Prepreg and molded article

Abstract

The present invention addresses the problem of providing a prepreg and a molded article that can achieve excellent flame retardancy even without containing a halogen-containing compound. This prepreg is characterized by containing (A) a urethane (meth) acrylate, (B) an ethylenically unsaturated monomer other than the urethane (meth) acrylate (A), (C) a polymerization initiator, (D) glass fibers, (E) a halogen-free and phosphorus-containing first flame retardant, and (F) a halogen-free and phosphorus-free second flame retardant, the first flame retardant (E) is one or more salts selected from the group consisting of phosphinic acid metal salts and ammonium polyphosphate salts containing active hydrogen, and the second flame retardant (F) is one or more compounds selected from the group consisting of melamine cyanurate and metal hydroxides.

Description

Technical Field

[0001] The present invention relates to prepregs and molded articles thereof. Background Art

[0002] Fiber-reinforced resin composites reinforced with reinforcing fibers such as carbon fibers and glass fibers have attracted attention for their lightweight, heat resistance, and excellent mechanical strength, and their use in various structural applications, such as the shells and various components of automobiles and aircraft, is expanding. As a molding method for such fiber-reinforced resin composites, for example, the following method is used: an intermediate material called a prepreg in which a thermosetting resin is impregnated in reinforcing fibers is used, and curing and molding are performed by autoclave molding or compression molding.

[0003] In view of the above characteristics, in recent years, studies have been made on using the aforementioned prepreg to manufacture the shells of portable terminals such as smartphones, tablet computers (hereinafter referred to as "PCs"), and notebook PCs. In order to ensure the freedom of coloring in the shell, the prepreg used in the shell of the aforementioned portable terminal preferably uses glass fibers instead of black carbon fibers.

[0004] The aforementioned portable terminal usually includes a lithium-ion secondary battery. Since the aforementioned lithium-ion secondary battery contains an organic solvent, there is a risk of fire. Therefore, in order to ensure safety in use, it is desirable that the prepreg used for molding the shell of the aforementioned portable terminal meets the flame retardancy standards specified by Underwriters Laboratories, Inc. (UL).

[0005] Conventionally, as a prepreg having flame retardancy, a prepreg containing a halogen-containing compound such as brominated phenol as a flame retardant is known (for example, see Patent Document 1). However, the aforementioned halogen-containing compound has a problem that it may have an impact on the environment.

[0006] As a resin composition containing a halogen-free flame retardant, Patent Document 2 proposes a resin composition containing polyphenylene ether, a styrene-based resin, a flame retardant, and glass fibers. As the aforementioned flame retardant, a flame retardant which is bisphenol A bis(diphenyl phosphate) and a condensed phosphate-based flame retardant are contained. According to Patent Document 2, regarding a molded article containing the aforementioned resin composition, when a vertical flame retardancy test is performed on a test piece having a thickness of 0.5 to 2.0 mm in accordance with UL94, the flame retardancy grade is V-0, and it is suitable as a cooling fan for electrical / electronic equipment.

[0007] However, as a prepreg used in the shell of the aforementioned portable terminal, in view of the requirements for lightweight and thin-walled, a more excellent flame retardancy grade is desired.

[0008] Prior Art Documents

[0009] Patent Documents

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 2009-521666

[0011] Patent Document 2: Japanese Patent Application Laid-Open No. 2020-015788 Summary of the Invention

[0012] Problems to be Solved by the Invention

[0013] The problem to be solved by the present invention is to provide a prepreg and a molded article thereof that can achieve excellent flame retardancy even without containing a halogen-containing compound.

[0014] Means for Solving the Problems

[0015] The present inventors have found that a prepreg containing a specific urethane (meth) acrylate, a specific ethylenically unsaturated monomer, a polymerization initiator, glass fiber, and a specific flame retardant can solve the above problems, and thus completed the present invention.

[0016] That is, the prepreg of the present invention is characterized by containing a urethane (meth) acrylate (A), an ethylenically unsaturated monomer (B) other than the urethane (meth) acrylate (A), a polymerization initiator (C), glass fiber (D), a first flame retardant (E) that does not contain halogen and contains phosphorus, and a second flame retardant (F) that does not contain halogen and does not contain phosphorus. The urethane (meth) acrylate (A) is a reaction product of a polyisocyanate (a1) and a polyol (a2) having an ethylenically unsaturated group and an aromatic skeleton, and / or a reaction product of a polyisocyanate (a1), a polyol (a3) that does not have an ethylenically unsaturated group and has an aromatic skeleton, and a (meth) acrylic hydroxyalkyl ester (a4). The first flame retardant (E) is one or more salts selected from the group consisting of metal hypophosphite salts and ammonium polyphosphate salts containing active hydrogen. The second flame retardant (F) is one or more compounds selected from the group consisting of melamine cyanurate and metal hydroxides.

[0017] The molded article of the present invention is characterized by comprising a cured product of the above prepreg.

