TW201630987A - Method for manufacturing carbon-fiber-reinforced plastic molded article - Google Patents

Abstract

Provided is a method for manufacturing a carbon-fiber plastic molded article, the method having at least the two steps of: a step [I] for molding, by press molding, a carbon-fiber-reinforced resin molding material [C] including at least carbon fibers [A] and a thermosetting resin composition [B] and obtaining a press-molded article; and a step [II] for coating the surface of the press-molded article by in-mold coating; wherein an insulating layer or an electroconductive layer is formed on the surface of the press-molded article in the step [II]. The present invention provides a method for manufacturing a carbon-fiber-reinforced plastic molded article having an excellent surface appearance, in which coating spots are suppressed when electrodeposition coating is performed.

Description

Method for manufacturing carbon fiber reinforced plastic molded article

The present invention relates to a method of producing a carbon fiber reinforced plastic molded article.

A molding material containing a reinforced fiber and a thermosetting resin is widely used for sports products, aerospace applications, and general industrial applications because of its light weight and excellent mechanical properties. The reinforced fibers used in the molding materials are reinforced in various forms depending on the application. For such reinforcing fibers, metal fibers such as aluminum fibers or stainless steel fibers, organic fibers such as aromatic polyamide fibers or PBO (polyparaphenylene benzoxazole) fibers, and cerium carbide fibers can be used. Or inorganic fibers or carbon fibers. From the standpoint of the balance of relative strength, relative rigidity, and lightness, carbon fibers are suitable, and polyacrylonitrile (PAN)-based carbon fibers can be suitably used.

Here, carbon fiber reinforced plastics composed of carbon fibers and thermosetting resins are used in various fields such as automobile parts, house equipment, and electric-electronic equipment because of excellent mechanical properties, water resistance, and corrosion resistance. In particular, the automobile member has a tendency to be widely used as an integral member combined with a metal member, regardless of the inside and outside.

There is a case where a resin coating film is formed on the surface of such a member for the purpose of preventing rust on the side of the metal member. As a method of forming the resin coating film, a general spray coating or an electrostatic coating in which a mist or powder coating material is adhered to a substrate by an electrostatic force is known, and the object to be coated is immersed in electricity. In the plating bath of the paint, an electric current is applied to the surface of the object to be coated by applying a current directly to the coating material (electro-resin). From the viewpoint of uniform formation of a coating film and a small number of film defects such as pinholes, an electrocoating system is employed as a particularly effective method.

The carbon fiber reinforced plastic surface integrated with the metal member is also applied with an electric coating. However, the coating of the carbon fiber reinforced plastic surface is affected by the conductive properties of the carbon fiber, and the coating of the surface of the carbon fiber is affected by the floating or dispersing spots of the carbon fiber, and the design property is impaired.

Therefore, when an electric coating is applied to the surface of the carbon fiber reinforced plastic, as a method for obtaining good surface smoothness and surface appearance, it is proposed to contain an unsaturated polyester, an ethylene monomer, and a thermoplastic resin in a predetermined weight ratio. A carbon fiber-reinforced sheet-like molding material of a polyisocyanate, a filler, a conductive carbon black, and a coarse carbon fiber bundle (for example, see Patent Document 1). However, this technique uses conductive carbon black to impart conductivity to a molded article, but there is a problem that the uniformity of electrocoating is insufficient due to the difference in electrical conductivity between the conductive carbon black and the carbon fiber.

In addition, as a method of obtaining a molded article having high surface smoothness or high film adhesion, it is proposed to obtain a molded article comprising a thermoplastic carbon fiber reinforced composite material at a predetermined mold temperature, and to add a half life of 1 second at 140 ° C. The coating of the initiator of less than 2,000 seconds above the clock is injected into the mold and hardened, and the thermoplastic carbon coated in the mold is applied. A method for producing a fiber-reinforced composite material (for example, refer to Patent Document 2). In addition, in the in-mold forming of SMC (Sheet Molding Compound), it is proposed to measure the resin pressure of the hardening process when the SMC is pressurized-compressed and the coating agent is injected to form a surface coating during the process of hardening the formed body. In addition, a molding method of injecting a coating agent at a time point when the resin pressure drop is stopped (for example, refer to Patent Document 3). However, electrocoating has not been considered in any of the literature.

Prior technical literature Patent literature

Patent Document 1 Japanese Patent Laid-Open Publication No. 2009-13306

Patent Document 2 Japanese Patent Laid-Open Publication No. 2012-232506

Patent Document 3 Japanese Patent Laid-Open No. 4-44823

Under such circumstances, development of a carbon fiber reinforced plastic having an excellent surface appearance in which coating spots are suppressed when an electrocoating is applied to a molded article is required.

In view of the problems of the prior art, the present invention has been made in an effort to provide a molded article of a carbon fiber-reinforced plastic molded article, which is capable of obtaining an excellent surface appearance in which a coating spot is suppressed when an electrocoating is applied.

In order to solve the above problems, the present invention includes the following configurations.

A method for producing a carbon fiber-reinforced plastic molded article, which comprises at least [I] a carbon fiber-reinforced resin molding material [C] comprising at least a carbon fiber [A] and a thermosetting resin composition [B] by press molding. a step of obtaining a pressure-molded article; [II] a step of coating the surface of the pressure-molded article by in-mold coating In the method of producing a carbon fiber plastic molded article of the two steps, in the step [II], an insulating layer or a conductive layer is formed on the surface of the press-formed product.

