Prepreg and molded article

Abstract

To provide a prepreg and a molded article thereof that achieve superior flame retardancy even without inclusion of a halogen-containing compound.SOLUTION: A prepreg according to the present invention comprises an urethane (meth)acrylate (A), an ethylenically unsaturated monomer (B) other than the urethane (meth)acrylate (A), a polymerization initiator (C), glass fibers (D), a first flame retardant (E) that is halogen-free and contains phosphorus, and a second flame retardant (F) that is halogen-free and phosphorus-free. The first flame retardant (E) is at least one salt selected from the group consisting of a metal salt of phosphinic acid and an ammonium salt of polyphosphoric acid containing active hydrogen. The second flame retardant (F) is at least one compound selected from the group consisting of melamine cyanurate and metal hydroxides.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Fiber-reinforced resin composite materials reinforced with reinforcing fibers such as carbon fibers and glass fibers have attracted attention for their characteristics of being lightweight while having excellent heat resistance and mechanical strength. Their use has been expanding in various structural applications, including the casings or various members of automobiles and aircraft. As a molding method for this fiber-reinforced resin composite material, for example, a method of curing and molding by autoclave molding or press molding using an intermediate material called a prepreg in which a thermosetting resin is impregnated into reinforcing fibers is used.

[0003] In view of the above characteristics, in recent years, it has been studied to manufacture the casings of portable terminals such as smartphones, tablet personal computers (hereinafter referred to as "PCs"), and notebook PCs using the prepreg. The prepreg used for the casing of the portable terminal is preferably made of glass fiber instead of black carbon fiber in order to ensure the degree of freedom in coloring of the casing.

[0004] The portable terminal usually includes a lithium-ion secondary battery. Since the lithium-ion secondary battery contains an organic solvent, there is a risk of ignition. Therefore, the prepreg for molding the casing of the portable terminal is desired to meet the UL (Underwriters Laboratories, Inc.)-specified flame retardancy standard in order to ensure safety in use.

[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 (see, for example, Patent Document 1). However, the halogen-containing compound has the disadvantage that there are concerns about its impact on the environment.

[0006] As a resin composition containing a halogen-free flame retardant, Patent Document 2 proposes a composition containing polyphenylene ether, a styrene-based resin, a flame retardant, and glass fiber, wherein the flame retardant contains a bisphenol A bis(diphenyl phosphate) flame retardant and a condensed phosphate ester-based flame retardant. According to Patent Document 2, 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 level of a molded article containing the resin composition is V-0, and it is considered suitable as a cooling fan for electric and electronic devices.

[0007] However, as a prepreg used for the housing of the mobile terminal, due to the requirements of weight reduction and thinning, it is desired that a more excellent flame retardancy level be further improved.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] 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 without containing a halogen-containing compound.

Means for Solving the Problems

[0010] The inventors of the present invention 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 solves the above problems, and thus completed the present invention.

[0011] That is, the prepreg according to the present invention contains 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 is halogen-free and phosphorus-containing, and a second flame retardant (F) that is halogen-free and phosphorus-free. 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) having no ethylenically unsaturated group but having an aromatic skeleton, and a hydroxyalkyl (meth) acrylate (a4). The first flame retardant (E) is at least one salt selected from the group consisting of metal phosphinate and ammonium polyphosphate containing active hydrogen. The second flame retardant (F) is at least one compound selected from the group consisting of melamine cyanurate and metal hydroxide, which is characterized in that.

[0012] The molded article according to the present invention is characterized by including a cured product of the prepreg described above.

Effects of the Invention

[0013] The prepreg of the present invention can achieve excellent flame retardancy in a molded article obtained from the prepreg without containing a halogen-containing compound.

Modes for Carrying Out the Invention

[0014] Embodiments of the present invention will be described below. The prepreg of the present embodiment contains 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 is halogen-free and phosphorus-containing, and a second flame retardant (F) that is halogen-free and phosphorus-free. 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) and a polyol (a3) having no ethylenically unsaturated group and an aromatic skeleton and a hydroxyalkyl (meth) acrylate (a4). The first flame retardant (E) is at least one salt selected from the group consisting of metal phosphinates and ammonium polyphosphates containing active hydrogen. The second flame retardant (F) is at least one compound selected from the group consisting of melamine cyanurate and metal hydroxides. That is, the prepreg of the present embodiment essentially contains both the first flame retardant (E) and the second flame retardant (F) as flame retardants.

