Unsaturated polyester resin composition and molded article

Abstract

Provided is an unsaturated polyester resin composition which has satisfactory resin flowability during molding and can give molded objects excellent in terms of molded-article appearance, dimensional accuracy, and strength and having few burrs. The unsaturated polyester resin composition contains inorganic fillers in an amount in a specific range, the inorganic fillers comprising a specific proportion of three inorganic fillers having respective average particle diameters.

Description

[Technical Field]

[0001] The present invention relates to an unsaturated polyester resin composition and a molded article. [Background technology]

[0002] Unsaturated polyester resin compositions, which are prepared by blending a fiber reinforcing material or an inorganic filler with an unsaturated polyester resin, have good resin flowability during molding and give cured products that are excellent in dimensional accuracy, heat resistance, and mechanical strength. Therefore, they are widely used in the production of chassis for office equipment and business machines, lamp reflectors for automobile headlamps, and the like.

[0003] For example, Patent Documents 1 and 2 disclose unsaturated polyester resin compositions containing inorganic fillers, fiber reinforcing materials, hollow fillers, and the like. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2005 / 103152 [Patent Document 2] International Publication No. 2016 / 035516 Summary of the Invention [Problem to be solved by the invention]

[0005] When producing a molded product, the unsaturated polyester resin composition flows into the gaps in the mold clearance and hardens, causing burrs to form on the molded product. Because the burrs must be removed in a removal process, the generation of a large amount of burrs poses a problem of increased production costs.

[0006] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an unsaturated polyester resin composition that has good resin flowability during molding, and is capable of giving a molded product that is excellent in appearance, dimensional accuracy, and strength, and has reduced burrs. [Means for solving the problem]

[0007] As a result of extensive research, the present inventors have found that, when the content of inorganic filler in an unsaturated polyester resin composition is within a specific range and the inorganic fillers having three different average particle sizes are used in a specific ratio, an unsaturated polyester resin composition can be realized which has good resin flowability during molding, and which is capable of giving a molded product which is excellent in appearance, dimensional accuracy, and strength, and which has reduced burrs, and has thereby completed the present invention.

[0008] That is, the present invention includes the following aspects. [Aspect 1] An unsaturated polyester resin composition comprising: (a) an unsaturated polyester resin; (b) an inorganic filler; (c) a metal soap; (d) a low-profile agent; (e) a fiber reinforcement material; and (f) a curing agent, the content of the (b) inorganic filler is 250 to 600 parts by mass relative to 100 parts by mass of the (a) unsaturated polyester resin, The (b) inorganic filler contains (b1) an inorganic filler having an average particle size of 0.5 to 5.0 μm, (b2) an inorganic filler having an average particle size of 6.0 to 50.0 μm, and (b3) an inorganic filler having an average particle size of 70.0 μm or more in a ratio of (b1):(b2):(b3)=60-75:7-15:15-30 relative to 100% by mass of the total of the inorganic fillers (b1), (b2), and (b3), Unsaturated polyester resin composition. [Aspect 2] The unsaturated polyester resin composition according to aspect 1, wherein the content of the (b) inorganic filler is 350 to 450 parts by mass per 100 parts by mass of the (a) unsaturated polyester resin. [Aspect 3] 3. The unsaturated polyester resin composition according to claim 1, wherein the inorganic filler (b) contains calcium carbonate. [Aspect 4] The unsaturated polyester resin composition according to any one of Aspects 1 to 3, wherein the content of the (e) fiber reinforcing material is 70 to 120 parts by mass per 100 parts by mass of the (a) unsaturated polyester resin. [Aspect 5] A molded article comprising a cured product of the unsaturated polyester resin composition according to any one of the first to fourth aspects. [Effects of the Invention]

[0009] According to the present invention, an unsaturated polyester resin composition can be provided that has good resin flowability during molding, and can give a molded article that is excellent in appearance, dimensional accuracy, and strength, and has reduced burrs. Furthermore, by curing the unsaturated polyester resin composition, a molded article that is excellent in appearance, dimensional accuracy, and strength, and has reduced burrs, can be provided. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the embodiments described below.

[0011] 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.

[0012] <Unsaturated polyester resin composition> One embodiment of the present invention is an unsaturated polyester resin composition comprising (a) an unsaturated polyester resin, (b) an inorganic filler, (c) a metal soap, (d) a low-profile agent, (e) a fiber reinforcement, and (f) a curing agent. Each component will be described below.

