Unsaturated polyester resin composition, molding material, and molded article

Abstract

An unsaturated polyester resin composition according to the present invention comprises a resin component that contains: an unsaturated polyester which is a reaction product of polybasic acid and polyhydric alcohol; and a polymerizable monomer which contains a styrene-based monomer and a polyfunctional (meth)acrylic acid ester. The polybasic acid includes polybasic acid having an unsaturated double bond. The unsaturated double bond concentration (A) of the unsaturated polyester is not more than 3.00 mmol / g. The unsaturated polyester resin composition satisfies formula (1). (1): (Unsaturated double bond concentration (B) of styrene-based monomer × mixed amount of styrene-based monomer / mixed amount of resin component × 100) / (unsaturated double bond concentration (A) of unsaturated polyester × mixed amount of unsaturated polyester / mixed amount of resin component × 100) > 2.00

Description

Unsaturated polyester resin composition, molding material, and molded article

[0001] The present invention relates to an unsaturated polyester resin composition, a molding material, and a molded article, and more specifically relates to an unsaturated polyester resin composition, a molding material comprising the unsaturated polyester resin composition, and a molded article comprising a cured product of the molding material.

[0002] Conventionally, molded articles formed from molding materials containing an unsaturated polyester resin composition (especially sheet molding compound (SMC), bulk molding compound (BMC), and thick molding compound (TMC)) are used in a wide range of fields because they are particularly excellent in mechanical properties, water resistance, electrical insulation, and corrosion resistance.

[0003] On the other hand, molded articles are required to have flexibility depending on their applications and purposes.

[0004] In such cases, it has been studied to reduce the unsaturated double bond concentration of the unsaturated polyester resin in the unsaturated polyester resin composition. This allows the crosslinking density to be lowered, and as a result, flexibility can be improved.

[0005] As such an unsaturated polyester resin composition, for example, a thermosetting molding material for press-fit molded articles comprising an unsaturated polyester resin having a double bond concentration of 2.0 mmol / g or less has been proposed (see, for example, Example 1 of Patent Document 1 below).

[0006] Japanese Patent Laid-Open No. 2004-161813

[0007] On the other hand, from the viewpoint of workability, unsaturated polyester is prepared by dissolving it in a large amount of styrene monomer.

[0008] At this time, if the unsaturated double bond concentration is high, most of the styrene monomer reacts with the unsaturated double bonds derived from the unsaturated polyester, so almost no styrene monomer remains in the molded article obtained using this unsaturated polyester resin composition. Therefore, the amount of residual styrene monomer can be reduced.

[0009] On the other hand, as mentioned above, when the concentration of unsaturated double bonds is reduced from the viewpoint of flexibility, the reaction between the styrene monomer and the unsaturated double bonds derived from the unsaturated polyester decreases, and most of the styrene monomer remains. As a result, molded articles obtained using this unsaturated polyester resin composition have the drawback of having a large amount of residual styrene monomer.

[0010] The present invention provides an unsaturated polyester resin composition that is excellent in flexibility and workability and can reduce the amount of residual styrene monomer, a molding material containing the unsaturated polyester resin composition, and a molded article containing a cured product of the molding material.

[0011] The present invention [1] is an unsaturated polyester resin composition comprising a resin component containing an unsaturated polyester and a polymerizable monomer, wherein the unsaturated polyester is a reaction product of a polybasic acid and a polyhydric alcohol, the polybasic acid includes a polybasic acid having an unsaturated double bond, the polymerizable monomer includes a styrene monomer and a polyfunctional (meth)acrylic acid ester, the unsaturated double bond concentration (A) of the unsaturated polyester is 3.00 mmol / g or less, and satisfies the following formula (1): (Unsaturated double bond concentration of styrene monomer (B) × Amount of styrene monomer / Amount of resin component × 100) / (Unsaturated double bond concentration of unsaturated polyester (A) × Amount of unsaturated polyester / Amount of resin component × 100) > 2.00 (1)

[0012] The present invention [2] includes the unsaturated polyester resin composition described in [1] above, which satisfies the following formula (2): (Unsaturated double bond concentration of styrene monomer (B) × Amount of styrene monomer / Amount of resin component × 100) / (Unsaturated double bond concentration of unsaturated polyester (A) × Amount of unsaturated polyester / Amount of resin component × 100 + Unsaturated double bond concentration of polyfunctional (meth)acrylic acid ester (C) × Amount of polyfunctional (meth)acrylic acid ester / Amount of resin component × 100) < 2.00 (2)

[0013] The present invention [3] includes a molding material comprising the unsaturated polyester resin composition described in [1] or [2] above and reinforcing fibers.

[0014] The present invention [4] includes a molded article comprising a cured product of the molding material described in [3] above.

[0015] In the unsaturated polyester resin composition of the present invention, the concentration (A) of unsaturated double bonds in the unsaturated polyester is 3.00 mmol / g or less. Therefore, flexibility can be improved.

[0016] Furthermore, this unsaturated polyester resin composition satisfies the following formula (1): (Unsaturated double bond concentration of styrene monomer (B) × Amount of styrene monomer / Amount of resin component × 100) / (Unsaturated double bond concentration of unsaturated polyester (A) × Amount of unsaturated polyester / Amount of resin component × 100) > 2.00 (1)

[0017] Therefore, work efficiency can be improved.

[0018] Furthermore, in this unsaturated polyester resin composition, the polymerizable monomer includes a polyfunctional (meth)acrylic acid ester. Therefore, the amount of residual styrene monomer can be reduced.

[0019] The molding material of the present invention contains the unsaturated polyester resin composition of the present invention. Therefore, molded articles obtained using this molding material exhibit excellent flexibility and allow for a reduction in the amount of residual styrene monomer.

[0020] The molded article of the present invention contains a cured product of the molding material of the present invention. Therefore, it has excellent flexibility and the amount of residual styrene monomer can be reduced.

[0021] 1. Unsaturated polyester resin composition The unsaturated polyester resin composition contains a resin component.

[0022] <Resin Components> The resin components include unsaturated polyester and polymerizable monomers.

[0023] <Unsaturated Polyesters> Unsaturated polyesters are obtained by the reaction of polybasic acids with polyhydric alcohols.

[0024] [Polybasic Acids] Polybasic acids include, as essential components, polybasic acids having an unsaturated double bond (preferably an ethylenically unsaturated bond) (hereinafter referred to as unsaturated bond-containing polybasic acids), and as optional components, polybasic acids not having an unsaturated double bond (hereinafter referred to as unsaturated bond-free polybasic acids).