[0018] Advantages of the Invention

[0019] The prepreg of the present invention can achieve excellent flame retardancy in a molded article obtained from the prepreg even without containing a halogen-containing compound. Detailed Description of the Invention

[0020] Hereinafter, embodiments of the present invention will be described. The prepreg of this embodiment is characterized by containing a urethane (meth)acrylate (A), an ethylenically unsaturated monomer (B) other than the urethane (meth)acrylate (A), a polymerization initiator (C), glass fiber (D), a first flame retardant (E) that does not contain halogen and contains phosphorus, and a second flame retardant (F) that does not contain halogen and does not contain phosphorus. The urethane (meth)acrylate (A) is a reaction product of a polyisocyanate (a1) and a polyol (a2) having an ethylenically unsaturated group and an aromatic skeleton, and / or a reaction product of a polyisocyanate (a1), a polyol (a3) that does not have an ethylenically unsaturated group and has an aromatic skeleton, and a (meth)acrylic hydroxyalkyl ester (a4). The first flame retardant (E) is one or more salts selected from the group consisting of metal salts of hypophosphorous acid and ammonium polyphosphate salts containing active hydrogen. The second flame retardant (F) is one or more compounds selected from the group consisting of melamine cyanurate and metal hydroxides. That is, the prepreg of this embodiment must contain both the first flame retardant (E) and the second flame retardant (F) as flame retardants.

[0021] From the aspect of further improving the heat resistance of the molded product, the polyisocyanate (a1) preferably contains a polyisocyanate having a cyclic skeleton. These polyisocyanates (a1) can be used alone or in combination of two or more.

[0022] Examples of the polyisocyanate (a1) include: 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, a carbodiimide-modified product of 4,4'-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, a nurate-modified product of diphenylmethane diisocyanate, a biuret-modified product, a urethane imine-modified product, a polyol-modified product modified with a polyol having a number average molecular weight of 1,000 or less such as diethylene glycol or dipropylene glycol, toluene diisocyanate (TDI), tolidine diisocyanate, 1,3-benzenedimethyl diisocyanate (XDI), 1,5-naphthalene diisocyanate, tetramethylxylene diisocyanate and other aromatic polyisocyanates; isophorone diisocyanate (IPDI), hydrogenated diphenylmethane diisocyanate, hydrogenated benzenedimethyl diisocyanate, norbornene diisocyanate and other alicyclic polyisocyanates; hexamethylene diisocyanate, a nurate-modified product of hexamethylene diisocyanate, a biuret-modified product, an adduct, dimer acid diisocyanate and other aliphatic polyisocyanates, etc.

[0023] Among them, from the aspect of further improving the heat resistance and the freedom of coloring of the molded product, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, XDI, and IPDI are preferred. In addition, these polyisocyanates (a1) can be used alone or in combination of two or more.

[0024] The aforementioned polyol (a2) has an ethylenically unsaturated group and an aromatic skeleton. From the aspect of further improving the heat resistance, polyfunctional epoxy (meth)acrylate is preferred. For example, the reaction product of bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol fluorene type epoxy resin, bisphenol type epoxy resins such as bis-cresol fluorene type, phenol novolac type epoxy resin, cresol novolac type epoxy resin and other novolac type epoxy resins with (meth)acrylic acid. It is preferably obtained by the reaction of an epoxy resin having an epoxy equivalent in the range of 180 to 500 with (meth)acrylic acid. From the balance of heat resistance and strength physical properties, the number of functional groups is preferably 1.5 to 3.0.

[0025] The aforementioned polyol (a3) has an aromatic skeleton and does not have an ethylenically unsaturated group. 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)bis(oxy)]bisethanol; alkylene oxide adducts of dihydroxynaphthalene compounds, 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene, etc. Among them, from the viewpoint of the balance of compatibility, heat resistance, water resistance, and strength physical properties, alkylene oxide adducts of bisphenol compounds are preferred. More preferably, it is an ethylene oxide adduct of a bisphenol compound with an average addition mole number of 2 to 10 moles.

[0026] As the aforementioned hydroxyalkyl (meth)acrylate (a4), for example, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxy-n-butyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-n-butyl (meth)acrylate, 3-hydroxy-n-butyl (meth)acrylate, etc. are cited. Among them, from the balance of strength physical properties, 2-hydroxyethyl (meth)acrylate is preferred. In addition, these hydroxyalkyl (meth)acrylates (a4) can be used alone or in combination of two or more.

[0027] In addition, if necessary, as a raw material for the aforementioned urethane (meth)acrylate (A), other polyols other than the aforementioned polyols (a2) to (a4) can be used in combination. As other polyols, polyester polyol, acrylic polyol, polyether polyol, polycarbonate polyol, polyalkylene polyol, etc. can be used.

[0028] From the aspect of further improving heat resistance and curability, the molar ratio (a3 / a4) of the aforementioned polyol (a3) to the aforementioned hydroxyalkyl (meth)acrylate (a4) is preferably 60 / 40 to 10 / 90, more preferably 50 / 50 to 20 / 80.

