additional experiments were conducted to investigate the relationship between the structure of the fiber-reinforced resin composite sheets and the flame retardant properties of the sheets. First, test pieces of the fiber-reinforced resin composite sheets in Examples 2-1 and 2-2 and Comparative Examples 2-1 and 2-2 were prepared by the following method.

[0142] (Example 2-1) In Example 2-1, a fiber-reinforced resin composite sheet containing a polycarbonate resin to which a flame retardant was added was obtained by the same method as in Example 1-1 described above. The volume content Vf of carbon fibers in the fiber-reinforced resin composite sheet was 53%, and the thickness of the fiber-reinforced resin composite sheet was 40 to 50 μm. Next, a test piece of the fiber-reinforced resin composite sheet having dimensions of 13 mm × 125 mm × 40 to 50 μm (thickness) was cut out from the obtained fiber-reinforced resin composite sheet.

[0143] The cross-section of the test piece of the fabricated fiber-reinforced resin composite sheet was observed using a laser microscope ("VK-X160", manufactured by Keyence Corporation). As shown in Fig. 5, the cross-sectional view of the test piece of the fiber-reinforced resin composite sheet in Example 2-1 shows a state in which a plurality of carbon fibers are laminated on both sides of a flame-retardant resin film containing a polycarbonate resin added with a flame retardant. Specifically, a plurality of carbon fibers are impregnated from the film surface into the interior at approximately half of each carbon fiber.

[0144] (Example 2-2) In Example 2-2, a fiber-reinforced resin composite sheet containing polyphenylene sulfide (PPS) resin was obtained by the same method as in Example 1-2 described above. The volume content Vf of carbon fibers in the fiber-reinforced resin composite sheet was 44.7%, and the thickness of the fiber-reinforced resin composite sheet was 50 μm. Subsequently, a test piece of a fiber-reinforced resin composite sheet with dimensions of 13 mm × 125 mm × 50 μm (thickness) was cut out from the obtained fiber-reinforced resin composite sheet.

[0145] The cross-section of the test piece of the fabricated fiber-reinforced resin composite sheet was observed in the same manner as in Example 2-1. As shown in Fig. 5, the cross-sectional view of the test piece of the fiber-reinforced resin composite sheet in Example 2-2 shows a state in which a plurality of carbon fibers are laminated on both sides of a flame-retardant resin film made of polyphenylene sulfide (PPS) resin. Specifically, a plurality of carbon fibers are impregnated from the film surface into the interior at approximately half of each carbon fiber.

[0146] (Comparative Example 2-1) In Comparative Example 2-1, first, a fiber-reinforced resin composite sheet containing a polycarbonate resin added with a flame retardant was obtained in the same manner as in Example 1-1 described above. Further, the sheet was sandwiched between iron plates heated to 300 °C and pressed at 5 kgf × 60 seconds using a press machine to obtain a fiber-reinforced resin composite sheet containing a polycarbonate resin added with a flame retardant in Comparative Example 2-1. The volume content Vf of carbon fiber in the fiber-reinforced resin composite sheet was 53%, and the thickness of the fiber-reinforced resin composite sheet was 38 μm. Next, a test piece of the fiber-reinforced resin composite sheet with dimensions of 13 mm × 125 mm × 38 μm (thickness) was cut out from the obtained fiber-reinforced resin composite sheet.

[0147] The cross-section of the test piece of the fabricated fiber-reinforced resin composite sheet was observed in the same manner as in Example 2-1. As shown in Fig. 5, the cross-sectional view of the test piece of the fiber-reinforced resin composite sheet in Comparative Example 2-1 showed a state in which a plurality of carbon fibers were completely impregnated inside the flame-retardant resin film containing a polycarbonate resin added with a flame retardant.

[0148] (Comparative Example 2-2) In Comparative Example 2-2, first, a fiber-reinforced resin composite sheet containing polyphenylene sulfide (PPS) resin was obtained in the same manner as in Example 1-2 described above. Further, the sheet was sandwiched between iron plates heated to 330 °C and pressed at 5 kgf × 60 seconds using a press machine to obtain a fiber-reinforced resin composite sheet containing polyphenylene sulfide (PPS) resin in Comparative Example 2-2. The volume content Vf of carbon fiber in the fiber-reinforced resin composite sheet was 44.7%, and the thickness of the fiber-reinforced resin composite sheet was 42 μm. Next, a test piece of the fiber-reinforced resin composite sheet with dimensions of 13 mm × 125 mm × 42 μm (thickness) was cut out from the obtained fiber-reinforced resin composite sheet.

[0149] The cross-section of the test piece of the produced fiber-reinforced resin composite sheet was observed in the same manner as in Example 2-1. As shown in Fig. 5, in the cross-sectional view of the test piece of the fiber-reinforced resin composite sheet in Comparative Example 2-2, a plurality of carbon fibers were completely impregnated inside the flame-retardant resin film made of polyphenylene sulfide (PPS) resin.

