JP2004269878A - Fiber-reinforced composite material, method for producing the same and integrally molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fiber-reinforced composite material (I) having excellent adhesion to a structural member (II) and physical characteristics, and to provide an integrally molded product (III) given by using the fiber-reinforced composite material. <P>SOLUTION: This fiber-reinforced composite material contains a reinforcing fiber and a thermosetting resin composition, wherein a film made out of a thermoplastic resin composition is formed on at least a part of a surface of the fiber-reinforced composite material, so that the film gives vertical adhesion values of ≥10 MPa at 40°C and of <10 MPa at 140°C which are given by subjecting a nylon 6 resin containing a short fiber of carbon in an amount of 30 wt% to injection molding on the film and then measuring the adhesion value in the vertical direction. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a fiber reinforced composite material (FRP) in which a matrix resin is reinforced with continuous reinforcing fibers and a method for producing the same, and more particularly, to an integrated molded article using this fiber reinforced composite material, which is molded when discarded. An object of the present invention is to provide a fiber-reinforced composite material which can be easily peeled and decomposed and can be easily separated for reuse, and a method for producing the same. An integrated molded article using the fiber-reinforced composite material is used for parts, members, housings, etc. of electric / electronic devices, OA devices, home electric appliances, automobiles or building materials.

  Fiber reinforced plastics are excellent in moldability, thinness, light weight, high rigidity, productivity, and economic efficiency, electrical and electronic equipment parts, automotive equipment parts, personal computers, OA equipment, AV equipment, mobile phones, telephones, facsimiles, and home appliances. It is frequently used for parts and housings of electric and electronic devices such as toy articles. However, for example, a fiber-reinforced plastic plate in which long fibers of a group of reinforcing fibers are arranged in a layered manner is a material that is particularly thin, lightweight, and excellent in rigidity. It was not suitable for easy production.

  On the other hand, metal materials such as Mg alloys are also used in electronic devices such as personal computers, mobile phones, personal digital assistants, OA equipment, and parts, members and housings such as automobiles and building materials because of their advantages such as easy formation of complicated shapes. Became used. However, even if an attempt is made to use a metal material for all parts and the like, there is a problem that the Mg alloy has a higher specific gravity than fiber-reinforced plastic, does not provide a sufficient weight-reducing effect, and is expensive.

  Therefore, there is a need for a technique for integrally joining a composite material such as a fiber reinforced plastic plate with a metal member or another injection molded product. In a molded product in which members made of such different materials are integrated with each other, the adhesion at the joint becomes a very important problem in terms of its function.

  As an integration method, a method using an adhesive has conventionally been generally employed.

  For example, Patent Document 1 discloses an electronic device housing in which a metal frame and an injection-molded rib are bonded with an epoxy resin-based paint.

However, the method using the adhesive disclosed in Patent Document 1 requires a preparation step and an application step of the adhesive, so that it is difficult to reduce the production cost, and the reliability of the adhesive strength is not sufficiently satisfied. is the current situation. Furthermore, when the integrated molded product is discarded, it is difficult to separate different materials, and even if it can be separated, there is a problem that it is difficult to reuse the remaining adhesive due to contamination.
JP 2001-298277 A (page 1, line 4)

  An object of the present invention is to solve the problems of the prior art and to provide a fiber-reinforced composite material and an integrated molded product having excellent adhesion to other members and excellent mechanical properties. It is another object of the present invention that a member of an integrated molded product can be easily disassembled after use and can be reused.

  That is, the present invention is a fiber-reinforced composite material comprising a reinforcing fiber and a thermosetting resin composition, wherein a film made of a thermoplastic resin composition is formed on at least a part of the surface thereof, and Vertical injection strength at the time of injection molding a nylon 6 resin containing 30% by weight of carbon fiber monofilament at 40 ° C. and less than 10 MPa at 140 ° C. (The first fiber-reinforced composite material of the present invention).

  Further, the present invention is a fiber-reinforced composite material comprising a reinforcing fiber and a thermosetting resin composition, wherein a film made of a thermoplastic resin composition is formed on at least a part of the surface thereof, and A fiber-reinforced composite material having a solubility parameter δ (SP value) of the thermoplastic resin constituting the thermoplastic resin composition of 9 to 16 (the second fiber-reinforced composite material of the present invention).

  The present invention also provides a laminating step of arranging the thermoplastic resin composition on at least a part of the surface of the thermosetting prepreg laminate, and melting the thermoplastic resin composition in parallel with the curing reaction of the thermosetting resin to form a coating. And a thermoforming step of forming the fiber-reinforced composite material.

  Further, the present invention is an integrated molded product, wherein the fiber-reinforced composite material of the present invention and another structural member are integrally joined.

  The fiber-reinforced composite material of the present invention can be easily integrated with other members and has excellent adhesive strength between members to be joined.

  Further, the integrated molded product of the present invention is excellent in mechanical properties and lightness, and can be easily disassembled at the time of disposal. In addition to having excellent electromagnetic wave shielding properties, it has low profile, light weight, and high rigidity, and is used as a housing for electric / electronic devices such as personal computers, displays, and personal digital assistants, as well as parts, members, and housings for automobiles and building materials. It is suitable.

  The fiber-reinforced composite material of the present invention comprises a reinforcing fiber and a thermosetting resin composition.

  As the reinforcing fibers, for example, aluminum, brass, metal fibers such as stainless steel, polyacrylonitrile-based, rayon-based, lignin-based, pitch-based carbon fibers, graphite fibers, insulating fibers such as glass, aramid, PBO, Organic fibers such as polyphenylene sulfide, polyester, acrylic, nylon, and polyethylene; and inorganic fibers such as silicon carbide and silicon nitride. These fibers may be subjected to a surface treatment. Examples of the surface treatment include a treatment with a coupling agent, a treatment with a sizing agent, a treatment for attaching an additive, and the like, in addition to a treatment for attaching a metal as a conductor. In addition, one type of these reinforcing fibers may be used alone, or two or more types may be used in combination.

  Above all, carbon fibers, particularly polyacrylonitrile-based carbon fibers, can be suitably used from the viewpoint of the balance between specific strength, specific rigidity, lightness and conductivity, because they can realize low cost.

  The carbon fiber has a surface oxygen concentration {O / C} of 0.05 to 0, which is a ratio of the number of atoms of oxygen (O) and carbon (C) on the surface of the fiber measured by X-ray photoelectron spectroscopy. 3, preferably 0.06 to 0.25, more preferably 0.07 to 0.2. When the surface oxygen concentration {O / C} is 0.05 or more, the amount of polar functional groups on the carbon fiber surface is secured, the affinity with the thermoplastic resin composition is increased, and strong adhesion can be obtained. . Further, when the ratio is 0.3 or less, the strength of the carbon fiber itself is hardly reduced by oxidation.

  In addition, as the form of the reinforcing fibers, those having an average length of 10 mm or more, which are layered and arranged, are preferable from the viewpoint of efficiently exhibiting the reinforcing effect of the reinforcing fibers. As a form of the reinforcing fiber layer, a form in which cloth, filaments, braids, filament bundles, spun yarns, and the like are arranged in one direction can be suitably used. In the case of laminating the layers arranged in one direction, it is preferable to laminate the layers while shifting the direction for each layer in order to reduce the strength anisotropy of the laminate. These layers may be used alone or in combination of two or more.

  The ratio of the reinforcing fibers to the fiber-reinforced composite material of the present invention is preferably from 5 to 75% by volume, more preferably from 10 to 65% by volume, from the viewpoint of moldability, mechanical properties and electromagnetic wave shielding properties.

  The thermosetting resin constituting the thermosetting resin preferably has a glass transition temperature of 60 ° C. or higher, more preferably 80 ° C. or higher, even more preferably 100 ° C. or higher. Since the integrated molded product mainly has a function of housing a heating element, its use environment is usually around 40 ° C, and its glass transition temperature is 60 ° C or higher, which results in excellent mechanical properties. Fiber reinforced composite material.