The carbon fiber reinforced plastic molded article obtained by the present invention is formed by in-mold coating during molding, and an insulating layer or a conductive layer is formed on the surface layer. Therefore, when the electroformed coating is applied to the molded article, the coating spot is applied. It is suppressed, and a molded article having an excellent surface appearance can be obtained. In addition, when the in-mold coating is performed at a specific timing calculated from the gelation time of the thermosetting resin composition, the coating film adhesion of the pressure-molded article and the coating agent is drastically improved. The carbon fiber reinforced plastic molded article of the present invention is extremely useful for an inner and outer member of an automobile, particularly a component-member to which an electric coating is applied in combination with a metal member.

[Formation for carrying out the invention]

Hereinafter, the present invention will be described in detail. In the present invention, the carbon fiber reinforced plastic molded article is obtained by molding the carbon fiber reinforced resin molding material [C] containing at least the carbon fiber [A] and the thermosetting resin composition [B] by a predetermined procedure. First, the constituent components of these will be described.

In the present invention, the carbon fiber [A] means a carbon fiber monofilament [a] (hereinafter also referred to as a single fiber) which is a bundle of a certain number or more, or a single fiber itself. The carbon fiber [A] can improve the mechanical properties such as strength and impact characteristics of the molded article by the fiber reinforcing effect. Further, the carbon fiber [A] may impart such properties to the molded article because of its conductivity or thermal conductivity.

Examples of the carbon fiber [A] include PAN-based carbon fibers, pitch-based carbon fibers, and fluorene-based carbon fibers. From the viewpoint of the balance between the strength of the obtained molded article and the modulus of elasticity, PAN-based carbon fibers are particularly preferred. Further, for the purpose of imparting higher conductivity, a metal-coated carbon fiber coated with a metal such as nickel, copper or ruthenium can also be used.

Further, the carbon fiber [A] is preferably a surface oxygen concentration ratio [O/C] of 0.05 to 0.5 in the ratio of the atomic number of oxygen (O) to carbon (C) on the surface of the fiber as measured by X-ray photoelectron spectroscopy. By. By ensuring the amount of functional groups on the surface of the carbon fiber [A] by the surface oxygen concentration ratio of 0.05 or more, it is possible to obtain a stronger bond with the matrix resin, and the strength of the molded article can be further enhanced. The surface oxygen concentration ratio is more preferably 0.08 or more, still more preferably 0.1 or more. On the other hand, the upper limit of the surface oxygen concentration ratio is not particularly limited, but from the viewpoint of the balance between the handleability and productivity of the carbon fiber [A], it is generally preferably 0.5 or less. The surface oxygen concentration ratio is more preferably 0.4 or less, still more preferably 0.3 or less.

The surface oxygen concentration ratio of the carbon fiber [A] can be determined by the following procedure in the order of X-ray photoelectron spectroscopy. First, when a sizing agent or the like adheres to the surface of the carbon fiber [A], the sizing agent adhering to the surface of the carbon fiber is removed by a solvent, and then the carbon fiber [A] is cut into 20 mm, developed, and arranged on a sample support stand made of copper. AlKα1 and 2 were used as the X-ray source, and the sample chamber was kept at 1 × 10 ^-8 Torr (1.33 × 10 ^-6 Pa). The kinetic energy value (KE) of the main peak of C _1s was adjusted to 1202 eV as a correction value of the charged peak at the time of measurement. The C _1s peak area is obtained by plotting the bottom line of the straight line as KE in the range of 1191 to 1205 eV. Further, the O _1s peak area is obtained by plotting the bottom line of the straight line as KE in the range of 947 to 959 eV. Here, the surface oxygen concentration ratio is calculated from the ratio of the O _1s peak area to the C _1s peak area by the atomic ratio from the sensitivity correction value inherent to the apparatus. When the Model ES-200 manufactured by International Electric Co., Ltd. was used as the X-ray photoelectron spectroscopy device, the sensitivity correction value was set to 1.74.

The means for controlling the surface oxygen concentration ratio [O/C] to 0.05 to 0.5 is not particularly limited, and examples thereof include an electrolytic oxidation treatment, a chemical liquid oxidation treatment, and a gas phase oxidation treatment. Further preferred is electrolytic oxidation treatment.

In addition, the average fiber diameter of the single fiber constituting the carbon fiber [A] is not particularly limited, but is preferably in the range of 1 to 20 μm from the viewpoint of mechanical properties and surface appearance of the obtained molded article. Good in the range of 3~15μm.

The number of the single fibers constituting the carbon fiber [A] is not particularly limited, but can be preferably used in the range of 100 to 350,000. special It is preferably used in the range of 1,000 to 250,000, and it is preferably used in the range of 1,000 to 100,000 from the viewpoint of balance between fluidity at the time of productivity or molding and mechanical properties of a molded article.

In addition, the carbon fiber [A] containing the sizing agent [b] improves the bundling property, the bending resistance and the abrasion resistance, and in the high-order processing step, it can suppress the generation of hairballs and broken wires, and also enables high-order workability. It is better to upgrade. Further, the paste property [b] can be imparted by imparting surface characteristics suitable for the functional group or the like on the surface of the carbon fiber [A], thereby improving the adhesion property and the composite comprehensive property.

The amount of adhesion of the sizing agent [b] is not particularly limited, but is preferably 0.01 to 10% by weight in 100% by weight of the carbon fibers [A] comprising the carbon fiber monofilament [a] and the sizing agent [b]. When the amount of the sizing agent [b] adhered is 0.01% by weight or more, the adhesion improving effect is sufficiently exhibited. The amount of adhesion is more preferably 0.05% by weight or more, still more preferably 0.1% by weight or more. On the other hand, when the amount of the sizing agent [b] adhered is 10% by weight or less, the physical properties of the matrix resin can be sufficiently maintained when used as a molding material. The amount of adhesion is more preferably 5% by weight or less, still more preferably 3% by weight or less.

