Fiber-reinforced molded material and molded product therewith

Abstract

To provide a fiber-reinforced molding material that can realize a molded product excellent in light-weight and fire retardancy and is excellent in impregnation and molding fluidity, and, a molded product using the fiber-reinforced molding material.SOLUTION: The fiber-reinforced molded material of the present invention includes a curable resin composition and carbon fibers, where a flame retardant (E) is one or more expandable graphite having an expansion ratio of 200 cm3 / g or more and an expansion starting temperature of 180°C or more to 280°C or less, the content of the flame retardant (E) is 3.5% by mass or more to 10.0% by mass or less relative to the total mass of the fiber-reinforced molded material, the content of inorganic hollow particles (F) is 2.0% by mass to 4.0% by mass relative to the total mass of the fiber-reinforced molded material, and the content of an ethylenically unsaturated monomer (B) is 8.5% by mass to 22.0% by mass relative to the total mass of the curable resin composition when the resin (A) is an urethane (meth)acrylate resin (Aa).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a fiber-reinforced molding material and a molded article using the same. [Background technology]

[0002] Conventionally, fiber-reinforced molding materials obtained by impregnating a thermosetting resin composition with reinforcing fibers such as carbon fibers have been known (for example, Patent Document 1). Known molding methods using the fiber-reinforced molding materials include those in which intermediate materials called sheet molding compounds (SMC) and bulk molding compounds (BMC) are used and cured and molded by techniques such as press molding and injection molding.

[0003] The fiber-reinforced molding material has attracted attention for its characteristics of being lightweight yet having excellent heat resistance and mechanical strength, and its use in battery cases for electric vehicles such as battery-powered electric vehicles and plug-in hybrid vehicles is being considered. It is desirable to realize a molded product for use in electric vehicle battery cases that combines light weight with a specific gravity of less than 1.4 and flame retardancy.

[0004] In order to improve the flame retardancy of molded articles using the fiber-reinforced molding material, it has been considered to reduce the organic components in the thermosetting resin composition, for example, by reducing the content of unsaturated monomers in the thermosetting resin composition. However, reducing the content of the unsaturated monomers can have disadvantages such as a decrease in the impregnation ability of the thermosetting resin composition into the carbon fiber and a decrease in the molding flowability of the fiber-reinforced molding material. Furthermore, increasing the content of the unsaturated monomers can have disadvantages such as an excessive increase in the molding flowability, which can lead to the formation of flash. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6241583 Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present invention is to provide a fiber-reinforced molding material that can realize molded articles that are lightweight and flame-retardant and that have excellent impregnation and molding flow properties, and a molded article using the fiber-reinforced molding material. [Means for solving the problem]

[0007] The fiber-reinforced molding material of the present invention is a fiber-reinforced molding material containing a curable resin composition and carbon fibers, wherein the curable resin composition contains a resin (A) containing one or more resins selected from the group consisting of a urethane (meth)acrylate resin (Aa) and an epoxy (meth)acrylate resin (Ab), an ethylenically unsaturated monomer (B) different from (A), a polyisocyanate (C), a polymerization initiator (D), a flame retardant (E), and inorganic hollow particles (F), and the flame retardant (E) has an expansion ratio of 200 cm 3 / g or more and one or more types of expandable graphite having an expansion onset temperature of 180°C or more and 280°C or less, the content of the flame retardant (E) is 3.5% by mass or more and 10.0% by mass or less, based on the total mass of the fiber-reinforced molding material, the content of the inorganic hollow particles (F) is 2.0% by mass or more and 4.0% by mass or less, based on the total mass of the fiber-reinforced molding material, the content of the ethylenically unsaturated monomer (B) is 8.5% by mass or more and 22.0% by mass or less, based on the total mass of the curable resin composition, when the resin (A) is a urethane (meth)acrylate resin (Aa), and is 22.0% by mass or more and 32.0% by mass or less, based on the total mass of the curable resin composition, when the resin (A) is an epoxy (meth)acrylate resin (Ab).

[0008] The molded article of the present invention is characterized by using the above-mentioned fiber-reinforced molding material. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a fiber-reinforced molding material that can realize molded articles that are lightweight and have excellent flame retardancy and that has excellent impregnation properties and molding flowability, and a molded article that uses the fiber-reinforced molding material. DETAILED DESCRIPTION OF THE INVENTION

[0010] The fiber-reinforced molding material of the present embodiment is a fiber-reinforced molding material containing a curable resin composition and carbon fibers, wherein the curable resin composition contains a resin (A) containing one or more selected from the group consisting of a urethane (meth)acrylate resin (Aa) and an epoxy (meth)acrylate resin (Ab), an ethylenically unsaturated monomer (B) different from (A), a polyisocyanate (C), a polymerization initiator (D), a flame retardant (E), and inorganic hollow particles (F), and the flame retardant (E) has an expansion ratio of 200 cm 3 / g or more and one or more types of expandable graphite having an expansion onset temperature of 180°C or more and 280°C or less, the content of the flame retardant (E) is 3.5% by mass or more and 10.0% by mass or less, based on the total mass of the fiber-reinforced molding material, the content of the inorganic hollow particles (F) is 2.0% by mass or more and 4.0% by mass or less, based on the total mass of the fiber-reinforced molding material, the content of the ethylenically unsaturated monomer (B) is 8.5% by mass or more and 22.0% by mass or less, based on the total mass of the curable resin composition, when the resin (A) is a urethane (meth)acrylate resin (Aa), and is 22.0% by mass or more and 32.0% by mass or less, based on the total mass of the curable resin composition, when the resin (A) is an epoxy (meth)acrylate resin (Ab).

[0011] Resin (A) The resin (A) includes one or more resins selected from the group consisting of urethane (meth)acrylate resins (Aa) and epoxy (meth)acrylate resins (Ab).