[0015] Since the heat resistance of the molded product is further improved, 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.

[0016] The polyisocyanate (a1) is, for example, 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 burette-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, tolylene diisocyanate (TDI), tolidine diisocyanate, 1,3-xylylene diisocyanate (XDI), 1,5-naphthalene diisocyanate, tetramethylxylylene diisocyanate and other aromatic polyisocyanates; alicyclic polyisocyanates such as isophorone diisocyanate (IPDI), hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, norbornene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate, a nurate-modified product of hexamethylene diisocyanate, a burette-modified product, an adduct product, dimer acid diisocyanate, and the like. Among these, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, XDI, and IPDI are preferable because the heat resistance and the degree of freedom of coloring of the molded product are further improved. These polyisocyanates (a1) can be used alone or in combination of two or more.

[0017] The polyol (a2) has an ethylenically unsaturated group and an aromatic skeleton. From the viewpoint of further improving the heat resistance, polyfunctional epoxy (meth)acrylate is preferable. For example, the reaction of bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol fluorene type epoxy resin, biscresol fluorene type, novolak type epoxy resins such as phenol novolak type epoxy resin and cresol novolak type epoxy resin with (meth)acrylic acid It is a substance. Preferably, it is obtained from the reaction of an epoxy resin having an epoxy equivalent in the range of 180 to 500 and (meth)acrylic acid. As the number of functional groups, 1.5 to 3.0 is preferable from the balance of heat resistance and strength physical properties.

[0018] The polyol (a3) has no ethylenically unsaturated group and has an aromatic skeleton. For example, 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, 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene, etc. Among these, from the viewpoint of the balance of compatibility, heat resistance, water resistance, and strength physical properties, alkylene oxide adducts of bisphenol compounds are preferable. More preferably, it is an ethylene oxide adduct of a bisphenol compound, and the average number of added moles is 2 to 10 moles.

[0019] Examples of the hydroxyalkyl (meth)acrylate (a4) 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, 3-hydroxy-n-butyl (meth)acrylate, etc. Among these, 2-hydroxyethyl (meth)acrylate is preferable from the balance of strength physical properties. These hydroxyalkyl (meth)acrylates (a4) can be used alone or in combination of two or more.

[0020] Further, if necessary, other polyols other than the polyols (a2) to (a4) can be used in combination as raw materials for the urethane (meth) acrylate (A). Examples of other polyols that can be used include polyester polyols, acrylic polyols, polyether polyols, polycarbonate polyols, polyalkylene polyols, and the like.

[0021] The molar ratio (a3 / a4) of the polyol (a3) to the hydroxyalkyl (meth) acrylate (a4) is preferably 60 / 40 to 10 / 90, more preferably 50 / 50 to 20 / 80, because the heat resistance and curability are further improved.

[0022] 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 is a raw material for the urethane (meth) acrylate (A), is preferably 0.7 to 1.3, more preferably 0.8 to 1.1, and even more preferably 0.8 to 1.0, in view of the balance between heat resistance and strength physical properties.

[0023] Examples of the ethylenically unsaturated monomer (B) include dimethacrylates of ethylene oxide adducts of bisphenol A, dimethacrylates of tricyclodecane dimethanol, dimethacrylates of 1,12-dodecanediol, dimethacrylates of hydrogenated bisphenol A, dimethacrylates of polytetramethylene glycol, 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, hexamethacrylates of ethylene oxide adducts of dipentaerythritol, and the like. From the viewpoint of the balance of curability, heat resistance, and strength physical properties, the molecular weight is preferably 320 to 2,000, the (meth)acrylic group equivalent is preferably 150 to 1,000, and more preferably 150 to 500. Similarly, from the viewpoint of the balance of curability, heat resistance, and strength physical properties, the number of functional groups is preferably 2 to 4, and more preferably 2.

