Molding materials and molded products

Abstract

Provided is a molding material which has a low specific gravity and exhibits good moldability. Provided is a molding material that contains: (A) a thermosetting resin; (B) a reactive diluent; (C) a thermoplastic resin; (D) hollow inorganic particles; and (E) a thermal polymerization initiator. The thermosetting resin (A) contains at least an unsaturated polyester resin. The content of the thermoplastic resin (C) is 5-15 mass%. The true density of the hollow inorganic particles (D) is 0.3-0.7 g / cm3. The pressure resistance strength of the hollow inorganic particles (D) is 10 MPa or more. The content of the hollow inorganic particles (D) is 35-70 vol%. If the specific gravity calculated from the blending quantity of the molding material is taken to be the theoretical specific gravity and the specific gravity measured using a test piece obtained by molding a contracted disk specified in JIS K 6911: 2006 by means of compression molding for a molding time of 3 minutes at a molding temperature of 150ºC and a molding pressure of 2 MPa and then cutting is taken to be the measured specific gravity, the difference between the measured specific gravity and the theoretical specific gravity (measured specific gravity minus theoretical specific gravity) is 0.03 or less.

Description

[Technical Field]

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

[0002] Conventionally, molding materials used as bulk molding compounds (BMC) or sheet molding compounds (SMC) have been widely used in applications such as chassis for office automation equipment or business machines, and lamp reflectors, such as automobile headlamps, due to their excellent properties such as mechanical strength, rigidity, surface smoothness, dimensional accuracy, heat resistance, and moldability.

[0003] By blending inorganic fillers or fiber reinforcing materials, it is possible to impart the various properties described above to molding materials, but on the other hand, the specific gravity of the molded product increases. Therefore, various efforts have been made to reduce the specific gravity of the molded product. For example, Patent Document 1 describes a resin composition containing a hollow filler. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-216879 Summary of the Invention [Problem to be solved by the invention]

[0005] The need for lower specific gravity of molded products is increasing year by year. Therefore, studies are being conducted to lower the specific gravity of the inorganic filler used in the molding material and increase the blending amount to lower the specific gravity of the molding material itself. However, if the blending amount of the inorganic filler is increased, the integrity of the molding material is lost, and it may not be possible to knead it well using a kneader or the like. If the specific gravity of the inorganic filler is reduced, the inorganic filler may be destroyed during kneading or molding, and the specific gravity of the molded product may not be reduced.

[0006] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a molding material having a low specific gravity and good moldability. Another object of the present invention is to provide a molded product having a low specific gravity and excellent surface smoothness and heat resistance. [Means for solving the problem]

[0007] The present invention includes the following aspects. [1] (A) Thermosetting resin, (B) a reactive diluent; (C) thermoplastic resin, (D) hollow inorganic particles, and (E) Thermal polymerization initiator A molding material comprising: the (A) thermosetting resin contains at least an unsaturated polyester resin, The content of the (C) thermoplastic resin is 5 to 15 mass %, The (D) hollow inorganic particles have a true density of 0.3 to 0.7 g / cm 3 and The (D) hollow inorganic particles have a pressure resistance strength of 10 MPa or more, The content of the (D) hollow inorganic particles is 35 to 70% by volume, A molding material in which, when the theoretical specific gravity is the specific gravity calculated from the blending amount of the molding material, and the measured specific gravity is the specific gravity measured on a test piece obtained by molding a shrink disk specified in JIS K 6911:2006 by compression molding at a molding temperature of 150°C, a molding pressure of 2 MPa, and a molding time of 3 minutes and cutting it out, the difference between the measured specific gravity and the theoretical specific gravity (measured specific gravity - theoretical specific gravity) is 0.03 or less. [2] The molding material according to [1], wherein the (D) hollow inorganic particles have a median diameter (d50) of 10 to 70 μm. [3] The molding material according to either [1] or [2], wherein the content of the (D) hollow inorganic particles is 20 to 50 mass %. [4] The molding material according to any one of [1] to [3], further comprising (F) a fiber reinforcing material, the content of the (F) fiber reinforcing material being 0.5 to 13 mass %. [5] A molded article comprising the molding material according to any one of [1] to [4] or a cured product thereof. [6] The molded article according to [5], which has a specific gravity of 0.5 to 0.8. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a molding material having a low specific gravity and good moldability, and also to provide a molded product having a low specific gravity and excellent surface smoothness and heat resistance. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the embodiments described below.

[0010] In the present disclosure, the term "ethylenically unsaturated bond" refers to a double bond formed between carbon atoms other than those forming an aromatic ring.