The component of the sizing agent [b] is not particularly limited, and examples thereof include an epoxy resin, a phenol resin, a polyethylene glycol, a polyurethane, a polyester, an emulsifier, and a surfactant. . Among them, an epoxy resin which easily exhibits adhesion to a matrix resin is preferable. These may be used alone or in combination of two or more.

The means for imparting the sizing agent [b] is not particularly limited, but is generally prepared by, for example, dissolving (including dispersing) the sizing agent [b] in a solvent (including in the case of dispersing the sizing agent). Upper in the dispersion medium) After the sizing treatment liquid is applied to the carbon fiber [A], the solvent is dried, vaporized, and removed, whereby the sizing agent [b] is imparted to the carbon fiber [A]. In the method of applying the sizing treatment liquid to the carbon fiber [A], for example, a method of immersing the carbon fiber [A] in the sizing treatment liquid through a roll, and a method of contacting the carbon fiber [A] with a roll to which the sizing treatment liquid is adhered, A method of spraying the sizing treatment liquid into a mist and blowing it on the carbon fiber [A]. Further, either batch type or continuous type may be used, but a continuous type which is excellent in productivity and capable of reducing deviation is preferable. In this case, it is preferred to control the concentration of the sizing treatment liquid, the temperature, the tension of the yarn, and the like in such a manner that the adhesion amount of the above-mentioned slurry [b] to the carbon fibers [A] is uniformly adhered within an appropriate range. Further, it is more preferable to vibrate the carbon fiber [A] by ultrasonic waves when the sizing agent [b] is imparted.

The drying temperature and the drying time should be adjusted in accordance with the amount of the compound to be attached, but the time required to completely remove the solvent for imparting the sizing agent [b] is shortened, and on the other hand, the thermal deterioration of the sizing agent is prevented and prevented. The drying temperature is preferably from 150 ° C to 350 ° C, more preferably from 180 ° C to 250 ° C from the viewpoint that the sizing-treated carbon fiber [A] is hardened and the spreadability of the bundle is deteriorated.

Examples of the solvent used in the sizing treatment liquid include water, methanol, ethanol, dimethylformamide, dimethylacetamide, acetone, and the like. From the viewpoint of easy handling and disaster prevention, water is preferred. Therefore, in the case where a compound which is insoluble or poorly soluble in water is used as the sizing agent, it is preferred to use an emulsifier or a surfactant and to carry out water dispersion. Specifically, as the emulsifier or the surfactant, an anion such as a styrene-maleic anhydride copolymer, an olefin-maleic anhydride copolymer, a naphthalenesulfonate hamarinin condensate, or a polyacrylic acid soda lime can be used. system Emulsifier; cationic emulsifier such as polyethylenimine or polyvinyl imidazoline; nonylphenol ethylene oxide adduct, polyvinyl alcohol, polyoxyethylene ether ester copolymer, sorbitan ester oxygen A nonionic emulsifier such as an alkane adduct or the like. The nonionic emulsifier having a small interaction is preferably not easily inhibited by the adhesive effect of the functional group contained in the sizing agent.

The thermosetting resin composition [B] is not particularly limited, and the composition or component can be appropriately selected without departing from the range in which the mechanical properties of the molded article are largely lowered. The constituent component of the thermosetting resin composition [B] may, for example, be a thermosetting resin, a curing agent, a thickener, a low shrinkage agent, a filler, an internal mold release agent, or the like. Examples of the thermosetting resin include a vinyl ester resin, an epoxy resin, an unsaturated polyester resin, a phenol resin, an epoxy acrylate resin, a urethane acrylate resin, a phenoxy resin, and an alkyd. Resin, urethane resin, maleic imine resin, cyanate resin, and the like. Further preferably, it comprises any one of a vinyl ester resin, an epoxy resin, an unsaturated polyester resin, and a phenol resin, or a mixture thereof, and more preferably any of a vinyl ester resin and an unsaturated polyester resin. a mixture of these.

In contrast to these preferred thermosetting resins, organic peroxides are generally used as a curing agent. For example, ketone peroxide, hydrogen peroxide, ruthenium peroxide, peroxy ketal, peroxyester, dialkyl peroxide, peroxydicarbonate, peroxymonocarbonate, etc., among the peroxyesters Further, it is preferred to use either butyl peroxybenzoate (TBPB) or tertiary butyl peroxyoctanoate (TBPO) or a mixture thereof.

Further, as the tackifier, an oxide or hydroxide of an alkaline earth metal such as magnesium oxide or a polyisocyanate compound can be preferably used.

As the low shrinkage agent, for example, polymethyl methacrylate, polystyrene, polyvinyl acetate, polyethylene, polyvinyl chloride, polycaprolactone, polybutadiene or the like can be preferably used.

The filler is added for the purpose of suppressing separation of the thermosetting resin composition [B], homogenization of fluidity, reduction in molding shrinkage, and improvement in rigidity. For example, calcium carbonate, or aluminum hydroxide, clay, barium sulfate or the like can be preferably used. Further, it is also possible to preferably use hollow glass beads for the purpose of low specific gravity.

As the internal mold release agent, for example, stearic acid, zinc stearate, calcium stearate or the like can be preferably used. When the internal mold release agent is added in excess, the mechanical properties or the coating film adhesion may be lowered. Therefore, it is preferably used in a range in which the mold release property is maintained.