[0013] [(a) Unsaturated polyester resin] In this disclosure, (a) unsaturated polyester resin refers to a composition obtained by dissolving a condensation product (unsaturated polyester) obtained by esterifying a polyhydric alcohol with an unsaturated polybasic acid and, optionally, a saturated polybasic acid, in a crosslinking agent (also referred to as a "reactive diluent"). The unsaturated polybasic acid is a polybasic acid having a polymerizable ethylenically unsaturated bond, and the saturated polybasic acid is a polybasic acid having no polymerizable ethylenically unsaturated bond.

[0014] Such unsaturated polyester resins are generally known in the technical field of the present invention and are described, for example, in "Polyester Resin Handbook" (published by Nikkan Kogyo Shimbun, 1988) and "Paint Terminology Dictionary" (edited by the Color Materials Association, published in 1993).

[0015] The polyhydric alcohol used as a raw material for the unsaturated polyester is not particularly limited, and any known polyhydric alcohol in the technical field of the present invention can be used. Examples of polyhydric alcohols include ethylene glycol, propylene glycol, butanediol, diethylene glycol, dipropylene glycol, triethylene glycol, pentanediol, hexanediol, neopentanediol, hydrogenated bisphenol A, bisphenol A, and glycerin. The polyhydric alcohols can be used alone or in combination.

[0016] Among these, at least one selected from the group consisting of propylene glycol, neopentanediol, bisphenol A, and hydrogenated bisphenol A is preferred from the viewpoint of excellent heat resistance, mechanical strength, and resin flowability during molding.

[0017] The unsaturated polybasic acid used as a raw material for the unsaturated polyester is not particularly limited, and any known unsaturated polybasic acid in the technical field of the present invention can be used. Examples of unsaturated polybasic acids include maleic anhydride, fumaric acid, citraconic acid, itaconic acid, and HET acid. The unsaturated polybasic acids can be used alone or in combination.

[0018] Among these, maleic anhydride or fumaric acid is preferred from the viewpoint of excellent heat resistance, mechanical strength, resin fluidity during molding, and the like.

[0019] The saturated polybasic acid, which is an optional raw material for the unsaturated polyester, is not particularly limited, and known ones can be used. Examples of saturated polybasic acids include phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, tetrachlorophthalic anhydride, and tetrabromophthalic anhydride. The saturated polybasic acids can be used alone or in combination.

[0020] Unsaturated polyesters can be synthesized by known methods using the raw materials described above. The various conditions for synthesizing unsaturated polyesters can be appropriately set depending on the raw materials and their amounts used. A typical example is a method in which esterification is carried out in a stream of inert gas such as nitrogen gas at a temperature of 140 to 230°C under pressure or reduced pressure. An esterification catalyst can be used in the esterification reaction, if necessary. Examples of the esterification catalyst include known catalysts such as manganese acetate, dibutyltin oxide, stannous oxalate, zinc acetate, and cobalt acetate. The esterification catalysts can be used alone or in combination.

[0021] The weight-average molecular weight (MW) of the unsaturated polyester is not particularly limited. It is preferably 3,000 to 25,000, more preferably 5,000 to 20,000, and even more preferably 7,000 to 18,000. In the present disclosure, the term "weight-average molecular weight" refers to a value measured using gel permeation chromatography (Shodex (registered trademark) GPC-101, Showa Denko K.K.) at room temperature (23°C) under the following conditions and determined using a standard polystyrene calibration curve. Column: LF-804 (Showa Denko K.K.) Column temperature: 40℃ Sample: 0.2% by mass solution of unsaturated polyester in tetrahydrofuran Flow rate: 1mL / min Eluent: tetrahydrofuran Detector: RI-71S

[0022] The crosslinking agent (reactive diluent) for dissolving the unsaturated polyester is not particularly limited as long as it has an ethylenically unsaturated bond polymerizable with the unsaturated polyester, and any known crosslinking agent in the technical field of the present invention can be used. Examples of crosslinking agents include styrene monomer, diallyl phthalate monomer, diallyl phthalate prepolymer, methyl methacrylate, and triallyl isocyanurate. These may be used alone or in combination.