[0025] (Polybasic acids containing unsaturated bonds) Examples of polybasic acids containing unsaturated bonds include ethylenically unsaturated aliphatic dibasic acids and their anhydrides, halides of ethylenically unsaturated aliphatic dibasic acids, and alkyl esters of ethylenically unsaturated aliphatic dibasic acids.

[0026] Examples of ethylenically unsaturated aliphatic dibasic acids include maleic acid, fumaric acid, itaconic acid, and dihydromuconic acid. Furthermore, polybasic acids containing unsaturated bonds include, for example, acid anhydrides derived from the above-mentioned ethylenically unsaturated aliphatic dibasic acids. An example of an acid anhydride derived from ethylenically unsaturated aliphatic dibasic acids is maleic anhydride.

[0027] Examples of polybasic acids containing unsaturated bonds include maleic anhydride and fumaric acid.

[0028] (Polybasic acids without unsaturated bonds) Examples of polybasic acids without unsaturated bonds include saturated aliphatic polybasic acids, saturated alicyclic polybasic acids, aromatic polybasic acids, anhydrides of these acids, halides of these acids, and alkyl esters of these acids.

[0029] Examples of saturated aliphatic polybasic acids include saturated aliphatic dibasic acids.

[0030] Examples of saturated aliphatic dibasic acids include saturated aliphatic dibasic acids having 2 to 7 carbon atoms, and saturated aliphatic dibasic acids having 8 or more carbon atoms.

[0031] Examples of saturated aliphatic dibasic acids having 2 to 7 carbon atoms include oxalic acid, malonic acid, succinic acid, methylsuccinic acid, 2,2-dimethylsuccinic acid, 2,3-dimethylsuccinic acid, 3,3-dimethylsuccinic acid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid, 2,2-dimethylglutaric acid, adipic acid, and pimelic acid.

[0032] Examples of saturated aliphatic dibasic acids having 8 or more carbon atoms include linear saturated aliphatic dibasic acids having 8 or more carbon atoms. Examples of linear saturated aliphatic dibasic acids having 8 or more carbon atoms include suberic acid, azelaic acid, and sebacic acid. Preferably, sebacic acid is given as a linear saturated aliphatic dibasic acid having 8 or more carbon atoms.

[0033] Furthermore, saturated aliphatic polybasic acids include acid anhydrides derived from the saturated aliphatic dibasic acids mentioned above. Examples of acid anhydrides derived from saturated aliphatic dibasic acids include oxalic anhydride and succinic anhydride.

[0034] From the viewpoint of water resistance, saturated aliphatic polybasic acids preferably include saturated aliphatic dibasic acids having 8 or more carbon atoms.

[0035] From the viewpoint of water resistance, the content of saturated aliphatic dibasic acids having 8 or more carbon atoms is, for example, 30 mol% to 70 mol%, preferably 50 mol% to 65 mol%, per 100 moles of total polybasic acids.

[0036] The content of saturated aliphatic polybasic acids is 20 mol% to 70 mol%, preferably 50 mol% to 65 mol%, based on 100 moles of total polybasic acids.

[0037] Examples of saturated alicyclic polybasic acids include saturated alicyclic dibasic acids.

[0038] Examples of saturated alicyclic dibasic acids include het acid, 1,2-hexahydrophthalic acid, 1,1-cyclobutanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid (cis- or trans-1,4-cyclohexanedicarboxylic acid or a mixture thereof). Examples of saturated alicyclic polybasic acids include acid anhydrides derived from the above saturated alicyclic dibasic acids. An example of an acid anhydride derived from saturated alicyclic dibasic acids is het acid anhydride.

[0039] The content of saturated alicyclic polybasic acids is, for example, 10 mol% or less, preferably 5 mol% or less, more preferably 1 mol% or less, and even more preferably 0 mol%, based on 100 moles of total polybasic acids. In other words, the polybasic acids more preferably do not contain saturated alicyclic polybasic acids.

[0040] Examples of aromatic polybasic acids include aromatic dibasic acids.

[0041] Examples of aromatic dibasic acids include phthalic acids (orthophthalic acid, isophthalic acid, terephthalic acid), trimellitic acid, and pyromellitic acid. Examples of aromatic polybasic acids include acid anhydrides derived from the above aromatic dibasic acids. An example of an acid anhydride derived from an aromatic dibasic acid is phthalic anhydride. Preferably, isophthalic acid is used as the aromatic dibasic acid.

[0042] The content of aromatic polybasic acids is, for example, 10 mol% to 80 mol%, preferably 15 mol% to 72 mol%, more preferably 16 mol% to 65 mol%, even more preferably 17 mol% to 50 mol%, particularly preferably 18 mol% to 30 mol%, and most preferably 19 mol% to 23 mol%, based on 100 moles of total polybasic acids.

[0043] The unsaturated polybasic acid, free from polybasic bonds, preferably includes at least an aromatic polybasic acid. More preferably, the unsaturated polybasic acid, free from polybasic bonds, includes a saturated aliphatic polybasic acid and an aromatic polybasic acid. Even more preferably, the unsaturated polybasic acid, free from polybasic bonds, includes only a saturated aliphatic polybasic acid and an aromatic polybasic acid.

[0044] The polybasic acid may be used alone or in combination of two or more kinds.

[0045] When the polybasic acid includes an unsaturated bond-containing polybasic acid and an unsaturated bond-free polybasic acid, the content of the unsaturated bond-containing polybasic acid relative to 100 mol of the total polybasic acid is, for example, 10 mol% to 45 mol%, preferably 12 mol% to 35 mol%, more preferably 15 mol% to 20 mol%. The content of the unsaturated bond-free polybasic acid is, for example, 55 mol% to 90 mol%, preferably 65 mol% to 88 mol%, more preferably 80 mol% to 85 mol%.

[0046] The polybasic acid preferably consists of an unsaturated bond-containing polybasic acid and an unsaturated bond-free polybasic acid.

[0047] [Polyhydric Alcohol] Examples of the polyhydric alcohol include dihydric alcohols and trihydric alcohols.

[0048] (Dihydric Alcohol) Examples of the dihydric alcohol include aliphatic diols, alicyclic diols, and aromatic diols.

[0049] Examples of the aliphatic diol include alkane diols and ether diols.