[0011] In this disclosure, "(meth)acrylic" means acrylic or methacrylic, "(meth)acrylate" means acrylate or methacrylate, "(meth)acryloyl" means acryloyl or methacryloyl, and "(meth)acryloxy" means acryloxy or methacryloxy.

[0012] <Molding material> The molding material of one embodiment includes (A) a thermosetting resin, (B) a reactive diluent, (C) a thermoplastic resin, (D) hollow inorganic particles, and (E) a thermal polymerization initiator. The molding material may further include (F) a fiber reinforcing material, if necessary.

[0013] (A) Thermosetting resin The (A) thermosetting resin contains at least an unsaturated polyester resin. The (A) thermosetting resin may optionally contain a vinyl ester resin, a urethane (meth)acrylate resin, a diallyl phthalate resin, an epoxy resin, or a combination of two or more of these. In the present disclosure, the unsaturated polyester resin, vinyl ester resin, and other resins refer to those that do not contain the (B) reactive diluent described below.

[0014] As the unsaturated polyester resin, those known in the art can be used. Unsaturated polyester is generally a compound obtained by polycondensation (esterification) of a polyhydric alcohol, an unsaturated polybasic acid, and optionally a saturated polybasic acid, and can be appropriately selected and used depending on the desired properties. The unsaturated polyester resin may be used alone or in combination of two or more.

[0015] The polyhydric alcohol used in the synthesis of the unsaturated polyester resin is not particularly limited, and known polyhydric alcohols can be used. Examples of polyhydric alcohols include alkanediols such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, and neopentanediol; (poly)oxyalkylene polyols such as diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, and polyethylene glycol; glycerin; and bisphenol compounds such as hydrogenated bisphenol A, bisphenol A, and bisphenol F. Among these, from the viewpoints of heat resistance and moldability, alkanediols and bisphenol compounds are preferred, and it is more preferable to use two or more selected from the group consisting of alkanediols and bisphenol compounds in combination, and it is even more preferable to use two or more selected from the group consisting of propylene glycol, neopentanediol, bisphenol A, and hydrogenated bisphenol A in combination. These polyhydric alcohols can be used alone or in combination.

[0016] The unsaturated polybasic acid used in the synthesis of the unsaturated polyester resin is not particularly limited as long as it is a polybasic acid having an ethylenically unsaturated bond, and known polybasic acids can be used. Examples of unsaturated polybasic acids include maleic acid, maleic anhydride, fumaric acid, citraconic acid, and itaconic acid. Among these, maleic acid, maleic anhydride, and fumaric acid are preferred from the viewpoints of heat resistance and moldability. These unsaturated polybasic acids can be used alone or in combination.

[0017] The saturated polybasic acid used in the synthesis of the unsaturated polyester resin is not particularly limited as long as it is a polybasic acid that does not have an ethylenically unsaturated bond, and known polybasic acids can be used. Examples of saturated polybasic acids include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, tetrachlorophthalic anhydride, and tetrabromophthalic anhydride. These saturated polybasic acids can be used alone or in combination.

[0018] The content of the unsaturated polyester resin in the (A) thermosetting resin is preferably 60 to 100 mass%, more preferably 80 to 100 mass%, and even more preferably 90 to 100 mass%. When the content of the unsaturated polyester resin is 60 mass% or more, the curability and moldability are good.

[0019] The weight-average molecular weight of the unsaturated polyester resin is preferably 6,000 to 35,000, more preferably 7,000 to 20,000, and even more preferably 8,000 to 15,000. If the weight-average molecular weight is 6,000 to 35,000, the moldability of the molding material will be even better.

[0020] In the present disclosure, the "weight average molecular weight" refers to a value measured at room temperature (23°C) using gel permeation chromatography (hereinafter also referred to as "GPC") under the following conditions and determined using a standard polystyrene calibration curve. Apparatus: Shodex (registered trademark) GPC-101 manufactured by Showa Denko K.K. Column: Showa Denko LF-804 Column temperature: 40℃ Sample: 0.2% by mass of sample in tetrahydrofuran Flow rate: 1mL / min Eluent: tetrahydrofuran Detector: RI-71S