[0024] The content of the ethylenically unsaturated monomer (B) in the total of the urethane (meth)acrylate (A) and the ethylenically unsaturated monomer (B) (hereinafter abbreviated as "content (B)") is preferably 5 to 50% by mass, and more preferably 10 to 40% by mass, because the balance between the prevention of contamination of the working environment and the handling properties of the prepreg, the quality of the molded product, and productivity is further improved.

[0025] The polymerization initiator (C) is not particularly limited, but an organic peroxide is preferred. Examples thereof include diacyl peroxide compounds, peroxyester compounds, hydroperoxide compounds, ketone peroxide compounds, alkyl perester compounds, percarbonate compounds, peroxyketals, etc., and can be appropriately selected according to the molding conditions. These polymerization initiators (C) can be used alone or in combination of two or more.

[0026] Among these, for the purpose of shortening the molding time, it is preferable to use a polymerization initiator having a 10-hour half-life at a temperature of 60°C or higher and 110°C or lower. If it is 70°C or higher and 105°C or lower, the life of the prepreg at room temperature is long, and it can be cured in a short time (within 5 minutes) by heating, which is preferable. By using it for the prepreg of this embodiment, the curability and moldability are more excellent. Examples of such a polymerization initiator 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-butylperoxydiethylacetate, t-butylperoxyisopropyl carbonate, t-butylperoxy 2-ethylhexyl carbonate, t-amylperoxyisopropyl carbonate, t-amylperoxy 2-ethylhexyl carbonate, t-hexylperoxyisopropyl carbonate, di-tert-butylperoxyhexahydroterephthalate, t-amylperoxytrimethylhexanoate, t-amylperoxyisononanoate, t-hexylperoxy-2-ethylhexanoate, n-butyl 4,4-di(t-butylperoxy)valerate, and the like. Depending on the molding conditions, an optimal organic peroxide is selected and used.

[0027] As the addition amount of the polymerization initiator (C), since both the curing characteristics and the storage stability are excellent, the range of 0.5 to 3 parts by mass is preferable with respect to 100 parts by mass in total of the urethane (meth)acrylate (A) and the ethylenically unsaturated monomer (B).

[0028] The shape of the glass fiber (D) is not particularly limited, and examples include a reinforcing fiber tow in which reinforcing fiber filaments are converged, a unidirectional material in which reinforcing fiber tows are aligned in one direction, a woven fabric, or a short-cut reinforcing fiber, or a non-woven fabric or paper made of short-cut reinforcing fibers. However, it is preferable to use a unidirectional material as the reinforcing fiber, and high mechanical properties can be obtained by laminating and molding.

[0029] When using the glass fiber (D) cut short, since the fluidity in the mold during molding and the appearance of the molded product are further improved, it is preferable to use carbon fiber cut to 2.5 to 50 mm.

[0030] In the case of a fabric, examples include a stitching sheet stitched so as not to loosen a sheet in which fiber bundles are aligned in one direction or a sheet laminated with angles changed, represented by plain weave, twill weave, damask weave, or non-crimp fabric.

[0031] The basis weight (weight per 1 m 2 of fiber) of the glass fiber (D) is not particularly limited, but is preferably 10 g / m 2 to 650 g / m 2 . When the basis weight is 10 g / m 2 or more, it is preferable because the unevenness of the fiber width is small and the mechanical properties are good. When the basis weight is 650 g / m 2 or less, it is preferable because the impregnation of the resin is good. This basis weight is more preferably 50 to 500 g / m 2 , and particularly preferably 50 to 300 g / m 2 .

[0032] The content rate of the 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, because the mechanical strength of the obtained molded product is further improved.

[0033] The prepreg of the present embodiment may contain other reinforcing fibers in addition to the glass fiber (D) as long as the degree of freedom in coloring of the molded product is not impaired. Examples of the other reinforcing fibers include silicon carbide fiber, alumina fiber, boron fiber, metal fiber, aramid fiber, vinylon fiber, tetoron fiber, basalt fiber, ceramic fiber, and the like.