[0012] [Urethane (meth)acrylate resin (Aa)] The urethane (meth)acrylate resin (Aa) is preferably a reaction product of the polyisocyanate (C) with a polyol (a1) having an ethylenically unsaturated group and an aromatic skeleton, and / or a reaction product of the polyisocyanate (C), a polyol (a2) having no ethylenically unsaturated group but an aromatic skeleton, and a hydroxyalkyl (meth)acrylate (a3).

[0013] The polyol (a1) has an ethylenically unsaturated group and an aromatic skeleton. Multifunctional epoxy (meth)acrylates are preferred because they provide improved heat resistance. Examples include reaction products of bisphenol-type epoxy resins such as bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol fluorene-type epoxy resins, and biscresol fluorene-type epoxy resins, as well as novolac-type epoxy resins such as phenol novolac-type epoxy resins and cresol novolac-type epoxy resins, with (meth)acrylic acid. Preferably, they are obtained by reacting an epoxy resin having an epoxy equivalent in the range of 180 to 500 with (meth)acrylic acid. The number of functional groups is preferably 1.5 to 3.0 in terms of the balance between heat resistance and strength properties.

[0014] The polyol (a2) has no ethylenically unsaturated groups and an aromatic skeleton. Examples include alkylene oxide adducts of bisphenol compounds, such as alkylene oxide adducts of bisphenol A, alkylene oxide adducts of bisphenol S, and alkylene oxide adducts of bisphenol F; alkylene oxide adducts of dihydroxybenzene compounds, such as 1,3-bis(2-hydroxyethoxy)benzene and 1,4-bis(2-hydroxyethoxy)benzene; alkylene oxide adducts of biphenol compounds, such as 2'-[(1,1'-biphenyl-4,4'-diyl)bisoxy]bisethanol; alkylene oxide adducts of dihydroxynaphthalene compounds, and 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene. Among these, alkylene oxide adducts of bisphenol compounds are preferred from the viewpoint of compatibility, heat resistance, water resistance, and balance of strength properties. More preferred are ethylene oxide adducts of bisphenol compounds, with an average number of moles added of 2 to 10 moles.

[0015] Examples of the hydroxyalkyl (meth)acrylate (a3) ​​include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxy-n-butyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-n-butyl (meth)acrylate, and 3-hydroxy-n-butyl (meth)acrylate. Among these, 2-hydroxyethyl (meth)acrylate is preferred from the viewpoint of the balance of strength and physical properties. These hydroxyalkyl (meth)acrylates (a3) ​​can be used alone or in combination of two or more.

[0016] If necessary, polyols other than the polyols (a1) to (a3) ​​can be used in combination as raw materials for the urethane (meth)acrylate (A). Examples of the other polyols that can be used include polyester polyols, acrylic polyols, polyether polyols, polycarbonate polyols, and polyalkylene polyols.

[0017] The molar ratio (a3 / a4) of the polyol (a2) to the hydroxyalkyl (meth)acrylate (a3) ​​is preferably 60 / 40 to 10 / 90, more preferably 50 / 50 to 20 / 80, in order to further improve heat resistance and curability.

[0018] The molar ratio (NCO / OH) of the isocyanate group (NCO) of the isocyanate compound to the hydroxyl group (OH) of the compound having a hydroxyl group, which are raw materials for the urethane (meth)acrylate (A), is preferably 0.7 to 1.3, more preferably 0.8 to 1.1, in view of the balance between heat resistance and strength properties.

[0019] [Epoxy (meth)acrylate resin (Ab)] The epoxy (meth)acrylate (a1) can be obtained by reacting an epoxy resin with (meth)acrylic acid and / or (meth)acrylic anhydride.

[0020] Examples of the epoxy resin (a1) include bisphenol type epoxy resins such as bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol fluorene type epoxy resins, and biscresol fluorene type epoxy resins; novolac type epoxy resins such as phenol novolac type epoxy resins and cresol novolac type epoxy resins; oxodoridone-modified epoxy resins; brominated epoxy resins of these resins; and glycidyl ethers of polyhydric alcohols such as dipropylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl ether of alkylene oxide adduct of bisphenol A, and diglycidyl ether of hydrogenated bisphenol A. Examples of epoxy resins include alicyclic epoxy resins such as bisphenol A, 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate, and 1-epoxyethyl-3,4-epoxycyclohexane; glycidyl esters such as phthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, diglycidyl-p-oxybenzoic acid, and dimer acid glycidyl ester; glycidyl amines such as tetraglycidyldiaminodiphenylmethane, tetraglycidyl-m-xylenediamine, triglycidyl-p-aminophenol, and N,N-diglycidylaniline; and heterocyclic epoxy resins such as 1,3-diglycidyl-5,5-dimethylhydantoin and triglycidyl isocyanurate. Among these, bifunctional aromatic epoxy resins are preferred because of their superior molded product strength, ease of handling of molding materials, and fluidity during molding of the molding materials, and bisphenol A epoxy resins and bisphenol F epoxy resins are more preferred. These epoxy resins can be used alone or in combination of two or more.

[0021] The reaction between the epoxy resin and (meth)acrylic acid is preferably carried out using an esterification catalyst at 60 to 140° C. A polymerization inhibitor or the like may also be used.