[0023] The content of the crosslinking agent (reactive diluent) in the (a) unsaturated polyester resin is not particularly limited, but from the viewpoints of workability, polymerizability, shrinkage of molded bodies, and the degree of freedom in adjusting the amount, the content of the crosslinking agent (reactive diluent) in the (a) unsaturated polyester resin is preferably 25 to 70 mass %, more preferably 30 to 68 mass %, and even more preferably 35 to 65 mass %, based on the total mass of the unsaturated polyester and the crosslinking agent.

[0024] (a) The unsaturated polyester resin may contain a polymerization inhibitor such as hydroquinone, if necessary.

[0025] [(b) Inorganic filler] In one embodiment of the unsaturated polyester resin composition, the content of the inorganic filler is set within a specific range, and the inorganic filler contains fillers having three different average particle sizes in a specific ratio.

[0026] The type of (b) inorganic filler is not particularly limited, and any filler known in the technical field of the present invention can be used. Examples of (b) inorganic fillers include calcium carbonate, silica, alumina, aluminum hydroxide, barium sulfate, wollastonite, clay, talc, mica, gypsum, silicic anhydride, and glass powder. These can be used alone or in combination. Among these, it is preferable to use at least calcium carbonate from the viewpoints of surface smoothness of the resulting molded article, cost reduction, and ease of availability.

[0027] (b) The shape of the inorganic filler is not particularly limited, and examples thereof include substantially spherical, ellipsoidal, scaly, and amorphous shapes.

[0028] (b) The true specific gravity of the inorganic filler is not particularly limited, but is preferably 1 to 10 g / cm 3 and more preferably 1.5 to 8 g / cm 3 and more preferably 2 to 5 g / cm 3 is.

[0029] The true specific gravity of the inorganic filler is 1g / cm 3 If the ratio is 10 g / cm or more, the mechanical properties of the resulting molded body will be better, and the true specific gravity of the inorganic filler will be 10 g / cm or more. 3 If it is less than this, the kneadability of the unsaturated polyester resin composition will be better.

[0030] The blending amount of (b) inorganic filler is 250 to 600 parts by mass, more preferably 300 to 550 parts by mass, and even more preferably 350 to 450 parts by mass, per 100 parts by mass of (a) unsaturated polyester resin.

[0031] When the blending amount of (b) inorganic filler is 250 parts by mass or more, the mechanical properties of the obtained molded article are better. When the blending amount of (b) inorganic filler is 600 parts by mass or less, the (b) inorganic filler is more uniformly dispersed in the unsaturated polyester resin composition, and therefore a homogeneous molded article can be produced.

[0032] The (b) inorganic filler is a combination of at least three types: (b1) an inorganic filler having an average particle size of 0.5 to 5.0 μm (hereinafter also referred to as "(b1) inorganic filler"), (b2) an inorganic filler having an average particle size of 6.0 to 50.0 μm (hereinafter also referred to as "(b2) inorganic filler"), and (b3) an inorganic filler having an average particle size of 70.0 μm or more (hereinafter also referred to as "(b3) inorganic filler").

[0033] By using at least three inorganic fillers (b1) to (b3) having different average particle sizes in combination, the flowability of the unsaturated polyester resin composition during molding can be improved, and the resulting molded article can have excellent appearance, dimensional accuracy, and strength properties, and can also have reduced burrs on the molded article.

[0034] In the present disclosure, the "average particle size" of (b) the inorganic filler means the particle size calculated from the specific surface area determined by the air permeability method according to the following formula: Average particle diameter [μm]=(6×10000) / (true specific gravity [g / cm 3 ]×Specific surface area [cm 2 / g])

[0035] The average particle size of the (b1) inorganic filler is preferably 0.7 μm or more, more preferably 1.0 μm or more. The average particle size of the (b1) inorganic filler is preferably 4.0 μm or less, more preferably 3.0 μm or less. By using the (b1) inorganic filler, a molded product with excellent appearance and strength can be obtained.

[0036] The average particle size of the (b2) inorganic filler is preferably 6.5 μm or more, more preferably 7.0 μm or more. The average particle size of the (b2) inorganic filler is preferably 40.0 μm or less, more preferably 30.0 μm or less. By using the (b2) inorganic filler, it is possible to obtain a molded product that has excellent appearance and strength properties while reducing burrs.

[0037] The average particle size of the (b3) inorganic filler is preferably 100 μm or more, more preferably 200 μm or more. The average particle size of the (b3) inorganic filler is preferably 500 μm or less, more preferably 400 μm or less, and even more preferably 360 μm or less. By using the (b3) inorganic filler, a molded product with reduced burrs can be obtained.