  As the thermosetting resin, for example, unsaturated polyester, vinyl ester, epoxy, phenol (resole type), urea / melamine, polyimide, and the like, or a copolymer, a modified product thereof, or a resin in which two or more kinds are blended are used. can do. Above all, those containing at least an epoxy resin are preferable from the viewpoint of the mechanical properties of the fiber-reinforced composite material.

  Further, an elastomer or a rubber component may be added to the thermosetting resin composition for improving impact resistance.

  It is important that the fiber-reinforced composite material of the present invention has a film formed of a thermoplastic resin composition formed on at least a part of its surface. Due to the coating, excellent adhesion to other members can be obtained.

  In the fiber-reinforced composite material according to the second aspect of the present invention, it is important that the solubility parameter δ (SP value) of the thermoplastic resin constituting the thermoplastic resin composition of the coating film is from 9 to 16, preferably from 10 to 10. To 15, more preferably 11 to 14. By setting it within the above range, the cohesive force of the molecular chains of the thermoplastic resin is large, the thermoplastic resin composition itself is not easily broken, and the affinity with the reinforcing fiber is increased, so that the strong adhesive force is obtained. Can be expressed.

  Examples of the thermoplastic resin capable of achieving such a solubility parameter δ include, for example, an amide bond, an ester bond, a urethane bond, an ether bond, an amino group, a hydroxyl group, a carboxyl group, a bond having a higher polarity than a hydrocarbon skeleton such as an aromatic ring, and a functional bond. Those having a group or a structure can be mentioned. Examples of such a thermoplastic resin composition containing an amide bond, an ester bond, a urethane bond, a hydroxyl group, and the like include a polyamide resin, a polyester resin, a polycarbonate resin, and an EVA resin. Examples of those containing an aromatic ring include styrene-based resins and PPS-based resins. The resin is not limited to being used alone, but may be a copolymer thereof, a modified product thereof, a resin obtained by blending at least two of them, or the like.

  Further, the weight average molecular weight of the thermoplastic resin constituting the thermoplastic resin composition of the coating is preferably 2,000 to 200,000, more preferably 5,000 to 150,000, and 10,000 to 100,000. Is more preferred. By being in the above range, the entanglement of the intermolecular force and the molecular chain is increased, and the strength of the thermoplastic resin itself is increased, so that the thermoplastic resin itself is not easily broken, and furthermore, when the thermoplastic resin is melted, It becomes easy to impregnate the reinforcing fibers, and can exhibit strong adhesive strength.

  Further, the glass transition temperature of the thermoplastic resin constituting the thermoplastic resin composition of the coating film is preferably from 15 to 300C, more preferably from 40 to 250C, and still more preferably from 80 to 200C. If the glass transition temperature is within the above temperature range, the thermoplastic resin composition is unlikely to be in a rubber state near room temperature, which is a normal use temperature, expresses strong adhesiveness, and becomes a rubber state at high temperatures and has an adhesive strength. Can be lower.

  Further, the melting point of the thermoplastic resin constituting the thermoplastic resin composition of the coating film is preferably 100 ° C. or more from the practicality of the molded article, and it is preferable that the thermoplastic resin is molten at a temperature at which the thermosetting resin is cured. Therefore, the temperature is preferably 350 ° C. or lower. The temperature is more preferably from 100 ° C to 250 ° C, and still more preferably from 150 to 220 ° C.

  Further, it is preferable that at least a part of the reinforcing fibers has both a portion of the same fiber buried in the thermosetting resin composition and a portion of the coating buried in the thermoplastic resin composition. The same fiber is buried in both layers of the thermoplastic resin composition and the thermoplastic resin composition, so that the bonding interface is reinforced by the effect of skewering, so that strong bonding can be obtained.

  The state near the bonding interface can be observed with an optical microscope, SEM or TEM. Upon observation, the resin may be dyed or the like to facilitate visual distinction.

The fiber-reinforced composite material of the present invention has an absolute value (| Ep-Es |) of a difference between the total surface free energy Ep of the thermoplastic resin composition and the total surface free energy Ep of the thermosetting resin composition of 10 mJ. preferably / m ² or less, more preferably 7 mJ / m ^2, more preferably not more than 5 mJ / m ^2. The fact that the total surface free energy of the two to be bonded is close means that they have a high affinity for each other. When the total free energy is 10 mJ / m ² or less, the thermoplastic resin composition is peeled off from the thermosetting resin composition. Can be prevented.

The fiber-reinforced composite material of the present invention has an absolute value (| Ep-Ef |) of a difference between the total surface free energy Ep of the thermoplastic resin composition and the total surface free energy Ef of the reinforcing fiber of 10 mJ / m ² or less. It is preferably 7 mJ / m ² or less, more preferably 5 mJ / m ² or less. By setting it to 10 mJ / m ² or less, it is possible to prevent the thermoplastic resin composition from peeling off the reinforcing fibers.

  The thermoplastic resin composition of the coating film may contain fillers and additives depending on the use and the like. As fillers or additives, inorganic fillers, flame retardants, conductivity-imparting agents, crystal nucleating agents, ultraviolet absorbers, antioxidants, vibration damping agents, antibacterial agents, insect repellents, deodorants, coloring inhibitors, heat Examples include stabilizers, release agents, antistatic agents, plasticizers, lubricants, coloring agents, pigments, foaming agents, coupling agents, and the like.

  In particular, addition of a flame retardant for applications requiring flame retardancy and addition of a conductivity-imparting agent for applications requiring conductivity are preferably employed. As the flame retardant, for example, a flame retardant such as a halogen compound, an antimony compound, a phosphorus compound, a nitrogen compound, a silicone compound, a fluorine compound, a phenol compound, and a metal hydroxide can be used. Among them, phosphorus compounds such as ammonium polyphosphate, polyphosphazene, phosphate, phosphonate, phosphinate, phosphine oxide, and red phosphorus can be preferably used from the viewpoint of suppressing environmental load. As the conductivity-imparting agent, for example, carbon black, amorphous carbon powder, natural graphite powder, artificial graphite powder, expanded graphite powder, pitch microbeads, vapor-grown carbon fiber, carbon nanotube, and the like can be used.

  The average thickness of the coating is preferably from 0.1 to 1000 μm, more preferably from 0.5 to 500 μm, and still more preferably from 1 to 100 μm. When the average thickness of the coating is within the above range, it is sufficient to obtain strong adhesion. The average thickness of the coating can be measured by observing the cross section of the coating with an optical microscope, SEM or TEM.

  The fiber-reinforced composite material according to the first aspect of the present invention has a vertical adhesive strength of 10 MPa or more at 40 ° C. when a nylon 6 resin containing 30% by weight of a single carbon fiber is injection-molded on a coating film, and 140 It is important that it is less than 10 MPa at ° C. For example, as one of the main uses of the integrated molded product of the present invention, in the case of housing the heating element, the use environment is usually around 40 ° C., so that the adhesive strength to withstand use in that environment is 10 MPa. It is important to secure the above, preferably 13 MPa or more, more preferably 18 MPa or more. On the other hand, when the adhesive strength at 140 ° C. as a temperature higher than the normal use environment is less than 10 MPa, preferably 8 MPa or less, and more preferably 6 MPa or less, the members which are different from each other by preheating at the time of use of the integrated molded product are used. Can be easily separated and collected and reused. The glass transition temperature of the thermosetting resin under a normal atmospheric atmosphere (normal pressure, 50% RH) is about 130 to 150 ° C., and is generally not used at a temperature higher than that. A major feature of the present invention is that the adhesive strength is reduced and the fiber-reinforced composite material and other molded products are easily decomposed. Further, as a standard material as another member to be bonded to the fiber-reinforced composite material of the present invention, a nylon 6 resin containing 30% by weight of short carbon fiber is adopted. Further details will be described later in Examples.

  The fiber-reinforced composite material of the present invention has at least one substantially flat portion in order to conform to its shape, because one of its main applications is, for example, a housing of an electric / electronic device as an electromagnetic shielding molded product. More preferably, 50% or more of the surface having the maximum area of the fiber-reinforced composite material forms a substantially flat surface. Assuming that the housing of an electric or electronic device is used as an application, the average thickness of the laminate is preferably 0.1 to 3 mm, more preferably 0.3 to 2 mm from the viewpoint of thinness and light weight. Preferably, it is 0.4 to 1.6 mm, more preferably, 0.5 to 1.2 mm. Here, the average thickness of the laminate is an average value of measured values of at least five points evenly distributed in the above-mentioned substantially flat portion. In the measurement of the average thickness, a part intentionally provided with a shape such as a rib part, a hinge part, and a concave and convex part is excluded.