[0022] [Ethylenically unsaturated monomer (B)] Examples of the ethylenically unsaturated monomer (B) include monofunctional methacrylate compounds such as benzyl methacrylate, phenoxyethyl methacrylate, phenoxy polyethylene glycol methacrylate, polyethylene glycol methacrylate alkyl ether, polypropylene glycol methacrylate alkyl ether, 2-ethylhexyl methacrylate, isodecyl methacrylate, lauryl methacrylate, isotridecyl methacrylate, n-stearyl methacrylate, tetrahydrofurfuryl methacrylate, isobornyl methacrylate, dicyclopentenyloxyethyl methacrylate, and dicyclopentanyl methacrylate; dimethacrylate compounds such as ethylene glycol dimethacrylate, propylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,3-butanediol dimethacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, bisphenol dimethacrylate, and 1,4-cyclohexanedimethanol dimethacrylate; and diallyl phthalate, divinylbenzene, and styrene. Among these, aromatic methacrylates are preferred because they provide molding materials with higher strength, and they may be used alone or in combination of two or more.

[0023] In the fiber-reinforced molding material of this embodiment, when a urethane (meth)acrylate (Aa) is used as the resin (A), the content of the ethylenically unsaturated monomer (B) is 8.5 mass% or more and 22.0 mass% or less, based on the total mass of the curable resin composition. This makes it possible to achieve both excellent impregnation of the curable resin composition into carbon fibers and excellent molding flowability of the fiber-reinforced molding material. If the content is below the lower limit, excellent impregnation cannot be achieved, and if it is above the upper limit, excellent molding flowability cannot be achieved.

[0024] Furthermore, in the fiber-reinforced molding material of this embodiment, when an epoxy (meth)acrylate resin (Ab) is used as the resin (A), the content of the ethylenically unsaturated monomer (B) is 22.0 mass% or more and 32.0 mass% or less, based on the total mass of the curable resin composition. This makes it possible to achieve both excellent impregnation of the curable resin composition into carbon fibers and excellent molding flowability of the fiber-reinforced molding material. If the content is below the lower limit, excellent impregnation cannot be achieved, and if it is above the upper limit, excellent molding flowability cannot be achieved.

[0025] [Polyisocyanate (C)] Polyisocyanate (C) improves the heat resistance of molded products, so it is It is preferable that the polyisocyanate (C) contains a polyisocyanate having the above properties. These polyisocyanates (C) can be used alone or in combination of two or more kinds.

[0026] Examples of the polyisocyanate (C) include 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, carbodiimide-modified 4,4'-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, nurate-modified diphenylmethane diisocyanate, biuret-modified diisocyanate, urethane imine-modified diphenylmethane diisocyanate, polyol-modified diisocyanate modified with a polyol having a number average molecular weight of 1,000 or less, such as diethylene glycol or dipropylene glycol, tolylene diisocyanate (TDI), and tolidine diisocyanate. aromatic polyisocyanates such as 1,3-xylylene diisocyanate (XDI), 1,5-naphthalene diisocyanate, and tetramethylxylylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate (IPDI), hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, and norbornene diisocyanate; and aliphatic polyisocyanates such as hexamethylene diisocyanate, nurate-modified hexamethylene diisocyanate, biuret-modified hexamethylene diisocyanate, adduct, and dimer acid diisocyanate. Among these, aromatic polyisocyanates are preferred because they provide molding materials with excellent handling properties (film peelability and tackiness). These polyisocyanates (a1) can be used alone or in combination of two or more.

[0027] [Polymerization initiator (D)] The polymerization initiator (D) is not particularly limited, but is preferably an organic peroxide, such as a diacyl peroxide compound, a peroxyester compound, a hydroperoxide compound, a ketone peroxide compound, an alkyl perester compound, a percarbonate compound, or a peroxyketal, and can be appropriately selected depending on the molding conditions. These polymerization initiators (D) can be used alone or in combination of two or more.

[0028] Among these, it is preferable to use a polymerization initiator having a temperature of 70°C or higher and 110°C or lower to obtain a 10-hour half-life in order to shorten the molding time. A temperature of 70°C or higher and 110°C or lower is preferable because the fiber-reinforced molding material has a long shelf life at room temperature and can be cured in a short time by heating, resulting in a better balance between curability and moldability. Examples of such polymerization initiators include 1,6-bis(t-butylperoxycarbonyloxy)hexane, 1,1-bis(t-butylperoxy)cyclohexane, 1,1-bis(t-amylperoxy)cyclohexane, 1,1-bis(t-hexylperoxy)cyclohexane, t-butylperoxydiethyl acetate, t-butylperoxyisopropyl carbonate, t-amylperoxyisopropyl carbonate, t-hexylperoxyisopropyl carbonate, di-tert-butylperoxyhexahydroterephthalate, and t-amylperoxytrimethylhexanoate.

[0029] When a urethane (meth)acrylate (Aa) is used as the resin (A), the amount of the polymerization initiator (D) added is preferably in the range of 0.5 to 3 parts by mass per 100 parts by mass of the total of the urethane (meth)acrylate (Aa) and the ethylenically unsaturated monomer (B), because this provides excellent curing characteristics and storage stability.

[0030] [Flame retardant (E)] Flame retardant (E) has an expansion ratio of 200 cm 3 The expanded graphite is one or more types having an expansion ratio of 200 cm or more and an expansion initiation temperature of 180°C or more and 280°C or less. When the expanded graphite is heated within the above temperature range, it forms a wall made of carbon by thermal expansion, thereby preventing the contact of combustible components in the fiber-reinforced molding material and the molded article with oxygen, thereby imparting flame retardancy to the fiber-reinforced molding material and the molded article. The expanded graphite has an expansion ratio of 200 cm or more and an expansion initiation temperature of 180°C or more and 280°C or less. When the expanded graphite is heated within the above temperature range, it forms a wall made of carbon by thermal expansion, thereby preventing the contact of combustible components in the fiber-reinforced molding material and the molded article with oxygen, thereby imparting flame retardancy to the fiber-reinforced molding material and the molded article. 3 If the expansion starting temperature is less than 180°C, the expanded graphite will expand during molding and become unusable, while if the expansion starting temperature exceeds 280°C, the fiber-reinforced molding material or molded product will burn before the expanded graphite expands. Commercially available expanded graphite products include EXP-50SL, EXP-50KK, EXP-80S, EXP-150S, and EXP-200S (Fuji Graphite Industries Co., Ltd.), 95332400A, 9550250, and 9950200 (Ito Graphite Industries Co., Ltd.), etc.