[0021] The degree of unsaturation of the unsaturated polyester resin is preferably 50 to 100 mol%, more preferably 60 to 100 mol%, and even more preferably 70 to 100 mol%. When the degree of unsaturation is within the above range, the moldability of the molding material is better. The degree of unsaturation of the unsaturated polyester resin can be calculated using the mole numbers of the unsaturated polybasic acid and saturated polybasic acid used as raw materials according to the following formula: Degree of unsaturation (mol %) = {(number of moles of unsaturated polybasic acid × number of ethylenically unsaturated bonds per molecule of unsaturated polybasic acid) / (number of moles of unsaturated polybasic acid + number of moles of saturated polybasic acid)} × 100

[0022] Vinyl ester resins known in the art can be used. Vinyl ester resins are generally compounds having an ethylenically unsaturated bond obtained by a ring-opening reaction between an epoxy group in an epoxy compound having two or more epoxy groups and a carboxy group of an unsaturated monobasic acid having an ethylenically unsaturated bond and a carboxy group. Examples of such vinyl ester resins are described in the Polyester Resin Handbook (published by Nikkan Kogyo Shimbun, 1988). Vinyl ester resins may be used alone or in combination.

[0023] As the urethane (meth)acrylate resin, for example, a resin obtained by introducing (meth)acryloyl groups into the hydroxyl groups or isocyanato groups at both ends of polyurethane obtained by reacting a polyhydric isocyanate with a polyhydric alcohol can be used.

[0024] As the polyhydric alcohol, any of the compounds described as raw materials for the unsaturated polyester resin can be used without any particular limitation.

[0025] Examples of polyisocyanates include aliphatic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, lysine triisocyanate, and trimethylhexane diisocyanate; alicyclic polyisocyanates such as hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4 (or 2,6)-diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), and 1,3-(isocyanatomethyl)cyclohexane; aromatic polyisocyanates such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate; and adducts, isocyanurates, and biurets of these polyisocyanates. Polyisocyanates may be used alone or in combination.

[0026] When introducing a (meth)acryloyl group, for example, a method of reacting a terminal isocyanato group with a hydroxyl group-containing (meth)acrylic compound, or a method of reacting a terminal hydroxyl group with an isocyanato group-containing (meth)acrylic compound such as 2-(meth)acryloyloxyethyl isocyanate, 2-(meth)acryloyloxypropyl isocyanate, or 1,1-bis(acryloyloxymethyl)ethyl isocyanate can be used. Examples of hydroxyl group-containing (meth)acrylic compounds include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, caprolactone-modified hydroxyalkyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, tris(hydroxyethyl)isocyanuric acid di(meth)acrylate, pentaerythritol tri(meth)acrylate, glycerin mono(meth)acrylate, and hydroxyethyl acrylamide, with 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, caprolactone-modified hydroxyalkyl (meth)acrylate, and hydroxyethyl acrylamide being preferred. The isocyanato group-containing (meth)acrylic compounds and hydroxyl group-containing (meth)acrylic compounds may each be used alone or in combination of two or more.

[0027] As the diallyl phthalate resin, any of those known in the art can be used. The diallyl phthalate resins may be used alone or in combination of two or more.

[0028] The epoxy resin is not particularly limited as long as it is a compound having two or more epoxy groups. Preferably, it is at least one selected from the group consisting of bisphenol-type epoxy compounds and novolac phenol-type epoxy compounds, and more preferably, it is a bisphenol-type epoxy compound. The epoxy resin may be used alone or in combination of two or more types.

[0029] Examples of bisphenol epoxy compounds include those obtained by reacting a bisphenol compound such as bisphenol A, bisphenol F, bisphenol S, and tetrabromobisphenol A with epichlorohydrin and / or methylepichlorohydrin, and those obtained by reacting a condensate of a compound obtained by glycidyl etherifying one or more of the above bisphenol compounds with one or more of the above bisphenol compounds with epichlorohydrin and / or methylepichlorohydrin. Among these, from the viewpoint of durability, a reaction product of a bisphenol compound with epichlorohydrin is preferred, and a reaction product of bisphenol A with epichlorohydrin is more preferred.

[0030] Examples of novolak phenol type epoxy compounds include those obtained by reacting phenol novolak or cresol novolak with epichlorohydrin and / or methyl epichlorohydrin.

[0031] The content of the (A) thermosetting resin is preferably 30 to 75 mass %, more preferably 35 to 65 mass %, based on the total mass of the (A) thermosetting resin and the (B) reactive diluent. When the content of the (A) thermosetting resin is 30 mass % or more, the workability of the molding material and the dimensional accuracy of the molded product are good. When the content of the (A) thermosetting resin is 75 mass % or less, the curability of the molding material is good.