[0029] From the balance of heat resistance and strength physical properties, the molar ratio (NCO / OH) of the isocyanate group (NCO) of the isocyanate compound, which is a raw material of the aforementioned urethane (meth)acrylate (A), to the hydroxyl group (OH) of the compound having a hydroxyl group is preferably 0.7 to 1.3, more preferably 0.8 to 1.1, and further preferably 0.8 to 1.0.

[0030] Examples of the aforementioned ethylenically unsaturated monomer (B) include dimethacrylates of ethylene oxide adducts of bisphenol A, tricyclodecane dimethanol dimethacrylate, 1,12-dodecanediol dimethacrylate, hydrogenated bisphenol A dimethacrylate, polytetramethylene glycol dimethacrylate, 9,9-bis[4-(2-methacryloyloxyethoxy)phenyl]fluorene, dimethacrylates of ethylene oxide adducts of isosorbide, dimethacrylates of ethylene oxide adducts of hydrogenated bisphenol A, trimethacrylates of ethylene oxide adducts of trimethylolpropane, tetramethacrylates of ethylene oxide adducts of pentaerythritol, and hexamethacrylates of ethylene oxide adducts of dipentaerythritol. From the balance of curability, heat resistance, and strength physical properties, the molecular weight is preferably 320 to 2,000, and the (meth)acryloyl equivalent is preferably 150 to 1,000, more preferably 150 to 500. Similarly, from the balance of curability, heat resistance, and strength physical properties, the number of functional groups is preferably 2 to 4, more preferably 2.

[0031] From the aspect of further improving the balance of preventing pollution of the working environment, prepreg workability, molded product quality, and productivity, the content of the aforementioned ethylenically unsaturated monomer (B) in the total of the aforementioned urethane (meth)acrylate (A) and the aforementioned ethylenically unsaturated monomer (B) (hereinafter, simply referred to as "content (B)") is preferably 5 to 50% by mass, more preferably 10 to 40% by mass.

[0032] The aforementioned polymerization initiator (C) is not particularly limited, and an organic peroxide is preferred. Examples include diacyl peroxide compounds, perester compounds, hydroperoxide compounds, ketone peroxide compounds, alkyl peracid ester compounds, percarbonate compounds, and peroxide ketals, which can be appropriately selected according to the molding conditions. In addition, these polymerization initiators (C) can be used alone or in combination of two or more.

[0033] In addition, in order to shorten the molding time, it is preferable to use a polymerization initiator having a temperature for obtaining a 10-hour half-life of 60°C or higher and 110°C or lower. If it is 70°C or higher and 105°C or lower, the prepreg has a long life at room temperature and can be cured in a short time (within 5 minutes) by heating. Therefore, it is preferable. Through the prepreg used in this embodiment, the curability and moldability are more excellent. Examples of such a polymerization initiator include 1,6-bis(tert-butylperoxycarbonyloxy)hexane, 1,1-bis(tert-butylperoxy)cyclohexane, 1,1-bis(tert-amylperoxy)cyclohexane, 1,1-bis(tert-hexylperoxy)cyclohexane, tert-butylperoxydiethylacetate, tert-butylperoxyisopropylcarbonate, tert-butylperoxy-2-ethylhexylcarbonate, tert-amylperoxyisopropylcarbonate, tert-amylperoxy-2-ethylhexylcarbonate, tert-hexylperoxyisopropylcarbonate, di-tert-butylperoxyhexahydroterephthalate, tert-amylperoxytri-methylhexanoate, tert-amylperoxynonanoate, tert-hexylperoxy-2-ethylhexanoate, n-butyl 4,4-bis(tert-butylperoxy)valerate, etc. According to the molding conditions, the most suitable organic peroxide is selected and used.

[0034] From the aspect that both the curing characteristics and storage stability are excellent, as the addition amount of the aforementioned polymerization initiator (C), relative to 100 parts by mass in total of the aforementioned urethane (meth)acrylate (A) and the aforementioned ethylenically unsaturated monomer (B), it is preferably in the range of 0.5 to 3 parts by mass.

[0035] The shape of the aforementioned glass fiber (D) is not particularly limited, and examples include a reinforcing fiber bundle formed by bundling reinforcing fiber filaments, a unidirectional material formed by aligning the reinforcing fiber bundle in one direction, a woven fabric, or a reinforcing fiber cut short, or a non-woven fabric, paper, etc. composed of a reinforcing fiber cut short. By using a unidirectional material as the reinforcing fiber and laminating and molding it, high mechanical properties can be obtained, so it is preferable.

[0036] In the case of using a glass fiber (D) cut short, from the aspect of further improving the fluidity in the mold during molding and the appearance of the molded product, it is preferable to use carbon fiber cut into 2.5 to 50 mm.

[0037] In the case of a fabric, examples include a stitched sheet obtained by stitching, in a non-scattering manner, a sheet formed by aligning fiber bundles in one direction or a sheet formed by laminating at different angles, represented by plain weave, twill weave, satin weave, or non-crimp fabric.