[0031] The content of the flame retardant (E) is 3.5% by mass or more and 10.0% by mass or less, based on the total mass of the fiber-reinforced molding material. This range allows for both excellent flame retardancy and excellent impregnation into carbon fibers. If the content is below this range, excellent flame retardancy cannot be obtained, and if it exceeds this range, excellent impregnation cannot be obtained. The content is preferably 4.5% by mass or more and 9.0% by mass or more, and preferably 6.0% by mass or less and 8.0% by mass or less.

[0032] [Inorganic hollow particles (F)] The inorganic hollow particles (F) contribute to lightweight properties. The inorganic hollow particles (F) are preferably made of soda-lime borosilicate glass, and examples of commercially available products include Glass Bubbles K37 and Glass Bubbles S38 (3M). From the viewpoint of survival rate, the inorganic hollow particles (F) preferably have a pressure resistance of 10 MPa or more.

[0033] The content of the inorganic hollow particles (F) is 2.0% by mass or more and 4.0% by mass or less, based on the total mass of the fiber-reinforced molding material. This range allows for both excellent lightness and excellent strength of the carbon fiber composite material. If the content is below this range, excellent lightness cannot be obtained, and if it exceeds this range, excellent strength cannot be obtained. The content is preferably 1.0% by mass or more and 3.0% by mass or more, and more preferably 1.5% by mass or less and 2.0% by mass or less.

[0034] [Other ingredients] The curable resin composition of this embodiment essentially contains a resin (A), an ethylenically unsaturated monomer (B), a polyisocyanate (C), a polymerization initiator (D), a flame retardant (E), and inorganic hollow particles (F), but may also contain other components, such as a thermosetting resin other than the urethane (meth)acrylate resin (Aa) or the epoxy (meth)acrylate resin (Ab), a thermoplastic resin, a polymerization inhibitor, a curing accelerator, a filler, a shrinkage reducing agent, a mold release agent, a thickener, a viscosity reducer, a pigment, an antioxidant, a plasticizer, a flame retardant, an antibacterial agent, an ultraviolet stabilizer, a reinforcing material, a photocuring agent, and an internal mold release agent.

[0035] Examples of the thermosetting resin include vinyl urethane resin, unsaturated polyester resin, acrylic resin, epoxy resin, phenol resin, melamine resin, furan resin, etc. These thermosetting resins may be used alone or in combination of two or more.

[0036] Examples of the thermoplastic resin include polyamide resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polycarbonate resin, urethane resin, polypropylene resin, polyethylene resin, polystyrene resin, acrylic resin, polybutadiene resin, polyisoprene resin, and those modified by copolymerization, etc. These thermoplastic resins may be used alone or in combination of two or more.

[0037] Examples of the polymerization inhibitor include hydroquinone, trimethylhydroquinone, pt-butylcatechol, t-butylhydroquinone, toluhydroquinone, p-benzoquinone, naphthoquinone, hydroquinone monomethyl ether, phenothiazine, copper naphthenate, copper chloride, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, etc. These polymerization inhibitors may be used alone or in combination of two or more.

[0038] Examples of the curing accelerator include metal soaps such as cobalt naphthenate, cobalt octenate, vanadyl octenate, copper naphthenate, and barium naphthenate, and metal chelate compounds such as vanadyl acetylacetate, cobalt acetylacetate, and iron acetylacetonate. Examples of amines include N,N-dimethylamino-p-benzaldehyde, N,N-dimethylaniline, N,N-diethylaniline, N,N-dimethyl-p-toluidine, N-ethyl-m-toluidine, triethanolamine, m-toluidine, diethylenetriamine, pyridine, phenylmorpholine, piperidine, and diethanolaniline. These curing accelerators may be used alone or in combination.

[0039] The fillers include inorganic compounds and organic compounds, and can be used to adjust the physical properties of the molded product, such as strength, elastic modulus, impact strength, and fatigue durability.

[0040] Examples of the inorganic compound include calcium carbonate, magnesium carbonate, barium sulfate, mica, talc, kaolin, clay, celite, asbestos, barite, baryta, silica, silica sand, dolomite limestone, gypsum, aluminum fine powder, hollow balloons, alumina, glass powder, aluminum hydroxide, kansuiite, zirconium oxide, antimony trioxide, titanium oxide, molybdenum dioxide, and iron powder.

[0041] Examples of the organic compounds include powders of natural polysaccharides such as cellulose and chitin, and synthetic resin powders. Examples of synthetic resin powders include organic powders composed of hard resins, soft rubbers, elastomers, or polymers (copolymers), and particles with multilayer structures such as core-shell structures. Specific examples include particles composed of butadiene rubber and / or acrylic rubber, urethane rubber, silicone rubber, polyimide resin powder, fluororesin powder, and phenolic resin powder. These fillers may be used alone or in combination of two or more.

[0042] Examples of the release agent include zinc stearate, calcium stearate, paraffin wax, polyethylene wax, carnauba wax, etc. Preferred examples include paraffin wax, polyethylene wax, carnauba wax, etc. These release agents may be used alone or in combination of two or more.

[0043] Examples of the thickener include metal oxides and hydroxides such as magnesium oxide, magnesium hydroxide, calcium oxide, and calcium hydroxide, and acrylic resin-based fine particles, and can be appropriately selected depending on the handleability of the fiber-reinforced molding material of the present invention. These thickeners may be used alone or in combination of two or more.