[0032] (B) Reactive diluent The (B) reactive diluent is a compound having at least one polymerizable ethylenically unsaturated bond as a polymerizable functional group in the molecule. The (B) reactive diluent may be a monofunctional monomer or a polyfunctional monomer. By using a molding material containing the (B) reactive diluent, it becomes easy to adjust the viscosity.

[0033] (B) Examples of monofunctional monomers used as reactive diluents include (meth)acrylamide compounds such as (meth)acrylamide, N-methylol (meth)acrylamide, methoxymethyl (meth)acrylamide, ethoxymethyl (meth)acrylamide, propoxymethyl (meth)acrylamide, and butoxymethoxymethyl (meth)acrylamide; methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate. Examples of suitable monofunctional monomers include (meth)acrylate compounds such as hydroxy-3-phenoxypropyl (meth)acrylate, 2-(meth)acryloyloxy-2-hydroxyethyl phthalate, glycerin mono(meth)acrylate, tetrahydrofurfuryl (meth)acrylate, glycidyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, and half (meth)acrylates of phthalic acid derivatives; aromatic vinyl compounds such as styrene, α-methylstyrene, α-chloromethylstyrene, and vinyltoluene; and carboxylic acid esters such as vinyl acetate and vinyl propionate. The monofunctional monomers may be used alone or in combination of two or more.

[0034] (B) Examples of polyfunctional monomers used as reactive diluents include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexane glycol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate. acrylate, glycerin di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 2,2-bis(4-(meth)acryloxydiethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxypolyethoxyphenyl)propane, 2-hydroxy-3-(meth)acryloyloxypropyl (meth)acrylate, ethylene glycol diglycidyl Ether di(meth)acrylate, diethylene glycol diglycidyl ether di(meth)acrylate, phthalic acid diglycidyl ester di(meth)acrylate, glycerin triacrylate, glycerin polyglycidyl ether poly(meth)acrylate, urethane (meth)acrylate (e.g., polyisocyanates such as tolylene diisocyanate, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, and hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate) Examples of the polyfunctional monomer include (meth)acrylate compounds such as tri(meth)acrylate of tris(hydroxyethyl)isocyanurate; aromatic vinyl compounds such as divinylbenzene, diallyl phthalate, and diallyl benzene phosphonate; dicarboxylic acid esters such as divinyl adipate; triallyl cyanurate; and (meth)acrylamide compounds such as methylene bis(meth)acrylamide, (meth)acrylamide methylene ether, and condensates of polyhydric alcohols and N-methylol (meth)acrylamide. The polyfunctional monomers may be used alone or in combination of two or more.

[0035] Among these, from the viewpoints of availability and cost, styrene monomer is preferred as the reactive diluent (B).

[0036] The total content of the (A) thermosetting resin and the (B) reactive diluent in the molding material is preferably 25 to 80 mass%, more preferably 30 to 65 mass%, and even more preferably 35 to 50 mass%. When the total content of the (A) thermosetting resin and the (B) reactive diluent is 25 mass% or more, the kneadability or fluidity during molding is good. When the total content of the (A) thermosetting resin and the (B) reactive diluent is 80 mass% or less, the dimensional accuracy of the molded product or the moldability of the molding material is good.

[0037] (C)Thermoplastic resin The thermoplastic resin (C) is not particularly limited as long as it exhibits thermal plasticity, and any resin known in the art can be used. The use of the thermoplastic resin (C) improves the integrity of the molding material, allowing the content of the hollow inorganic particles (D) to be increased while maintaining good moldability, thereby lowering the specific gravity of the molding material.

[0038] Examples of (C) thermoplastic resins include polystyrene, polymethyl methacrylate, polyvinyl acetate, saturated polyester, and styrene-butadiene rubber. These thermoplastic resins may be used alone or in combination. Among them, polystyrene and styrene-butadiene rubber are preferred from the viewpoint of dimensional accuracy and color unevenness of molded products.

[0039] The content of the (C) thermoplastic resin in the molding material is 5 to 15 mass %, and preferably 7 to 13 mass %. When the content of the (C) thermoplastic resin is 5 mass % or more, the dimensional stability of the molded product or the kneadability of the molding material is good. When the content of the (C) thermoplastic resin is 15 mass % or less, the curability of the molding material is good.

[0040] (D) Hollow inorganic particles Examples of (D) hollow inorganic particles include glass balloons, silica balloons, and alumina balloons. Among these, glass balloons are preferred from the viewpoint of pressure resistance. These hollow inorganic particles may be used alone or in combination of two or more. By using (D) hollow inorganic particles, the specific gravity of the molding material can be reduced, and this can be molded to obtain a molded product with a low specific gravity.