  Further, assuming that the fiber-reinforced composite material of the present invention is used as a housing of an electric / electronic device, a bending elasticity based on ASTM D790 is considered from the viewpoint of protecting a mounted member from damage, bending, and deformation of a molded product. The rate is preferably 20 GPa or more, and more preferably 30 GPa or more. When the fiber-reinforced composite material has in-plane anisotropy of flexural modulus, the minimum value is evaluated. Further details of the measurement method will be described later in Examples.

  In addition, the fiber-reinforced composite material of the present invention preferably has a radio wave shielding property at a frequency of 1 GHz measured by an Advantest method of 30 dB or more, more preferably 40 dB or more, and still more preferably 50 dB or more. Further details of the measurement method will be described later in Examples.

  Next, the integrated molded article of the present invention is obtained by integrally bonding the fiber-reinforced composite material of the present invention and another structural member via a coating made of a thermoplastic resin composition. By being bonded via the coating, strong integrity can be obtained. Furthermore, there is a peeling / decomposing property under an atmosphere at a high temperature, specifically, a temperature higher than the melting point or softening point of the thermoplastic resin film of the coating of the fiber reinforced composite material of the present invention which is a part of the constituent element. This makes it extremely easy to separate and separate each member even during disposal. This is an excellent property that can greatly reduce the labor for reusing a discarded molded product.

  The joint surface preferably has a coating of the fiber-reinforced composite material of the present invention in 50% by area or more of the joint surface, more preferably 70% or more of the joint surface area, and an adhesive layer on the entire joint surface. It is particularly preferred to have

  In addition, it is also preferable to use a combination of fitting and fitting.

  As the "another member", for example, may be a metal material such as aluminum, iron, magnesium, titanium and alloys thereof, or may be fiber-reinforced composite materials of the present invention, or from a thermoplastic resin composition It is good.

  Further, it is preferable to use a thermoplastic resin composition reinforced with reinforcing fibers as “another member” because a lightweight property that cannot be realized when a metal material is employed is obtained.

  Examples of the thermoplastic resin used for “another member” include polyester such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), and liquid crystal polyester. , Polyethylene (PE), polypropylene (PP), polyolefins such as polybutylene, styrene resins, polyoxymethylene (POM), polyamide (PA), polycarbonate (PC), polymethylene methacrylate (PMMA), polychlorinated Vinyl (PVC), polyphenylene sulfide (PPS), polyphenylene ether (PPE), modified PPE, polyimide (PI), polyamideimide (PAI), polyetherimide (PEI), polysulfone (PSU) , Modified PSU, polyether sulfone, polyketone (PK), polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyarylate (PAR), polyethernitrile (PEN), phenol Resins, phenoxy resins, fluororesins such as polytetrafluoroethylene, and thermoplastic elastomers such as polystyrene, polyolefin, polyurethane, polyester, polyamide, polybutadiene, polyisoprene, and fluorine, and the like. And modified resins, and resins blended with two or more types. In particular, PPS resin is preferred from the viewpoint of heat resistance and chemical resistance, polycarbonate resin and styrene resin are preferred from the viewpoint of molded product appearance and dimensional stability, and polyamide resin is preferred from the viewpoint of molded product strength and impact resistance. More preferably used.

  Further, another elastomer or rubber component may be added to improve impact resistance. Further, other fillers and additives may be contained within a range that does not impair the purpose of the present invention, depending on the use and the like. For example, inorganic fillers, flame retardants, conductivity-imparting agents, crystal nucleating agents, ultraviolet absorbers, antioxidants, vibration damping agents, antibacterial agents, insect repellents, deodorants, coloring inhibitors, heat stabilizers, release agents , An antistatic agent, a plasticizer, a lubricant, a coloring agent, a pigment, a dye, a foaming agent, an antifoaming agent, and a coupling agent. Examples of the conductivity-imparting agent include carbon black, amorphous carbon powder, natural graphite powder, artificial graphite powder, expanded graphite powder, pitch microbeads, vapor-grown carbon fiber, carbon nanotube, and the like. It is preferably used for the purpose of further enhancing.

  The material of the reinforcing fiber used in "another structural member" can be selected based on the same concept as the reinforcing fiber in the fiber-reinforced composite material of the present invention described above. However, when "another structural member" is formed by injection molding, it is preferable that the reinforcing fibers be short fibers and are uniformly dispersed in the thermoplastic resin composition. In this case, the compounding ratio of the thermoplastic resin to the reinforcing fibers is such that when the reinforcing fibers are carbon fibers, the thermoplastic resin is 25 to 95% by weight, and the carbon fibers are carbon fibers in view of the balance between moldability, strength and lightness. Is preferably 5 to 75% by weight, more preferably 35 to 85% by weight of a thermoplastic resin and 15 to 65% by weight of a carbon fiber.

  "Another structural member" has a volume resistivity of preferably 100 Ω · cm or less, more preferably 70 Ω · cm or less, and preferably 50 Ω · cm or less, assuming use as a housing of an electric / electronic device. More preferred.

  In the monolithic molded article of the present invention, the layered layer of the reinforcing fiber, which is a preferred embodiment of the fiber-reinforced composite material of the present invention, has an electromagnetic wave shielding property assuming the use as a housing of electric / electronic equipment. In view of the above, the fiber-reinforced composite material of the present invention preferably forms at least a part of the top surface of the housing, more preferably 50% or more of the projected area of the top surface, and the projected area of the top surface It is particularly preferable to constitute 70% or more of the above. Here, the projected area is a scale representing the size of the molded product surface obtained from the external dimensions of the molded product.

  The shape of the integrated molded product of the present invention may have a curved surface, a rib, a hinge, a boss, and a hollow portion. Further, the molded product may be subjected to a surface decoration treatment by plating, painting, vapor deposition, insert, stamping, laser irradiation, or the like.

  Examples of the use of the integrated molded product of the present invention include a personal computer, a display, an OA device, a mobile phone, a portable information terminal, a facsimile, a compact disk, a portable MD, a portable radio cassette, a PDA (a portable information terminal such as an electronic notebook). , Video cameras, digital still cameras, optical equipment, audio equipment, air conditioners, lighting equipment, recreational goods, toy goods, and other home appliances, electric and electronic equipment housings and internal members such as trays and chassis, their cases, and mechanical parts , Panels and other building materials, motor parts, alternator terminals, alternator connectors, IC regulators, potentiometer bases for light days, suspension parts, various valves such as exhaust gas valves, fuel related, various exhaust or intake pipes, air intake Rusnorkel, intake manifold, various arms, various frames, various hinges, various bearings, fuel pump, gasoline tank, CNG tank, engine cooling water joint, carburetor main body, carburetor spacer, exhaust gas sensor, cooling water sensor, oil temperature sensor , Brake pad wear sensor, throttle position sensor, crankshaft position sensor, air flow meter, brake butt wear sensor, thermostat base for air conditioner, heating hot air flow control valve, brush holder for radiator motor, water pump impeller, turbine vane, Wiper motor related parts, distributor, starter switch, starter relay, transmission wire Harness, window washer nozzle, air conditioner panel switch board, fuel related electromagnetic valve coil, fuse connector, battery tray, AT bracket, headlamp support, pedal housing, handle, door beam, protector, chassis, frame, armrest, horn terminal, Step motor rotor, lamp socket, lamp reflector, lamp housing, brake piston, noise shield, radiator support, spare tire cover, seat shell, solenoid bobbin, engine oil filter, ignition device case, under cover, scuff plate, pillar trim, propeller shaft, Wheels, fenders, fascias, bumpers, bumper beams, bonnets, aero parts, platforms Foams, cowl louvers, roofs, instrument panels, spoilers and various modules, etc., parts related to automobiles and motorcycles, components and skins, landing gear pods, winglets, spoilers, edges, rudder, elevators, failings, ribs and other aircraft Related parts, members, and outer plates are included. In particular, the integrated molded product of the present invention makes use of its excellent electromagnetic wave shielding properties as an electromagnetic wave shield molded product, and is suitable for electric and electronic equipment housings and external members. It is suitable as a housing for a necessary notebook personal computer or portable information terminal.