[0044] The internal mold release agent is preferably at least one selected from the group consisting of aliphatic hydrocarbons, aliphatic esters, and fatty acid metal salts. By including such an internal mold release agent in the curable resin composition, when the fiber-reinforced molding material is cured by heating and pressurizing it in a mold, and the resulting molded article is removed from the mold, the expanded graphite does not firmly adhere to the mold and can be smoothly removed.

[0045] [Carbon fiber] As the carbon fiber, various types of fibers can be used, such as polyacrylonitrile-based, pitch-based, rayon-based, etc. Among these, polyacrylonitrile-based fibers are preferred because high-strength carbon fibers can be easily obtained.

[0046] The number of filaments in the fiber bundle used as the carbon fiber is preferably 1,000 to 60,000, as this further improves resin impregnation and the mechanical properties of the molded product.

[0047] The carbon fibers are preferably cut to a length of 2.5 to 50 mm, and more preferably cut to a length of 5 to 40 mm, as this improves the flowability in the mold during molding, and the appearance and mechanical properties of the molded product.

[0048] The fiber-reinforced molding material of this embodiment preferably contains carbon fibers in an amount of 20% by mass or more and 60% by mass or less, since this further improves the mechanical properties of the resulting molded article. If the carbon fiber content is less than 20% by mass, the strength of the molded article may be insufficient, while if the carbon fiber content exceeds 60% by mass, the curable resin composition may not sufficiently impregnate the carbon fibers, causing swelling in the molded article and resulting in insufficient strength of the molded article.

[0049] Furthermore, when the fiber-reinforced molding material of this embodiment contains cut carbon fibers as the carbon fibers, it is preferable that the carbon fibers are impregnated into the curable resin composition with their fiber directions random.

[0050] The fiber-reinforced molding material of this embodiment is preferably a sheet molding compound (SMC) or a bulk molding compound (BMC) from the viewpoints of excellent productivity and moldability with diverse designs.

[0051] Examples of methods for producing the SMC include using a mixer such as a conventional mixer, intermixer, planetary mixer, roll, kneader, or extruder to mix and disperse components such as resin (A), ethylenically unsaturated monomer (B), polyisocyanate (C), polymerization initiator (D), flame retardant (E), and inorganic hollow particles (F). The resulting curable resin composition is then uniformly coated onto upper and lower carrier films. The carbon fibers are sandwiched between the curable resin compositions on the upper and lower carrier films. The entire assembly is then passed through impregnation rolls to apply pressure to impregnate the carbon fibers with the curable resin composition, and the assembly is then wound into a roll or folded zigzag. Furthermore, aging is preferably performed at a temperature of 25 to 60°C. Examples of suitable carrier films include polyethylene film, polypropylene film, polyethylene-polypropylene laminate film, polyethylene terephthalate, and nylon.

[0052] The BMC can be produced in the same manner as the SMC, by mixing and dispersing components such as the resin (A), ethylenically unsaturated monomer (B), polyisocyanate (C), polymerization initiator (D), flame retardant (E), and inorganic hollow particles (F) using a mixer such as a conventional mixer, intermixer, planetary mixer, roll, kneader, or extruder, and then mixing and dispersing the carbon fibers in the resulting curable resin composition. Also, as with the SMC, it is preferable to age the BMC at a temperature of 25 to 60°C.

[0053] The molded article of this embodiment is preferably molded by hot compression molding of SMC or BMC from the viewpoints of excellent productivity and design versatility obtained from the fiber-reinforced molding material.

[0054] The heat compression molding method involves, for example, weighing a predetermined amount of molding material such as SMC or BMC, placing it in a mold preheated to 110-180°C, clamping the mold with a compression molding machine, shaping the molding material, maintaining a molding pressure of 0.1-30 MPa to cure the molding material, and then removing the molded product to obtain a molded product. Specific molding conditions are preferably a mold temperature of 120-160°C and a molding pressure of 1-10 MPa maintained for 1-2 minutes per mm of molded product thickness, and more preferably a mold temperature of 140-160°C and a molding pressure of 1-10 MPa maintained for 30-90 seconds per mm of molded product thickness, as this further improves productivity.

[0055] Molded articles obtained from the fiber-reinforced molding material of this embodiment are lightweight and have excellent flame retardancy, and therefore can be suitably used for battery cases for electric vehicles, sports components, housings for office automation equipment, and the like.

[0056] The present invention will be described in more detail below with reference to specific examples. [Example]

[0057] [Preparation of Curable Resin Composition] In this example, 26.8 parts by mass of Newpol BPE-20 (manufactured by Sanyo Chemical Industries, Ltd.: EO adduct of bisphenol A, hydroxyl equivalent: 164 g / eq), 18.9 parts by mass of Newpol BPE-40 (manufactured by Sanyo Chemical Industries, Ltd.: EO adduct of bisphenol A, hydroxyl equivalent: 204 g / eq), 2.2 parts by mass of PEG-300 (manufactured by Sanyo Chemical Industries, Ltd.: polyethylene glycol, hydroxyl equivalent: 150 g / eq), 35.0 parts by mass of 1,3-butanediol dimethacrylate, and SZ-2000 (manufactured by Sakai Chemical Industries, Ltd.) were used. A thermosetting resin composition was obtained by mixing 0.5 parts by mass of 3M Corporation's zinc stearate (as inorganic hollow particles), 6.0 parts by mass of Glass Bubbles K37 (3M Japan Ltd.'s inorganic balloon, soda-lime borosilicate glass 98% by weight, density 0.30-0.39, median particle size 45 μm) as inorganic hollow particles, 0.8 parts by mass of Trigonox 122-C80 (Kayaku Nouryon Co., Ltd.'s organic peroxide) as a polymerization initiator, 13.0 parts by mass of EXP-50SL (Fuji Graphite Industries Co., Ltd.'s expanded graphite) as a flame retardant, and 85.1 parts by mass of Millionate MR-200 (Tosoh Corporation's mixture of polymethylene polyphenyl polyisocyanate and diphenylmethane diisocyanate). The thermosetting resin composition contained a urethane (meth)acrylate resin (Aa). The expanded graphite EXP-50SL had an expansion ratio of 300 cm. 3 / g, expansion starting temperature is 200°C, and particle size is +50mesh 75%. The content of ethylenically unsaturated monomers relative to the total mass of the thermosetting resin composition is 14.8 mass%. The molar ratio (NCO / OH ratio) of the isocyanate group (NCO) of the polyisocyanate to the hydroxyl group (OH) of the polyol and monool is 0.95.