[0038] The inorganic fillers (b1) to (b3) are contained in a ratio of (b1):(b2):(b3) of 60-75:7-15:15-30 relative to 100% by mass of the total of the inorganic fillers (b1), (b2), and (b3). In order to further reduce burrs in the obtained molded article and to achieve excellent surface smoothness and mechanical strength, the ratio is preferably 60-70:10-15:20-25.

[0039] By setting the mass ratio of the inorganic fillers (b1) to (b3) within the above range, it is possible to obtain a molded body that has excellent appearance and strength properties, while also reducing burrs. If the mass ratio is outside the above range, any one of the appearance, strength properties, and burr reduction properties of the molded body will be impaired.

[0040] [(c) Metal soap] (c) Metal soap is a component generally used as a mold release agent in the technical field of the present invention. There are no particular limitations on the (c) metal soap, and any known metal soap in the technical field of the present invention can be used. Examples of (c) metal soap include calcium stearate, zinc stearate, aluminum stearate, and magnesium stearate. (c) Metal soaps can be used alone or in combination.

[0041] The blending amount of (c) metal soap is not particularly limited, but is preferably 1 to 15 parts by mass, and more preferably 2 to 10 parts by mass, per 100 parts by mass of (a) unsaturated polyester resin.

[0042] If the blending amount of (c) metal soap is 1 part by mass or more, the mold releasability of the obtained molded article will be better. On the other hand, if the blending amount of (c) metal soap is 15 parts by mass or less, bleeding of (c) metal soap onto the surface of the molded article can be prevented, and thus a molded article that satisfies the desired fogging properties and applicability of the undercoat agent can be obtained.

[0043] [(d) Low-shrinkage agent] The (d) low shrinkage agent is not particularly limited, and any agent known in the technical field of the present invention can be used. Examples of low shrinkage agents include thermoplastic polymers commonly used as low shrinkage agents, such as polystyrene, polymethyl methacrylate, polyvinyl acetate, saturated polyester, and styrene-butadiene rubber. The (d) low shrinkage agents can be used alone or in combination of two or more.

[0044] The content of the (d) low shrinkage agent is preferably 10 to 40 parts by mass, and more preferably 20 to 35 parts by mass, per 100 parts by mass of the (a) unsaturated polyester resin. If the amount of the (d) low shrinkage agent is 10 parts by mass or more, the shrinkage rate of the molded article is small, and the desired dimensional accuracy can be obtained. On the other hand, if the amount of the (d) low shrinkage agent is 40 parts by mass or less, the mechanical properties of the molded article are improved.

[0045] [(e) Fiber reinforcement] (e) The fiber reinforcement is a material with an aspect ratio of 3 or more. The aspect ratio can be measured by the microscopic method described in Japanese Industrial Standard JIS Z 8900-1:2008 "Particles for Calibration of Particle Size Measuring Devices."

[0046] The (e) fiber reinforcing material is not particularly limited, and any material known in the technical field of the present invention can be used. Examples of the (e) fiber reinforcing material include various organic and inorganic fibers such as glass fiber, pulp, polyethylene terephthalate fiber, vinylon fiber, carbon fiber, aramid fiber, and wollastonite. Among these, glass fiber is preferred, and chopped strand glass cut to a fiber length of about 1.5 to 25 mm is more preferred.

[0047] The content of the (e) fiber reinforcement is preferably 70 to 120 parts by mass, and more preferably 75 to 100 parts by mass, per 100 parts by mass of the (a) unsaturated polyester resin. If the blending amount of the (e) fiber reinforcement is 70 parts by mass or more, the mechanical properties of the molded article will be better. On the other hand, if the blending amount of the (e) fiber reinforcement is 120 parts by mass or less, the (e) fiber reinforcement will be more uniformly dispersed in the unsaturated polyester resin composition, allowing the production of a homogeneous molded article.

[0048] [(f) Hardener] The (f) curing agent is not particularly limited as long as it is a radical polymerization initiator capable of polymerizing ethylenically unsaturated bonds, and any known curing agent in the technical field of the present invention can be used. Examples of the (f) curing agent include organic peroxides such as 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. The (f) curing agents can be used alone or in combination of two or more.