[0038] As the unit area weight (weight per 1 m 2 of fiber) of the glass fiber (D), there is no particular limitation, and it is preferably 10 g / m2 ~650 g / m 2 。When the basis weight is 10 g / m 2 or more, the non-uniformity of the fiber width is small and the mechanical properties become good, so it is preferred. When the basis weight is 650 g / m 2 or less, the impregnation of the resin becomes good, so it is preferred. The basis weight is more preferably 50 to 500 g / m 2 , and particularly preferably 50 to 300 g / m 2 .

[0039] From the aspect of further improving the mechanical strength of the obtained molded product, the content rate of the aforementioned glass fiber (D) in the prepreg of the present embodiment is preferably in the range of 20 to 85% by mass, and more preferably in the range of 40 to 80% by mass.

[0040] The prepreg of the present embodiment can contain other reinforcing fibers in addition to the aforementioned glass fiber (D) within the range that does not impair the coloring freedom of the molded product. Examples of other reinforcing fibers include silicon carbide fiber, alumina fiber, boron fiber, metal fiber, aromatic polyamide fiber, vinylon fiber, Tetoron fiber, basalt fiber, ceramic fiber, etc.

[0041] The prepreg of the present embodiment is characterized in that, as a flame retardant, it must contain both a first flame retardant (E) that does not contain halogen and contains phosphorus and a second flame retardant (F) that does not contain halogen and does not contain phosphorus. The first flame retardant (E) is one or more salts selected from the group consisting of metal hypophosphite salts and ammonium polyphosphate salts containing active hydrogen.

[0042] The first flame retardant (E) forms a protective layer called char during combustion, and this protective layer blocks oxygen, thereby contributing to flame retardancy. On the other hand, the second flame retardant (F) contributes to flame retardancy by generating water during combustion to take away the combustion heat, or by generating non-active gases to reduce the oxygen concentration, etc. The mechanism of contributing to flame retardancy is different from that of the first flame retardant (E). By making the prepreg of the present embodiment contain these two flame retardants (E) and (F), the molded product obtained from this prepreg can obtain excellent flame retardancy. In addition, since both of these two flame retardants (E) and (F) do not contain halogen (halogen-free), it is possible to prevent the impact of halogen release on the environment during the manufacturing process of the prepreg and the molded product.

[0043] In contrast, in the case where the prepreg contains the aforementioned first flame retardant (E) but does not contain the aforementioned second flame retardant (F), and in the case where the prepreg contains the aforementioned second flame retardant (F) but does not contain the aforementioned first flame retardant (E), the molded product obtained from this prepreg cannot obtain excellent flame retardancy.

[0044] The first flame retardant (E) is one or more salts selected from the group consisting of metal hypophosphites and ammonium polyphosphates containing active hydrogen. They are halogen-free and phosphorus-containing compounds. As the first flame retardant (E), one or more salts can be used, or two or more salts can be used.

[0045] Examples of the metal hypophosphite include aluminum hypophosphites such as aluminum dimethylphosphinate, aluminum ethylmethylphosphinate, aluminum diethylphosphinate, aluminum methyl-n-propylphosphinate, aluminum methylphenylphosphinate, and aluminum diphenylphosphinate; calcium hypophosphites such as calcium dimethylphosphinate, calcium ethylmethylphosphinate, calcium diethylphosphinate, calcium methyl-n-propylphosphinate, calcium methylphenylphosphinate, and calcium diphenylphosphinate; magnesium hypophosphites such as magnesium dimethylphosphinate, magnesium ethylmethylphosphinate, magnesium diethylphosphinate, magnesium methyl-n-propylphosphinate, magnesium methylphenylphosphinate, and magnesium diphenylphosphinate; zinc hypophosphites such as zinc dimethylphosphinate, zinc ethylmethylphosphinate, zinc diethylphosphinate, zinc methyl-n-propylphosphinate, zinc methylphenylphosphinate, and zinc diphenylphosphinate, etc. Examples of commercially available products include EXOLIT OP1230, OP1240, OP1312, OP1400, OP930, OP935, OP945 TP (manufactured by Clariant Plastics & Coatings).

[0046] Examples of commercially available ammonium polyphosphates containing active hydrogen include FCP-770, FCP-790 (manufactured by Suzuhiro Chemical Co., Ltd.).

[0047] As the second flame retardant (F), it is preferable to use one or more compounds selected from the group consisting of melamine cyanurate and metal hydroxides. Examples of the aforementioned metal hydroxides include aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, etc. As the second flame retardant (F), one or more compounds can be used, or two or more compounds can be used.

[0048] In addition to the first flame retardant (E) and the second flame retardant (F), the prepreg of the present embodiment may further contain a halogen-free third flame retardant (G). Examples of the aforementioned third flame retardant (G) include red phosphorus, phosphonates, phosphates, aromatic phosphates, aromatic condensed phosphates, phosphonitriles, etc. Examples of commercially available products include Novaexcel 140, Nonnen73, DAIGUARD-880, TPP, TCP, CDP, PX-110, CR-733S, CR-741, PX-200, DAIGUARD-580, DAIGUARD-850, Rabitle FP-110, Rabitle FP-100, etc.