[0041] (D) The true density of the hollow inorganic particles is 0.3 to 0.7 g / cm 3 and 0.3 to 0.5 g / cm 3 It is preferable that the density is 0.38 to 0.45 g / cm 3 (D) The true density of the hollow inorganic particles is more preferably 0.3 g / cm. 3 If the true density of the (D) hollow inorganic particles is less than 0.7 g / cm, the pressure resistance strength of the (D) hollow inorganic particles themselves will be insufficient, and the (D) hollow inorganic particles will be damaged during the production of the molding material or during molding. 3 If the diameter is larger than this, the hollow inorganic particles (D) will have a high specific gravity. In either case, the desired low specific gravity as a molding material cannot be achieved, which is undesirable.

[0042] The pressure resistance of the (D) hollow inorganic particles is 10 MPa or more, and preferably 20 MPa or more. If the pressure resistance of the (D) hollow inorganic particles is less than 10 MPa, the (D) hollow inorganic particles will be destroyed during production of the molding material or during molding, making it impossible to achieve the desired low specific gravity of the molded product, which is undesirable. There is no particular upper limit to the pressure resistance of the (D) hollow inorganic particles, but it is generally 200 MPa or less.

[0043] In the present disclosure, the pressure resistance strength of the (D) hollow inorganic particles is the pressure value at which 10% by volume of the (D) hollow inorganic particles are broken when pressure is applied to the (D) hollow inorganic particles dispersed in glycerol in accordance with ASTM D3102-78 (1982) "Practice for Determination of Isostatic Collapse Strength of Hollow Glass Microspheres."

[0044] The median diameter (d50) of the (D) hollow inorganic particles is preferably 10 to 70 μm, more preferably 15 to 60 μm, and even more preferably 20 to 50 μm. When the median diameter (d50) of the (D) hollow inorganic particles is 10 μm or more, the viscosity of the molding material can be kept within an appropriate range. When the median diameter (d50) of the (D) hollow inorganic particles is 70 μm or less, the (D) hollow inorganic particles are not destroyed during production of the molding material or during molding, and the (D) hollow inorganic particles do not increase in specific gravity, resulting in good surface smoothness and specific gravity of the molded product.

[0045] In the present disclosure, the median diameter (d50) of the (D) hollow inorganic particles is determined by a laser diffraction / scattering method.

[0046] The content of the (D) hollow inorganic particles in the molding material is 35 to 70 volume %, preferably 50 to 65 volume %, and more preferably 55 to 65 volume %. If the content of the (D) hollow inorganic particles is less than 35 volume %, the specific gravity of the molded product will be high, which is undesirable. If the content of the (D) hollow inorganic particles is more than 70 volume %, the molding material will not be able to achieve integrity and will not be able to be sufficiently kneaded. This will result in poor moldability of the molding material and a significant decrease in surface smoothness of the molded product. In the present disclosure, the content (vol %) of the (D) hollow inorganic particles is the content at a temperature condition of 23°C, and is the theoretical volume % calculated by dividing the amount of each raw material used by its specific gravity to determine the theoretical volume of each, and then dividing the theoretical volume of the (D) hollow inorganic particles by the sum of the theoretical volumes of each raw material determined above.

[0047] The content of the (D) hollow inorganic particles in the molding material is preferably 20 to 50 mass %, more preferably 30 to 50 mass %, and even more preferably 35 to 45 mass %.

[0048] The kneadability and moldability of the molding material are significantly affected by the content (volume %) of the (D) hollow inorganic particles, and therefore it is preferable to control the content of the (D) hollow inorganic particles on a volume basis rather than on a mass basis.

[0049] (E) Thermal polymerization initiator As the (E) thermal polymerization initiator, peroxides known in the art can be used. Examples of the (E) thermal polymerization initiator include t-butyl peroxyoctoate, benzoyl peroxide, 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, t-butylperoxyisopropyl carbonate, t-butyl peroxybenzoate, dicumyl peroxide, and di-t-butyl peroxide. These thermal polymerization initiators may be used alone or in combination of two or more.

[0050] The content of the (E) thermal polymerization initiator in the molding material is preferably 0.1 to 5 mass %, more preferably 0.5 to 4 mass %, and even more preferably 0.8 to 3 mass %. When the content of the (E) thermal polymerization initiator is within the above range, good curability can be obtained as a molding material.