[0049] The content of the (f) curing agent is not particularly limited and may be appropriately set depending on the raw materials used. The content of the (f) curing agent is preferably 1 to 10 parts by mass, more preferably 1 to 8 parts by mass, and even more preferably 1 to 5 parts by mass, relative to 100 parts by mass of the (a) unsaturated polyester resin.

[0050] [Other ingredients] In addition to the above components, the unsaturated polyester resin composition of the present invention may contain components known in the technical field of the present invention, such as thickeners, pigments, and viscosity reducers, to the extent that the effects of the present invention are not impaired.

[0051] The thickener is not particularly limited, but examples thereof include metal oxides other than (b) inorganic fillers, such as magnesium oxide, magnesium hydroxide, calcium hydroxide, and calcium oxide, and isocyanate compounds. The thickeners may be used alone or in combination of two or more.

[0052] [Method of producing unsaturated polyester resin composition] The unsaturated polyester resin composition can be produced by a method commonly used in the technical field of the present invention, for example, by kneading the components using a kneader or the like.

[0053] [Method for producing a molded article of an unsaturated polyester resin composition] The unsaturated polyester resin composition can be molded into a desired shape and cured to produce a molded article. The molding and curing methods are not particularly limited, and include methods commonly used in the technical field of the present invention, such as compression molding, transfer molding, and injection molding. [Example]

[0054] EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0055] <(a) Preparation of Unsaturated Polyester Resin> A four-neck flask equipped with a thermometer, a stirrer, an inert gas inlet, and a reflux condenser was charged with 0.93 kg (9.5 mol) of maleic anhydride, 0.07 kg (0.5 mol) of phthalic anhydride, and 0.76 kg (10 mol) of propylene glycol. The mixture was then heated to 200°C with stirring under a nitrogen gas stream to carry out an esterification reaction, yielding an unsaturated polyester. The resulting unsaturated polyester had an unsaturation degree of 95 mol% and a weight-average molecular weight of 8,000. Styrene monomer was then added to the resulting unsaturated polyester in an amount of 30% by mass relative to the total mass of the unsaturated polyester and the styrene monomer, yielding (a) an unsaturated polyester resin.

[0056] <Examples 1 to 2, Comparative Examples 1 to 7> The materials constituting the unsaturated polyester resin composition were charged according to the formulation shown in Table 1 and kneaded using a double-arm kneader at 25°C for 30 minutes to obtain an unsaturated polyester resin composition. The unsaturated polyester resin (a) shown in Table 1 was obtained by the above method and contains 30% by mass of styrene monomer.

[0057] <Material> The materials used in the examples and comparative examples are as follows. (b) Inorganic filler (b1) Calcium carbonate (S-1200BM, Bihoku Funka Kogyo Co., Ltd., average particle size: 1.8 μm, true specific gravity: 2.7 g / cm 3 ) (b2) Calcium carbonate (Tankal R heavy carbon, Maruo Calcium Co., Ltd., average particle size: 7.4 μm, true specific gravity: 2.7 g / cm 3 ) (b3) Calcium carbonate (Kansuiseki KD-70, Calfine Co., Ltd., average particle size: 300 μm, true specific gravity: 2.7 g / cm 3 ) (c) Metal soap Calcium stearate (Tannan Chemical Industry Co., Ltd.) (d) Low-shrinkage agent Polystyrene (weight average molecular weight 200,000, Sekisui Plastics Co., Ltd.) (e) Fiber reinforcement Chopped strand glass (fiber length: 9 mm, Nippon Electric Glass Co., Ltd.) (f) Hardener t-Butyl peroxybenzoate (NOF Corporation)

[0058] <Evaluation> The unsaturated polyester resin compositions obtained in the Examples and Comparative Examples were measured or evaluated for kneadability, in-mold flowability of the resin composition, surface smoothness of the molded product, molding shrinkage, strength properties (flexural strength and flexural modulus), and flowability using a thin-walled flow mold to confirm low flash. The measurement and evaluation methods were as follows. The results are shown in Table 1.

[0059] (1) Mixability When preparing the unsaturated polyester resin composition (kneading for 30 minutes at 25°C using a double-arm kneader), whether or not a uniform unsaturated polyester resin composition without poor dispersion was obtained was visually evaluated. The evaluation criteria are shown below. Good: The unsaturated polyester resin composition is uniform. Poor: The unsaturated polyester resin composition is poorly dispersed.