The carbon fiber reinforced resin molding material [C] contains carbon fiber [A] and thermosetting resin composition [B]. The form of the carbon fiber-reinforced resin molding material [C] is not particularly limited as long as it can be obtained by press molding, and can be appropriately selected depending on the shape of the molded article, necessary mechanical properties, and the like. The form of the carbon fiber [A] contained in the carbon fiber-reinforced resin molding material [C] is not particularly limited, and may be any of continuous fibers and discontinuous fibers, or a combination thereof. Here, in the present invention, a fiber having a fiber length of more than 100 mm is referred to as a continuous fiber, and a fiber having a fiber length of 100 mm or less is referred to as a discontinuous fiber.

In the case of using the carbon fiber [A] of the continuous fiber, examples of the carbon fiber-reinforced resin molding material [C] include, for example, a prepreg or a thermosetting resin composition [B] impregnated with a multiaxial fabric. Fabrics, etc. Moreover, the multiaxial fabric refers to a laminate of a bundle of fiber reinforced materials that are conjugated in one direction and a layered shape (multiaxial fabric substrate), and a nylon yarn, a polyester yarn, a glass fiber yarn, or the like. A needle thread is a fabric which is interwoven between the front surface and the back surface of the laminated body of the laminated body in the thickness direction and which is knitted back and forth along the surface direction.

Further, in the case of using the carbon fiber [A] of the discontinuous fiber, in the case of the carbon fiber-reinforced resin molding material [C], the thermosetting resin composition [B] may be impregnated with the strand of the carbon fiber [A]. A random mat that is broken and dispersed and configured in an overlapping manner. The carbon fiber reinforced resin molding material [C] is exemplified by, for example, impregnating the thermosetting resin composition [B] with SMC (Sheet Molding Compound), BMC (Bulk Molding Compound), and nonwoven fabric.

In the form of the carbon fiber-reinforced resin molding material [C] exemplified above, it is preferable that the carbon fiber [A] is discontinuous in view of the balance between the fluidity at the time of molding, the molding cycle, and the mechanical properties of the obtained molded article. The form of the fiber is used, and it is more preferable to use SMC or BMC. Here, the fiber length of the carbon fiber [A] is preferably 5 to 100 mm. Since the fluidity and the mechanical properties of the molded article are effectively exhibited in such a range, it is preferable. More preferably 5 to 50 mm, and even more preferably 10 to 35 mm.

The method for producing a carbon fiber-reinforced plastic molded article of the present invention has at least a pressurization of a carbon fiber-reinforced resin molding material [C] Step [I] (hereinafter, also referred to as step [I]), which is formed into a press-molded article by molding, and a step of coating the surface of the press-molded article by in-mold coating [II] (hereinafter, also referred to as 2 steps for step [II]).

In the step [I], the method of obtaining the press-formed product by press molding of the carbon fiber-reinforced resin molding material [C] can be formed by a known method without any particular limitation. For example, the carbon fiber reinforced resin molding material [C] is placed in a mold cavity of a mold which has been heated to a curing temperature of the thermosetting resin composition [B] in advance, and is pressurized by a press machine. A method in which the resin is allowed to flow and the resin is cured in the mold while maintaining the pressure to obtain a molded article.

In the step [II], the coating of the molded article is carried out in the mold. When the molded article which has been released from the mold is completely cured after the thermosetting resin composition [B] is completely cured, the carbon fiber mesh may be transferred to the coating surface, or the step may be complicated.

In the step [II], a known method can be used without any particular limitation regarding the method of performing in-mold coating. For example, a so-called pre-molding method in which a coating agent is applied to a mold in advance, a carbon fiber-reinforced resin molding material [C] is placed thereon, and pressure-molded is formed, and a coating film is formed simultaneously with the molding. Or, after the carbon fiber-reinforced resin molding material [C] is press-formed, a coating agent is injected into the mold to form a coating film on the surface of the molded article. Here, in the injection method, when the coating agent is injected, the mold is slightly raised to form a gap between the molded article and the mold, and a coating agent is injected into the coating material; or the molded article is not formed. A method of forming a gap between the dies and injecting a high pressure of the coating agent is preferably used in the present invention. From the uniformity of the coating, or It is more preferable to perform in-mold coating by an injection method from the viewpoint of easily controlling the timing of in-mold coating described later and obtaining a molded article having more excellent coating film adhesion.

In the above step [II], an insulating layer or a conductive layer is formed on the surface layer of the pressure-molded article by a coating film formed by a coating agent. When the electroformed coating is further applied to the obtained molded article [D] by the insulating layer or the conductive layer, a molded article having excellent surface appearance in which the electrocoating spot is suppressed is obtained. . Specifically, in the case where the insulating layer or the conductive layer is not present, the conductivity of the surface layer of the molded article is in a state of lack of uniformity due to the conductivity of the carbon fiber [A]. That is, the carbon fiber [A] floats on the surface or agglomerated portion, etc., and the surface layer of the molded article has high conductivity, the electrocoating is applied in a dark color, and the carbon fiber [A] sparse region is reversed. Due to the thinning of the electric painting, the electric painting spots are formed.

When the surface layer of the molded article is covered by the insulating layer, even if electroless coating is applied, the coating material does not precipitate on the surface, and the uniform surface appearance formed by the in-mold coating can be maintained. Further, in the case where the surface layer of the molded article is covered with the conductive layer, the conductive property of the coating agent is uniformly exhibited, and uniform electrocoating can be applied to the surface layer.