[0150] <Additional Flame Retardancy Test of Fiber-Reinforced Resin Composite Sheet> Regarding the test pieces of the fiber-reinforced resin composite sheets produced in Example 2-1, Example 2-2, Comparative Example 2-1, and Comparative Example 2-2, the flame retardancy was determined by a method different from the above-described method. As the test method, first, the test piece of the produced fiber-reinforced resin composite sheet was hung with a clamp. Next, the flame of the prepared gas burner was adjusted to be blue. Then, the gas burner was moved so that the test piece of the fiber-reinforced resin composite sheet hung with a clamp was positioned at a location about 1 cm away from the tip of the flame of the gas burner. In this way, the flame was applied from the lower part of the test piece of the fiber-reinforced resin composite sheet hung with a clamp, and the state at the initial stage of ignition, specifically, 1 second after ignition, was observed.

[0151] Fig. 6 is an image showing the results of the additional flame retardancy test of the test pieces of each fiber-reinforced resin composite sheet. Specifically, Fig. 6 is an image 1 second after ignition in the test piece of each fiber-reinforced resin composite sheet. As can be seen from Fig. 6, the test pieces of Example 2-1 and Example 2-2, in which the carbon fibers were impregnated from the film surface to the inside at approximately half of each carbon fiber, showed a tendency that the flame was less likely to spread compared to the test pieces of Comparative Example 2-1 and Comparative Example 2-2, in which a plurality of carbon fibers were completely impregnated inside the resin film. This is presumably because the test pieces of Example 2-1 and Example 2-2 were laminated in a state where a plurality of non-combustible carbon fibers were exposed without being completely impregnated on the flame-retardant resin film, suppressing the spread of the flame. Thus, the fiber-reinforced resin composite sheet in the present embodiment is considered to have very excellent flame retardancy because not only the resin film has flame retardant properties but also a plurality of reinforcing fibers are laminated on the flame-retardant resin film.

[0152] This application is based on Japanese Patent Application No. 2020-075392 filed on April 21, 2020, the content of which is incorporated herein.

[0153] In order to represent the present invention, the present invention has been appropriately and sufficiently described through embodiments and examples with reference to specific examples and the like above. However, those skilled in the art should recognize that it is possible to easily make changes and / or improvements to the above-described embodiments and examples. Therefore, as long as the modified or improved forms implemented by those skilled in the art do not depart from the scope of the claims described in the claims, the modified or improved forms are construed to be included within the scope of the claims of the claims.

Industrial Applicability

[0154] The present invention relates to the technical field of fiber-reinforced resin composite sheets, and can improve the flame retardancy, moldability, and strength under high-temperature conditions of the sheets, and can be widely used as materials for sports and leisure members, industrial members such as automobiles and aircraft, and housings and components of electrical or electronic devices.

Claims

1. A fiber-reinforced resin composite sheet comprising a flame-retardant resin film made of a thermoplastic resin composition having a glass transition temperature Tg of 90°C or higher, and a plurality of carbon fibers obtained by opening a carbon fiber bundle and oriented in the same direction and laminated on the flame-retardant resin film, wherein the flammability classification of the flame-retardant resin film determined in a UL94VTM combustion test conforming to ASTM D4804 standard is VTM-0, the volume content Vf of the carbon fibers is 30% or more and 65% or less, the thickness of the fiber-reinforced resin composite sheet is 20 μm or more and 100 μm or less, the flammability classification of the fiber-reinforced resin composite sheet determined in a UL94-5V combustion test conforming to ASTM D5048 standard is 5V-A or 5V-B, and the thermoplastic resin composition contains one or more selected from polyphenylene sulfide resin, polyether ether ketone resin, polyether ketone ketone resin, polyether imide resin, polyether sulfone resin, and liquid crystal polymer resin.

2. The fiber-reinforced resin composite sheet according to claim 1, wherein the carbon fibers are laminated on both surfaces of the flame-retardant resin film.

3. The fiber-reinforced resin composite sheet according to any one of claims 1 to 2, wherein the thickness of the flame-retardant resin film is 5 μm or more and 50 μm or less.

4. A fiber-reinforced composite material in which a plurality of the fiber-reinforced resin composite sheets according to any one of claims 1 to 3 are laminated in the thickness direction, wherein the fiber-reinforced composite material is laminated in a state where the fiber directions of the carbon fibers of the plurality of the fiber-reinforced resin composite sheets have an angular difference in a two-dimensional direction.

5. A fiber-reinforced composite material in which the fiber-reinforced resin composite sheet according to any one of claims 1 to 3 is in the form of a plurality of chopped materials and laminated in the thickness direction, wherein the chopped material is formed such that the fiber-reinforced resin composite sheet has a rectangle with a short side length of 2 mm or more and 50 mm or less and a long side length of 2 mm or more and 80 mm or less, and the fiber-reinforced composite material is laminated in a state where the fiber directions of the carbon fibers of the plurality of the chopped materials are two-dimensionally random.

6. A resin molded product comprising the fiber-reinforced resin composite material according to claim 4 or 5.

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