[0034] The prepreg of this embodiment essentially contains both a first halogen-free and phosphorus-containing flame retardant (E) and a second halogen-free and phosphorus-free flame retardant (F) as flame retardants, and is characterized in that the first flame retardant (E) is one or more salts selected from the group consisting of metal phosphinates and ammonium polyphosphates containing active hydrogen.

[0035] The first flame retardant (E) forms a protective layer called char during combustion, and this protective layer contributes to flame retardancy by blocking oxygen. On the other hand, the second flame retardant (F) contributes to flame retardancy by generating water during combustion to deprive the heat of combustion, or by generating an inert gas to reduce the oxygen concentration, etc., and has a different mechanism of contributing to flame retardancy from that of the first flame retardant (E). By containing these two types of flame retardants (E) and (F) in the prepreg of this embodiment, excellent flame retardancy can be obtained in the molded article obtained from the prepreg. In addition, since both of these two types of flame retardants (E) and (F) are halogen-free, it is possible to prevent the environmental impact caused by the release of halogen during the manufacturing process of the prepreg and the molded article.

[0036] In contrast, when the prepreg contains the first flame retardant (E) but does not contain the second flame retardant (F), and when the prepreg contains the second flame retardant (F) but does not contain the first flame retardant (E), excellent flame retardancy cannot be obtained in the molded article obtained from the prepreg.

[0037] The first flame retardant (E) is one or more salts selected from the group consisting of metal phosphinates and ammonium polyphosphates containing active hydrogen. These are halogen-free and phosphorus-containing compounds. As the first flame retardant (E), one or more salts may be used, or two or more salts may be used.

[0038] Examples of the metal phosphinate salts include aluminum phosphinates such as aluminum dimethylphosphinate, aluminum ethylmethylphosphinate, aluminum diethylphosphinate, aluminum methyl-n-propylphosphinate, aluminum methylphenylphosphinate, and aluminum diphenylphosphinate; calcium phosphinates such as calcium dimethylphosphinate, calcium ethylmethylphosphinate, calcium diethylphosphinate, calcium methyl-n-propylphosphinate, calcium methylphenylphosphinate, and calcium diphenylphosphinate; magnesium phosphinates such as magnesium dimethylphosphinate, magnesium ethylmethylphosphinate, magnesium diethylphosphinate, magnesium methyl-n-propylphosphinate, magnesium methylphenylphosphinate, and magnesium diphenylphosphinate; zinc phosphinates such as zinc dimethylphosphinate, zinc ethylmethylphosphinate, zinc diethylphosphinate, zinc methyl-n-propylphosphinate, zinc methylphenylphosphinate, and zinc diphenylphosphinate; and the like. Commercially available products include EXOLIT OP1230, OP1240, OP1312, OP1400, OP930, OP935, OP945 TP (manufactured by Clariant Plastics & Coatings), and the like.

[0039] Examples of commercially available products of the ammonium polyphosphate salt containing active hydrogen include FCP-770, FCP-790 (manufactured by Suzuhiro Chemical Co., Ltd.), and the like.

[0040] 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 metal hydroxide include aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, and the like. As the second flame retardant (F), one or more compounds may be used, or two or more compounds may be used.

[0041] In addition to containing the first flame retardant (E) and the second flame retardant (F), the prepreg of this embodiment may further contain a halogen-free third flame retardant (G). Examples of the third flame retardant (G) include red phosphorus, phosphonic acid esters, phosphoric acid esters, aromatic phosphoric acid esters, aromatic condensed phosphoric acid esters, phosphazenes, etc. Commercially available products include NOVA Excel 140, Nonen 73, DAIGUARD-880, TPP, TCP, CDP, PX-110, CR-733S, CR-741, PX-200, DAIGUARD-580, DAIGUARD-850, Rabitol FP-110, Rabitol FP-100, etc.

[0042] As components of the prepreg of this embodiment, those other than the above may be used. For example, it can 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.

[0043] Examples of the thermosetting resin include vinyl ester resin, unsaturated polyester resin, phenol resin, melamine resin, furan resin, bismaleimide resin, etc. These thermosetting resins can be used alone or in combination of two or more.