  Next, the method for producing a fiber-reinforced composite material of the present invention includes a laminating step of disposing a thermoplastic resin composition on at least a part of the surface of a prepreg laminate including a thermosetting resin, and curing the thermosetting resin composition. A heat molding step of melting the thermoplastic resin composition to form a film in parallel with the reaction. That is, the thermoplastic resin is disposed on the surface layer of the thermosetting resin composition before curing in a film form, and then cured at a temperature equal to or higher than the melting point of the thermoplastic resin, whereby the thermosetting resin composition and the thermoplastic resin are cured. Can be obtained.

  The reinforcing fibers can be aligned with a drum wind or the like.

  Examples of the means for forming a laminate include a hand lay-up molding method, a spray-up molding method, a vacuum back molding method, a pressure molding method, an autoclave molding method, a press molding method, and a transfer molding method. From the viewpoint, a vacuum back molding method, a press molding method, a transfer molding method and the like are preferably used.

  As a method of dispersing the reinforcing fibers in the thermoplastic resin in “another structural member”, for example, a known method of melt-kneading the thermoplastic resin and the reinforcing fibers can be adopted. Examples of the molding means of "another structural member" include, for example, injection molding, extrusion molding, and press molding. In particular, injection molding has high productivity and is industrially suitable, and has ribs, hinges, and bosses. It is preferably used because a molded article having a complicated shape can be easily mass-produced.

  As a procedure for integrating the fiber-reinforced composite material of the present invention and “another structural member”, for example, the following construction methods 1 to 3 can be exemplified.

  Method 1: A method in which the fiber-reinforced composite material of the present invention is preliminarily formed and both are integrated simultaneously with the formation of “another structural member”. For example, the fiber reinforced composite material of the present invention is manufactured in advance by press molding, processed to a predetermined size, post-processed, inserted into an injection mold, and then integrated by injection molding "another structural member". How to let.

  Method 2: A method in which “another structural member” is preliminarily formed, and the fiber-reinforced composite material of the present invention is formed simultaneously with the molding. For example, "another structural member" is manufactured in advance by injection molding and post-processed is inserted into a press die, and then the prepreg that will be the fiber-reinforced composite material of the present invention is laid up, and the melting point of the thermoplastic resin or higher. A method that integrates by vacuum back molding at a temperature of

  Method 3: A method in which the fiber-reinforced composite material of the present invention and “another structural member” are separately formed in advance, and the two are integrated. For example, the fiber-reinforced composite material of the present invention, which is manufactured in advance by press molding, processed to a predetermined size, and post-processed, and "another structural member" manufactured and post-processed in advance by injection molding, in the same manner as in Method 2, How to integrate.

  Means for producing the integrated molded article of the present invention by bonding the fiber-reinforced composite material of the present invention and “another structural member” include, for example, a thermoplastic resin composition of a film in the fiber-reinforced composite material of the present invention. Attach "another structural member" at a process temperature equal to or higher than the melting point of the constituting thermoplastic resin, and then join the fiber-reinforced composite material of the present invention and the "another structural member" by cooling, thereby achieving adhesion and Integration can be achieved simultaneously.

  Examples and comparative examples are shown below. In the compounding ratios shown in the examples and comparative examples, "%" without any particular comment means% by weight.

(Evaluation and measurement method)
(1) Evaluation of vertical adhesive strength A molded product obtained by melt-bonding a thermoplastic molding material based on a nylon-based resin at a temperature equal to or higher than its melting point by injection molding on a target bonding surface of a fiber-reinforced composite material. Do it. Specific examples are shown below.

(Material of the member to be bonded)
A nylon 6 resin CM1001 manufactured by Toray Co., Ltd. was supplied from a main hopper to a TEX-30α type twin screw extruder (screw diameter 30 mm, L / D = 32) of Nippon Steel Works Co., Ltd. A chopped carbon fiber “Torayca” TS-12 (chopped yarn length 6 mm) manufactured by Toray Industries, Inc. is supplied from a downstream side hopper, and sufficiently kneaded at a barrel temperature of 260 ° C. and a screw rotation speed of 150 rpm. Degassing was performed from the vent. The supply was adjusted by a weight feeder so that the carbon fiber content was 30% by weight. The molten resin was discharged from a die opening (inner diameter 5 mm), and the obtained strand was cooled and cut with a cutter to obtain a pellet-shaped molding material. The obtained pellets were dried at 90 ° C. for 3 hours by hot air drying and then at 80 ° C. for 6 hours under vacuum, and sufficiently dried so that the water content became 0.1% or less.

(injection molding)
Next, using a J350EIII type injection molding machine manufactured by Japan Steel Works, the fiber-reinforced composite material of each Example and Comparative Example was placed in a mold, and the surface having a coating made of a thermoplastic resin composition was treated as an injection molding material. It was placed so that it could be integrated, and the material of the member to be bonded was injection-molded at a temperature of 280 ° C. so that the thickness of the injection-molded material portion became 3 mm to obtain an integrated molded product as shown in FIG.

(Tensile test)
A vertical adhesive strength evaluation sample (b in FIG. 6) was cut out into a 10 mm square from the integrated molded product. As a measuring device, using "Instron" (registered trademark) 5565 type universal material testing machine (manufactured by Instron Japan Co., Ltd.), the sample was fixed with a jig (a in FIG. 6), At a temperature of two points of 140 ° C., a tensile test was performed in which the tensile load was pulled in a direction of 90 ° from the bonded surface at a tensile speed of 1.27 mm / min, and the maximum load was divided by the bonded area to obtain a vertical bond strength (MPa). ).
The number of samples was n = 5.

  For a molded product that can be gripped by an Instron chuck, the molded product was directly held between the chucks and a tensile test was performed. Those that could not be gripped were coated with an adhesive (ThreeBond 1782, manufactured by ThreeBond Co., Ltd.) and left at 23 ± 5 ° C. for 4 hours and then at 50 ± 5% RH for 4 hours to adhere to the jig. As the test result, only the value at which the bonded and integrated portion was peeled off was adopted, and the result of peeling off the jig and the molded product was deleted.

(2) Adhesive strength based on ISO4587 Two test pieces TP1 per sample were cut out from the fiber-reinforced composite materials of Examples and Comparative Examples based on the rules of ISO4587. The shape and dimensions were 100 mm in length (TP1L in FIG. 4) and 25 mm in width (TP1W in FIG. 4) based on the provisions of ISO4587. If it is difficult to cut out a test piece having this size, the same size may be substituted with a proportionally reduced size.
The two prepared test pieces TP1 were faced to each other so that the coating of each thermoplastic resin composition became a joint. The length of the joint (BPL in FIG. 4) was 12.5 mm. The two test pieces TP1 are heated to a temperature at which the resin of the thermoplastic resin composition sufficiently melts (a temperature 10 ° C. higher than the melting point), and the two test pieces TP1 are adhered at a pressure of 50 MPa for 1 minute, and cooled while clamping. Then, the two were joined to form a tensile test piece.

As the tensile tester, “Instron” (trademark) 5565 type universal material testing machine (manufactured by Instron Japan Co., Ltd.) was used. At the two temperatures of 40 ° C. and 140 ° C. during the test, A tensile test was performed at a tensile speed of 1.27 mm / min. It was confirmed that it was broken near the joining position (near the boundary), and the value obtained by dividing the strength (unit: kN) by the surface area of the joining portion was defined as the adhesive strength (unit: MPa).
The number of samples was n = 5.

(3) Flexural modulus Evaluated in accordance with ASTM D790. Four test pieces cut out from substantially flat portions of the fiber-reinforced composite material at different angles of 0, 45, 90, and 135 degrees with respect to the longitudinal direction of the fiber-reinforced composite material were prepared. When the test piece is intentionally provided with a shape such as a rib portion, a hinge portion, and a concavo-convex portion, the measurement of the thickness of the test piece is performed excluding this portion. The minimum value of the flexural modulus obtained in these test pieces was adopted as the flexural modulus referred to herein.