[0050] Examples of the alkane diol include alkane diols having 2 to 10 carbon atoms. Examples of the alkane diol having 2 to 10 carbon atoms include ethylene glycol, propylene glycol (1,2- or 1,3-propanediol, or a mixture thereof), butylene glycol (1,2- or 1,3- or 1,4-butylene glycol, or a mixture thereof), 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2,2-trimethylpentanediol, and 3,3-dimethylolheptane. Propylene glycol is preferable as the alkane diol.

[0051] Examples of ether diols include diethylene glycol, triethylene glycol, and dipropylene glycol. Diethylene glycol is preferred as the ether diol.

[0052] Examples of alicyclic diols include cyclohexanediol (1,2- or 1,3- or 1,4-cyclohexanediol or mixtures thereof), cyclohexanedimethanol (1,2- or 1,3- or 1,4-cyclohexanedimethanol or mixtures thereof), cyclohexanediethanol (1,2- or 1,3- or 1,4-cyclohexanediethanol or mixtures thereof), and hydrogenated bisphenol A.

[0053] Examples of aromatic diols include ethylene oxide adducts of bisphenol A and propylene oxide adducts of bisphenol A.

[0054] (Trihydric alcohols) Examples of trihydric alcohols include glycerin, trimethylolpropane, and triisopropanolamine.

[0055] Preferably, dihydric alcohols are used as polyhydric alcohols. More preferably, aliphatic diols are used as polyhydric alcohols.

[0056] Polyhydric alcohols can be used alone or in combination of two or more types.

[0057] [Reaction of polybasic acids with polyhydric alcohols] Unsaturated polyesters are prepared by reacting polybasic acids with polyhydric alcohols.

[0058] The equivalent ratio of the polyhydric alcohol to the polybasic acid (hydroxyl group of the polyhydric alcohol / carboxyl group of the polybasic acid) is, for example, 0.9 to 1.2, preferably 0.95 to 1.1.

[0059] The reaction temperature is, for example, 150°C to 250°C, preferably 190°C to 230°C.

[0060] In addition, known solvents and known reaction catalysts may be added to the above reaction as needed.

[0061] This process prepares unsaturated polyester.

[0062] The concentration of unsaturated double bonds (A) in the unsaturated polyester is 3.00 mmol / g or less, preferably 2.50 mmol / g or less, more preferably 2.00 mmol / g or less, even more preferably 1.50 mmol / g or less, particularly preferably 1.30 mmol / g or less, most preferably 1.00 mmol / g or less, and also, for example, 0.10 mmol / g or more, preferably 0.50 mmol / g or more.

[0063] If the concentration of unsaturated double bonds (A) in the unsaturated polyester is below the above upper limit, the crosslinking density can be reduced, and as a result, flexibility can be improved.

[0064] On the other hand, if the concentration of unsaturated double bonds (A) in unsaturated polyester exceeds the above upper limit, the crosslinking density increases, resulting in a decrease in flexibility.

[0065] The concentration of unsaturated double bonds (A) in unsaturated polyester can be calculated using the following formula (3): Concentration of unsaturated double bonds (A) (millimoles / g) = (Number of moles of polybasic acid containing unsaturated bonds) / (Amount of polybasic acid and polyhydric alcohol used - Water obtained from the reaction of polybasic acid and polyhydric alcohol) (3)

[0066] The acid value of unsaturated polyester (measurement method: in accordance with JIS K6901 (2008)) is, for example, 5 mg KOH / g to 40 mg KOH / g, preferably 10 mg KOH / g to 30 mg KOH / g, and more preferably 20 mg KOH / g to 30 mg KOH / g.

[0067] The weight-average molecular weight of the unsaturated polyester is, for example, 2,000 to 25,000, preferably 4,000 to 20,000.

[0068] Note that the weight-average molecular weight is the weight-average molecular weight converted to polystyrene using GPC (gel permeation chromatography).

[0069] The content of unsaturated polyester is, for example, 55% to 90% by mass, preferably 65% ​​to 85% by mass, and more preferably 70% to 80% by mass, relative to the resin component.

[0070] Unsaturated polyesters can be used alone or in combination of two or more types.

[0071] <Polymerizable Monomers> Polymerizable monomers include styrene monomers and polyfunctional (meth)acrylic acid esters. (Meth)acrylic includes acrylic and methacrylic (the same applies hereinafter).

[0072] If the polymerizable monomer includes a polyfunctional (meth)acrylic acid ester, the amount of residual styrene monomer in a molded article obtained using an unsaturated polyester resin composition can be reduced.

[0073] [Styrene-based monomers] Examples of styrene-based monomers include styrene, vinyltoluene, t-butylstyrene, and chlorostyrene. Styrene is preferred as the styrene-based monomer.

[0074] The concentration of unsaturated double bonds (B) of the styrene monomer is, for example, 8.00 mmol / g to 11.00 mmol / g, preferably 9.00 mmol / g to 10.00 mmol / g.

[0075] The concentration of unsaturated double bonds (B) in styrene monomers can be calculated using the following formula (4): Concentration of unsaturated double bonds (B) (millimoles / g) = (Number of unsaturated double bonds) / (Molecular weight of styrene monomer) × 1000 (4)

[0076] The content of styrene monomer is, for example, 60 to 92 parts by mass, preferably 65 to 85 parts by mass, more preferably 70 to 82 parts by mass, and even more preferably 75 to 80 parts by mass, based on 100 parts by mass of the total amount of styrene monomer and polyfunctional (meth)acrylic acid ester.

[0077] The content of styrene monomer is, from the viewpoint of flexibility, for example, 35 parts by mass or less, preferably 30 parts by mass or less, more preferably 25 parts by mass or less, or for example, 10 parts by mass or more, preferably 15 parts by mass or more, based on 100 parts by mass of the total amount of unsaturated polyester and styrene monomer.

[0078] The content of styrene monomers is, for example, 60% to 92% by mass, preferably 65% ​​to 85% by mass, more preferably 70% to 82% by mass, and even more preferably 75% to 80% by mass, relative to the polymerizable monomer.

[0079] Styrene monomers can be used alone or in combination of two or more types.

[0080] [Polyfunctional (meth)acrylic acid esters] Examples of polyfunctional (meth)acrylic acid esters include difunctional (meth)acrylic acid esters, trifunctional (meth)acrylic acid esters, and trifunctional or more (meth)acrylic acid esters.