[0044] Examples of the thermoplastic resin include polyamide resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polycarbonate resin, polyurethane resin, polypropylene resin, polyethylene resin, polystyrene resin, acrylic resin, polybutadiene resin, polyisoprene resin, and those modified by copolymerization, etc. Among these, polyamide resin and polyurethane resin are preferred because of their high effect of improving brittleness. These thermoplastic resins can be used alone or in combination of two or more. Also, the thermoplastic resin can be added and used in particle form, or melted and mixed for use. When using the particulate thermoplastic resin, from the viewpoint of dispersibility in the fiber, the particle size is preferably 30 μm or less, and more preferably 5 - 20 μm.

[0045] Examples of the polymerization inhibitor include hydroquinone, trimethylhydroquinone, p-t-butylcatechol, t-butylhydroquinone, toluhydroquinone, p-benzoquinone, naphthoquinone, hydroquinone monomethyl ether, phenothiazine, copper naphthenate, copper chloride, etc. These polymerization inhibitors can be used alone or in combination of two or more.

[0046] Examples of the curing accelerator include metal soaps such as cobalt naphthenate, cobalt octenoate, vanadyl octenoate, copper naphthenate, barium naphthenate, etc., and metal chelate compounds such as vanadyl acetylacetate, cobalt acetylacetate, iron acetylacetonate, etc. Also, 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, diethanolaniline, etc. These curing accelerators can be used alone or in combination of two or more.

[0047] The fillers include inorganic compounds and organic compounds, and can be used to adjust physical properties such as the strength, elastic modulus, impact strength, and fatigue durability of the molded product.

[0048] 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 balloon, alumina, glass powder, aluminum hydroxide, gypsum stone, zirconium oxide, antimony trioxide, titanium oxide, molybdenum dioxide, iron powder, etc.

[0049] Examples of the organic compound include natural polysaccharide powders such as cellulose and chitin, and synthetic resin powders. Examples of the synthetic resin powder include powders of organic substances composed of hard resins, soft rubbers, elastomers, or polymers (copolymers), and particles having a multilayer structure such as a core-shell type. Specifically, examples include particles composed of acrylic particles, polyamide particles, butadiene rubber and / or acrylic rubber, urethane rubber, silicone rubber, etc., polyimide resin powder, fluororesin powder, phenol resin powder, and the like. These fillers can be used alone or in combination of two or more.

[0050] Examples of the release agent include zinc stearate, calcium stearate, paraffin wax, polyethylene wax, carnauba wax, and the like. Preferably, paraffin wax, polyethylene wax, carnauba wax, and the like are mentioned. These release agents can be used alone or in combination of two or more.

[0051] Examples of the thickener include metal oxides and metal hydroxides such as magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, etc., and acrylic resin-based fine particles, etc., which can be appropriately selected according to the handleability of the prepreg of this embodiment. These thickeners can be used alone or in combination of two or more.

[0052] The prepreg of this embodiment can be obtained, for example, first by using a known mixer such as a planetary mixer or a kneader to mix the polyisocyanate (a1), the polyol (a2), and / or (a3), the hydroxyalkyl (meth)acrylate (a4), and resin components such as 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. The obtained resin solution is impregnated into the glass fiber (D), and further sandwiched with a release PET film from above and rolled by a rolling machine to obtain a sheet in step 1. This is allowed to stand at room temperature to 50°C, and can be obtained by step 2 of reacting the isocyanate group of the polyisocyanate (a1) with the hydroxyl groups of the polyol (a2), and / or (a3) and (a4). Further, in step 1, a resin solution in which the polyisocyanate (a1), the polyol (a2), and / or (a3), and (a4) have been partially reacted in advance can also be used within a range that does not impair the impregnability into the fibers.

[0053] In order to ensure sufficient flame retardancy in the molded article, the total content of the first flame retardant (E) and the second flame retardant (F) preferably has a lower limit of 40 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 60 parts by mass or more with respect to 100 parts by mass in total of the resin components. 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 total content is preferably 140 parts by mass or less, more preferably 130 parts by mass or less, and even more preferably 110 parts by mass or less.