(4) Electromagnetic wave shielding performance Evaluation was performed by the Advantest method. A 120 mm x 120 mm flat plate was cut out from the fiber reinforced composite material of each of the examples and comparative examples to obtain a test piece. In the evaluation, the test piece was placed in a completely dry state (water content: 0.1% or less), and a conductive paste (Doitite manufactured by Fujikura Kasei Co., Ltd.) was applied to the four sides, and the conductive paste was sufficiently dried.

  The test piece was inserted into a shield box, and the electromagnetic wave shielding property (unit: dB) at a frequency of 1 GHz was measured with a spectrum analyzer to determine the electromagnetic wave shielding property. The higher the radio wave shielding property, the better the electromagnetic wave shielding property.

(5) Volume specific electric resistance A test piece having a width of 12.7 mm and a length of 65 mm was cut out from “another structural member” and subjected to measurement in a completely dry state (water content: 0.1% or less). First, a conductive paste (Doitite manufactured by Fujikura Kasei Co., Ltd.) was applied to the cross section of both ends of the test piece, and the conductive paste was sufficiently dried. The resistance value was measured with a digital multimeter (made by FLUKE). The value obtained by subtracting the contact resistance of a measuring instrument, a jig, etc. from the electric resistance value is multiplied by the area of the conductive paste application surface, and the value is divided by the length of the test piece to obtain a volume specific electric resistance value (unit: Ω). Cm).

(6) Determination of Solubility Parameter δ (SP Value) In the present invention, the solubility parameter δ (SP value) refers to a value of a repeating unit of a polymer at 25 ° C. determined by the method of Fedors. The method is described in RFFedors, Polym. Eng. Sci., 14 (2), 147 (1974). That is, in the structural formula of the compound to be determined, it is determined by the following formula from the data of the evaporation energy and the molar volume of the atoms and atomic groups.
δ = (ΣΔei / ΣΔvi) ^1/2
Here, in the formula, Δei and Δvi represent the evaporation energy and the molar volume of the atom or atomic group, respectively. The structural formula of the compound to be determined is determined by using ordinary structural analysis techniques such as IR, NMR, and mass spectrum.

(7) Total surface free energy The total surface free energy was evaluated as follows.

(A) Total surface free energy (Es) of thermosetting resin composition
40 g of the uncured thermosetting resin composition used in each of Examples and Comparative Examples was placed in a container made of “Teflon (registered trademark)” (50 × 50 × 50 mm) and heated at 150 ° C. for 30 minutes. It was cured to obtain a cured resin.

  After this epoxy resin cured product was cut into a size of 30 mm in length and 15 mm in width, the surface was polished with a grinder (Refine Polisher 200 and Automax AMO-210 manufactured by Refinetech Co., Ltd.) to a particle size of # 600. , 5 minutes at # 800, 15 minutes at # 1000, 20 minutes at # 1200, and 30 minutes at # 1500 for 30 minutes at a rotation speed of 100 rpm. Thereafter, polishing particles METAPOLISH (No. 1 manufactured by Fujimi Incorporated Co., Ltd.) were polished with a polishing buff pan cloth (manufactured by Refinetech Co., Ltd.) at 100 rpm for 5 minutes while flowing simultaneously with water. Thereafter, polishing particles METAPOLISH (No. 5 manufactured by Fujimi Incorporated) were polished with a suede cloth (manufactured by Refinetech Co., Ltd.) at 100 rpm for 5 minutes while flowing simultaneously with water in the same manner as described above.

  50 μl of each liquid of water, ethylene glycol, and tricresol phosphate was dropped on this flat plate, and the droplet formed on each flat plate was observed, and the contact angle θs between the flat plate and the droplet was measured (see FIG. 5). .

  The obtained contact angle θs is substituted into the approximate expression of Owens (a polar component and a non-polar component of the surface tension unique to each liquid, and an expression constituted by the contact angle θs) together with the surface tension components of each liquid, and X and Y are substituted for X and Y. After plotting, the polar component of the surface free energy of the thermosetting resin composition is determined by the square of the slope a when a straight line is approximated by the least square method.

Similarly, the non-polar component of the surface free energy of the thermosetting resin composition is determined from the Y slice at that time. The sum of the two was defined as the total surface free energy of the thermoplastic resin constituting the thermosetting resin composition.
Y = aX + b
X = (polar component of liquid surface tension (unit: mJ / m ² )) ^1/2 / (non-polar component of liquid surface tension (unit: mJ / m ² )) ^1/2
Y = (1 + COS θs) · (polar component of liquid surface tension (unit: mJ / m ² )) / 2 (non-polar component of liquid surface tension (mJ / m ² )) ^1/2
Polar component of surface free energy of thermosetting resin composition = a ²
Non-polar component of surface free energy of thermosetting resin composition = b ²
Total surface free energy (Es) of the thermosetting resin composition = a ² + b ²
The polar and non-polar components of the surface tension of each liquid are as follows.
・ Purified water Surface tension 72.8 mJ / m ² , polar component 51.0 mJ / m ² , non-polar component 21.8 mJ / m ²
・ Ethylene glycol Surface tension 48.0 mJ / m ² , polar component 19.0 mJ / m ² , non-polar component 29.0 mJ / m ²
Tricresol phosphate Surface tension 40.9 mJ / m ² , polar component 1.7 mJ / m ² , non-polar component 39.2 mJ / m ²
(B) Total surface free energy (Ep) of thermoplastic resin composition
The thermoplastic resin composition used for forming the coating film in each Example and Comparative Example was heated at 180 ° C. for 3 minutes while applying a pressure of 6 MPa, and then cooled to produce a flat plate having a length of 30 mm, a width of 15 mm and a thickness of 2 mm. did.

  The surface of this flat plate was polished under the same conditions as in the above (A). 50 μl of each liquid of water, ethylene glycol, and tricresole phosphate is dropped on this flat plate, and the droplet formed on each flat plate is observed, and the contact angle θp between the flat plate and the droplet is measured.

  Similarly to the above (A), the obtained contact angle θp is calculated by substituting it into an approximate equation of Owens, and is set as the total surface free energy of the thermoplastic resin composition.

(C) Surface free energy of reinforcing fiber (Ef)
The case where carbon fiber is used as the reinforcing fiber will be described.

  A single fiber of carbon fiber was calculated using the approximate equation of Owens based on each contact angle measured by the Wilhelmi method in each liquid of purified water, ethylene glycol, and tricresol phosphate.

  First, one single fiber is taken out from a carbon fiber bundle using a DCAT11 manufactured by DataPhysics, cut into eight pieces with a length of 12 ± 2 mm, and then cut into a dedicated holder FH12 (a flat plate whose surface is coated with an adhesive substance). Affix in parallel with a fiber spacing of 2-3 mm. Thereafter, the ends of the single fibers are trimmed and set in the DCAT 11 of the holder. In the measurement, the cell containing each liquid is brought close to the lower ends of the eight single fibers at a speed of 0.2 mm / s, and immersed to 5 mm from the tips of the single fibers. Thereafter, the single fiber is pulled up at a speed of 0.2 mm / s. This operation is repeated four times or more. The force F applied to the single fiber while immersed in the liquid is measured by an electronic balance. Using this value, the contact angle θf is calculated by the following equation.

COS θf = (force F (unit: mN) received by eight single fibers) / ((8 (number of single fibers) × circumference of single fibers (unit: m) × surface tension of liquid (unit: mJ / m)) ² ))
In addition, the measurement was implemented about the single fiber extracted from three different places of the carbon fiber bundle. That is, the average value of the contact angles for a total of 24 single fibers for one carbon fiber bundle was determined.

  The obtained contact angle θf is substituted into the approximate expression of Owens (the polar and non-polar components of the surface tension unique to each liquid, and the expression composed of the contact angle θf) together with the surface tension components of each liquid, and X, Y After that, the polar component of the surface free energy of the reinforcing fiber is determined by the square of the slope a when a straight line is approximated by the least square method.