[0051] (F) Fiber reinforcement The molding material may further contain (F) a fiber reinforcement. The (F) fiber reinforcement is a fibrous substance with an aspect ratio of 3 or more. The aspect ratio can be measured by a microscopic method described in JIS Z 8900-1:2008, "Particles for Calibration of Particle Diameter Measuring Devices." Examples of the (F) fiber reinforcement include organic and inorganic fibers such as glass fiber, pulp fiber, Tetron (registered trademark) fiber, vinylon fiber, carbon fiber, aramid fiber, and wollastonite. Examples of the form of the (F) fiber reinforcement include a sheet-like material using continuous or discontinuous fibers, roving, and chopped strands. The (F) fiber reinforcement may be used alone or in combination of two or more types. Among these, glass fiber is preferred from the standpoints of cost and dispersibility, and chopped strand glass is more preferred.

[0052] The fiber length of the (F) fiber reinforcing material is not particularly limited, but is preferably 1 mm to 25 mm, more preferably 1.5 mm to 15 mm, and even more preferably 1.5 mm to 13 mm. A fiber length of 1 to 25 mm improves kneadability with resin and fluidity during molding. The fiber length is the number average value measured using a vernier caliper or a micrometer on an optical microscope for 100 fibers randomly selected.

[0053] When a (F) fiber reinforcement is used, the content of the (F) fiber reinforcement in the molding material is preferably 0.5 to 13 mass%, more preferably 3 to 13 mass%, and even more preferably 4 to 13 mass%. When the content of the (F) fiber reinforcement is 0.5 mass% or more, the molding material has good moldability. When the content of the (F) fiber reinforcement is 13 mass% or less, the content of the (D) hollow inorganic particles can be relatively increased, thereby allowing the molded product to have a desired low specific gravity. When the content of the (F) fiber reinforcement is 13 mass% or less, it is possible to prevent the (F) fiber reinforcement from destroying the (D) hollow inorganic particles during molding, which also contributes to achieving the desired low specific gravity.

[0054] (G) Optional component In addition to the above components, the molding material of one embodiment may optionally contain inorganic fillers, mold release agents, thickeners, viscosity reducers, pigments, etc. When these components are used, each component may be used in an amount typically used depending on the purpose.

[0055] Examples of inorganic fillers include powders such as calcium carbonate, aluminum hydroxide, wollastonite, clay, talc, mica, and silicic anhydride.

[0056] As the release agent, for example, stearic acid, zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, or carnauba wax can be used in an appropriate ratio.

[0057] Examples of the thickener include metal oxides such as magnesium oxide, magnesium hydroxide, calcium hydroxide, and calcium oxide, and isocyanate compounds.

[0058] <Method of manufacturing molding material> The form of the molding material is not particularly limited, but a thermosetting resin molding material such as a bulk molding compound (hereinafter referred to as "BMC") or a sheet molding compound (hereinafter referred to as "SMC") is preferred from the viewpoint of diversifying the shape of the cured product and providing excellent productivity.

[0059] The BMC molding material can be produced by a method typically used in BMC production, such as kneading under the following conditions using a kneader. The components, except for the (F) fiber reinforcement, are added to a double-arm kneader with the jacket temperature set to 20-50°C, the lid is closed, and the mixture is kneaded for 20-60 minutes until the components are sufficiently dispersed and form a putty. After the resin mixture has formed into a putty, the lid is opened, and the (F) fiber reinforcement is gradually added over 1-2 minutes while kneading. After the specified amount has been added, the lid is closed, and the mixture is kneaded for 5-60 minutes until the (F) fiber reinforcement is uniformly dispersed. After kneading is complete, the resulting BMC is packaged in a laminate film of polyethylene film and polyethylene terephthalate film, vinylon film, or the like.

[0060] SMC molding materials can be produced using a standard SMC manufacturing apparatus using the following method. First, all components except for the (F) fiber reinforcement are mixed using a mixer or similar to obtain a resin mixture. While there are no particular restrictions on the order in which the raw materials are mixed or the type of mixer, a mixing temperature of 20 to 45°C is preferred. Next, the resin mixture is applied to carrier films installed above and below the SMC manufacturing apparatus to a uniform thickness. There are no particular restrictions on the carrier films as long as they are commonly used, but polyethylene film, polypropylene film, etc. can be used. Next, the (F) fiber reinforcement, cut to a predetermined length, such as 12 to 25 mm, is sprayed onto the lower carrier film coated with the resin mixture. The resulting sheet is then sandwiched between the upper and lower carrier films and passed through impregnation rolls while applying pressure to the entire surface to form a sheet, which is then wound into a roll or packaged in a zigzag fold. The resulting sheet is preferably aged at room temperature to 60°C for 1 to 240 hours. By aging at room temperature to 60°C for 1 to 240 hours, the carrier film can be easily peeled off, and there is little stickiness when the carrier film is peeled off, resulting in a sheet with good workability.