[0081] Examples of difunctional (meth)acrylic acid esters include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, and polyethylene glycol di(meth)acrylate.

[0082] Examples of trifunctional (meth)acrylic acid esters include trimethylolpropane tri(meth)acrylate.

[0083] Examples of trifunctional or more (meth)acrylic acid esters include pentaerythritol tetra(meth)acrylate and dipentaerythritol hexa(meth)acrylate.

[0084] Preferably, a trifunctional (meth)acrylic acid ester is used as a polyfunctional (meth)acrylic acid ester. More preferably, trimethylolpropane trimethacrylate is used as a polyfunctional (meth)acrylic acid ester.

[0085] The unsaturated double bond concentration (C) of the polyfunctional (meth)acrylic acid ester is, for example, 8.00 mmol / g to 12.00 mmol / g, preferably 8.30 mmol / g to 11.00 mmol / g, more preferably 8.50 mmol / g to 10.00 mmol / g, and even more preferably 8.60 mmol / g to 9.00 mmol / g.

[0086] The concentration of unsaturated double bonds (C) in polyfunctional (meth)acrylic acid esters can be calculated using the following formula (5): Concentration of unsaturated double bonds (C) (millimoles / g) = (number of unsaturated double bonds) / (molecular weight of polyfunctional (meth)acrylic acid ester) × 1000 (5)

[0087] The content of the polyfunctional (meth)acrylic acid ester is, for example, 8 to 40 parts by mass, preferably 15 to 35 parts by mass, more preferably 18 to 30 parts by mass, and even more preferably 20 to 25 parts by mass, based on 100 parts by mass of the total amount of styrene monomer and polyfunctional (meth)acrylic acid ester.

[0088] The content of the polyfunctional (meth)acrylic acid ester is, for example, 8% to 40% by mass, preferably 15% to 35% by mass, more preferably 18% to 30% by mass, and even more preferably 20% to 25% by mass, relative to the polymerizable monomer.

[0089] Polyfunctional (meth)acrylic acid esters can be used alone or in combination of two or more types.

[0090] [Monofunctional (meth)acrylic acid esters] Polymerizable monomers may also include monofunctional (meth)acrylic acid esters.

[0091] Examples of monofunctional (meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate), 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, and stearyl (meth)acrylate.

[0092] The content of monofunctional (meth)acrylic acid ester is, for example, 10% by mass or less, preferably 5% by mass or less, more preferably 1% by mass or less, and even more preferably 0% by mass, relative to the polymerizable monomer. In other words, the polymerizable monomer is more preferably free of monofunctional (meth)acrylic acid ester and consists of styrene monomers and polyfunctional (meth)acrylic acid ester.

[0093] Monofunctional (meth)acrylic acid esters can be used alone or in combination of two or more types.

[0094] The content of polymerizable monomers is, for example, 10% to 45% by mass, preferably 15% to 35% by mass, and more preferably 20% to 30% by mass, relative to the resin component.

[0095] <Low-shrinkage agent> The resin component may also contain a low-shrinkage agent if necessary.

[0096] Shrinkage reducers are added to suppress curing shrinkage and thermal shrinkage, thereby improving appearance.

[0097] Examples of low-shrinkage agents include polyethylene, polystyrene, crosslinked polystyrene, polyvinyl acetate-polystyrene block copolymer, polyvinyl acetate, polymethyl methacrylate, styrene-based thermoplastic elastomers, and saturated polyester resins.

[0098] Furthermore, the low-shrinkage agent can also be dissolved in the polymerizable monomer to prepare a polymerizable monomer solution of the low-shrinkage agent.

[0099] In a polymerizable monomer solution of a low-shrinkage agent, the solid content concentration of the low-shrinkage agent is, for example, 20% by mass or more, and for example, 70% by mass or less, preferably 50% by mass or less.

[0100] The content of the low-shrinkage agent is, for example, 10% by mass or less, preferably 5% by mass or less, more preferably 1% by mass or less, and even more preferably 0% by mass, relative to the resin component. In other words, the resin component is even more preferably free of the low-shrinkage agent and consists of an unsaturated polyester and a polymerizable monomer.

[0101] Shrinkage-reducing agents can be used alone or in combination of two or more types.

[0102] <Additives> The unsaturated polyester resin composition may contain additives as needed, to the extent that they do not impair the effects of the present invention.

[0103] Examples of additives include fillers, release agents, curing agents, polymerization inhibitors, thickeners, flame retardants, colorants, wetting and dispersing agents, patterning agents, antibacterial agents, hydrophilic agents, photocatalysts, UV absorbers, UV stabilizers, separation inhibitors, silane coupling agents, antistatic agents, thixotropic agents, thixotropic stabilizers, and polymerization accelerators. Additives can be used individually or in combination of two or more.

[0104] [Fillers] Examples of fillers include inorganic fillers. Examples of inorganic fillers include oxides (e.g., alumina, titanium oxide), hydroxides (e.g., magnesium hydroxide, aluminum hydroxide), carbonates (e.g., calcium carbonate), sulfates (e.g., barium sulfate), silica (e.g., crystalline silica, fused silica, fumed silica, dry silica (aerosil)), hollow fillers, silicates (e.g., silica sand, diatomaceous earth, glass powder, glass balloons, mica, clay, kaolin, talc), fluorides (e.g., fluorite), phosphates (e.g., calcium phosphate), metal powders, ceramics, milled fibers, and clay minerals (e.g., smectite). Preferably, fillers include hydroxides and carbonates. More preferably, fillers include hydroxides. Even more preferably, fillers include aluminum hydroxide.

[0105] The proportion of the filler is, for example, 40 to 600 parts by mass, preferably 50 to 300 parts by mass, and more preferably 70 to 200 parts by mass, per 100 parts by mass of the resin component.

[0106] The fillers can be used individually or in combination of two or more types.

[0107] [Release Agents] Examples of release agents include fatty acids, fatty acid metal salts, liquid waxes, fluoropolymers, and silicone polymers. Examples of fatty acids include stearic acid and lauric acid. Examples of fatty acid metal salts include zinc stearate and calcium stearate.

[0108] Preferably, the release agent is a fatty acid metal salt, and more preferably, zinc stearate.

[0109] The proportion of the release agent is, for example, 1 to 10 parts by mass, preferably 3 to 8 parts by mass, per 100 parts by mass of the resin component.

[0110] Release agents can be used alone or in combination of two or more types.