[0054] In order to ensure the effect of adding the second flame retardant (F), the mass ratio of the second flame retardant (F) to the first flame retardant (E) preferably has a lower limit of 0.5 or more, more preferably 0.8 or more, and even more preferably 1.0 or more. On the other hand, in order to ensure the effect of adding the first flame retardant (E), the upper limit of the mass ratio is preferably 5 or less, more preferably 3 or less, and even more preferably 2 or less.

[0055] In order to ensure ease of handling during lamination, the thickness of the prepreg of this embodiment preferably has a lower limit of 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 product thinner and ensure the impregnation property of the resin, the upper limit of the thickness is preferably 1.0 mm or less, more preferably 0.6 mm or less.

[0056] As a method for obtaining a molded product from the prepreg obtained above, for example, the release PET film is peeled from the prepreg, 1 to 10 prepregs are laminated, and then the prepregs are put into a mold preheated to 90°C to 160°C, and the mold is clamped by a compression molding machine to shape the prepregs. By maintaining a molding pressure of 0.1 to 10 MPa, the prepregs are cured, and then the molded product is taken out to obtain a molded product.

[0057] Examples of the molded product obtained from the prepreg of this embodiment include the casings of portable terminals such as smartphones, tablet PCs, and notebook PCs, hinge parts, and bezels of smartwatches. Since the prepreg of this embodiment can achieve a flame retardancy level of V-0 when a vertical burning test is performed in accordance with UL94 when the thickness of the molded product is 0.1 mm or more and 0.4 mm or less, it is particularly suitable for the casings of the portable terminals.

Examples

[0058] The present invention will be described in more detail below with specific examples.

Examples

[0059] (1) Preparation of prepreg resin composition 1,3-Xylylene diisocyanate (hereinafter abbreviated as "XDI"): 23.9 parts by mass, 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as "MDI"): 6.5 parts by mass, hydroxyethyl methacrylate (hereinafter abbreviated as "HEMA"): 31.7 parts by mass, Newpol BPE-20 (manufactured by Sanyo Chemical Industries, Ltd.: EO adduct of bisphenol A, hydroxyl equivalent: 164 g / eq): 4.3 parts by mass, Newpol BPE-40 (manufactured by Sanyo Chemical Industries, Ltd.: EO adduct of bisphenol A, hydroxyl equivalent: 204 g / eq): 6.2 parts by mass, PEG-300 (manufactured by Sanyo Chemical Industries, Ltd.: polyethylene glycol, hydroxyl equivalent: 150 g / eq): 0.5 parts by mass, Polyolite FPS-200 (manufactured by DIC Corporation: bifunctional polyol, hydroxyl equivalent: 4500 g / eq): 2.4 parts by mass, PTMG1000 (manufactured by Mitsubishi Chemical Corporation: polytetramethylene glycol, hydroxyl equivalent: 500 g / eq): 0.6 parts by mass, 4.4 parts by mass of the thermoplastic resin described below, and 19.5 parts by mass of MIRAMER M-245 (manufactured by American Specialty Chemicals Co., Ltd.: bifunctional methacrylate monomer) as a polymerizable monomer, to obtain resin component X. The total of the resin component X is 100 parts by mass.

[0060] The thermoplastic resin was 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 abbreviated as "1,4-BG"), and 26 parts by mass of MDI, casting it into a vat, and reacting it under the conditions of 90°C for 24 hours. The weight average molecular weight of the obtained thermoplastic resin was 50,000.

[0061] (2) Preparation of prepreg The obtained resin composition for prepreg was applied to one side of a release PET film, and then impregnated into 150.0 parts by mass of glass fiber ("H105" manufactured by Unitika Ltd.) by the hand lay-up method. After covering with the same release PET film, it was aged under the conditions of 45°C for 24 hours to produce prepreg (1). The thickness of the prepreg was 0.15 mm.

[0062] (3) Evaluation of molded products The obtained prepreg was laminated so that the total thickness became 0.3 mm and 0.4 mm. The obtained laminate was filled in the center of a flat metal mold coated with a release agent and compression molded with 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 × a width of 13 mm to produce 5 test pieces each as molded products.