[0061] <Molded products> A molded article according to one embodiment can be obtained by molding the molding material. By using the molding material, a molded article having a low specific gravity and excellent physical properties such as surface smoothness, rigidity, and heat resistance can be obtained. By heating the molding material after molding as necessary, a molded article containing a cured product of the molding material can also be obtained.

[0062] The specific gravity of the molded article is preferably 0.5 to 0.8, and more preferably 0.6 to 0.8. When the specific gravity of the molded article is 0.5 or more, the moldability is good. When the specific gravity of the molded article is 0.8 or less, a sufficiently low specific gravity can be achieved. The specific gravity of the molded article in this disclosure is the numerical value of the specific gravity of a compression molded article measured in accordance with JIS K 6911:2006.

[0063] The difference (measured specific gravity - theoretical specific gravity) between the specific gravity obtained by actually measuring the molded article (measured specific gravity) and the specific gravity calculated from the blending amount of the molding material (theoretical specific gravity) is 0.03 or less, and preferably 0.02 or less. When the difference between the measured specific gravity and the theoretical specific gravity is 0.03 or less, it is possible to obtain a molded article with a desired low specific gravity in which the shape of the (D) hollow inorganic particles is sufficiently maintained during molding. The measured specific gravity in this disclosure is a value measured at 23°C on a test piece obtained by molding and cutting out a shrink disk specified in JIS K 6911:2006 by compression molding at a molding temperature of 150°C, a molding pressure of 2 MPa, and a molding time of 3 minutes.

[0064] <Method of manufacturing molded products> Molded articles can be produced by subjecting the above-mentioned molding materials to various molding methods, such as compression molding, transfer molding, and injection molding. [Example]

[0065] EXAMPLES The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0066] [Preparation of molding material] Example 1 Using a double-arm kneader with the jacket temperature set to 40°C, the components were kneaded for 30 minutes according to the composition shown in Table 1, to obtain a molding material for Example 1.

[0067] Examples 2 to 5 Molding materials of Examples 2 to 5 were obtained in the same manner as in Example 1, except that the compositions shown in Table 1 were used.

[0068] (Comparative Examples 1 to 9) Molding materials of Comparative Examples 1 to 9 were obtained in the same manner as in Example 1, except that the compositions shown in Table 2 were used.

[0069] [Raw materials] The following raw materials were used:

[0070] (A) Thermosetting resin Unsaturated polyester resin: Resin obtained by polycondensation of maleic acid (100 mol), propylene glycol (50 mol), and neopentanediol (50 mol) (weight average molecular weight 11,000, specific gravity 1.1)

[0071] (B) Reactive diluent Styrene monomer (Asahi Kasei Corporation, specific gravity 0.91)

[0072] (C)Thermoplastic resin Polystyrene (Sekisui Plastics Co., Ltd., weight average molecular weight 200,000, specific gravity 1.05) Styrene-butadiene rubber (product name: Asaprene (trademark) T-411, manufactured by Asahi Kasei Corporation, styrene / butadiene ratio = 30 / 70, specific gravity 0.95)

[0073] (D) Hollow inorganic particles Glass balloon (product name: K25, manufactured by 3M Japan Ltd., pressure resistance 5 MPa, true density 0.25 g / cm 3 , median diameter (d50) 55 μm) Glass balloon (product name: VS5500, manufactured by 3M Japan Ltd., pressure resistance 38 MPa, true density 0.38 g / cm 3 , median diameter (d50) 44 μm) Glass balloon (product name: K46, manufactured by 3M Japan Ltd., pressure resistance 41 MPa, true density 0.46 g / cm 3 , median diameter (d50) 40 μm)

[0074] (E) Thermal polymerization initiator t-Butyl peroxybenzoate (NOF Corporation)

[0075] (F) Fiber reinforcement Glass chop (Nitto Boseki Co., Ltd., fiber length 3.0 mm)

[0076] (G) Optional component (mold release agent) Calcium stearate (NOF Corporation)

[0077] [Evaluation method] The molding materials were evaluated for the following items. (1)(D) Content of hollow inorganic particles (volume%) The calculation was made using the theoretical volume calculated from the specific gravity and blending amount of each raw material.

[0078] (2) Theoretical specific gravity It was calculated from the blend amount of molding material.