[0111] [Curing agent] Examples of curing agents include peroxides. Examples of peroxides include benzoyl peroxide, t-butyl peroxyisopropyl carbonate, t-amyl peroxyisopropyl carbonate, t-hexyl peroxyisopropyl monocarbonate, 1,1-bis(t-butyl peroxy)cyclohexane, t-butyl peroxy-2-ethylhexanoate, amyl peroxy-2-ethylhexanoate, 2-ethylhexyl peroxy-2-ethylhexanoate, t-butyl peroxybenzoate, t-hexyl peroxybenzoate, and t-hexyl peroxyacetate. Preferably, t-butyl peroxyisopropyl carbonate is used as the curing agent.

[0112] The proportion of the curing agent is, for example, 0.1 to 5 parts by mass, preferably 0.5 to 2 parts by mass, per 100 parts by mass of the resin component.

[0113] The hardening agent can be used alone or in combination of two or more types.

[0114] [Polymerization inhibitors] Polymerization inhibitors adjust the pot life and curing reaction.

[0115] Examples of polymerization inhibitors include hydroquinone compounds, benzoquinone compounds, catechol compounds, phenol compounds, and N-oxyl compounds.

[0116] Preferred polymerization inhibitors include benzoquinone compounds, hydroquinone compounds, and N-oxyl compounds.

[0117] An example of a benzoquinone compound is p-benzoquinone.

[0118] Examples of hydroquinone compounds include hydroquinone, methylhydroquinone, and t-butylhydroquinone. Preferably, t-butylhydroquinone is used as the hydroquinone compound.

[0119] More preferably, benzoquinone compounds are used as polymerization inhibitors.

[0120] The polymerization inhibitor content is, for example, 0.01 to 2 parts by mass per 100 parts by mass of the resin component.

[0121] Polymerization inhibitors can be used alone or in combination of two or more types.

[0122] [Thickener] A thickener is added to increase the viscosity of the unsaturated polyester resin composition to a level suitable for heat compression molding. Preferably, the thickener is added before (preferably immediately before) impregnating the unsaturated polyester resin composition with reinforcing fibers (described later).

[0123] Examples of thickeners include alkaline earth metal oxides and alkaline earth metal hydroxides. Examples of alkaline earth metal oxides include magnesium oxide. Examples of alkaline earth metal hydroxides include magnesium hydroxide and calcium hydroxide. Furthermore, isocyanate monomers (e.g., toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI)) and their prepolymers can also be used as thickeners.

[0124] Preferably, alkaline earth metal oxides are used as thickeners. More preferably, magnesium oxide is used as a thickener.

[0125] The content ratio of the thickener is, for example, 0.1 to 20 parts by mass per 100 parts by mass of the resin component. In particular, when the thickener is an alkaline earth metal oxide and an alkaline earth metal hydroxide, the content ratio of the thickener is, for example, 0.1 to 1 part by mass per 100 parts by mass of the resin component. Furthermore, when the thickener is an isocyanate monomer and its prepolymer, the content ratio of the thickener is, for example, 0.1 to 20 parts by mass per 100 parts by mass of the resin component.

[0126] Thickening agents can be used alone or in combination of two or more types.

[0127] [Flame retardants] Examples of flame retardants (excluding aluminum hydroxide) include phosphorus-containing flame retardants, nitrogen-containing flame retardants, expanded graphite, halogen-based flame retardants, antimony trioxide, zinc stannate, and zinc borate. Preferably, the flame retardants include phosphorus-containing flame retardants, nitrogen-containing flame retardants, and expanded graphite.

[0128] Phosphorus-containing flame retardants contain phosphorus but do not contain nitrogen. Examples of phosphorus-containing flame retardants include red phosphorus, phosphate esters, polyphosphates, and phosphinate metal salts.

[0129] Examples of phosphate esters include trimethyl phosphate, triethyl phosphate, tributyl phosphate, and tricresyl phosphate.

[0130] Examples of polyphosphates include aluminum polyphosphate.

[0131] Examples of phosphinate metal salts include aluminum trisdiethylphosphinate and aluminum trismethylethylphosphinate.

[0132] Furthermore, commercially available phosphorus-containing flame retardants can be used. Specifically, the OP series (specifically Exolit OP1230 (aluminum trisdiethylphosphinate), manufactured by Clariant Chemicals) is an example.

[0133] Preferably, phosphorus-containing flame retardants include metal phosphinate salts, and more preferably, aluminum trisdiethylphosphinate.

[0134] Nitrogen-containing flame retardants contain nitrogen but do not contain phosphorus. Examples of nitrogen-containing flame retardants include triazine compounds.

[0135] Triazine compounds are compounds that have a triazine skeleton. Examples of triazine compounds include melamine, acetogyanamine, benzoguanamine, melon, melam, succinoguanamine, ethylenedimelamine, triguanamine, and melamine cyanurate.

[0136] Furthermore, commercially available nitrogen-containing flame retardants can be used. Specifically, MC-4000 (melamine cyanurate, manufactured by Nissan Chemical Corporation) is one example.

[0137] Preferably, a triazine compound is used as a nitrogen-containing flame retardant. More preferably, melamine cyanurate is used as a nitrogen-containing flame retardant.

[0138] Examples of phosphorus and nitrogen-containing flame retardants include ammonium polyphosphate and melamine polyphosphate.

[0139] Expanded graphite is a graphite intercalation compound produced by inserting sulfuric acid or other substances between the layers of flaky natural graphite. Expanded graphite expands at temperatures of approximately 150 to 300°C as the intercalations expand.

[0140] The average particle size of the expanded graphite is 150 μm or less, preferably 100 μm or less, and for example, 10 μm or more, preferably 50 μm or more.

[0141] The average particle size of expanded graphite can be determined by observing it with an optical microscope, measuring the maximum diameter (long axis) and the particle size in the direction perpendicular to the maximum diameter (short axis) for any 50 expanded graphite samples, and calculating the average value of the long and short axes.

[0142] Commercially available expanded graphite can also be used. Specifically, product number 9510045 from Ito Graphite Industry Co., Ltd. is one example.

[0143] Flame retardants can be used alone or in combination of two or more types.

[0144] The flame retardant content is, for example, 1 to 30 parts by mass per 100 parts by mass of the resin component.

[0145] <Preparation of Unsaturated Polyester Resin Composition> An unsaturated polyester resin composition is prepared by mixing a resin component with additives that are added as needed.