Similarly, the non-polar component of the surface free energy of the reinforcing fiber is determined from the Y slice at that time. The sum of both is defined as the total surface free energy of the reinforcing fibers.
Y = aX + b
X = (polar component of liquid surface tension (unit: mJ / m ² )) ^1/2 / (non-polar component of liquid surface tension (unit: mJ / m ² )) ^1/2
Y = (1 + COS θf) · (polar component of liquid surface tension (unit: mJ / m ² )) / 2 (non-polar component of liquid surface tension (unit: mJ / m ² )) ^1/2
Polar component of surface free energy of reinforcing fiber = a ²
Non-polar component of surface free energy of reinforcing fiber = b ²
Surface free energy (Ef) of reinforcing fiber = a ² + b ²
The absolute value of the difference between the total surface energies was calculated using Es, Ep, and Ef obtained as described above.

(8) Evaluation of Glass Transition Temperature and Melting Point The glass transition temperature was determined by differential scanning calorimetry (DSC) at a heating rate of 10 ° C./min in accordance with JIS K7121, and the glass transition temperature was specified from the endothermic peak of the measurement piece. . In collecting the sample, the thermosetting resin layer of the fiber-reinforced composite material was cut out without separating the reinforcing fiber group.

(9) {O / C} Evaluation of Carbon Fiber Surface Evaluation was performed by a known technique using X-ray photoelectron spectroscopy.

(10) Evaluation of weight average molecular weight Evaluation was performed using a known technique by gel permeation chromatography.

(11) Evaluation of average thickness of coating film FIG. 7 shows a schematic diagram of a cross section of the laminate. From the TEM observation photograph of the cross section of the laminate, the thickness from the surface of the thermoplastic resin composition layer c to the interface f of the thermosetting resin composition is measured. The measurement is performed at 10 points, and the average value is defined as the average coating thickness.

(Example 1)
One embodiment of the method for producing a fiber-reinforced composite material of the present invention will be described with reference to an exploded perspective view of a model housing for electric / electronic equipment in FIG.

In the figure, the following were made as fiber-reinforced composite materials. That is, a carbon fiber woven fabric having a length of 350 mm and a width of 300 mm (trade cloth CO6343 manufactured by Toray Industries, Inc.) is laminated with a prepreg having a carbon fiber content of 57% by volume impregnated with an epoxy resin, and a nylon-based spunbond is formed on the outermost surface thereof. A nonwoven fabric sheet (trade name: Dynac LNS-0050, basis weight 50 g / m ² , melting point 135 ° C, solubility parameter δ (SP value) 13.0, weight average molecular weight 18,000, manufactured by Kureha Chemical Co., Ltd.) was laminated. Then, it was formed into a vacuum bag and cured by heating at 140 ° C. for 1 hour to obtain a fiber-reinforced composite material (I) having a thickness of 0.9 mm. On the surface of the fiber reinforced composite material, the nonwoven fabric was melted and adhered in a film form, and the film thickness was 25 μm. The crow transition temperature of the fiber-reinforced composite material was 130 ° C. The absolute value of the difference between the total surface free energy of the thermosetting resin composition of the fiber-reinforced composite material and that of the film-shaped thermoplastic resin composition was 9. The absolute value of the difference between the total surface free energy of the reinforcing fiber of the fiber-reinforced composite material and the film-shaped thermoplastic resin composition was 8. The vertical adhesive strength of this fiber reinforced composite material was 21 MPa in a 40 ° C. atmosphere, and 2 MPa in a 140 ° C. atmosphere.

  Next, the fiber-reinforced composite material (I) is placed in a mold using a J350EIII type injection molding machine manufactured by Japan Steel Works, Ltd., and the thermoplastic resin described in the section of the test thermoplastic resin pellets is removed. In use, another structural member (II) shown in FIG. 3 was injection molded. As for the obtained integrally molded product (III), a casing in which (I) and (II) were firmly joined together was obtained.

  When the bending elastic modulus, the electromagnetic wave shielding property, and the like of the housing were measured by the above-described methods, the bending elastic modulus was 55 GPa, the electromagnetic wave shielding property was 55 dB, and the standing wall portion of the housing, which is another structural member (II), was used. The volume resistivity was 4.5 Ω · cm.

(Example 2)
180 ° C.-curable prepreg (reinforced fiber group consisting of a large number of carbon filaments arranged in one direction (Toray Co., Ltd., trading card, {O / C} = 0.08)), the content of the reinforcing fiber group being 12. A prepreg having a weight ratio (Wf) of 70% and a volume ratio (Vf) of 61% is laminated, and a nylon film (type 1401, thickness 50 μm, melting point 210 ° C., solubility parameter δ (SP value)) is formed on the outermost layer. 4. Using a weight average molecular weight of 20,000, manufactured by Toray Synthetic Film Co., Ltd.), preheat at 225 ° C. for 3 minutes on a hot plate before press molding to melt the nylon film, and then press molding machine. The mixture was heated at 150 ° C. for 30 minutes while applying a pressure of 6 MPa to obtain a fiber-reinforced composite material (I) having an average thickness of 0.9 mm. On the surface of the fiber-reinforced composite material, a nylon film was melted and adhered in a film form, and the film thickness was 40 μm. The crow transition temperature of the fiber-reinforced composite material was 180 ° C. The absolute value of the difference between the total surface free energy of the thermosetting resin composition of the fiber-reinforced composite material and that of the film-shaped thermoplastic resin composition was 8. The absolute value of the difference between the total surface free energy of the reinforcing fibers of the fiber-reinforced composite material and the film-shaped thermoplastic resin composition was 7. The vertical adhesive strength of this fiber reinforced composite material was 15 MPa in a 40 ° C. atmosphere and 8 MPa in a 140 ° C. atmosphere.

  A housing was molded from this fiber-reinforced composite material in the same manner as in Example 1, and a housing that was firmly and integrally joined was obtained. When the bending elastic modulus and the electromagnetic wave shielding property of the housing were measured in the same manner as in Example 1, the bending elastic modulus was 54 GPa, the electromagnetic wave shielding property was 53 dB, and the volume of the housing standing wall as another structural member (II). The specific resistance was 4.0 Ω · cm.

(Example 3)
The matrix resin is an epoxy resin (thermosetting resin) and is composed of a group of reinforcing fibers consisting of a large number of carbon filaments (Toray's trading card, {O / C} = 0.08) arranged in one direction, From the prepreg in which the content of the reinforcing fiber group is 70% in weight ratio (Wf) and 61% in volume ratio (Vf), the fiber direction is 45 °, −45 °, 90 ° with the length direction as 0 ° direction. , -45 °, prepare five prepreg sheets cut to a length of 350 mm and a width of 300 mm so as to be 45 °, and the fiber direction is 45 °, -45 °, 90 °, -45 °, 45 ° from above. To produce a laminated prepreg sheet.

On the other hand, as a thermoplastic resin composition, a terpolymer polyamide resin (manufactured by Toray Industries, Inc., terpolymer polyamide resin CM4000, polyamide 6/66/610, melting point 150 ° C., solubility parameter δ (SP value)) 13. 3, a nonwoven fabric having a weight average molecular weight of 20,000) and a width of 1,000 mm was used. The basis weight of this nonwoven fabric was 30 g / m ² . From this heat bonding substrate, a rectangular heat bonding substrate having a length of 350 mm and a width of 300 mm was prepared. Two substrates for thermal bonding were laminated and laminated on the upper surface of the laminated prepreg sheet so that the length direction and the width direction coincided with each other.

  Next, press molding was performed. After preheating at 160 ° C. for 5 minutes with a press molding machine to melt the substrate for thermal bonding, it was heated at 150 ° C. for 30 minutes while applying a pressure of 6 MPa to cure the thermosetting resin. After curing, the mixture was cooled at room temperature and released from the mold to produce a fiber-reinforced composite material having a thermoplastic resin composition layer formed on the surface of a laminate having an average thickness of 0.7 mm. The glass transition temperature of this fiber reinforced composite material was 130 ° C. The absolute value of the difference between the total surface free energy of the thermosetting resin composition of the fiber-reinforced composite material and that of the film-shaped thermoplastic resin composition was 5. The absolute value of the difference between the total surface free energy of the reinforcing fibers of the fiber-reinforced composite material and the film-like thermoplastic resin composition was 4. The adhesive strength based on ISO4587 of this fiber reinforced composite material was 20 MPa in a 40 ° C. atmosphere and 8 MPa in a 140 ° C. atmosphere. Further, the flexural modulus of this fiber-reinforced composite material was 25 GPa, and the electromagnetic wave shielding property was 55 dB.