[0079] (3) Molded product specific gravity (measured specific gravity) A shrink disk as specified in JIS K 6911:2006 was molded by compression molding at a molding temperature of 150°C, a molding pressure of 2 MPa, and a molding time of 3 minutes. Test pieces were then cut out and their specific gravity (23°C) was measured according to JIS K 6911:2006.

[0080] (4) Formability Disks for measuring appearance after heating, as specified in JIS K 6911:2006, were obtained by compression molding at a molding temperature of 150°C, a molding pressure of 2 MPa, and a molding time of 3 minutes. The releasability and filling properties of the disks for measuring appearance were evaluated visually. The evaluation criteria were A: very good, B: good, C: slightly poor, and D: poor.

[0081] (5) Surface appearance Disks for measuring appearance after heating, as specified in JIS K 6911:2006, were obtained by compression molding at a molding temperature of 150°C, a molding pressure of 2 MPa, and a molding time of 3 minutes. The surface appearance of the disks for measuring appearance was evaluated visually. The evaluation criteria were A: very good, B: good, C: somewhat poor, and D: poor.

[0082] (6) Glossiness The heated appearance measurement disks specified in JIS K 6911:2006 were obtained by compression molding at a molding temperature of 150°C, a molding pressure of 2 MPa, and a molding time of 3 minutes. The gloss of the appearance measurement disks was measured using a HANDY GLOSSMETER PG-1M manufactured by Nippon Denshoku Industries Co., Ltd., according to Method 3 of JIS Z 8741:1997 "Specular glossiness - Measurement method."

[0083] (7) Heat resistance (appearance after heating) Disks for measuring the appearance after heating, as specified in JIS K 6911:2006, were obtained by compression molding at a molding temperature of 150°C, a molding pressure of 2 MPa, and a molding time of 3 minutes. The appearance change at 180°C was evaluated based on JIS K 6911:2006 "Appearance after heating." The evaluation criteria were A: no change, B: blistering, and C: cracking.

[0084] The compositions and evaluation results of the molding materials of Examples 1 to 5 are shown in Table 1, and the compositions and evaluation results of the molding materials of Comparative Examples 1 to 9 are shown in Table 2. The molding materials of Comparative Examples 1, 2, 6, and 7 could not be produced in an integrated form, so their properties were not evaluated.

[0085] [Table 1]

[0086] [Table 2] [Industrial Applicability]

[0087] The molding material and molded article of the present invention can be widely used in applications such as chassis for office automation equipment or business machines, and lamp reflectors such as automobile headlamps.

Claims

1. (A) thermosetting resin, (B) a reactive diluent; (C) thermoplastic resin, (D) hollow inorganic particles, and (E) Thermal polymerization initiator A molding material comprising: The (A) thermosetting resin contains at least an unsaturated polyester resin, the reactive diluent (B) is a compound having at least one polymerizable ethylenically unsaturated bond, The content of the (C) thermoplastic resin is 5 to 15 mass %, The true density of the hollow inorganic particles (D) is 0.3 to 0.7 g / cm ３ and the (D) hollow inorganic particles have a pressure resistance strength of 10 MPa or more, and the pressure resistance strength is a pressure value measured when 10% by volume of the (D) hollow inorganic particles are broken when pressure is applied to the (D) hollow inorganic particles dispersed in glycerol in accordance with ASTM D3102-78 (1982) "Practice for Determination of Isostatic Collapse Strength of Hollow Glass Microspheres"; The content of the (D) hollow inorganic particles is 35 to 70% by volume, The content of the (D) hollow inorganic particles is 30 to 50 mass %, A molding material in which, when the theoretical specific gravity is a specific gravity calculated from the blending amount of the molding material, and the measured specific gravity is a specific gravity measured on a test piece obtained by molding a shrink disk specified in JIS K 6911:2006 by compression molding at a molding temperature of 150°C, a molding pressure of 2 MPa, and a molding time of 3 minutes and cutting out the disk, the difference between the measured specific gravity and the theoretical specific gravity (measured specific gravity - theoretical specific gravity) is 0.03 or less.

2. The molding material according to claim 1, wherein the median diameter (d50) of the hollow inorganic particles (D) is 10 to 70 μm.

3. The molding material according to claim 1 or 2, further comprising a fiber reinforcement (F), wherein the content of the fiber reinforcement (F) is 0.5 to 13 mass %.

4. A molded article comprising the molding material according to any one of claims 1 to 3 or a cured product thereof.

5. 5. The molded article according to claim 4, having a specific gravity of 0.5 to 0.8.

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