In the case of the insulating layer, it is preferable that the surface resistance value of the molded article [D] after coating is 10 (the seventh power) or more. More preferably, the surface resistance value is 10 or more (Omega) or more. Within such a range, it is preferable to apply an electroless coating and to maintain a uniform surface appearance.

In addition, it is preferable that the conductive layer is 10 or less (Ω) or less in the case of measuring the surface resistance value of the coated molded article [D]. More preferably, the surface resistance value is 10 to the power of -1 (Ω). Within such a range, it is preferable to be able to apply a coating which suppresses the coating spot and obtains a uniform surface appearance.

In addition, the method of measuring the surface resistance value is not particularly limited, and, as a specific example, it is possible to cut 80 mm × 50 mm × from the coated molded product [D] in accordance with JIS K7194 (1994). A 2 mmt flat plate was used, and a method of measuring the surface resistance value (Ω) by a four-probe method at a voltage of 10 V was applied using "Loresta" (registered trademark) GP MCP-T600 type (manufactured by Mitsubishi Chemical Corporation). In addition, in the case of the surface resistance value in the range which cannot be measured by this method, a flat plate of 100 mm × 100 mm × 2 mmt is cut out from the coated molded product [D] according to JIS K6911 (1995), and used. "Hiresta" (registered trademark) UP MCP-HT450 (manufactured by Mitsubishi Chemical Analytech Co., Ltd.), and a method of measuring the surface resistance value (Ω) by a double ring electrode method at an applied voltage of 1000 V.

The method of exhibiting the above-described preferred range of insulating properties or conductive properties is not particularly limited, but it is preferred to control the conductivity of the coating agent from the viewpoint of ease of control and uniformity.

Here, the method of controlling the conductivity of the coating agent is not particularly limited, but a polyester resin, an acrylic resin, or a polyurethane resin is used as a main component of a general coating agent. Etc., the coating itself has high insulation properties. In addition, as a coating agent The method of improving the insulation resistance, that is, the method of increasing the surface resistance of the insulating layer, or adding inorganic particles such as talc or mica, or glass beads to the coating agent, without impairing the effects of the present invention. Insulating particles.

Further, as a method of imparting conductive properties to the coating agent, for example, a method of adding a conductive filler may be mentioned. Here, the conductive filler means that it has conductivity and can be dispersed in a coating agent to improve conductivity, and is not particularly limited as long as it does not impair the effects of the present invention. Specifically, for example, a carbon material such as carbon black or a milled fiber, or a powder of a metal represented by gold, silver, nickel, copper, aluminum or the like can be given. In terms of the form of the preferred conductive filler, it is a fine powder or a granular solid in the form of a chip. Among them, carbon black is preferred from the viewpoint of the balance between the effect of improving the conductive property and the uniform dispersibility and the fluidity of the coating agent.

In the present invention, the timing of the migration from the step [I] to the step [II], that is, the timing of starting the in-mold coating after the press molding, is preferably the gelation of the thermosetting resin composition [B]. When the time is T _g (seconds), the step is started after 2T _g to 4T _g (seconds) from the time point when the heating-pressurizing carbon fiber-reinforced resin molding material [C] is started in the step [I]. II]. The timing of starting the in-mold coating is preferably after 2T _g to 3.5T _g (seconds), and more preferably after 2.5T _g to 3.5T _g (seconds). By performing in-mold coating at such an opportunity, the thermosetting resin composition [B] and the coating agent are mixed and reacted, and the physical property due to the anchoring effect and the chemical reaction due to the chemical reaction The adhesion is promoted, and the surface of the molded article obtained in the step [I] and the adhesion to the coating film of the coating agent are drastically improved, which is preferable.

Moreover, the gelation time T _g (seconds) of the thermosetting resin composition [B] can be obtained by the following procedure. In other words, the thermosetting resin composition [B] of 2 cm ³ was weighed, and the "Curelastometer" (registered trademark) V type manufactured by Orientec Co., Ltd. was used, and the hardening characteristics were measured under the same temperature conditions as the actual molding step. From the start of the measurement to the torque of more than 0.001N. The time until m is taken as the gelation time T _g (seconds) of the thermosetting resin composition [B]. The timing of starting the above step [II] may be determined as long as the T _g (seconds) measured in advance is determined.

It is preferred to start the aforementioned step [II] at the timing when the Barcol hardness of the molded article becomes 10 to 20 in the step [I]. In such a range, the adhesion between the thermosetting resin composition [B] and the coating film of the coating agent is drastically improved. Further, the Barco hardness of the molded article was measured in accordance with JIS K7060 (1995), and the value measured in the form A was used. Using a carbon fiber reinforced resin molding material [C], a flat plate of 100 mm × 100 mm × 2 mmt is press-formed under the same conditions as the actual molding step, and a molded article at a time point when a predetermined time elapses from the start of heating-pressing is started. The surface hardness was measured by a Barcol hardness meter, and the relationship between the heating-pressing time and the Barcol hardness of the molded article was determined. The timing of starting the above step [II] may be determined as long as the relationship between the heating-pressurization time obtained from the above and the Barcol hardness of the molded article is determined.

The method of controlling the Barcol hardness of the molded article to the above-mentioned preferred range is not particularly limited. However, when the gelation time of the thermosetting resin composition [B] is T _g (second), the step is In [I], starting from the start of heating-pressurizing the carbon fiber-reinforced resin molding material [C], the step [II] is started after 2T _g to 4T _g (seconds), whereby the Barcol hardness can be controlled to such a preferable The scope is better.