[0049] As components of the prepreg of the present embodiment, components other than those described above may also be used. For example, it may contain thermosetting resins, thermoplastic resins, polymerization inhibitors, curing accelerators, fillers, low shrinkage agents, mold release agents, thickeners, viscosity reducers, pigments, antioxidants, plasticizers, antibacterial agents, ultraviolet stabilizers, reinforcing materials, photocuring agents, etc.

[0050] As the aforementioned thermosetting resins, for example, vinyl ester resins, unsaturated polyester resins, phenolic resins, melamine resins, furan resins, bismaleimide resins, etc. can be cited. In addition, these thermosetting resins can be used alone or in combination of two or more.

[0051] As the aforementioned thermoplastic resins, for example, polyamide resins, polyethylene terephthalate resins, polybutylene terephthalate resins, polycarbonate resins, polyurethane resins, polypropylene resins, polyethylene resins, polystyrene resins, acrylic resins, polybutadiene resins, polyisoprene resins, and resins obtained by modifying them through copolymerization, etc. can be cited. Among them, from the aspect of high improvement effect on brittleness, polyamide resins and polyurethane resins are preferred. In addition, these thermoplastic resins can be used alone or in combination of two or more. In addition, the thermoplastic resin can be added and used in particle form or melt-mixed. In the case of using the thermoplastic resin in particle form, from the viewpoint of dispersibility in the fiber, the particle size is preferably 30 μm or less, more preferably 5 - 20 μm.

[0052] As the aforementioned polymerization inhibitors, for example, hydroquinone, trimethylhydroquinone, p-tert-butylcatechol, tert-butylhydroquinone, methylhydroquinone, p-benzoquinone, naphthoquinone, monomethyl ether of hydroquinone, phenothiazine, copper naphthenate, copper chloride, etc. can be cited. These polymerization inhibitors can be used alone or in combination of two or more.

[0053] As the aforementioned curing accelerators, for example, metal soaps such as cobalt naphthenate, cobalt octenoate, vanadium octenoate, copper naphthenate, barium naphthenate, etc., and metal chelate compounds such as vanadyl acetylacetonate, cobalt acetylacetonate, iron acetylacetonate, etc. can be cited. In addition, as amines, 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, diethanol aniline, etc. can be cited. These curing accelerators can be used alone or in combination of two or more.

[0054] As the aforementioned fillers, there are inorganic compounds and organic compounds, which can be used to adjust physical properties such as the strength, elastic modulus, impact strength, fatigue durability, etc. of the molded product.

[0055] Examples of the inorganic compound include calcium carbonate, magnesium carbonate, barium sulfate, mica, talc, kaolin, clay, diatomaceous earth, asbestos, vermiculite, barite, silica, silica sand, dolomite limestone, gypsum, aluminum micropowder, hollow spheres, alumina, glass powder, aluminum hydroxide, gypsum spar, zirconia, antimony trioxide, titanium oxide, molybdenum dioxide, iron powder, etc.

[0056] Examples of the organic compound include natural polysaccharide powders such as cellulose and chitin, synthetic resin powders, etc. As the synthetic resin powder, powders of organic substances composed of hard resins, soft rubbers, elastomers or polymers (copolymers), etc., and particles having a multilayer structure such as a core-shell type can be used. Specifically, acrylic particles, polyamide particles, particles composed of butadiene rubber and / or acrylic rubber, polyurethane rubber, silicone rubber, etc., polyimide resin powder, fluororesin powder, phenolic resin powder, etc. can be cited. These fillers can be used alone or in combination of two or more.

[0057] Examples of the mold 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 mold release agents can be used alone or in combination of two or more.

[0058] Examples of the thickener include metal oxides and metal hydroxides such as magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, etc., acrylic resin-based fine particles, etc., and can be appropriately selected according to the workability of the prepreg of the present embodiment. These thickeners can be used alone or in combination of two or more.

[0059] The prepreg of the present embodiment can be obtained, for example, through the following steps: Step 1, first, using a known mixer such as a planetary mixer or a kneader, mix the resin components such as the polyisocyanate (a1), the polyol (a2) and / or (a3), the (meth)acrylic hydroxyalkyl ester (a4) and the ethylenically unsaturated monomer (B) with the polymerization initiator (C), the first flame retardant (E) and the second flame retardant (F) to prepare a resin solution, impregnate the obtained resin solution into the glass fiber (D), and then sandwich it from the upper surface with a release PET film and roll it using a rolling mill to obtain a sheet; Step 2, let it stand at room temperature to 50 °C to allow the isocyanate group of the polyisocyanate (a1) to react with the hydroxyl groups of the polyol (a2) and / or (a3) and (a4). In addition, in Step 1, within the range that does not impair the impregnation property in the fiber, a resin solution obtained by partially reacting the polyisocyanate (a1), the polyol (a2) and / or (a3), and (a4) in advance can also be used.

[0060] In order to ensure sufficient flame retardancy in the molded article, with respect to a total of 100 parts by mass of the aforementioned resin components, the lower limit of the total content of the first flame retardant (E) and the second flame retardant (F) is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, and still more preferably 60 parts by mass or more. On the other hand, in order to suppress the increase in the viscosity of the resin composition and ensure sufficient moldability, the upper limit of the aforementioned total content is preferably 140 parts by mass or less, more preferably 130 parts by mass or less, and still more preferably 110 parts by mass or less.