[0060] (2) In-mold flowability of resin composition A spiral flow mold (cross-sectional shape: trapezoidal with an upper side of 6 mm, a base of 8 mm, and a height of 2 mm) was attached to a transfer molding machine (Technomarushi Co., Ltd.), and a spiral flow test was performed under conditions of a mold temperature of 150°C and an injection pressure of 10 MPa to measure the flow length (cm). The measurement results and evaluation results are shown in Table 1. A flow length of 30 cm or more indicates good in-mold fluidity of the resin composition.

[0061] (3) Molded product surface smoothness Using a transfer molding machine (Technomarushi Co., Ltd.), transfer molded articles (φ117 mm, thickness 3 mm) were produced under the conditions of a molding temperature of 150°C, an injection pressure of 20 MPa, and a molding time of 1 minute. The appearance of the resulting transfer molded articles was visually inspected and evaluated according to the following criteria. Good: The entire surface is glossy and has no sink marks. Poor: The surface is either entirely or partially lacking in gloss, or has sink marks either entirely or partially.

[0062] (4) Mold shrinkage rate Using a compression molding machine (Technomarushi Co., Ltd.), shrink disks (φ90 mm × 11 mm) specified in JIS K-6911 5.7 were produced by compression molding under conditions of a molding temperature of 160°C, a molding pressure of 10 MPa, and a molding time of 3 minutes, and the molding shrinkage rate (%) was calculated in accordance with JIS K-6911 5.7. The results are shown in Table 1.

[0063] (5) Strength properties (flexural strength and flexural modulus) Using a compression molding machine (Technomarushi Co., Ltd.), flexural modulus test pieces (90 mm x 10 mm x 4 mm) specified in JIS K-6911 5.17 were prepared by compression molding under conditions of a molding temperature of 150°C, a molding pressure of 10 MPa, and a molding time of 3 minutes.The flexural strength (MPa) and flexural modulus (MPa) were measured in accordance with JIS K-6911 5.17 and evaluated according to the following criteria.The measurement results and strength property evaluation results are shown in Table 1. Good: Flexural strength is 130 MPa or more and flexural modulus is 13 MPa or more Poor: Flexural strength is less than 130 MPa or flexural modulus is less than 13 MPa

[0064] (6) Thin-wall fluidity (burr evaluation) To evaluate flashing, a transfer molding machine (Technomarushi Co., Ltd.) was used to produce a transfer molding product under the conditions of a molding temperature of 150°C, an injection pressure of 20 MPa, and a molding time of 1 minute. The length (mm) of flashing generated on the resulting transfer molding product was measured and evaluated according to the following criteria. The measurement results and flash evaluation results are shown in Table 1. Good: No burrs of 20 mm or more have occurred in the 140 μm gap of the mold. Defective: A burr of 20 mm or more occurred in the 140 μm gap of the mold.

[0065] [Table 1] [Industrial Applicability]

[0066] According to the present invention, it is possible to provide an unsaturated polyester resin composition which has good resin flowability during molding, and which can give a molded product which is excellent in appearance, dimensional accuracy, and strength and has reduced burrs.

Claims

1. An unsaturated polyester resin composition comprising: (a) an unsaturated polyester resin; (b) an inorganic filler; (c) a metal soap; (d) a low-profile agent; (e) a fiber reinforcement; and (f) a curing agent, the content of the (b) inorganic filler is 250 to 600 parts by mass relative to 100 parts by mass of the (a) unsaturated polyester resin, The (b) inorganic filler comprises (b1) an inorganic filler having an average particle size of 0.5 to 5.0 μm, (b2) an inorganic filler having an average particle size of 6.0 to 50.0 μm, and (b3) an inorganic filler having an average particle size of 70.0 μm or more and 360 μm or less, in a ratio of (b1):(b2):(b3)=60 to 75:7 to 15:15 to 30, relative to 100% by mass of the total of the inorganic fillers (b1), (b2), and (b3); The content of the (e) fiber reinforcing material is 70 to 120 parts by mass per 100 parts by mass of the (a) unsaturated polyester resin. Unsaturated polyester resin composition.

2. 2. The unsaturated polyester resin composition according to claim 1, wherein the content of the inorganic filler (b) is 350 to 450 parts by mass per 100 parts by mass of the unsaturated polyester resin (a).

3. 3. The unsaturated polyester resin composition according to claim 1, wherein the inorganic filler (b) comprises calcium carbonate.

4. A molded article comprising a cured product of the unsaturated polyester resin composition according to any one of claims 1 to 3.

Images