[0063] Regarding the obtained test pieces, a vertical burning test was conducted in accordance with UL94V. The upper end of the test piece was vertically attached to a clamp, and cotton was placed 300 mm below the test piece. An operation was performed to bring the blue flame (height 20 mm) of methane gas to the lower end of the test piece with a gas burner for 10 seconds, and the burning time was measured. If the burning was within 30 seconds, it was further brought into contact with the flame for 10 seconds to measure the burning time. The presence or absence of ignition of the cotton due to the dropping of the dripping matter and the presence or absence of burning at the clamp attachment position were observed. These operations were performed on 5 test pieces. The judgment criteria are shown in Table 1. The results of the vertical burning test are shown in Table 2.

[0064]

Table 1

Examples

[0065] In this example, a prepreg resin composition was prepared in the same manner as in Example 1, except that as the second flame retardant (F), 50.0 parts by mass of BX053Y (aluminum hydroxide manufactured by Nippon Light Metal Co., Ltd.) was used in addition to 30.0 parts by mass of MC-6000. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

Example

[0066] In this example, a prepreg resin composition was prepared in the same manner as in Example 2, except that a third flame retardant (G) was further added. As the third flame retardant (G), 25.0 parts by mass of CR-733S (aromatic condensed phosphate ester manufactured by Daihachi Chemical Industry Co., Ltd.) was used. Using the obtained prepreg resin composition, a prepreg was produced in the same manner as in Example 1. Test pieces were produced in the same manner as in Example 1, except that the obtained prepregs were laminated so that the total thicknesses were 0.1 mm, 0.2 mm, 0.3 mm, and 0.4 mm.

Example

[0067] In this example, a prepreg resin composition was prepared in the same manner as in Example 1, except that as the first flame retardant (E), 30.0 parts by mass of EXOLIT OP 1230 (metal phosphinate manufactured by Clariant Plastics & Coatings) was used instead of Firecut P-770, and as the second flame retardant (F), 50 parts by mass of BX053Y was used instead of MC-6000. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

Example

[0068] In this example, a prepreg resin composition was prepared in the same manner as in Example 4, except that 30.0 parts by mass of EXOLIT OP 1312 (a metal phosphinate manufactured by Clariant Plastics & Coatings) was used as the first flame retardant (E) instead of EXOLIT OP 1230. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

Example

[0069] In this example, a prepreg resin composition was prepared in the same manner as in Example 1, except that 0.8 part by mass of Trigonox 122-C80 (an organic peroxide manufactured by Kayaku Nouryon Co., Ltd.) was used as the polymerization initiator instead of Trigonox 421-70. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

Example

[0070] In this example, a prepreg resin composition was prepared in the same manner as in Example 4, except that 0.8 part by mass of Trigonox 122-C80 was used as the polymerization initiator instead of Trigonox 421-70. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

Example

[0071] In this example, a prepreg resin composition was prepared in the same manner as in Example 5, except that 0.8 part by mass of Trigonox 122-C80 was used as the polymerization initiator instead of Trigonox 421-70. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0072] [Comparative Example 1] In this comparative example, a prepreg resin composition was prepared in the same manner as in Example 1, except that no first flame retardant (E) was added, 50.0 parts by mass of BX053Y was added instead of MC-6000 as the second flame retardant (F), and 30.0 parts by mass of CR-733S was added as the third flame retardant (G). Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0073] [Comparative Example 2] In this comparative example, a prepreg resin composition was prepared in the same manner as in Comparative Example 1, except that the addition amount of BX053Y as the second flame retardant (F) was changed to 100.0 parts by mass. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0074] [Comparative Example 3] In this comparative example, a prepreg resin composition was prepared in the same manner as in Comparative Example 1, except that 30.0 parts by mass of Adeka Stab FP-900L (manufactured by ADEKA CORPORATION: aromatic condensed phosphate ester) was added instead of CR-733S as the third flame retardant (G). Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0075] [Comparative Example 4] In this comparative example, a prepreg resin composition was prepared in the same manner as in Comparative Example 3, except that the addition amount of BX053Y as the second flame retardant (F) was changed to 100.0 parts by mass. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0076] [Comparative Example 5] In this comparative example, a prepreg resin composition was prepared in the same manner as in Comparative Example 1, except that 30.0 parts by mass of Adeka Stab FP-600 (manufactured by ADEKA CORPORATION: aromatic condensed phosphate ester) was added as the third flame retardant (G) instead of CR-733S. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0077] [Comparative Example 6] In this comparative example, a prepreg resin composition was prepared in the same manner as in Comparative Example 5, except that the addition amount of BX053Y as the second flame retardant (F) was changed to 100.0 parts by mass. Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1.