[0061] In order to ensure the effects brought about by adding the second flame retardant (F), the lower limit of the mass ratio of the second flame retardant (F) to the first flame retardant (E) is preferably 0.5 or more, more preferably 0.8 or more, and still more preferably 1.0 or more. On the other hand, in order to ensure the effects brought about by adding the first flame retardant (E), the upper limit of the aforementioned mass ratio is preferably 5 or less, more preferably 3 or less, and still more preferably 2 or less.

[0062] In order to ensure ease of operation during lamination, the lower limit of the thickness of the prepreg of the present embodiment is preferably 0.02 mm or more, more preferably 0.05 mm or more. On the other hand, in order to make the thickness of the molded article thinner and ensure resin impregnation, the upper limit of the aforementioned thickness is preferably 1.0 mm or less, more preferably 0.6 mm or less.

[0063] As a method for obtaining a molded article from the prepreg obtained above, for example, the following method can be used: Peel off the aforementioned release PET film from the prepreg, laminate 1 to 10 sheets of prepreg, then put them into a mold preheated to 90°C to 160°C, close the mold with a compression molding machine to shape the prepreg, maintain a molding pressure of 0.1 to 10 MPa, thereby curing the prepreg, and then take out the molded article to obtain the molded article.

[0064] Examples of the molded article obtained from the prepreg of the present embodiment include the housings of portable terminals such as smartphones, tablet PCs, and notebook PCs, hinge parts, and the bezels of smart watches. When the thickness of the molded article obtained from the prepreg of the present embodiment is 0.1 mm or more and 0.4 mm or less, the flame retardancy grade can achieve V-0 when performing a vertical burning test according to UL94, so it is particularly suitable for the housings of the aforementioned portable terminals.

[0065] [Examples]

[0066] Specific examples are given below to illustrate the present invention in more detail.

[0067] [Example 1]

[0068] (1) Preparation of prepreg resin composition

[0069] The resin component X is mixed with 1.6 parts by mass of a polymerization initiator (“Trigonox 421-70” manufactured by Chemische Fabrik Lamberti GmbH, an organic peroxide), 30.0 parts by mass of Fire Cut P-770 (manufactured by Suzuka Chemical Co., Ltd.: ammonium polyphosphate-based) as the first flame retardant (E), and 30.0 parts by mass of MC-6000 (manufactured by Nissan Chemical Industries, Ltd.: melamine cyanurate-based) as the second flame retardant (F) to obtain a resin composition for prepreg. The aforementioned resin component X includes: 23.9 parts by mass of 1,3-phenylenedimethylene diisocyanate (hereinafter simply referred to as “XDI”), 6.5 parts by mass of 4,4'-diphenylmethane diisocyanate (hereinafter simply referred to as “MDI”), 31.7 parts by mass of 2-hydroxyethyl methacrylate (hereinafter simply referred to as “HEMA”), 4.3 parts by mass of NEWPOL BPE-20 (manufactured by Sanyo Chemical Industries, Ltd.: EO adduct of bisphenol A, hydroxyl equivalent: 164 g / eq), 6.2 parts by mass of NEWPOL BPE-40 (manufactured by Sanyo Chemical Industries, Ltd.: EO adduct of bisphenol A, hydroxyl equivalent: 204 g / eq), 0.5 parts by mass of PEG-300 (manufactured by Sanyo Chemical Industries, Ltd.: polyethylene glycol, hydroxyl equivalent: 150 g / eq), 2.4 parts by mass of POLYLITE FPS-200 (manufactured by DIC Corporation: bifunctional polyol, hydroxyl equivalent: 4500 g / eq), 0.6 parts by mass of PTMG1000 (manufactured by Mitsubishi Chemical Corporation: polytetramethylene glycol, hydroxyl equivalent: 500 g / eq), 4.4 parts by mass of a thermoplastic resin described later, and 19.5 parts by mass of MIRAMER M-245 (manufactured by Miwon Specialty Chemical Co., Ltd.: bifunctional methacrylate monomer) as a polymerizable monomer. In addition, the total of the aforementioned resin component X is 100 parts by mass.

[0070] The aforementioned thermoplastic resin is synthesized by mixing 71 parts by mass of PTMG1000 (manufactured by Mitsubishi Chemical Corporation: polytetramethylene ether glycol), 3 parts by mass of 1,4-butanediol (hereinafter simply referred to as “1,4-BG”), and 26 parts by mass of MDI, casting it in a tank, and reacting it under the conditions of 90 °C for 24 hours. The weight-average molecular weight of the obtained thermoplastic resin is 50,000.

[0071] (2) Production of prepreg

[0072] After the obtained resin composition for prepreg is coated on one side of a release PET film, it is impregnated into 150.0 parts by mass of glass fiber (“H105” manufactured by Unitika Ltd.) by the hand lay-up method, covered with the same release PET film, and aged under the conditions of 45 °C for 24 hours to produce prepreg (1). The thickness of the prepreg is 0.15 mm.