As described above, the molded article [D] obtained by the step [II] is capable of obtaining a molded article having an excellent surface appearance in which the electric coating spot is suppressed when the electrocoating is applied. It can be preferably used for the application of electrocoating. When the coated molded article [D] is subjected to electrocoating for the purpose of coating, a conductive layer having a surface appearance of no plaque can be obtained by forming a conductive layer on the surface layer of the molded article in advance. In addition, when the coated molded article [D] is applied as an integral member combined with another member, the layer formed by the surface layer of the molded article is an insulating layer, and only the other layer can be used. The member is electrocoated and the electrocoating is not applied to the finished molded article [D] to maintain the surface quality of the molded article.

Therefore, the preferred use of the carbon fiber reinforced plastic molded article obtainable by the present invention includes an instrument panel, a door beam, a lower cover, a lamp cover, a pedal cover, a radiator support member, a spare tire cover, Various modules such as the front end; automobile parts, components and outer plates such as cylinder head cover, bearing retainer, intake manifold, pedal, etc.; landing gear pod, aileron, spoiler, edge, pointer, fairing, rib Aircraft-related parts, components and outer panels; tools for falling heads, wrenches, etc.; and telephones, fax machines, VTRs, photocopiers, televisions, microwave ovens, audio equipment, cosmetics, laser discs (registered trademarks), Household-business electrical products such as refrigerators and air conditioners. In addition, a member for an electric-electronic device such as a casing used for a personal computer or a mobile phone or a keyboard support that supports a keyboard inside a personal computer may be used. Among them, an automobile member that is used in combination with a metal member can be more preferably used.

Example

Hereinafter, the present invention will be described in detail by way of examples, but the invention should not be construed as limited.

[Evaluation method] (1) Gelation time T _g of the thermosetting resin composition [B]

2 cm ³ of the thermosetting resin composition [B] was weighed, and the "Curelastometer" (registered trademark) V type manufactured by Orientec Co., Ltd. was used, and the hardening characteristics were measured under the same temperature conditions as the actual molding steps. The measurement starts from the torque to more than 0.001N. The time until m is taken as the gelation time T _g (seconds) of the thermosetting resin composition [B].

(2) Barcol hardness of carbon fiber reinforced resin molding material [C]

Using a carbon fiber reinforced resin molding material [C], a flat plate of 100 mm × 100 mm × 2 mmt was press-formed under the same conditions as the actual forming step, and from the start of heating-pressurization, at a predetermined time The surface hardness of the molded article was measured in accordance with JIS K7060 (1995) using a Barcol hardness meter (GYZJ934-1 manufactured by Barber-Colman Co., Ltd.).

(3) Surface resistance value of the finished molded article [D]

According to JIS K7194 (1994), a flat plate of 80 mm × 50 mm × 2 mmt was cut out from the finished molded product [D], and "Loresta" (registered trademark) GP MCP-T600 type (manufactured by Mitsubishi Chemical Analytech Co., Ltd.) was used. The surface resistance value (Ω) was measured by a four-probe method at a voltage of 10 V. In addition, in the range which cannot be measured by this method, a 100 mm × 100 mm × 2 mmt flat plate is cut out from the coated molded product [D] in accordance with JIS K6911 (1995), and used. "Hiresta" (registered trademark) UP MCP-HT450 type (manufactured by Mitsubishi Chemical Analytech Co., Ltd.), and the surface resistance value (?) was measured by a double ring electrode method at an applied voltage of 1000V.

(4) Coating adhesion of the finished molded product [D]

The coating film adhesion was evaluated by a cross-cut method, and the cross-cut method was cut out from the coated molded article [D] by 100 mm × 100 mm × 2 mmt in accordance with JIS K5600 (1999). A flat plate was used, and a special jig was used on the surface thereof, and a 6×6 lattice-shaped cut with a gap of 1 mm was drawn, and the tape was crimped and peeled off for testing. The results were evaluated in the classifications 0 to 5 (six stages) described in JIS K5600, and judged based on the following criteria, and A, B, and C were regarded as qualified.

A: Category 0 (the edge of the cut is smooth, and any grid mesh is not peeled off)

B: Category 1 (the coating film at the intersection of the cut has a small peeling)

C: Category 2 (coating film peeling along the edge of the cut, and/or peeling off at the intersection)

D: Classification 3 to 5 (the film is partially or comprehensively peeled off along the edge of the cut).

(5) Evaluation of electric painting spot

In the molded article [D] which was coated, the electrocoating surface of the electrocoater was subjected to visual inspection for the method described later, and the electrocoating property was evaluated. The results were judged based on the following criteria, and A and B were regarded as qualified.

A: in the case where the layer formed on the surface layer of the molded article is a conductive layer, there is no coating spot, and a uniform coating is applied over the entire surface of the molded article, or In the case where the layer formed on the surface layer of the molded article is an insulating layer, the coating is not attached at all.

B: When the layer formed on the surface layer of the molded article is a conductive layer, the coating is applied over the entire surface of the molded article, but the unevenness is present in a part or the layer formed on the surface layer of the molded article is an insulating layer. The coating is not attached at all, but there is a bump in a part

C: When the layer formed on the surface layer of the molded article is a conductive layer, a portion where the electroless coating is applied is present in a part of the molded article, or a layer formed on the surface layer of the molded article is an insulating layer. A part of the molded article has an area where the electrocoating is adhered.