[0078] [Comparative Example 7] In this comparative example, a prepreg resin composition was prepared in the same manner as in Comparative Example 2, except that 15.0 parts by mass of CR-733S and 15.0 parts by mass of FP-900L were added as the third flame retardant (G). Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1. and test pieces were produced.

[0079] [Comparative Example 8] In this comparative example, a prepreg resin composition was prepared in the same manner as in Comparative Example 7, except that 15.0 parts by mass of FP-900L and 15.0 parts by mass of FP-600 were added as the third flame retardant (G). Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1. and test pieces were produced.

[0080] [Comparative Example 9] In this comparative example, a prepreg resin composition was prepared in the same manner as in Comparative Example 7, except that 15.0 parts by mass of CR-733S and 15.0 parts by mass of FP-600 were added as the third flame retardant (G). Then, using the obtained prepreg resin composition, a prepreg and test pieces were produced in the same manner as in Example 1. Test specimens were prepared.

[0081] The results of the vertical burning tests on the test specimens of Examples 1 to 8 and Comparative Examples 1 to 9 are shown in Tables 2 and 3.

[0082] [Table 2]

[0083] [Table 3]

[0084] The prepregs of Examples 1 to 8 contain at least both the first flame retardant (E) and the second flame retardant (F) as flame retardants. As shown in Table 2, all the test specimens with a thickness of 0.3 to 0.4 mm obtained from the prepregs of Examples 1 to 8 have a flame retardancy evaluation of 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 molded articles with a thickness of 0.1 to 0.2 mm. And it is presumed that the prepregs of Examples 1, 2, and 4 to 8 can also achieve excellent flame retardancy when molding molded articles with a thickness of 0.1 to 0.2 mm, similar to Example 3.

[0085] 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, all the test specimens with a thickness of 0.3 to 0.4 mm obtained from the prepregs of Comparative Examples 1 to 9 have a flame retardancy evaluation of V-1 or V non-conformance. 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.

[0086] In addition, the prepregs of Comparative Examples 7 and 9 contain a flame retardant (CR-733S) which is bisphenol A bisdiphenyl phosphate and a condensed phosphate ester-based flame retardant (FP-900L or FP-600), similar to the resin composition disclosed in Patent Document 2, and further contain a second flame retardant (F), but the flame retardancy evaluation of test pieces with a thickness of 0.3 to 0.4 mm was V non-compliant. From this, it can be understood that the combination of a flame retardant which is bisphenol A bisdiphenyl phosphate and a condensed phosphate ester-based flame retardant (FP-900L or FP-600) as the flame retardant added to the prepreg is insufficient to ensure the flame retardancy of molded articles with a thickness of 0.3 to 0.4 mm.

Claims

1. It contains urethane (meth) acrylate (A), ethylenically unsaturated monomer (B) other than the urethane (meth) acrylate (A), polymerization initiator (C), glass fiber (D), halogen-free and phosphorus-containing first flame retardant (E), and halogen-free and phosphorus-free second flame retardant (F), wherein the urethane (meth) acrylate (A) is a reaction product of polyisocyanate (a1) and polyol (a2) having an ethylenically unsaturated group and an aromatic skeleton, and / or a reaction product of polyisocyanate (a1), polyol (a3) having no ethylenically unsaturated group but having an aromatic skeleton, and hydroxyalkyl (meth) acrylate (a4), the first flame retardant (E) is one or more salts selected from the group consisting of metal phosphinate and ammonium polyphosphate containing active hydrogen, and the second flame retardant (F) is one or more compounds selected from the group consisting of melamine cyanurate and metal hydroxide. A prepreg characterized by this.

2. A molded article characterized by being 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 level of V-0 when a vertical combustion test is carried out in accordance with UL94.

4. The molded article according to Claim 3, which is a housing of a mobile terminal.

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