[0073] (3) Evaluation of the molded product

[0074] The obtained prepreg was laminated so that the overall thickness was 0.3 mm and 0.4 mm. The obtained laminate was filled into the center of a flat plate mold coated with a mold release agent, and compression molding was carried out using a compression molding machine under the conditions of a pressure of 4 MPa, an upper mold temperature of 110 °C, a lower mold temperature of 110 °C, and a molding time of 10 minutes. Then, it was cut into strips with a length of 125 mm and a width of 13 mm, and thus 5 test pieces each as molded products were produced.

[0075] For the obtained test pieces, a vertical burning test was carried out in accordance with UL94V. The upper end of the test piece was vertically installed on a jig, and cotton was set 300 mm below the test piece. An operation was carried out using a gas burner to bring the blue flame of methane gas (height 20 mm) into contact with the lower end of the test piece for 10 seconds, and the burning time was measured. When the burning was within 30 seconds, it was further brought into contact with the flame for 10 seconds, and the burning time was measured. The ignition of the cotton caused by the dropping of drips and the burning at the jig installation position were observed. These operations were carried out on 5 test pieces. The judgment criteria are shown in Table 1. The results of the vertical burning test are shown in Table 2.

[0076] [Table 1]

[0077]

[0078] [Example 2]

[0079] In this example, as the second flame retardant (F), in addition to using 30.0 parts by mass of MC-6000, 50.0 parts by mass of BX053Y (manufactured by Nippon Light Metal Co., Ltd.: aluminum hydroxide) was also used. Except for this, a prepreg resin composition was prepared in the same manner as in Example 1. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0080] [Example 3]

[0081] In this example, a third flame retardant (G) was further added. Except for this, a prepreg resin composition was prepared in the same manner as in Example 2. As the third flame retardant (G), 25.0 parts by mass of CR-733S (manufactured by Daihachi Chemical Industry Co., Ltd.: aromatic condensed phosphate) was used. Using the obtained prepreg resin composition, a prepreg was produced in the same manner as in Example 1. The obtained prepreg was laminated so that the overall thickness was 0.1 mm, 0.2 mm, 0.3 mm, and 0.4 mm, and except for this, test pieces were produced in the same manner as in Example 1.

[0082] [Example 4]

[0083] In this example, as the first flame retardant (E), 30.0 parts by mass of EXOLIT OP1230 (manufactured by Clariant Plastics & Coatings Ltd.: metal hypophosphite) was used instead of Fire Cut P-770. As the second flame retardant (F), 50 parts by mass of BX053Y was used instead of MC-6000. Except for this, a prepreg resin composition was prepared in the same manner as in Example 1. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0084] [Example 5]

[0085] In this example, as the first flame retardant (E), 30.0 parts by mass of EXOLIT OP1312 (manufactured by Clariant Plastics & Coatings Ltd.: metal hypophosphite) was used instead of EXOLIT OP1230. Except for this, a prepreg resin composition was prepared in the same manner as in Example 4. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0086] [Example 6]

[0087] In this example, as the polymerization initiator, 0.8 parts by mass of Trigonox122-C80 (manufactured by Chemische Fabrik Stockhausen GmbH, organic peroxide) was used instead of Trigonox421-70. Except for this, a prepreg resin composition was prepared in the same manner as in Example 1. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0088] [Example 7]

[0089] In this example, as the polymerization initiator, 0.8 parts by mass of Trigonox122-C80 was used instead of Trigonox421-70. Except for this, a prepreg resin composition was prepared in the same manner as in Example 4. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0090] [Example 8]

[0091] In this example, as the polymerization initiator, 0.8 parts by mass of Trigonox122-C80 was used instead of Trigonox421-70. Except for this, a prepreg resin composition was prepared in the same manner as in Example 5. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0092] [Comparative Example 1]

[0093] In this comparative example, the first flame retardant (E) was not added at all. As the second flame retardant (F), 50.0 parts by mass of BX053Y was added instead of MC-6000, and as the third flame retardant (G), 30.0 parts by mass of CR-733S was added. Other than this, a prepreg resin composition was prepared in the same manner as in Example 1. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0094] [Comparative Example 2]

[0095] In this comparative example, the addition amount of BX053Y as the second flame retardant (F) was changed to 100.0 parts by mass. Other than this, a prepreg resin composition was prepared in the same manner as in Comparative Example 1. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0096] [Comparative Example 3]

[0097] In this comparative example, as the third flame retardant (G), 30.0 parts by mass of ADK STAB FP-900L (manufactured by ADEKA CORPORATION: aromatic condensed phosphate ester) was added instead of CR-733S. Other than this, a prepreg resin composition was prepared in the same manner as in Comparative Example 1. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0098] [Comparative Example 4]

[0099] In this comparative example, the addition amount of BX053Y as the second flame retardant (F) was changed to 100.0 parts by mass. Other than this, a prepreg resin composition was prepared in the same manner as in Comparative Example 3. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0100] [Comparative Example 5]