(Reference Example 1) Production of carbon fiber [A]

Using a copolymer containing polyacrylonitrile as a main component, after spinning, firing, and surface oxidation treatment, 24,000 total filaments, a single fiber diameter of 7 μm, and a mass per unit length of 1.6 g/m were obtained. Carbon fiber having a specific gravity of 1.8 g/cm ³ and a surface oxygen concentration ratio of [O/C] of 0.12. The carbon fiber had a strand tensile strength of 4,880 MPa and a strand tensile modulus of 225 GPa.

Here, the surface oxygen concentration ratio was obtained by using the surface-oxidized carbon fiber, and was determined by the following procedure using X-ray photoelectron spectroscopy. First, the carbon fiber bundle was cut into 20 mm, spread out and arranged on a copper sample support stand. The measurement was carried out by using AlKα1 and 2 as the X-ray source and maintaining the sample chamber at 1 × 10 ^-8 Torr. As the correction value of the peak accompanying charging at the time of measurement, the kinetic energy value (KE) of the main peak of C _1s was adjusted to 1202 eV. As the KE, the bottom line of the straight line is drawn in the range of 1191 to 1205 eV, thereby obtaining the C _1s peak area. Further, as the KE, the bottom line of the straight line is drawn in the range of 947 to 959 eV, thereby obtaining the O _1s peak area. The surface oxygen concentration ratio was calculated from the atomic ratio from the ratio of the O _1s peak area to the C _1s peak area using the sensitivity correction value inherent to the apparatus. As a X-ray photoelectron spectroscopy apparatus, the Model ES-200 manufactured by International Electric Co., Ltd. was used, and the sensitivity correction value was 1.74.

As a sizing agent, a sizing treatment liquid in which glycerin polyglycidyl ether (epoxy equivalent: 140 g/eq) was dissolved in water was prepared. By immersing the carbon fiber in a sizing treatment liquid through a roll, a sizing agent is applied to the carbon fiber bundle, and then dried at 230 ° C to obtain a carbon fiber [A].

(Reference Example 2) Production of carbon fiber reinforced resin molding material [C]

The carbon fiber [A] obtained in accordance with Reference Example 1 was cut into a predetermined length by a rotary cutter, and dispersed in a uniform dispersion manner to obtain a discontinuous carbon fiber mat having an isotropic alignment of fibers. Weighing 1kg/m ² ). By supplying the thermosetting resin composition [B] to the discontinuous carbon fiber mat, it is impregnated with a roll to obtain a sheet-like carbon fiber-reinforced resin molding material [C].

(Reference Example 3) Electro-coating method of the molded article [D] after coating

The molded article [D] to which the in-mold coating has been applied is immersed in the electrocoating liquid, and a voltage is applied between the coated molded article [D] and the counter electrode to form the coating particles on the molded article. The surface is precipitated. Further, the coating conditions were performed after being boosted to a voltage of 100 V at a step-up rate of 2 V/sec, and then energized for 180 seconds. After the electricity was turned on, the liquid was removed, washed with ion-exchanged water, and then subjected to sintering treatment.

[Use raw materials] . Carbon fiber [A]

[A-1] The carbon fiber to which the sizing agent was obtained according to Reference Example 1 was used.

. Thermosetting resin composition [B]

100 parts by weight of "DERAKANE" (registered trademark) made of vinyl ester (Dow-Chemical) as a [B-1] thermosetting resin, and a grade 3 butyl peroxybenzene as a hardener 1 part by weight of a formic acid ester ("PERBUTYL (registered trademark) Z"), and 7 parts by weight of magnesium oxide ("MgO #40" manufactured by Kyowa Chemical Industry Co., Ltd.) as a tackifier . The results measured gelation time T _g in 140 ℃, T _g = 40 seconds.

. In-mold coating agent [Coat]

[Coat-1] A two-component acrylic-urethane resin-based paint ("RETAN (registered trademark) PG60" manufactured by Kansai Paint Co., Ltd.) was used.

[Coat-2] 100 parts by weight of "RETAN (registered trademark) PG60" manufactured by Kansai Paint Co., Ltd.) was used to add insulation to Japan. 20 parts by weight of "MICRO ACE (registered trademark) P-4" manufactured by the company, and uniformly dispersed.

[Coat-3] 100 parts by weight of a two-component acrylic-urethane resin-based paint ("RETAN (registered trademark) PG60" manufactured by Kansai Paint Co., Ltd.) was used as a conductive filler, and Mitsubishi Chemical was added. The carbon black "#3050B" was prepared in an amount of 10 parts by mass and uniformly dispersed.

[Coat-4] 100 parts by weight of a two-component acrylic-urethane resin-based paint ("RETAN (registered trademark) PG60" manufactured by Kansai Paint Co., Ltd.) was used as a conductive filler to add Mitsubishi Chemical. The carbon black "#3050B" was prepared in an amount of 35 parts by mass and uniformly dispersed.

(Examples 1 to 6)

Using the carbon fiber [A] and the thermosetting resin composition [B] described in Table 1, a sheet-like carbon fiber-reinforced resin molding material [C] was obtained in accordance with Reference Example 2. Here, the carbon fiber-reinforced resin molding material [C] has a carbon fiber weight content of 45% and a basis weight of 2 kg/m ² .

The carbon fiber-reinforced resin molding material [C] was heated-pressurized at a mold temperature of 140 ° C and a mold clamping pressure of 10 MPa to form a press molding (step [I]).

Then, the gelation time T _g of the thermosetting resin composition [B] measured in advance is used as a reference, and from the time when the heating-pressurization is started, after the time (injection time) described in Table 1, The upper mold was raised by 0.5 mm, and the coating agent described in Table 1 was injected and pressurized again to carry out in-mold coating (step [II]).