[0058] [Preparation of SMC] The obtained thermosetting resin composition was applied to a laminate film of polyethylene and polypropylene in an average amount of 1470 g / m using an SMC manufacturing apparatus. 2After applying the curable resin composition to the laminate film, carbon fibers cut to a length of 12.5 mm from carbon fiber roving ("T700SC-12000-50C" manufactured by Toray Industries, Inc.) were dropped uniformly from the air onto the laminate film so that the fibers had no fiber orientation, were uniform in thickness, and the carbon fiber content relative to the total mass of the fiber-reinforced molding material was 30% by mass. The curable resin composition was then sandwiched between other laminate films to which the curable resin composition had been similarly applied, thereby impregnating the reinforcing fibers with the thermosetting resin composition. The laminate film was then left to stand for 48 hours at 40°C to obtain an SMC with a laminate film as a fiber-reinforced molding material. The SMC had a basis weight of 2.1 kg / m. 2 It was.

[0059] [Production of molded products] The obtained SMC with laminate film was cut to a size of 265 mm long x 265 mm wide, and two sheets of SMC with the laminate film peeled off were stacked together. This was then placed in the center of a flat mold (mold interior area: 300 mm x 300 mm) heated to an upper mold temperature of 150°C and a lower mold temperature of 140°C, and compression molded under pressure and heating at a surface pressure of 13 MPa for 3 minutes, resulting in a flat molded product measuring 300 mm long x 300 mm wide x 2 mm thick. [Example]

[0060] In this example, a thermosetting resin composition was obtained in exactly the same manner as in Example 1, except that EXP-50KK (expanded graphite manufactured by Fuji Graphite Industries Co., Ltd.) was used as the flame retardant instead of EXP-50SL. The expanded graphite EXP-50KK has an expansion ratio of 200 cm 3 / g, expansion starting temperature 260 to 280°C, and particle size +50 mesh 75%. An SMC with a laminate film and a molded article were produced in the same manner as in Example 1, except that the obtained thermosetting resin composition was used. [Example]

[0061] In this example, a thermosetting resin composition was obtained in exactly the same manner as in Example 1, except that EXP-80S (expanded graphite manufactured by Fuji Graphite Industries Co., Ltd.) was used as the flame retardant instead of EXP-50SL. The expanded graphite EXP-80S has an expansion ratio of 200 cm 3 / g, expansion starting temperature 180°C, particle size +50 mesh 75%. An SMC with a laminate film and a molded article were produced in the same manner as in Example 1, except that the obtained thermosetting resin composition was used. [Example]

[0062] In this example, except that the amount of 1,3-butanediol dimethacrylate added was changed to 60.0 parts by mass and the amount of EXP-50SL added as the flame retardant was changed to 25.0 parts by mass, a thermosetting resin composition was obtained in exactly the same manner as in Example 1. Then, an SMC with a laminate film and a molded article were produced in the same manner as in Example 1, except that the obtained thermosetting resin composition was used. [Example]

[0063] In this example, except that the amount of 1,3-butanediol dimethacrylate added was changed to 21.0 parts by mass and the amount of EXP-50SL added as the flame retardant was changed to 25.0 parts by mass, a thermosetting resin composition was obtained in exactly the same manner as in Example 1. Then, an SMC with a laminate film and a molded article were produced in the same manner as in Example 1, except that the obtained thermosetting resin composition was used. [Example]

[0064] In this example, except that the amount of EXP-50SL added as the flame retardant was changed to 35.0 parts by mass, a thermosetting resin composition was obtained in exactly the same manner as in Example 1. Then, an SMC with a laminate film and a molded article were produced in the same manner as in Example 1, except that the obtained thermosetting resin composition was used. [Example]

[0065] In this example, except that the amount of the inorganic hollow particles added was changed to 4.0 parts by mass and the amount of EXP-50SL added as the flame retardant was changed to 25.0 parts by mass, a thermosetting resin composition was obtained in exactly the same manner as in Example 1. Then, an SMC with a laminate film and a molded article were produced in the same manner as in Example 1, except that the obtained thermosetting resin composition was used. [Example]

[0066] In this example, except that the amount of the inorganic hollow particles added was changed to 15.0 parts by mass and the amount of the expanded graphite EXP-50SL added as the flame retardant was changed to 25.0 parts by mass, a thermosetting resin composition was obtained in exactly the same manner as in Example 1. Then, an SMC with a laminate film and a molded article were produced in the same manner as in Example 1, except that the obtained thermosetting resin composition was used. [Example]