  When the cross section of the obtained fiber reinforced composite material was observed by TEM and SEM, it was found that continuous filaments were arranged in the thermoplastic resin layer. That is, it was shown that reinforcing fibers were present in the thermosetting resin layer and the thermoplastic resin layer of the fiber-reinforced composite material, and reinforced the interface between the two resins.

(Example 4)
The matrix resin is an epoxy resin (thermosetting resin) and is composed of a group of reinforcing fibers consisting of a large number of carbon filaments (Toray's trading card, {O / C} = 0.08) arranged in one direction, From the prepreg in which the content of the reinforcing fiber group is 70% in weight ratio (Wf) and 61% in volume ratio (Vf), the fiber direction is 45 °, −45 °, 90 ° with the length direction as 0 ° direction. , -45 °, prepare five prepreg sheets cut to a length of 350 mm and a width of 300 mm so as to be 45 °, and the fiber direction is 45 °, -45 °, 90 °, -45 °, 45 ° from above. To produce a laminated prepreg sheet.

On the other hand, pellets of a copolymerized polyester resin (manufactured by Toyobo Co., Ltd., Copolyester resin Byron GM400, melting point 143 ° C., solubility parameter δ (SP value) 10.7, weight average molecular weight 25000) were used as the thermoplastic resin composition. This was pressed at 200 ° C. for 3 minutes while applying a pressure of 18 MPa to prepare a film-like substrate for heat bonding having a basis weight of 80 g / m ² . This substrate for thermal bonding was cut into a rectangular shape having a length of 350 mm and a width of 300 mm, and was laminated on the upper surface of the laminated prepreg sheet so that the length direction and the width direction coincided.

  Next, press molding was performed. After preheating at 160 ° C. for 5 minutes with a press molding machine to melt the substrate for thermal bonding, it was heated at 150 ° C. for 30 minutes while applying a pressure of 6 MPa to cure the thermosetting resin. After curing, the mixture was cooled at room temperature and released from the mold to produce a fiber-reinforced composite material having a thermoplastic resin composition layer formed on the surface of a laminate having an average thickness of 0.7 mm. The glass transition temperature of this fiber reinforced composite material was 130 ° C. The absolute value of the difference between the total surface free energy of the thermosetting resin composition of the fiber-reinforced composite material and that of the film-shaped thermoplastic resin composition was 5. The absolute value of the difference between the total surface free energy of the reinforcing fibers of the fiber-reinforced composite material and the film-like thermoplastic resin composition was 4. The adhesive strength based on ISO4587 of this fiber reinforced composite material was 18 MPa in a 40 ° C. atmosphere and 6 MPa in a 140 ° C. atmosphere. Further, the flexural modulus of this fiber-reinforced composite material was 25 GPa, and the electromagnetic wave shielding property was 55 dB.

  When the cross section of the obtained fiber reinforced composite material was observed by TEM and SEM, it was found that continuous filaments were arranged in the thermoplastic resin layer. That is, it was shown that reinforcing fibers were present in the thermosetting resin layer and the thermoplastic resin layer of the fiber-reinforced composite material, and reinforced the interface between the two resins.

(Comparative Example 1)
A fiber-reinforced composite material (I) was obtained in the same manner as in Example 1 except that the nylon-based spunbond nonwoven fabric was not used. The two-component acrylic adhesive 3921/3926 manufactured by Three Bond Co., Ltd. was applied and bonded using the obtained fiber-reinforced composite materials (I) as an adhesive, and then left standing at room temperature for 24 hours to bond and bond strongly. A strength test specimen was obtained. The vertical adhesive strength was 25 MPa in a 40 ° C. atmosphere and 17 MPa at 140 ° C.

  Separately, a metal spacer having the same shape as that of the fiber-reinforced composite material (I) is placed on the injection molding die instead of the fiber-reinforced composite material (I). ) Was injection molded. The two-component acrylic adhesive 3921/3926 manufactured by Three Bond Co., Ltd. was applied as an adhesive to the obtained fiber-reinforced composite material (I) and another structural member (II) as an adhesive, and allowed to stand at room temperature for 24 hours for bonding. As a result, a firmly bonded housing was obtained. As a result of evaluation in the same manner as in Example 1, the elastic modulus was 56 GPa, the electromagnetic wave shielding property was 55 dB, and the volume resistivity of the standing wall was 4.0 Ω · cm.

(Comparative Example 2)
In Example 3, without preheating, heating was performed at 150 ° C. for 30 minutes while applying a pressure of 6 MPa to perform press molding, and after completion of curing, cooled at room temperature, demolded, and average thickness. A fiber reinforced composite material in which a thermoplastic resin composition was formed on a 0.7 mm laminate was manufactured. The glass transition temperature of this fiber reinforced composite material was 130 ° C. The absolute value of the difference between the total surface free energy of the thermosetting resin composition of the fiber-reinforced composite material and that of the film-shaped thermoplastic resin composition was 5. The absolute value of the difference between the total surface free energy of the reinforcing fibers of the fiber-reinforced composite material and the film-like thermoplastic resin composition was 4. The vertical adhesive strength of this fiber reinforced composite material was 1 MPa in a 40 ° C. atmosphere and 0.4 MPa in a 140 ° C. atmosphere. Further, the flexural modulus of this fiber-reinforced composite material was 25 GPa, and the electromagnetic wave shielding property was 55 dB.

  A cross section of the obtained fiber-reinforced composite material was observed by TEM and SEM in the same manner as in Example 3, but it was found that continuous filaments were not arranged in the thermoplastic resin layer.

(Comparative Example 3)
The matrix resin is an epoxy resin (thermosetting resin) and is composed of a group of reinforcing fibers composed of a large number of carbon filaments (Toray Co., Ltd., trading card, {O / C} = 0.08) arranged in one direction, From the prepreg in which the content of the reinforcing fiber group is 70% in weight ratio (Wf) and 61% in volume ratio (Vf), the fiber direction is 45 °, −45 °, 90 ° with the length direction as 0 ° direction. , -45 °, prepare five prepreg sheets cut to a length of 350 mm and a width of 300 mm so as to be 45 °, and the fiber direction is 45 °, -45 °, 90 °, -45 °, 45 ° from above. To produce a laminated prepreg sheet.
On the other hand, as the thermoplastic resin composition, pellets of a polypropylene resin (manufactured by Sumitomo Mitsui Polyolefin Co., Ltd., melting point: 165 ° C., solubility parameter δ (SP value): 8.3) were used at 200 ° C. while applying a pressure of 18 MPa. After pressing for 1 minute, a film-like substrate for heat bonding having a basis weight of 80 g / m ² was prepared. This substrate for thermal bonding was cut into a rectangular shape having a length of 350 mm and a width of 300 mm, and was laminated on the upper surface of the laminated prepreg sheet so that the length direction and the width direction coincided.

  Next, press molding was performed. After preheating at 180 ° C. for 5 minutes with a press molding machine to melt the base material for thermal bonding, the thermosetting resin was cured by heating at 150 ° C. for 30 minutes while applying a pressure of 6 MPa. After curing, the mixture was cooled at room temperature and released from the mold to produce a fiber-reinforced composite material having a thermoplastic resin composition formed on a laminate having an average thickness of 0.7 mm. The glass transition temperature of this fiber reinforced composite material was 130 ° C. The absolute value of the difference between the total surface free energy of the thermosetting resin composition of the fiber-reinforced composite material and that of the film-shaped thermoplastic resin composition was 7. The absolute value of the difference between the total surface free energy of the reinforcing fibers of the fiber-reinforced composite material and the film-shaped thermoplastic resin composition was 7. The vertical adhesive strength of this fiber reinforced composite material was 1.5 MPa in a 40 ° C. atmosphere and 1 MPa in a 140 ° C. atmosphere. Further, the flexural modulus of this fiber-reinforced composite material was 25 GPa, and the electromagnetic wave shielding property was 55 dB.