[0146] Furthermore, in the above preparation, an unsaturated polyester resin can also be prepared by first dissolving an unsaturated polyester in a polymerizable monomer (preferably styrene) and, if necessary, blending in the above-mentioned additives. In other words, the unsaturated polyester resin contains an unsaturated polyester and a polymerizable monomer.

[0147] Furthermore, after preparing the unsaturated polyester resin, polymerizable monomers can be added when mixing this unsaturated polyester resin with additives as needed.

[0148] This is used to prepare an unsaturated polyester resin composition.

[0149] Furthermore, the unsaturated polyester resin composition satisfies the following formula (6): (Unsaturated double bond concentration of styrene monomer (B) × Amount of styrene monomer / Amount of resin component × 100) / (Unsaturated double bond concentration of unsaturated polyester (A) × Amount of unsaturated polyester / Amount of resin component × 100) > 2.00 (6)

[0150] In the above equation (6), the left side is an index (which may be referred to as the index (B / A)) that shows the concentration of unsaturated double bonds (B) of styrene monomers relative to the concentration of unsaturated double bonds (A) of unsaturated polyesters.

[0151] In other words, as the index (B / A) increases, the concentration of unsaturated double bonds in styrene monomers (B) tends to be higher than the concentration of unsaturated double bonds in unsaturated polyesters (A).

[0152] If the unsaturated polyester resin composition satisfies formula (6) above (in other words, if the index (B / A) exceeds 2.00), the unsaturated polyester is prepared by dissolving in a large amount of styrene monomer, thus improving workability (specifically, the workability of the mixture of unsaturated polyester and polymerizable monomer).

[0153] On the other hand, if the unsaturated polyester resin composition does not satisfy formula (6) above (in other words, if the index (B / A) is 2.00 or less), the unsaturated polyester will not be sufficiently dissolved by the styrene monomer, resulting in reduced workability.

[0154] Furthermore, the index (B / A) is preferably 2.20 or higher, more preferably 2.50 or higher, and even more preferably 3.00 or higher, from the viewpoint of workability. Also, from the viewpoint of reducing residual styrene monomers, it is, for example, 7.00 or lower, preferably 6.00 or lower, more preferably 5.00 or lower, even more preferably 4.00 or lower, and particularly preferably 3.50 or lower.

[0155] Furthermore, as described above, in the unsaturated polyester resin composition, the polymerizable monomer includes a polyfunctional (meth)acrylic acid ester. Such an unsaturated polyester resin composition preferably satisfies the following formula (7): (Unsaturated double bond concentration of styrene monomer (B) × Amount of styrene monomer / Amount of resin component × 100) / (Unsaturated double bond concentration of unsaturated polyester (A) × Amount of unsaturated polyester / Amount of resin component × 100 + Unsaturated double bond concentration of polyfunctional (meth)acrylic acid ester (C) × Amount of polyfunctional (meth)acrylic acid ester / Amount of resin component × 100) < 2.00 (7)

[0156] In the above formula (7), the left side is an index (which may be referred to as the index (B / (A+C))) that shows the concentration of unsaturated double bonds (B) of styrene monomers relative to the total amount of unsaturated double bond concentration (A) of unsaturated polyesters and unsaturated double bond concentration (C) of polyfunctional (meth)acrylic acid esters.

[0157] In other words, as the index (B / (A+C)) decreases, the concentration of unsaturated double bonds in styrene monomers (B) tends to decrease relative to the total amount of unsaturated double bonds in unsaturated polyesters (A) and polyfunctional (meth)acrylic acid esters (C).

[0158] If an unsaturated polyester resin composition satisfying formula (6) also satisfies formula (7) (in other words, if the index (B / (A+C)) is less than 2.00), the concentration of unsaturated double bonds (C) of the polyfunctional (meth)acrylic acid ester relative to the concentration of unsaturated double bonds (B) of the styrene monomer can be increased. As a result, the amount of residual styrene monomer in a molded article obtained using the unsaturated polyester resin composition can be further reduced.

[0159] Furthermore, the index (B / (A+C)) is preferably 1.80 or less from the viewpoint of further reducing the amount of residual styrene monomer, and, from the viewpoint of flexibility, for example, greater than 1.10, preferably 1.50 or more.

[0160] A molding material can be prepared by blending reinforcing fibers into such an unsaturated polyester resin composition. A molded article can then be obtained from this molding material by a known method.

[0161] 2. Molding material The molding material comprises an unsaturated polyester resin composition and reinforcing fibers.

[0162] <Reinforcement Fibers> Examples of reinforcement fibers include inorganic fibers, organic fibers, and natural fibers. Examples of inorganic fibers include glass fibers, carbon fibers, metal fibers, and ceramic fibers. Examples of organic fibers include polyvinyl alcohol-based fibers, polyester-based fibers, polyamide-based fibers, fluororesin-based fibers, and phenol-based fibers. Examples of natural fibers include hemp and kenaf.

[0163] Preferably, the reinforcing fiber is an inorganic fiber. More preferably, the reinforcing fiber is a glass fiber.

[0164] The reinforcing fibers can take the following forms, for example: cloth (e.g., roving cloth), mat (e.g., chopped strand mat, preformable mat, continuous strand mat, and surfacing mat), strand, roving, nonwoven, and paper forms.

[0165] The length of the reinforcing fibers is not particularly limited, but is preferably 1.5 mm or more, preferably 5 mm or more, more preferably 20 mm or more, and also, for example, 80 mm or less, preferably 40 mm or less, from the viewpoint of improving strength.

[0166] <Preparation of Molding Material> To prepare the molding material, reinforcing fibers are blended into an unsaturated polyester resin composition. Specifically, the reinforcing fibers are impregnated with the resin composition.

[0167] Known methods can be used to prepare the resin composition. Specifically, these include SMC (sheet molding compound), TMC (thick molding compound), and BMC (bulk molding compound). SMC is preferred.

[0168] The reinforcing fiber content is, for example, 10% to 50% by mass, preferably 10% to 30% by mass, relative to the molding material.

[0169] This yields a molding material (preferably a sheet-like molding material) containing an unsaturated polyester resin composition and reinforcing fibers.

[0170] Furthermore, this molding material contains the above-mentioned unsaturated polyester resin composition. As a result, molded articles obtained using this molding material have excellent flexibility and a reduced amount of residual styrene monomer.

[0171] 3. Molded product: The molded product includes a cured product of the above-mentioned molding material.