[0067] In this example, first, an epoxy(meth)acrylate resin solution was prepared by mixing 70.0 parts by mass of epoxy(meth)acrylate and 30.0 parts by mass of phenoxyethyl methacrylate. Next, 100 parts by weight of the resulting epoxy (meth)acrylate resin solution, 0.5 parts by weight of the SZ-2000, 6.0 parts by weight of the inorganic hollow particles, 1.0 part by weight of Trigonox 117 (organic peroxide, manufactured by Kayaku Nouryon Co., Ltd.) as a polymerization initiator, 10.0 parts by weight of EXP-50SL as a flame retardant, and 18.6 parts by weight of MR-200 as the polyisocyanate were mixed to obtain a thermosetting resin composition. The thermosetting resin composition contains an epoxy (meth)acrylate resin (Ab). The molar ratio (NCO / OH ratio) of the isocyanate group (NCO) of the polyisocyanate to the hydroxyl group (OH) of the epoxy (meth)acrylate was 0.55. [Example]

[0068] In this example, a thermosetting resin composition was obtained in exactly the same manner as in Example 9, except that the amount of phenoxy methacrylate added was changed to 18.0 parts by mass. Then, an SMC with a laminate film and a molded article were produced in the same manner as in Example 1, except that the obtained thermosetting resin composition was used.

[0069] (Comparative Example 1) In this comparative example, except that the amount of EXP-50SL added as the flame retardant was changed to 10.0 parts by mass, a thermosetting resin composition was obtained in exactly the same manner as in Example 1. Then, an SMC with a laminate film and a molded article were produced in the same manner as in Example 1, except that the obtained thermosetting resin composition was used.

[0070] (Comparative Example 2) In this comparative example, except that the amount of EXP-50KK added as the flame retardant was changed to 10.0 parts by mass, a thermosetting resin composition was obtained in exactly the same manner as in Example 2. Then, an SMC with a laminate film and a molded article were produced in the same manner as in Example 1, except that the obtained thermosetting resin composition was used.

[0071] (Comparative Example 3) In this comparative example, a thermosetting resin composition was obtained in exactly the same manner as in Example 3, except that the amount of EXP-80S added as the flame retardant was changed to 10.0 parts by mass. Then, an SMC with a laminate film and a molded article were produced in the same manner as in Example 1, except that the obtained thermosetting resin composition was used.

[0072] Comparative Example 4 In this comparative example, a thermosetting resin composition was obtained in exactly the same manner as in Example 1, except that EXP-100S (expanded graphite manufactured by Fuji Graphite Industries Co., Ltd.) was used as the flame retardant instead of EXP-50SL. The expanded graphite EXP-100S has an expansion ratio of 130 cm 3 / g, expansion starting temperature 180°C, particle size -100mesh 60%. An SMC with a laminate film and a molded article were produced in the same manner as in Example 1, except that the obtained thermosetting resin composition was used.

[0073] (Comparative Example 5) In this comparative example, a thermosetting resin composition was obtained in exactly the same manner as in Example 1, except that the amount of 1,3-butanediol dimethacrylate added was changed to 15.0 parts by mass and the amount of the expanded graphite EXP-50SL added as the flame retardant was changed to 25.0 parts by mass. Then, an SMC with a laminate film and a molded article were produced in the same manner as in Example 1, except that the obtained thermosetting resin composition was used.

[0074] (Comparative Example 6) In this comparative example, except that the amount of 1,3-butanediol dimethacrylate added was changed to 65.0 parts by mass and the amount of EXP-50SL added as the flame retardant was changed to 25.0 parts by mass, a thermosetting resin composition was obtained in exactly the same manner as in Example 1. Then, an SMC with a laminate film and a molded article were produced in the same manner as in Example 1, except that the obtained thermosetting resin composition was used.

[0075] (Comparative Example 7) In this comparative example, except that the amount of EXP-50SL added as the flame retardant was changed to 40.0 parts by mass, a thermosetting resin composition was obtained in exactly the same manner as in Example 1. Then, an SMC with a laminate film and a molded article were produced in the same manner as in Example 1, except that the obtained thermosetting resin composition was used.

[0076] (Comparative Example 8) In this comparative example, except that the amount of the inorganic hollow particles added was changed to 2.0 parts by mass and the amount of EXP-50SL added as the flame retardant was changed to 25.0 parts by mass, a thermosetting resin composition was obtained in exactly the same manner as in Example 1. Then, an SMC with a laminate film and a molded article were produced in the same manner as in Example 1, except that the obtained thermosetting resin composition was used.

[0077] Comparative Example 9 In this comparative example, except that the amount of the inorganic hollow particles added was changed to 20.0 parts by mass and the amount of EXP-50SL added as the flame retardant was changed to 25.0 parts by mass, a thermosetting resin composition was obtained in exactly the same manner as in Example 1. Then, an SMC with a laminate film and a molded article were produced in the same manner as in Example 1, except that the obtained thermosetting resin composition was used.

[0078] (Comparative Example 10) In this comparative example, a thermosetting resin composition was obtained in exactly the same manner as in Example 9, except that the amount of phenoxy methacrylate added was changed to 25.0 parts by mass. Then, an SMC with a laminate film and a molded article were produced in the same manner as in Example 1, except that the obtained thermosetting resin composition was used.

[0079] Next, the obtained SMCs and molded articles of Examples 1 to 10 and Comparative Examples 1 to 10 were evaluated as follows.

[0080] [Impregnability] The obtained SMC with laminate film was cut in the thickness direction, and the cross section was observed at a magnification of 50x using a digital microscope VHX-5000 (manufactured by Keyence Corporation), and the impregnation of the thermosetting resin composition into the carbon fiber was evaluated according to the following criteria: The cross sections were observed in two directions, one in any direction and the other perpendicular to that direction (total of two directions with a length of 300 mm). <Evaluation> ⊚: There were two or less unimpregnated areas. ◯: There were 3 to 5 or less unimpregnated areas. △: There were 6 to 10 or less unimpregnated areas. ×: There were 11 or more unimpregnated areas or the unimpregnated areas were widespread.