[0101] In this comparative example, as the third flame retardant (G), 30.0 parts by mass of ADK STAB FP-600 (manufactured by ADEKA CORPORATION: aromatic condensed phosphate ester) was added instead of CR-733S. Other than this, a prepreg resin composition was prepared in the same manner as in Comparative Example 1. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0102] [Comparative Example 6]

[0103] In this comparative example, the addition amount of BX053Y as the second flame retardant (F) was changed to 100.0 parts by mass, and except for this, a prepreg resin composition was prepared in the same manner as in Comparative Example 5. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0104] [Comparative Example 7]

[0105] In this comparative example, as the third flame retardant (G), 15.0 parts by mass of CR-733S and 15.0 parts by mass of FP-900L were added, and except for this, a prepreg resin composition was prepared in the same manner as in Comparative Example 2. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0106] [Comparative Example 8]

[0107] In this comparative example, as the third flame retardant (G), 15.0 parts by mass of FP-900L and 15.0 parts by mass of FP-600 were added, and except for this, a prepreg resin composition was prepared in the same manner as in Comparative Example 7. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0108] [Comparative Example 9]

[0109] In this comparative example, as the third flame retardant (G), 15.0 parts by mass of CR-733S and 15.0 parts by mass of FP-600 were added, and except for this, a prepreg resin composition was prepared in the same manner as in Comparative Example 7. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0110] The results of the vertical burning tests of the test pieces of Examples 1 to 8 and Comparative Examples 1 to 9 are shown in Tables 2 and 3.

[0111] [Table 2]

[0112]

[0113] [Table 3]

[0114]

[0115] The prepregs of Examples 1 to 8 contain at least both a first flame retardant (E) and a second flame retardant (F) as flame retardants. As shown in Table 2, the flame retardancy evaluations of test pieces with a thickness of 0.3 to 0.4 mm obtained from the prepregs of Examples 1 to 8 were all V-0. From this, it can be understood that the prepregs of Examples 1 to 8 can achieve excellent flame retardancy when manufacturing molded articles with a thickness of 0.3 to 0.4 mm. Furthermore, it can be understood that the prepreg of Example 3 can also achieve excellent flame retardancy even in thin-walled molded articles with a thickness of 0.1 to 0.2 mm. Moreover, it is speculated that in the prepregs of Examples 1, 2, and 4 to 8, excellent flame retardancy can also be achieved in the same manner as in Example 3 when molding molded articles with a thickness of 0.1 to 0.2 mm.

[0116] In contrast, the prepregs of Comparative Examples 1 to 9 do not contain both the first flame retardant (E) and the second flame retardant (F) as flame retardants. As shown in Table 3, the flame retardancy evaluations of test pieces with a thickness of 0.3 to 0.4 mm obtained from the prepregs of Comparative Examples 1 to 9 were all V-1 or V non-compliant. From this, it can be understood that the prepregs of Comparative Examples 1 to 9 cannot achieve excellent flame retardancy when manufacturing molded articles with a thickness of 0.3 to 0.4 mm.

[0117] In addition, the prepregs of Comparative Examples 7 and 9 contain a flame retardant (CR-733S) as bisphenol A bis(diphenyl phosphate) and a condensed phosphate-based flame retardant (FP-900L or FP-600) in the same manner as the resin composition disclosed in Patent Document 2, and further contain a second flame retardant (F), but the flame retardancy evaluation of the test piece with a thickness of 0.3 to 0.4 mm was V non-compliant. From this, it can be understood that the combination of the flame retardant as bisphenol A bis(diphenyl phosphate) and the condensed phosphate-based flame retardant (FP-900L or FP-600) is insufficient for ensuring the flame retardancy of molded articles with a thickness of 0.3 to 0.4 mm as the flame retardants added to the prepregs.

Claims

1. A prepreg, characterized in that, Comprising a urethane (meth)acrylate (A), an ethylenically unsaturated monomer (B) other than the urethane (meth)acrylate (A), a polymerization initiator (C), glass fiber (D), a first flame retardant (E) that does not contain halogen and contains phosphorus, and a second flame retardant (F) that does not contain halogen and does not contain phosphorus, The urethane (meth)acrylate (A) is a reaction product of a polyisocyanate (a1) and a polyol (a2) having an ethylenically unsaturated group and an aromatic skeleton, and / or a reaction product of a polyisocyanate (a1), a polyol (a3) that does not have an ethylenically unsaturated group and has an aromatic skeleton, and a hydroxyalkyl (meth)acrylate (a4), The first flame retardant (E) is one or more salts selected from the group consisting of metal hypophosphite salts and ammonium polyphosphate salts containing active hydrogen, The second flame retardant (F) is one or more compounds selected from the group consisting of melamine cyanurate and metal hydroxides.

2. A molded article, characterized in that, It is a cured product of the prepreg according to claim 1.

3. The molded article according to claim 2, having a thickness of 0.1 mm or more and 0.4 mm or less, and having a flame retardancy rating of V-0 when a vertical burning test is carried out in accordance with UL94.

4. The molded article according to claim 3, which is a housing of a portable terminal.

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