[0172] To harden the molding material, it must first be aged to increase its viscosity so that it can be subjected to heat compression molding (described later).

[0173] During the aging process, the aging temperature is, for example, between 20°C and 50°C. The aging time is, for example, between 8 and 120 hours.

[0174] This allows the molding material to maintain its shape.

[0175] Next, the molding material is heat-compressed using a known method.

[0176] The conditions for heat compression molding are set appropriately according to the purpose and application. In heat compression molding, the molding temperature is, for example, 100°C to 200°C. The molding pressure is, for example, 0.1 MPa to 20 MPa, preferably 1 MPa to 15 MPa, and more preferably 5 MPa to 12 MPa.

[0177] This allows the molding material to be shaped and cured, resulting in a molded product.

[0178] Furthermore, examples of molding methods by shape hardening include press molding, injection molding, transfer molding, calendering, pultrusion, resin transfer molding, preform-matched die molding, double belt press molding, and extrusion molding. Preferably, molding methods by shape hardening include press molding, injection molding, double press molding, and calendering. More preferably, molding methods by shape hardening include press molding and injection molding. Even more preferably, molding methods by shape hardening include press molding.

[0179] The thickness of the molded product is, for example, 4.0 mm or less, preferably 3.5 mm or less, more preferably 3.0 mm or less, even more preferably 2.5 mm or less, particularly preferably 2.0 mm or less, most preferably 1.5 mm or less, even more preferably 1.0 mm or less, even more preferably 0.8 mm or less, even more preferably 0.6 mm or less, and also, for example, 0.2 mm or more.

[0180] Furthermore, from the viewpoint of attaching various parts to the molded product, the molded product may have, in addition to the portion having the thickness described above, a thick-walled portion that is relatively thicker and a thin-walled portion that is relatively thinner. Such thick-walled and thin-walled portions may be formed, for example, to constitute ribs or bosses for attaching various parts.

[0181] The molded product contains a cured product of the above-mentioned molding material. Therefore, it has excellent flexibility and the amount of residual styrene monomer can be further reduced.

[0182] 4. Effects In the unsaturated polyester resin composition, the concentration of unsaturated double bonds (A) in the unsaturated polyester is 3.00 mmol / g or less. This allows for a lower crosslinking density, and as a result, flexibility can be improved.

[0183] Furthermore, this unsaturated polyester resin composition satisfies the following formula (8): (Unsaturated double bond concentration of styrene monomer (B) × Amount of styrene monomer / Amount of resin component × 100) / (Unsaturated double bond concentration of unsaturated polyester (A) × Amount of unsaturated polyester / Amount of resin component × 100) > 2.00 (8)

[0184] Therefore, work efficiency can be improved.

[0185] Furthermore, in this unsaturated polyester resin composition, the polymerizable monomer includes a polyfunctional (meth)acrylic acid ester. Therefore, the amount of residual styrene monomer can be reduced.

[0186] More specifically, molded products require flexibility depending on their application and purpose.

[0187] In such cases, it is advisable to consider lowering the concentration of unsaturated double bonds in the unsaturated polyester. This can lower the crosslinking density and improve flexibility.

[0188] On the other hand, from the standpoint of workability, unsaturated polyesters are prepared by dissolving them in a large amount of styrene-based monomers.

[0189] In this case, if the concentration of unsaturated double bonds is high, most of the styrene monomers react with the unsaturated double bonds derived from the unsaturated polyester, so that almost no styrene monomers remain in the molded article obtained using this unsaturated polyester resin composition. Therefore, the amount of remaining styrene monomers can be reduced.

[0190] On the other hand, as mentioned above, when the concentration of unsaturated double bonds is reduced from the viewpoint of flexibility, the reaction between the styrene monomer and the unsaturated double bonds derived from the unsaturated polyester decreases, and most of the styrene monomer remains. As a result, molded articles obtained using this unsaturated polyester resin composition have the drawback of having a large amount of residual styrene monomer.

[0191] In this unsaturated polyester resin composition, from the viewpoint of flexibility, the concentration of unsaturated double bonds in the unsaturated polyester is adjusted to be low (the concentration of unsaturated double bonds (A) in the unsaturated polyester is 3.00 mmol / g or less).

[0192] Furthermore, from the standpoint of workability, the unsaturated polyester is prepared by dissolving it in a large amount of styrene-based monomer, satisfying the above formula (8).

[0193] On the other hand, in this unsaturated polyester resin composition, the polymerizable monomer contains a polyfunctional (meth)acrylic acid ester. As a result, a large amount of styrene monomer reacts with the polyfunctional (meth)acrylic acid ester, thus reducing the amount of residual styrene monomer.

[0194] Based on the above, this unsaturated polyester resin composition offers excellent flexibility and workability, and reduces the amount of residual styrene monomer.

[0195] The present invention will be described in further detail below with reference to examples. However, the following description represents one embodiment of the present invention, and the present invention is not limited to these descriptions.

[0196] The specific numerical values ​​such as blending ratios (content percentages), physical properties, and parameters used in the following description can be replaced with the corresponding upper limits (values ​​defined as "less than or equal to" or "less than") or lower limits (values ​​defined as "greater than or equal to" or "greater than") of the blending ratios (content percentages), physical properties, and parameters described in the "Modes for Carrying Out the Invention" section above. Furthermore, unless otherwise specified in the following description, "parts" and "%" refer to mass.

[0197] <Details of Ingredients> The details of the ingredients are shown below. Aluminum hydroxide: average particle size 8 μm Calcium carbonate: average particle size 3 μm Phosphorus-containing flame retardant: metal phosphinate salt (tris-diethylphosphinate aluminum), product name "Exolit OP1230", manufactured by Clariant Chemicals Nitrogen-containing flame retardant: melamine cyanurate, nitrogen content 49% by mass, product name "MC-4000", manufactured by Nissan Chemical Corporation Expanded graphite: product name "9510045", manufactured by Ito Graphite Industry Co., Ltd.

[0198] <Synthesis of Unsaturated Polyesters> Synthesis Example 1 Unsaturated polyesters were prepared by reacting 100.0 moles of propylene glycol, 17.0 moles of fumaric acid, 60.1 moles of sebacic acid, and 22.9 moles of isophthalic acid at a reaction temperature of 200°C until the acid value reached 27 mg KOH / g. Table 1 also shows the amount of water obtained from the reaction of the polybasic acid and polyhydric alcohol.