[0081] [Molding fluidity] When the molded article was produced, the area where the SMC was not filled to the end of the flat mold (hereinafter referred to as "short shot") and the length of the burr in the obtained molded article were visually observed, and the molding flowability was evaluated according to the following evaluation criteria. The width of the share edge of the flat mold was approximately 50 mm. <Evaluation> ⊚: No short shots occurred at all, and the short shots were within the range of the burr shear edges that occurred in the molded product. 〇: Short shot area is 0cm 2 Super 3cm 2 or the molded product had flash beyond the share edge. △: Short shot area is 3cm 2 More than 5cm 2 or the molded product had flash beyond the share edge. ×: Short shot area is 5cm 2 or more, or burrs beyond the shear edge were formed on the molded product.

[0082] [Flame retardant] The laminate film was peeled off from the resulting SMC with laminate film, and multiple SMC sheets were stacked to a total thickness of 2 mm. The resulting laminate was placed in the center of a flat plate mold coated with a release agent and compression-molded in a compression molding machine under conditions of 13 MPa pressure, upper mold temperature 150°C, lower mold temperature 140°C, and molding time 3 minutes. Test specimens were then prepared by cutting into strips 125 mm long x 13 mm wide. The resulting test specimen was subjected to a vertical flame test in accordance with UL94V. The top end of the test specimen was attached vertically to a clamp, and cotton was placed 300 mm below the specimen. A blue flame (20 mm high) of methane gas was applied to the bottom end of the specimen using a gas burner for 10 seconds, and the burning time was measured. If the burning lasted less than 30 seconds, the flame was applied for an additional 10 seconds, and the burning time was measured. Observations were made to see if the cotton ignited due to the dropping of the material, and if there was any burning at the clamp attachment point. These procedures were performed on five test specimens. The UL94 judging criteria are shown in Table 1.

[0083] [Table 1]

[0084] [Lightweight] The specific gravity of the obtained molded article was measured using a hydrometer. If the measured specific gravity was less than 1.40, it was judged to be excellent in lightness, and if the specific gravity was 1.40 or more, it was judged to be poor in lightness.

[0085] The evaluation results are shown in Tables 2 to 5.

[0086] [Table 2]

[0087] [Table 3]

[0088] [Table 4]

[0089] [Table 5]

[0090] As shown in Tables 2 and 3, the fiber-reinforced molding materials of Examples 1 to 10 all had good carbon fiber impregnation with the thermosetting resin composition, rated at Fair or higher, and also had desired molding fluidity, rated at Fair or higher. Furthermore, the fiber-reinforced molding materials can produce molded articles with flame retardancy of V1 or higher and excellent lightness.

[0091] On the other hand, as shown in Table 4, the fiber-reinforced molding materials of Comparative Examples 1 to 4 were good in both the impregnation of the thermosetting resin composition into the carbon fiber and the molding flowability, marked with an ◯, but had poor flame retardancy. Also, as shown in Table 5, the fiber-reinforced molding materials of Comparative Examples 5 to 7 and 9 to 10 were poor in either the impregnation of the thermosetting resin composition into the carbon fiber or the molding flowability, marked with an X. The fiber-reinforced molding material of Comparative Example 8 was good in both the impregnation of the thermosetting resin composition into the carbon fiber and the molding flowability, marked with an ◯, and the resulting molded article had excellent flame retardancy but was poor in lightness.

Claims

1. A fiber-reinforced molding material comprising a curable resin composition and carbon fibers, The curable resin composition comprises a resin (A) containing one or more resins selected from the group consisting of a urethane (meth)acrylate resin (Aa) and an epoxy (meth)acrylate resin (Ab); an ethylenically unsaturated monomer (B) different from the (A), a polyisocyanate (C), and The composition contains a polymerization initiator (D), a flame retardant (E), and inorganic hollow particles (F), The flame retardant (E) has an expansion ratio of 200 cm ３ / g or more and one or more types of expandable graphite having an expansion starting temperature of 180°C or more and 280°C or less, The content of the flame retardant (E) is 3.5% by mass or more and 10.0% by mass or less relative to the total mass of the fiber-reinforced molding material, The content of the inorganic hollow particles (F) is 2.0% by mass or more and 4.0% by mass or less relative to the total mass of the fiber-reinforced molding material, a content of the ethylenically unsaturated monomer (B) of from 8.5% by mass to 22.0% by mass, both relative to the total mass of the curable resin composition, when the resin (A) is a urethane (meth)acrylate resin (Aa); and from 22.0% by mass to 32.0% by mass, both relative to the total mass of the curable resin composition, when the resin (A) is an epoxy (meth)acrylate resin (Ab).

2. 2. The fiber-reinforced molding material according to claim 1, wherein the content of the carbon fiber is 20% by mass or more and 60% by mass or less based on the total mass of the fiber-reinforced molding material.

3. 3. The fiber-reinforced molding material according to claim 1, wherein the urethane (meth)acrylate resin (Aa) is a reaction product of the polyisocyanate (C) with a polyol (a1) having an ethylenically unsaturated group and an aromatic skeleton, and / or a reaction product of the polyisocyanate (C) with a polyol (a2) having no ethylenically unsaturated group but an aromatic skeleton, and a hydroxyalkyl (meth)acrylate (a3).

4. the curable resin composition further contains an internal mold release agent, 3. The fiber-reinforced molding material according to claim 1, wherein the internal mold release agent comprises at least one selected from the group consisting of aliphatic hydrocarbons, aliphatic esters, and fatty acid metal salts.

5. A molded product using the fiber-reinforced molding material according to claim 1 or 2.

Images