The surface resistance value of the obtained molded article [D] and the coating film adhesion were evaluated. Then, the obtained coated molded article [D] was subjected to electrocoating in accordance with Reference Example 3, and visual inspection was performed. The various measurement results and evaluation results are summarized in Table 1.

(Comparative Example 1)

Using the carbon fiber [A] and the thermosetting resin composition [B] described in Table 2, a sheet-like carbon fiber-reinforced resin molding material [C] was obtained in accordance with Reference Example 2. Here, the carbon fiber-reinforced resin molding material [C] has a carbon fiber weight content of 45% and a basis weight of 2 kg/m ² .

The carbon fiber-reinforced resin molding material [C] was heated-pressurized at a mold temperature of 140 ° C and a mold clamping pressure of 10 MPa to form a press molding (step [I]). At this time, the in-mold coating was not applied, and after heating-pressurization until the resin was cured, the mold was released, and an uncoated molded article was obtained. The surface resistance value of the obtained uncoated molded article was measured. Then, the uncoated molded article was subjected to electrocoating in accordance with Reference Example 3, and visual inspection was performed. The various measurement results and evaluation results are summarized and shown in Table 2.

(Comparative Example 2)

Using the carbon fiber [A] and the thermosetting resin composition [B] described in Table 2, a sheet-like carbon fiber-reinforced resin molding material [C] was obtained in accordance with Reference Example 2. Here, the carbon fiber-reinforced resin molding material [C] has a carbon fiber weight content of 45% and a basis weight of 2 kg/m ² .

The carbon fiber-reinforced resin molding material [C] was heated-pressurized at a mold temperature of 140 ° C and a mold clamping pressure of 10 MPa to form a press molding (step [I]). At this time, after the in-mold coating was not applied, the mold was released after heating-pressurization until the resin was cured, and an uncoated molded article was obtained.

The coating material described in Table 2 was applied by spraying to the obtained uncoated molded article, and dried and sintered to obtain a molded article [D]. The surface resistance value of the obtained molded article [D] and the coating film adhesion were evaluated. Then, the obtained coated molded article [D] was subjected to electrocoating in accordance with Reference Example 3, and visual inspection was performed. The various measurement results and evaluation results are summarized and shown in Table 2.

With respect to Examples 1 to 6, it was possible to obtain an in-mold coating surface without pinholes, and it was possible to form an insulating layer or a conductive layer having a very smooth and uniform surface quality. As a result, in Examples 1 to 4, it was possible to obtain a molded article in which no coating material adhered at all even when electrocoating was applied. Further, in Examples 5 and 6, it was possible to uniformly precipitate the coated particles on the entire surface. In addition, in the third embodiment, the hardening of the molded article was carried out at the time of the injection of the coating agent compared with the other examples. Therefore, it was confirmed that the coating film adhesion property was lowered, but it was confirmed that there was no problem. grade.

On the other hand, in Comparative Example 1, since the electro-coating was performed without applying the in-mold coating, the conductivity of the carbon fibers became a surface having many spots due to the unevenness of the conductivity.

In Comparative Example 2, instead of in-mold coating, the coating agent was applied by spraying after demolding, so that the carbon fiber mesh was transferred during the spray coating, and the coating was produced after the electrocoating. Bump. In addition, The adhesion between the molded article and the coating film is remarkably lowered. Further, after the molded article is released from the mold, the pretreatment, the application by the spray, the drying, and the sintering are performed. Therefore, the steps from the press molding to the electrocoating are complicated, and the molding efficiency is greatly lowered.

[Industrial availability]

According to the carbon fiber-reinforced plastic molded article obtained by the present invention, the surface conductivity is controlled, and when the electrocoating is applied, the coating spot is suppressed, so that it has an excellent surface appearance and can be used in various applications. In particular, it is suitable for various parts and components of electric-electronic equipment, OA equipment, home electric appliances, or parts of automobiles, internal components, and frames.

Claims (6)

A method for producing a carbon fiber reinforced plastic molded article, which comprises at least [I] forming a carbon fiber reinforced resin molding material [C] comprising at least a carbon fiber [A] and a thermosetting resin composition [B] by press molding. a step of obtaining a press-molded article; [II] a method for producing a carbon fiber-plastic molded article in which two steps of coating the surface of the press-molded article by in-mold coating are applied, in the step [II] An insulating layer or a conductive layer is formed on the surface of the press-formed product. The method for producing a carbon fiber reinforced plastic molded article according to claim 1, wherein the insulating layer or the conductive layer of the step [II] is an insulating layer having a surface resistance value of 10 or more (7 Ω) or a surface resistance value of 10 A conductive layer below the first power (Ω). The method for producing a carbon fiber reinforced plastic molded article according to claim 1 or 2, wherein, when the gelation time of the thermosetting resin composition [B] is T _g (second), in the step [I], This step [II] is started from the time when the heating and pressurization of the carbon fiber-reinforced resin molding material [C] is started after 2T _g to 4T _g (seconds). The method for producing a carbon fiber reinforced plastic molded article according to any one of claims 1 to 3, wherein in the step [I], the step is started at a timing when the Barcol hardness of the press-molded article becomes 10 to 20 [II] . The method for producing a carbon fiber-reinforced plastic molded article according to any one of claims 1 to 4, further comprising the step of applying an electrocoating to the coated surface of the molded article obtained in the step [II]. The method for producing a carbon fiber reinforced plastic molded article according to any one of claims 1 to 5, wherein the carbon fiber [A] is a discontinuous fiber having a fiber length of 5 to 100 mm.