[0199] Synthesis Examples 2 to 8: Unsaturated polyesters were prepared using the same procedure as in Synthesis Example 1. However, the formulations of each component were modified as shown in Table 1.

[0200] <Production of Unsaturated Polyester Resin Compositions, Molding Materials, and Molded Articles> Examples 1 to 28 and Comparative Examples 1 to 18 [Production of Unsaturated Polyester Resin Compositions] Based on the descriptions in Tables 2 to 7, unsaturated polyester and polymerizable monomers were mixed to produce a mixture containing unsaturated polyester and polymerizable monomers. Also, based on the descriptions in Tables 2 to 7, unsaturated polyester, polymerizable monomers, a low-shrinkage agent, a filler, a release agent, a curing agent, and a polymerization inhibitor were mixed using a kneader. This obtained an unsaturated polyester resin composition.

[0201] [Manufacturing of Molding Materials] According to the formulations described in Tables 2 to 7, magnesium oxide was added as a thickener to an unsaturated polyester resin composition, followed by the addition of reinforcing fibers. Molding materials (SMC) were then prepared using a known SMC impregnation machine. In Examples 19 and 20, magnesium oxide was added as a thickener to an unsaturated polyester resin composition, followed by the addition of reinforcing fibers, and then the mixture was prepared. Molding materials (BMC) were then prepared.

[0202] [Manufacturing of molded products] Using a 300 mm x 300 mm metal sheet and a press, the amount of material put into the mold was adjusted to obtain molded products with thicknesses of 2 mm and 3 mm by heat compression molding.

[0203] In detail, the molding process was carried out under the following conditions: mold temperature of 140°C for both the product surface and back surface, molding pressure of 10 MPa, and mold holding time of 300 seconds. After that, the molded product was demolded and immediately cooled by sandwiching it between steel plates. This is how the molded product was manufactured.

[0204] <Evaluation> [Amount of Residual Styrene] Molded products (3 mm thick) of each example and comparative example were left at 25°C for one week. Sample solutions were prepared in accordance with JIS K6904:2016, and the amount of residual styrene (amount of residual styrene when the molded product is considered to be 100% by mass) was quantified. The results are shown in Tables 2 to 7.

[0205] (Flexibility) The flexibility of molded articles (2 mm thick) of each example and comparative example was evaluated. Specifically, the test was stopped at a central point deflection corresponding to a 1% bending strain (0.85 mm at a support distance of 32 mm for a molded article (test piece) with a thickness of 2 mm) in accordance with the bending test method A - 3-point bending conditions of JIS K7017:1999, and the presence or absence of cracks on the outer surface of the removed test piece was checked. Flexibility was evaluated based on the following criteria. The results are shown in Tables 2 to 7. A: No cracks were found. B: Cracks were found.

[0206] (Workability) The workability of the mixtures of each example and comparative example was evaluated. Specifically, 15 kg of the resin component was filled into an 18-liter metal plate can (JIS Z 1602:2003) with a nozzle attached to the top plate. The nozzle lid was removed, and the resin component was extracted from the nozzle at room temperature, tilting the can to prevent spillage. After the remaining amount was small, the can was left standing with the nozzle facing downwards for 10 minutes. Workability was evaluated based on the following criteria. The results are shown in Tables 2 to 7. {Criteria} A: The amount extracted was 90% or more of the amount filled. B: The amount extracted was less than 90% of the amount filled.

[0207] <Discussion> Example 1 and Comparative Example 1 have the same index (B / A). Therefore, they have a similar level of workability.

[0208] Furthermore, in Example 1, the polymerizable monomer contains a polyfunctional (meth)acrylic acid ester. Therefore, it can be seen that the amount of residual styrene can be reduced.

[0209] On the other hand, in Comparative Example 1, the polymerizable monomer does not contain a polyfunctional (meth)acrylic acid ester. Therefore, it is clear that the amount of residual styrene cannot be reduced.

[0210] This also applies to comparisons between Examples 2 to 10 and Comparative Examples 2 to 10, between Examples 12 to 15 and Comparative Examples 13 to 18, and between Examples 12, 25 to 29 and Comparative Examples 1 to 6.

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[0218] The above invention is provided as an illustrative embodiment of the present invention, but this is merely illustrative and should not be interpreted restrictively. Modifications of the present invention that are obvious to those skilled in the art are included in the claims below.

[0219] The unsaturated polyester resin composition, molding material, and molded articles of the present invention are suitably used in various components such as, for example, fire-resistant materials (e.g., fire-resistant sheets, particularly fire-resistant sheets for EV batteries (protective materials to prevent thermal runaway and fire spread inside battery packs)), insulating materials (e.g., electrical insulating materials, particularly EV battery insulating sheets (insulating sheets to prevent short circuits between battery terminals and metal cases), and busbar covers (e.g., insulating covers to prevent electric shock and short circuits of busbars)), building materials, housings, cast materials, machine parts, electronic and electrical components, vehicles, ships, aircraft, and the like.

Claims

It contains resin components including unsaturated polyester and polymerizable monomers, The aforementioned unsaturated polyester is a reaction product of a polybasic acid and a polyhydric alcohol. The aforementioned polybasic acid includes a polybasic acid having an unsaturated double bond, The polymerizable monomer comprises a styrene monomer and a polyfunctional (meth)acrylic acid ester. The concentration (A) of unsaturated double bonds in the unsaturated polyester is 3.00 mmol / g or less. An unsaturated polyester resin composition that satisfies the following formula (1). (Unsaturated double bond concentration of styrene monomer (B) × Amount of styrene monomer / Amount of resin component × 100) / (Unsaturated double bond concentration of unsaturated polyester (A) × Amount of unsaturated polyester / Amount of resin component × 100) > 2.00 (1) An unsaturated polyester resin composition according to claim 1, satisfying the following formula (2). (Unsaturated double bond concentration of styrene monomer (B) × Amount of styrene monomer / Amount of resin component × 100) / (Unsaturated double bond concentration of unsaturated polyester (A) × Amount of unsaturated polyester / Amount of resin component × 100 + Unsaturated double bond concentration of polyfunctional (meth)acrylic acid ester (C) × Amount of polyfunctional (meth)acrylic acid ester / Amount of resin component × 100) < 2.00 (2) 　 A molding material comprising an unsaturated polyester resin composition of claim 1 or 2 and reinforcing fibers. 　 A molded article comprising a cured product of the molding material described in claim 3.

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