  When the cross section of the obtained fiber reinforced composite material was observed by TEM and SEM, it was found that continuous filaments were arranged in the thermoplastic resin layer. That is, it was shown that reinforcing fibers were present in the thermosetting resin layer and the thermoplastic resin layer of the fiber-reinforced composite material, and reinforced the interface between the two resins.

  The following is clear from Examples 1 to 4 and Comparative Examples 1 to 3.

  In the integrated molded articles of Examples 1 to 4, the fiber-reinforced composite material adheres firmly, and the value of the adhesive strength at room temperature is also excellent. In the 140 ° C. atmosphere, the adhesive strength is greatly reduced, and the adhesive is easily separated and decomposed, and it is clear that the thermosetting resin composition and the thermoplastic resin composition are easily separated from each other and have excellent reusability. . The housing bonded with the acrylic adhesive of Comparative Example 1 has excellent adhesive strength at 40 ° C., but still has high adhesive strength even at 140 ° C., and is difficult to disintegrate into each resin composition, and is separated. Reuse is not easy.

  In the fiber reinforced composite materials of Examples 3 and 4, the two fiber reinforced composite materials are firmly adhered to each other, and the adhesive strength is also excellent. In the fiber reinforced composite materials of Comparative Examples 2 and 3, the adhesion between the two fiber reinforced composite materials is weak, and the value of the adhesive strength is also low.

It is a perspective view of an example in which an integrated molded product (III) of the present invention is used as an electronic device housing which is an electromagnetic shielding molded product. FIG. 2 is a perspective view of a molded product used for evaluation of vertical adhesive strength according to the present invention. FIG. 4 is an exploded perspective view for explaining a manufacturing process of an embodiment in which the electromagnetic wave shield molded product (III) of the present invention is used as a model housing of an electric / electronic device. It is a test piece shape of the adhesive strength evaluation based on ISO4587 of the fiber reinforced composite material of this invention. 3 illustrates a contact angle θ between a flat plate and a solvent. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram of the perpendicular | vertical adhesive strength evaluation apparatus of the fiber reinforced composite material of this invention. It is a figure which showed typically the average thickness of the coat of the fiber reinforced composite material of the present invention.

Explanation of reference numerals

I: Fiber reinforced composite material constituting electromagnetic wave shield molded product (I)
II: Another structural member that composes the electromagnetic shielding product (II)
III: Molded product with integrated electromagnetic shielding (III)
TP1: Test piece TP1L: Length of test piece TP1 TP1W: Width of test piece TP1 BP: Joint of test piece BPL: Length of joint of test piece a: Tensile jig b: Integrated molded product c: Heat Thermoplastic resin composition d: Reinforcing fiber e: Thermosetting resin composition f: Interface between thermoplastic resin composition and thermosetting resin composition

Claims (27)

A fiber-reinforced composite material comprising a reinforcing fiber and a thermosetting resin composition, wherein a film made of a thermoplastic resin composition is formed on at least a part of the surface thereof, and a short carbon fiber is formed on the film. A fiber-reinforced composite material having a vertical adhesive strength of not less than 10 MPa at 40 ° C. and less than 10 MPa at 140 ° C. when injection-molded with a nylon 6 resin containing 30% by weight of fibers. A fiber-reinforced composite material comprising a reinforcing fiber and a thermosetting resin composition, wherein a film made of a thermoplastic resin composition is formed on at least a part of the surface thereof, and the thermoplastic resin composition of the film The fiber-reinforced composite material having a solubility parameter δ (SP value) of the thermoplastic resin constituting 9 to 16 which is 9 to 16. 3. The fiber-reinforced composite material according to claim 1, wherein the reinforcing fibers are carbon fibers. The surface oxygen concentration {O / C}, which is the ratio of the number of atoms of oxygen (O) and carbon (C) on the surface of the carbon fiber measured by X-ray photoelectron spectroscopy of the carbon fiber, is 0.05 to 0.3. The fiber-reinforced composite material according to claim 3, wherein The fiber-reinforced composite material according to any one of claims 1 to 4, wherein the average length of the reinforcing fibers is 10 mm or more, and the long fiber group is stacked and arranged in a layered manner. The fiber-reinforced composite material according to any one of claims 1 to 5, wherein the content of the reinforcing fiber is 5 to 75% by volume. The fiber-reinforced composite material according to any one of claims 1 to 6, wherein the thermosetting resin constituting the thermosetting resin composition has a glass transition temperature of 60 ° C or higher. The fiber-reinforced composite material according to any one of claims 1 to 7, wherein the thermosetting resin composition contains at least an epoxy resin. The fiber-reinforced composite material according to any one of claims 1 to 8, wherein the thermoplastic resin constituting the thermoplastic resin composition has a glass transition temperature of 15 to 300 ° C. The fiber reinforced composite material according to any one of claims 1 to 9, wherein the melting point of the thermoplastic resin constituting the thermoplastic resin composition is 100 to 350 ° C. The thermoplastic resin composition contains at least one selected from the group consisting of a polyamide resin, a polyester resin, a styrene resin, a polycarbonate resin, a PPS resin, an EVA resin, a urethane resin, and an acrylic resin. The fiber-reinforced composite material according to claim 1. The fiber reinforced composite material according to any one of claims 1 to 11, wherein the thermoplastic resin constituting the thermoplastic resin composition has a weight average molecular weight of 2,000 to 200,000. At least a part of the reinforcing fibers has both a part buried in the thermosetting resin composition and a part buried in the thermoplastic resin composition for the same fiber, any one of claims 1 to 12. The fiber-reinforced composite material according to any one of the above. The absolute value (| Ep-Es |) of the difference between the total surface free energy Ep of the thermoplastic resin composition and the total surface free energy Ep of the thermosetting resin composition is 10 mJ / m ² or less. 14. The fiber-reinforced composite material according to any one of 1 to 13. Absolute value of the difference between the total surface free energy Ep and total surface free energy Ef of the reinforcing fibers of the thermoplastic resin composition (| Ep-Ef |) is 10 mJ / m ² or less, more of claims 1 to 14 The fiber-reinforced composite material according to any one of the above. The fiber-reinforced composite material according to any one of claims 1 to 15, wherein an average thickness of the coating made of the thermoplastic resin composition is 0.1 to 1000 µm. The fiber-reinforced composite material according to any one of claims 1 to 16, having an average thickness of 0.1 to 3 mm. The fiber-reinforced composite material according to any one of claims 1 to 17, having a flexural modulus based on ASTM D790 of 20 GPa or more. The fiber-reinforced composite material according to any one of claims 1 to 18, wherein a radio wave shielding property at a frequency of 1 GHz measured by an Advantest method is 30 dB or more. A laminating step of disposing the thermoplastic resin composition on at least a part of the surface of the thermosetting prepreg laminate, and a heat molding step of melting the thermoplastic resin composition and forming a coating in parallel with the curing reaction of the thermosetting resin And a method for producing a fiber-reinforced composite material. 20. An integrated molded product, wherein the fiber-reinforced composite material according to any one of claims 1 to 19 and another structural member are integrally bonded via a film made of the thermoplastic resin composition. 22. The integrated molded product according to claim 21, wherein the "another structural member" is a metal material. 22. The integrated molded product according to claim 21, wherein the "another structural member" is the fiber-reinforced composite material according to any one of claims 1 to 19. 22. The integrated molded product according to claim 21, wherein the "another structural member" is a molded product made of a thermoplastic resin composition. 25. The integrated molded product according to claim 24, wherein the molded product made of the thermoplastic resin composition further contains carbon fibers. The integrated molded product according to any one of claims 21 to 25, wherein the volume resistivity of the “another structural member” is 100 Ω · cm or less. The integrated molded product according to any one of claims 21 to 26, which is used for any one of a part, a member, and a housing of an electric / electronic device, an OA device, a home appliance, an automobile, or a building material.

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